army aviation digest - apr 1970

8/12/2019 Army Aviation Digest - Apr 1970

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UNITED

DIRECTOR OF ARMY AVIATION ACSFORDEPARTMENT OF THE ARMY

MG Allen M. Burdett Jr .

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COMMANDANT , U. S . ARMY AVIATION SCHOOLMG Delk M. Oden

ASST COMDT U. S. ARMY AVIATION SCHOOLCOL Bill G . Smith

DIGEST EDITORIAL STAFFLTC Robert E. luckenbill ChiefRichard K. Tierney EditorWilliam H. SmithJoe lewelsLinda McGowan

GRAPHIC ART SUPPORTHarry A. PickelDorothy L CrowleyAngela A. Akin

DIRECTOR, U. S. ARMY BOARD FOR AVIATIONACCIDENT RESEARCH

COL Eugene B. Conrad

USABAAR PUBLICATIONS AND GRAPHICS DIVPierce L Wiggin ChiefWilliam E. CarterJack DeloneyTed KontosCharles MabiusMary W . Windham

ABOUT THE COVERInside the embattled ARVN compound at Hue in the Republicof Vietnam the wounded arehurriedly loaded aboard WarrantOfficer Fred Ferguson's UH-l.For his actions WO Ferguson wasawarded the Medal of Honor. See"Stay Clear of Hue" on page 12.

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RMY VI TION

1GESAPRIL 1970 VOLUME 16 NUMBERVIEWS FROM READERS THE SOLDIER-AVIATOR, BG Sidney B. Berry POTPOURRI SUPERCOOL AND COMPANY, CW2 Joseph M. Wilson MAINTENANCE MATIERSNIGHT VERTIGO, CPT Terry P GardnerSTAY CLEAR OF HUE LTC Wilfred A JacksonA CLOSER LOOK AT THE WRIT, MAJ James G. MoreauAEROM EDICETERNAL VIGILANCE, CW3 Norman F CatesCHARLIE AND DANNY'S WRITE-INIT'S THAT TIME AGAIN, CPT Hubert J. Bell Jr.ASSIGNMENT: VIETNAM , LTC Billy E RutherfordSONIC ANALYSIS-MAINTENANCE THROUGH SOUNDS Blair Poteate Jr.WAR STORIES, CPT James W FilsonMAINTENANCE TRAINING IN WARRANT CAREER PROGRAMCW4 William H. ChambersMISPLACED CONFIDENCEMILK RUN, CW3 jul ius A JordanCAN A COMPUTER PREVENT AIRCRAFT ACC DENTS?LTC James R MassengillINADVERTENT IFR, CW3 George J. Combs

A SENSE OF URGENCYPROFESSIONALISM, LTC Loren C StrangePEARL S-NO SURVIVAL EQUIPMENT NECESSARYMAJ Alfred G Borth, MSCATIITUDE CHECK, CW3 Lloyd N. Washer SEE AND BE SEEN, Laurel D SandUSAASO SEZTHE QUARTER MILLION DOLLAR TIP Back Co

The mission of the U. S. ARMY AVIATION DIGEST is to provide information of an operationalor functional nature concerning safety and aircraft accident prevent ion, training maintenanceoperations research and development aviation me d icine, and other related data.The DIGEST is an official Department of the Army periodical published monthly under thesupervision of the Commandant U. S. Army Aviation School. Views expressed herein are notnecessarily those of Department of the Army or the U. S. Army Aviation Schoo l. Photos areU. S. Army unless otherwise specified . Material may be reprinted prov ided credit is given to theDIGEST and to the author unless otherwise indicated .Articles , photos , and items of interest on Army aviation are invited. Direct communication . isauthorized to: Editor , U. S. Army Aviation Digest , Fort Rucker, Ala. 36360.Use of funds for printing this publication has been approved by Headquarters Departmentof the Army, 3 November 1967.

Active Army units receive distribution under the pinpoint distribution system as outlined inAR 310-1. Complete DA Form 12 4 and send directly to CO AG Publications Center , 2800Eastern Boulevard, Baltimore Md. 21220 . For any change in distributioll requirements initiate arevised DA Form 12 4.National Guard and Army Reserve units submit requiremc 1ts through their State adiutantsgeneral and U. S. Army Corps commanders respectively.For those not eligible for official distribution or who desire personal copIes of the DIGEST,paid subscriptions $4.50 domestic and $5.50 overseas are available from the Superintendent ofDocuments U. S. Government Printing Office Washington D. C. 20402.


3/68

VFR

JEWSROME DERS

Sir:The pilot of a U-21 aircraft rampedhis aircraft downwind at our airfield ina moment of haste and did not secure

the propellers. Consequently, the propswere turning through in a _ reverseddirection at approximately 30 to 40rpm as a result of the 25-knot windswhich occurred during his absence.

I am under the impression that whenthe engine of a turbine is shut off andno oil pressure is reaching the threemain bearings to the N 1 impeller shaft,it may cause serious damage to thesebearings if the propeller is allowedto spin or freewheel in the wind.Will you please send me an answerto this question as it has created agreat deal of controversy. . . .

WOl J. J. Howell52nd Aviation DetachmentAPO San Francisco 96259

The Department of MaintenanceTraining (DOMT), u S. Army A viation School, Ft. Rucker, Ala., researched this problem for us and replied to the effect that paragraph 3-75,TM 55-1510-209-10/1, dated March1969, advises the pilot to tie downthe propellers to prevent wind millingwith 2:ero oil pressure i f stron windsare anticipated while the aircraft is unattended. In the absence of specificcriteria to define stron or hi h winds,local military weather personnel wereof the opinion that steady winds of 20to 25 knots could be considered strong.

t was the consensus of opinion ofDOMT and contractor maintenancepersonnel that slow windmilling of theprops- will not cause damage. However, due to the requirement of a onehour cooling period before installationof the standard prop tied own device(which cover the exhaust ports andsecures the prop), some other deviceshould be used to secure the props ifthe aircraft is to be left unattendedprior to the end of the cooldown period.

APRIL 1970

Sir:For several years now you haveregaled (?) us with the derring-do of

that intrepid airman, Horatio Frozzleforth. You have carefully cataloguedhis lack of jUdgment, dangerous habits,disregard for his passengers' welfareand safety and his complete disdain forArmy regulations. With such a complete file assembled, why has one ofhis many commanding officers not takenaction to eliminate him not only fromthe aviation program but also from theArmy? Perhaps a friend in USABAARis covering for him.

We have all known Frozzleforthsin our tenure of service but happilythey didn't last long. Several eliminatedthemselves while others hung on forvarious board proceedings to do thejob for them. Only your fictional herohas managed to continue his destructivepath up the promotion trail without encountering a commanding officer whobelieves in utilizing the Manual ofCourts-Martial to augment his aviationsafety program.

t appears that we long-suffering readers will be stuck with the tales ofColonel Frozzleforth or even GeneralFrozzleforth when his time in gradecomes up. No doubt this will be followed by Son of Frozzleforth, etc.Please save us from a fate worse thanmissed minimums Kill off Frozzleforthonce and for all in a spectacular crashthat involves all the pilot error crashcauses for the past 12 months. I wouldbe most happy to furnish the funeraldetail.LTC Paul L. StanselU. S Army Infantry CenterFt. Benning, Ga. 31905

Well, colonel, one out of 21,000aviators isn't a bad percentage--andif we killed off old Froz we'd lose agood teaching point. But, "Son ofFrozzleforth -truthfully we hadn't yetthought of that.

(

Sir:I am submitting the attached articlefor consideration and publication inthe DIGEST with the hope that it will

inform aviators being assigned toUSARV of the efforts being made toput the P in personnel.We are constantly seeking new methods for improving our replacementprocessing. The preference sheet mentioned in the article, as well as thephone caIl to our field grade officersand senior warrant officers, are recentadditions to our processing proceduresand have received favorable commentsfrom our aviators.

LTC George E. Derrick is currentlythe chief of the A viator AssignmentBranch. LTC Derrick was with boththe Aviation Warrant Officer Branchand Armor Branch at DA. MAJ RobertB Treat Jr. is the aviator companygrade and warrant officer assignmentsofficer working with LTC Derrick. Iwas formerly the chief of the AviatorAssignment Branch until moving tomy present job. Hope you can usethe article.

LTC Billy E. RutherfordChief, Off Repl DivHQ, USARVAPO San Francisco 96375

LTC Rutherford's article "Assignment: Vietnam" appears on page 26 ofthis issue.Sir:

am wrItmg this letter in hopethat I might enlist the help of yourpUblication. The 12th Aviation Group(Combat) has been in Vietnam since18 June 1965.

t has come to our attention thatthere has never been a history writtenof the 12th Aviation Group.We have very little to go on in theway of documents and there are noContinued on page 5


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THE SOLDIER AVIATORBrigadier General Sidney D BerryAssistant Commandant U S Army Infantry School

Aviation and ground tactics in today's Army are not separatefunctions but rather a combination which form an unbeatableteam. By the same token, the av ator, as a vital part of thl5team, Is more than a mere technician with the sole mission ofmastering h s aircraft. He Is a flying sold,er who is always a50ldler first and an aviator second. His responslbilites andloals are the same CiS those of the man on the ground

U S ARMY AVIATION DIGEST


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NOTICE THAT Army avi-ator is a two word term.This means that Army aviators aresoldier aviators. First they are sol-diers, members of the United StatesArmy, and they have the same

APRIL 1970

mission to serve their country andsociety that every soldier of ourArmy ha .But a closer look reveals thatArmy aviators are more than justplain soldiers. They are soldierswith sp cial aviation skills andcapabilitie which they put at the

service of all other soldiers in ourArmy.Unfortunately there are a fewpilots flying Army aircraft who

look primarily and sometimeselusively at their role as aviators.These pilot are technicians-technician without a sense of under-standing-technicians really with-out heart and soul. They focus ontechnical proficiency and how tofly

However, almost all Army avi-ators want to be-and are-farmore than technicians. They relatetheir particular skills and capabil-itie to the whole Army. TheseArmy aviators--or these soldier-aviators-have a sense of missionand purpose that makes them an


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heSoldier Aviatorintegral part of the entire UnitedStates Army and all of its traditions and service to our country.To me this is the meaning of theterm Army aviator.

Let me tell you how groundcombat soldiers feel about soldieraviatO rs. We look upon them asbeing sO ldiers with skills and capabilities that are not just useful tothe Army, but bsolutely essentialLet s put it in the context ofcombat in the Republic of Vietnam. The ground combat soldieris flown into battle abO ard the assault helicopter. Indeed, before heis flown into battle -it is the Armyaviator-flying light observationaircraft-who scouts out the targets, finds the enemy, defines theobjective and assists in placingthe fire support on the O bjective.This makes it more possible andmore feasible for the ground soldiers to make an airmobile assaultwith minimum casualties to themselves and the soldier-aviators.Usually when the ground combat soldier is landed by airmobileassault, he immediately becomes

entirely dependent upon the soldier-aviator for every bit of hissupport. The Army aviator resupplies the infantryman with food,water and the ammunition neededto engage the enemy. Wheneverhe runs into an enemy position thathe cannot handle with his ownorganic weapons, the infantrymancalls on other soldiers for help.They may be artillery-soldiers oraviator-soldiers, but they are othersoldiers.When a ground combat soldieris wounded , he knows full wellthat a soldier-aviator will comewith a medical evacuation helicopter to fly him out of the hell heis in to the finest medical care inthe world.

And when the battle is won, theground combat soldier is flown outof the battlefield by the soldier-avi

t o r ~ or perhaps to another battlefield that has just developed because other soldier-aviators havefound new targets.Army aviators are the reallynew element in military operationsin this century. How does a nonflying soldier look at the flyingsoldier? With deep respect, withadmiration, with affection, yes, andwith an utter and complete sense

of dependence upon that soldieraviator. t is reassuring to knowthat whatever mission soldier-aviators are asked to perform, theywill do simply as a matter ofcourse, no matter how great theobstacles or difficulties. And themO st remarkable thing is that theground soldier comes to acceptthese exploits merely as being commonplace. This is probably theground soldier s highest tribute tothe flying soldier.How do soldier-aviators look atthose soldiers on the ground? Idon t speak first-hand on this; butI speak from observing, talkingwith, flying with, living with andfighting beside many flying soldiers. I m repeating their views, butI think that this is an accuratereport.

The soldier-aviator views theground soldier with almost exactlythe same mixture of attitudes andemotions that the ground soldierviews the flying soldier: respect,admiration, affection. This mutualfeeling is something that developsin the heart. t is more an emotionthan a thought or mental process.It is quite important that the soldier-aviator comes to feel a strongsense of responsibility for andobligation to the soldier on theground. He knows the strong dependence, the utter reliance, thatthe ground oldier has on the flying soldier. And the flying soldierlives up to these high expectationsof the ground soldier.This sense of responsibility andobligation causes the soldier-aviator flying the gunship, the slickor the medevac chopper to bravethe thickest of fire so someone onthe ground can have the chanceto live. This is one soldier risking his life for that of another soldier nd you can bet that he will .

The United States Army a s inno other military force in the worldtoday-has blended ground andaviation operations into a unityof ground warfare. Army aviationis an integral , organic part ofground operations. Our Army doesnot separate aviation and groundfunctions. We do not separate flying soldiers and ground soldiers.We view the flying soldier and theground soldier as an inseparable,unbeatable team joined in a singleeffort.

But this is only a beginning. OurArmy has yet a long way to go inachieving the maximum operational and combat effectiveness of itsair-ground team. The Army aviators who don their wings todayjoin with their flying and groundsoldier contemporaries in workingtoward an Army aviation-groundteam that is more tightly knit, moreimaginative and more effective thanever before. This is an absolutelyessential part of the Armys future.

U. S. ARMY AVIATION DIGEST


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Don't l t This Opportunity\ Slip Through

) Your Fingers.

RE D

SEVEN NEW AND revisedfield manuals have recentlybeen completed for publication bythe Doctrine Directorate of theCombat Development Command(CDC), Ft. Belvoir, Va. Distribution will be made through the Ad-jutant General channels as eachbecomes available.

The publication of a revision toFM 1-15, Aviation Battalion,Group and Brigade will updateand consolidate material previously contained in the April 1967 edition of FM 1-15 and the April1968 edition of FM 1-20, Nondivisional Combat Aviation Battalion, Group and Brigade. Thisrevision deletes all applicatorymaterial from the manual, deletesor reduces duplicated material, up-dates titles of aviation units andadds air traffic and airspace control elements to conform to currentdoctrine.

Nomex No-NoGunners in some helicopterunits are cleaning weapons whilewearing their Nomex flight suits,a flight surgeon reports. As a resultthe flight suit becomes saturatedwith grease and cleaning solventsolution. Of course, this does nothing to help it fire protection qualities.Several 'N am returnees havementioned that in some units crewmen are permitted to wear theNomex shirt outside the trousers.This practice could lead to possibleinadvertent separation of the twopieces at a critical moment, resulting in far more serious burns.APRIL 1970

ATC School At RuckerThe first three classes to betrained in the newly located AirTraffic Controller School at Ft.Rucker, Ala., were graduated 3February 1970. Prior to October1969 all Army air traffic controllers were trained at Kee ler Air

Force Base, Biloxi, Miss.Last February, 12 students weregraduated from the Air TrafficController Tower Operator Courseand three from the Ground Control Approach (GCA) Course.

Four students were graduated fromthe Approach Control (AC)Course in March.All students in the three coursesstudy the same common subjectsfor the first seven weeks and thenreceive their FAA basic controllercertification. Next, they are separated to study their own specialities. The Control Tower OperatorCourse lasts 3 weeks, the GCACourse 14 weeks and the ACCourse 16. Subjects studied include weather, F regulations,navigation, communications, flightassistance services, en route training and airports.

While the school was locatedat Keesler AFB, both Army andAir Force equipment were used intraining. This necessitated some retraining of students who use onlyArmy equipment in the field andhad not had an opportunity to become familiar with it. However,this problem has been eliminatedsince training at Ft. Rucker involves Army equipment only.

Home At LastSergeant Major Cyril G. Man-ning's departure from the Republicof Vietnam last January was awell thought out move. In fact, ittook him eight years of Vietnamduty to decide to come home. Theway he put it, I wanted to makesure that when I went back to theStates, I'd stay there permanently.

SGM Manning started out as theArmy Assistant Aviation Advisorto the Vietnamese Armed ForcesField Command in 1962 and afterward joined the 1st Aviation Brigade as one of its first enlistedmen.

In 1965 he was selected by theArmy Aviation Association ofAmerica as the Aviation Soldier ofthe Year and traveled from Vietnam to Washington, D. C., to receive his award.We hope that SMG Manningfinds his new ha rdship tour inthe States a comfortable one andwe wish him a hearty welcomehome for a job well done.

FM RevisedThe revised FM 6-102, FieldArtillery Battalion, Aerial FieldArtillery, is a guide for aerialartillery commanders and supported commanders and includes

doctrine, organization and employment of aerial artillery. This revision will add doctrinal guidancepertaining to the fires of nonorganic armed helicopters and willimplement usage of the termaerial field artillery (AFA) toreplace the term aerial artillery.5


8/68

Supercool nd ompanySupercool a veteran combat pilot breaks in a new crewand learns the hard way what it means to achieve teamwork.Will Hotstuff the green new guy get up in time to preflightthe aircraft? Will Itchy the crew chief make sure the fuelcap s secured? Will Trigger the new door gunner rememberto wear his flight gloves? Read on and find out

T WAS ABOUT 2200 hoursand everyone was sitting arounddiscussing the humorous thingsthat had happened on their mis-sions that day. Someone had setup a $700 stereo in his tent sothere was music. About this timeLieutenant Smith walked in withthe next day's missions. Super-cool checked things over quicklyand saw that he had the artillerymission with Hotstuff as copilotand Itchy and Trigger as crewchief and gunner.Hotstuff is new and so is Trig-ger, Supercool thought, but theartillery mission is simple so thereshouldn't be any problems. Let'ssee, takeoff is 0630, so if I get upat 0545 that'll give me time to eatand walk to the aircraft with about15 minutes to crank and take off.Hotstuff will preflight and reportthe ship up at 0530. With theseclosing thoughts Supercool wentto bed to get the good night's sleepthat flight surgeons urge.Supercool was straight-hedidn't drink, got plenty of sleep

and always ate a hearty breakfastbefore a flight. He rememberedthe things he was told in flightschool about accidents that werecaused by slow reflexes from drink-ing and/or not eating breakfast.The next thing that entered

CW2 Joseph M. Wilson

Supercool's world was his alarmclock. t was 0530 and it usuallytook him about 15 minutes towake up and get dressed. By0545 he had shaved and dressedand was on the way to the messhall with that ton of extra equip-ment that was necessary for fly-ing in the Republic of Vietnam.About halfway to the mess hall,Captain Jones stopped him, "Whyisn't your ship called up?""What do you mean?""Well, it hasn't been called up.You'd better get out there andpreflight that thing; battalion isalready on the phone.""But . . . well, I thought. . . "Supercool rolled his eyes andthought, Boy, that Hotstuff Youcan't take your eyes off these newpilots 10 minutes and already theystart to goof up. I'll bet he's stillracked out.Supercool went into Stuff's tentand sure enough . . . zzzzzzzzzzzz"Hey Gct up You were sup-posed to have been out and pre-flighted the ship by now."Hotstuff sat up, "Oh, I'm flyingwith you today? What time are wesupposed to take off?"Supercool was speechless. Well,what could he say? "We take offat 0630 and hurry-we're flyingColonel Campbell and he's a

stickler on times.""Sure thing," Hotstuff replied.As a new pilot he hadn't beentold about the one hour missionready times. But he knew now.By the time Hotstuff was fullyawake Supercool was beating feetto the aircraft. He quickly de-posited his gear in the cockpit andbegan his preflight. After about15 minutes he cranked the ship,hurried an electrical check andturned on the radios."War Bum 877, this is War

Bum control, over.""This is 877, we're up and mis-sion ready at this time.""Roger, this is War Bum con-trol. Be sure to report to ops afteryour mission today, over."Ah . . . roger." Supercoollooked at his watch and it was0615-not bad time considering,but there went the good breakfast.He decided he'd let the UH-l idlebecause by the time he let the en-gine cool and started it again hewould be late for his mission.While he was waiting for his pilotSupercool glanced back at hiscrew. What greeted him wasenough to scare any good aircraftcommander. There sat Triggerno gloves, sleeves rolled up, hel-met unsnapped, vigorously flexinghis trigger finger.

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"Trigger, where are yourgloves?"What gloves?""The gloves you're supposed towear when you fly. Itchy, gostraighten him out .""Yes sir."By this time Itchy was alreadycoming through the cargo compartment yelling at Trigger loudenough that he didn't need to usethe intercom.It was 0630 now and there wasno copilot in sight.Boy, Colonel Campbell is goingto ream me out if I'm not there ontime. Where is Hotstuff anywaySupercool frantically thOUght. Iguess I had best call control andsee i they can find him."War Bum control, this is War

Bum 877, over.""This is control. Go ahead."Ah roger, have you seenmy copilot around there?""Roger, he just walked throughthe door. He's trying to find outwhat ship he is supposed to fly.We'll send him down. Also, beadvised you are late for your takeoff time.""Roger. "From the way things had startedit sure looked like it was going

to be a long day. Supercool sawhis copilot approaching and alsonoticed that the gunner was aboutsquared away. Things weren't toobad if they were only 10 minuteslate taking off. Maybe the colonelwould drink an extra cup of coffeetoday.After takeoff, Hotstuff contactedthe colonel's dispatcher to tellhim they were inbound and wouldarrive at 0700, right on time (at110 knots). Things weren't goingquite so bad, but he had missedbreakfast.Old Cool was just beginning tothink that things weren't as grimas he had imagined when he wasinterrupted by a blast from Hotstuff."Say, Supercool, do you want torefuel?"APRIL 1970

"What?""Well, we only have 150 poundsof fuel and I thought that was alittle low for this mission."After this exchange, Supercoolwasn't sure what to do. f hestopped and refueled he would belate, but if he ran out of fuel hewould be even later. Not muchchoice.With this thought racing throughhis mind, Supercool shot an approach into the refueling area withone of those nifty sideways flaresthat always stopped a Huey on adime-and once in a while onsmall trees, telephone poles or unsuspecting POL men.While the crew chief was tryingto teach the gunner how to refuelan aircraft, Supercool was startingto sweat. Well, not much can bedone now he thought, so I mightas well make the best of things.The crew chief and gunner hoppedinto the ship and called "bothsides up." They knew they werelate so they were rushing thingstoo.

Ten very long minutes later theytouched down at the hotspot at0715. The colonel was a littleanxious, to say the least."Let's go, I have an appointment with the general at 0745.Supercool expedited things asmuch as possible with a Vietnamtakeoff that helped take some ofthe excess color out of the colonel'sface. But again luck was withSupercool and by holding 110knots he made it on time.

At destination, the colonel gavehim instructions to return to thehotspot and fly a resupply mission,but to return at 1045 sharp."O.K., take the ship and returnto the hotspot," Supercool directedhis copilot, "while I check withflight following and artillery."With this, Hotshot took the controls and executed a takeoff similarto the one Supercool had made.This took all of the color out ofSupercool's face."What do you think you're do-

ing-you trying to kill us all?" Theintercom wasn't needed for Stuff tohear Cool's remark, although itwas used. This confused Stuff bec use he thought this was thetype takeoff that all the old handsused. Oh well, after I gain a littlemore experience I guess I canmake those takeoffs, Stuff thought.The rest of the day was fairlyuneventful except for the timewhen Supercool started to take offwith the colonel half in and halfout of the aircraft; or when theyhad to delay a mission becausethe fuel cap hadn't been replacedwhen they refueled; plus the timea C-130 appeared mysteriouslyout the right window. Funny howthe radomes on the front of thosethings can look so big.Come to think of it, it was arather hectic day for Supercool,but it was his fault. He was responsible for the team effort thatdidn't materialize.Whl n more than one persontries to accomplish a goal, a teambecomes involved. No one is sogood that he can complete a mission by himself. This refers to any

mission-flying, working or anything. Since we are concerned withaviation, let's examine how teamwork is involved in every phase ofaviation, especially inside the air-craft. .

Teamwork has to start from themoment a mission is assigned. Theaircraft commander must checkwith the entire crew and briefeach one on the mission and whathe expects of them. This is especially important anytime there isa new crew member. It also is important that the members of thecrew constantly cross-check eachother to ensure that all are doingtheir jobs properly. Anytime oneteam member fails in his job, theother members have to pick up hisportion. It was Supercool's responsibility to ensure these points.As it happened, he lucked u -he could have missed more thanjust his breakfast.


10/68

WHEN P INTINGR T R BL DES

Painted Vibrations: A requirementinitiated in 1969 asked that rotorblades be painted contrastingcolors of black and white to enable better overhead spotting. This

aln enancepainting caused untold man-hoursin not only painting but most ofall in working out vibrations(usually lateral types). These vibrations were caused by uneven painting and varying densities of blackand white paints. To avoid thisproblem the following proceduresshould be incorporated into thiscolor conversion: Ensure that both blades arethoroughly cleaned and wipeddown with an appropriate solvent. Weigh out even amounts ofblack and white paints. Usuallythe densities of black and whitepaints, even of the same brand,will vary. Use the same brands. A consistent procedure shouldbe used when applying the paint.It is a good idea to have the sameman do all the painting. After the paint has dried,lightly sand both blades with avery fine grain. This will ensure asmooth consistent airflow over therotor blades.

The application of these procedures ensures a minimum of manhours in the conversion. t shouldbe noted however that even withthis carefulness a close checkshould be made to determine ifvibrations have developed since itis very difficult to apply this paintevenly. Until factory producedmatching black and white bladesare in the inventory we will haveto be continually aware of thelateral vibration related to homemade paint jobs.

Note After flying the newlypainted blades for several hourswearing of paint will be seen. Thiswearing will cause lateral vibrations if wearing is uneven. Thismay require repainting and sanding. A check should be made everyseveral hours of flying for paintwear.

O-Ring Installation: Be extracareful when installing the packing performed (O-Ring), P NMS29561-146, FSN 5330-067-9994, in the engine oil filter, toinclude tightening of bolt, P NSP806, FSN 5306-446-6481. Incorrect installation of these components can cause serious engineoil problems. Remember, do notreuse an O-Ring or one that hasbeen damaged or installed incorrectly and taken out again.

* *OV l Oxygen Exhaust: Do notdisconnect oxygen lines to regulator unless it is certain that thecylinders have no pressure. f thepressure is not known, exhaust thesystem by placing the oxygensupply switch to ON and thediluter demand switch at 100 percent oxygen. Reference TM55-1510-204-20 chapter 11, section IV, pages 130, 132 and 133.



11/68

Caution With the switches set asdescribed above the oxygen systempressure will not be exhausted.With the diluter demand switch inthe 100 percent oxygen position,oxygen will be delivered to theuser upon demand only. With thesupply switch in the ON positionand the emergency pressure control lever in the Emergency position the system pressure will bedepleted. The same caution shoulde applied to the U-21 aircraftsince the oxygen systems areequipped with the same pressuredemand regulator.

U-21 Emergency Static ir Source:The emergency static air sourceon the U-21 is controlled by around knob on the upper rightcorner of the instrument panel.This system provides an alternatesource of static air for certainflight instruments in the event ofblockage in the normal staticsystem. To activate the emergencysystem, the knob is rotated in acounterclockwise direction. TM55-1510-209-10, paragraph 3-16,dated March 1969, and the pilot'schecklist both read EmergencyStatic Air Source-OFF. Pilotsare turning the knob clockwise toensure this OFF position. After anumber of pilots have performedthis check, the knob could be tootight to be rotated to the ON position in the event of normal systemAPRIL 1970

rs failure. The emergency systemwould then not be available foruse.There are two ways to correctthis situation. One is to changethe TM and pilot's checklist toread as follows: Emergency staticair source--check for freedom ofrotation and then OFF.The other method is to designatean OFF position on the panel behind the knob and mark the knobwith an arrow. The knob could bedrilled and a tab located on thepanel to accommodate a safetywire. The knob could then besafetied in the OFF position withbreakaway wire. A visual check ofthe knob and wire would thenensure the OFF position. Thissystem will prevent the possibilityof the handle being tightened tothe OFF position and assure positive operation when needed.

*Check The Ring: When performing a preflight inspection and postflight inspection on your UH-ICand AH-lG helicopters inspectthe safety on the Friction Collect Assembly Ring P N540-011-488-3, FSN 5340-947-6258) for security; also the bootdust and moisture seal that encloses your friction collet (P N204-010-453-1, FSN 1615-615-3398) .

f there is an indication thatthe boot is being twisted--check

the safety on the ring since it couldmean the safety has been broken,thereby causing the ring to backoffThis has been noted to happenfrequently on both the UH-lCand AH-IG HueyCobra.

D-54 Hydraulic Pressure Line:In the Republic of Vietnam considerable problems occurred withthe rigid hydraulic starter pressureline breaking on the CH-54. Itwas found that by replacing therigid type line with a flexible lineconsiderably less trouble was encountered. If the flex line did fail,it would require only about 15minutes to replace as comparedto approximately four hours forthe rigid line.

H-47 Corrosion: Some CH-47units have experienced corrosionof the structure beneath the flooring of the CH-47 caused by theaccumulation of water and othermaterials being trapped in thewater-tight compartments beneaththe flooring. In extreme cases thiscan also seriously affect the aircraft's center of gravity. Openingthe fuselage drains during extendedperiods of aircraft down time toallow water to drain and air tocirculate through the compartments will aid in correcting thisproblem.


12/68

MIGRTVERTIGOI . .' S AN ASSAULT helicopter.l.contpany the '116th was pri-marily engaged in contbat operations in support of the 25thfantry Division based at Cu' Chi,Republic of Vietnam . The slicks(Hornets) and the guns (Stingers)provided support t a n ~ n g from

combat assaults to the usual routine (ash and trash) missions.We had become well versed inthe aspects and techniques of acombat assault and, along withthe ground units of the TropicLightning Division, had developedinto a coordinated team that couldwork extremely well together in, any situation. Due to this fact, bothwe 25th and the 116th had a high. ''regard for each otlier and often it;wasthis mutual respect that caused.the two to give just that little extraor to "hang it out" a little furtherto help the other guy.' Such was the case late oneevening in August. With the monsoon season well at hand, we wereaware of the torrential rains andhigh winds that can literally popup out of nowhere. It had beenan easy day. Eagle flights justnorth of Saigon had experienceda b s o l ~ t e l y no e


13/68

eboth experienced ,\\vertigo caused by Idarkness, heavy rainand uneven terrairy

- --, ' -. ; t , > - - - > - ~ . g ~ , : ~ < -;. : ; ;; C ,,tum the main fuel line d i r e ~ t y . i w ~ t h e grotffiQ-:gn ~ c W ~ { i r r t ; 0 t f i r t u p e c ~ ~ -front of us. (painted white) seemed n o ~ g h wa. ' e n o u ~ h J b l t l -:t t ~ ~ w D 1 ~ : f t ~ t @ f l 6 p s .to be movmg up and down. Sud- beer would J u s t ~ ~ i ~ aela::-JO the -ba Sedenly the left end of the pipe It should be obvious::.:tnat we f i a v e b e e nseemed to rise in the air as the both experienced (although fortu- ~ Q ; - a n d , wif117 = the i n gright end went down. T h ~ n the nately not simultaneously) pilot weather, hovering shou hf- no( haveopposite happened, only at a much vertigo (spatial disorientation) even been considered.faster rate. Things seemed to be caused by torrential rain i llumi- When the rain stopped fourpinning around in a kaleidoscope nated under the close-in brilliancy cautious and weary crew inembersof white lights, red lights, instru- of an electric landing light. over returncd safcly to the nest forments and rain, rain, rain. Luckily, uneven terrain. Also, we both were that cold beer.I immediately realized what was tired and complacent. It was neither skill nor exwrong and took the only action The cases of vertigo were mild perience that saved us from a co tpossible-I yelled at the aircraft in one sense. We both realized ly accident. Luck was on our sidecommander that he had it. He took what was wrong, we knew what that night and got us out of acontrol and attempted to hover to do about it and we both re- ituation no aviator should ev rforward. At this point I felt the covered quickly. 'Still, it was the get himself intoaircraft begin to roll left and right first time 'either of us had gotten Desire to accomplish the mison its l o n g i t u d i n a ~ axis, and I again piiot vertigo, even though we both sion and to do more than nece -felt that queasy feeling of dis- had over 800 hours in the UH-l. sary is an admirable quality, butorientation sweep over me. How- Thinking it over, we realize that when it endangers l ife and equipever, I rather sloppily plopped the we never should have flown so f a ~ ment the purpose s qefeated.APRIL 1970


14/68

STAY [LEAH OF HUEThe warning was to stay clear of Hue because the enemy was mounting heavyassaults on the city and inflicting extensive damage and numerous casualtiesWarrant Officer Fred Ferguson knew his wounded comrades needed to beevacuated immediately He ignored the warning and flew his UH into HueThe decision resulted in the rescue of several critically wounded men and theMedal of Honor for WO Ferguson

Lieutenant Colonel Wilfred A. Jackson

THE NIGHT OF 30 January1968 had been long and nerveracking because the LZ had beenunder continuous rocket and mor-tar attack since before midnight.Consequently, as dawn broke overthe Hue area of the Republic ofVietnam that Wednesday, the heli-copter crews of C Company 227thAviation Battalion AH), 1stCavalry Division (Airmobile)were uneasy To make mattersworse, missions for the day weredelayed due to low overcast condi-tions extending north to the DMZ.By 0930 hours the clouds hadmoved to the north clearing Hueand word was received for C Com-pany to take off and head forCamp Evans to support the Cav s3rd Infantry Brigade. The 227thscommander elected to accompanyC Company to Camp Evans whilethe remainder of the battalion wasto move north to rejoin the restof the division.At 1000 hours, the battalioncommander took off and turnednorth. He was flying with thecommander of C Company, the

battalion sergeant major and fourpassengers. As they passed overthe city of Hue their UH-l re-ceived intense 12.7 mm machine-gun fire. The ship took numeroushits and was forced to land in thecity below.Seconds after touchdown, thehelicopter was raked with small

arms fire and a round from anRPG (rocket propelled grenade),fired at point blank range, crashedthrough the right windshield anddetonated against the pilot s seat.The aircraft lay smoking in arice paddy, a scant 100 yards froman ARVN Army Republic ofVietnam) compound. Fire was be-ing received from every direction.The ship had landed amid an NVANorth Vietnamese Army) bat-talion which had surrounded andwas attacking the South Viet-namese engineer company in thecompound. .

The C Company commander,gunner and crew chief moved tothe edge of the rice paddy anddetermined that the compoundwas still in friendly hands andwould offer sanctuary for thewounded crew and passengers. The227th commander, who had beenwounded and blown clear of theHuey by the exploding RPG , laiddown a base of fire which coveredthe withdrawal of the passengersinto the compound. He then fol-lowed them inside the protectivewalls of the compound to relativesafety. Contact with the outsideworld, more particularly the air-craft of the 227th, was establishedusing radio equipment of theARVN engineers.

The word had been received.Two helicopters had monitoredthe Mayday call and tried to

respond by following the strickenship to the ground. But they weredriven off by intense fire fromheavy and light automatic weap-ons.Following the initial attempt to


15/68

Streaking from the emb ttled com-pound, WO Ferguson s Hueyc me under even heavier enemyfire th n it encountered onthe w y in. Time nd g inthe aircraft w s rocked s ittook hits, but WO Fergusonm de it to safety with hisw.ounded


16/68

OF HUE REPUBLIC OF VIETNAM31 JANUARY 8

answer the Mayday, three moreaircraft made a try at flyingthrough the withering hail of fireto reach the isolated bastion andretrieve the wounded crew andpassengers.

The radio transmissions werefrequent concerning the fate of themen on the ground and those making the unsuccessful attempts toretrieve them. These calls wereclosely monitored by aircraft crewsand ground control stations alike.The order was finally put out

for all to hear: Stay cle r of HueDuring this action Warrant Officer Fred Ferguson was flying alogistical mission nearby and hadbeen monitoring the radio trafficconcerning his battalion commander and crew. He completed his assigned mission and hastened tojoin a flight of gunships in thevicinity of Hue. Ignoring the obvious futility of an attempt to approach the besieged compound, hequickly briefed his crew, determined his flight path and alertedhis company commander on theground that he was going to attempt a rescue. He was warnedof the improbability of the successof any such venture and advisedto stay clear of the area.

The tempo of fire from lightand heavy automatic weapons di-

rected at the ARVN compoundhad increased through the day.The walls had been assaulted bythe NVA and mortar rounds wereinflicting extensive damage to thecompound.Within the compound the CCompany commander had beenhit and the 227ths commanderhad been wounded again by fragments of the exploding mortars.WO Ferguson acknowledgedthe transmission which warnedhim of the danger, and then an-nounced that he was 2 minutes outon final approach and intended totry to effect the rescue.

The three accompaning gunshipswere suppressing with every weapon they had as WO Ferguson wentin oblivious to the fire coming athim from all quadrants. His shipreceived hit after hit, shatteringglass, ripping holes in the airframeand scattering debris throughoutthe cabin. He bore in straight forthe compound with as much speedas his crippled Huey would givehim.

The helicopter s skids were onlyinches from the railroad tracksover which WO Ferguson flew. Hewatched as the enemy gunnersstood on roof tops, in doorwaysand in the streets, trying desperately to knock him and his ship

from the air. The hail of fire wasmurderous but was being answeredto some extent by his own doorgunner and crew chief.WO Ferguson flared his ship ashe crossed the compound wall andpulled every ounce of power available in his effort to slow his aircraft for a landing in the only cleararea within the fire raked walls.His skids had scarcely touchedthe ground when the woundedwere loaded aboard, four Americans and one South Vietnamesewho had taken a 12.7 mm roundnear his left ear.As the helicopter was liftedfrom the blood-soaked pad, threemortar rounds landed on the spotwhere the UH l had been onlyseconds before. The concussion ofthe exploding rounds lifted thetail boom and spun the aircraft tothe left. Without hesitation WOFerguson continued the left turnand exited the compound by thesame route used on the approach.As he streaked for safety, thecurtain of fire thrown at the departing aircraft was even heavierand more intense than it had beenon the approach. Time and againWO Ferguson s aircraft was rockedby enemy fire. One of the escorting gunships had its fuel tank shotaway and the pilot reported thathe was going down.In spite of the severe damagehis helicopter had sustained fromthe enemy fire and shell fragments,WO Ferguson completed his mission, delivering his wounded passengers to medical facilities at PhuBai.His day of days was over. Hisfateful Huey would never flyagain. WO Frederick E. Fergusondidn t have to risk his l ife in fact,no one could have blamed him ihe hadn t attempted the rescue under the circumstances. But he did,knowing the possible consequences.To call him a hero seems inadequate. But he is a hero in thefullest and most sincere sense ofthe word.

4 U. S. ARMY AVIATION DIGEST


17/68

JEWSROME DERS

Continued from Pagepictures. Could you please ask anyonewho served in the 12th Aviation Groupfrom 1965 through 1968 and has anypictures or pertinent information concerning the 12th Aviation Group'sdevelopment to write to me.

Any help that you can give us inthis matter would be greatly appreciated.

Sir:

W01 David A. LindemanBiographical HistorianHeadquarters & Headquarters Co12th Aviation Group (Combat)APO San Francisco 96266

Here in the frozen tundra, north ofthe 49th, we of the Canadian ArmedForces enjoy very much receiving andreading your magazine AVIATION DIGEST.All of your articles provide a valuablesource of information and, althoughsome do not pertain directly to ouroperations, it is interesting to note themany areas of concern that we mutually share.One of our mutual areas of concernappears to be the attitude of our personnel toward safety. As evidence ofthis, I draw your attention to thesafety slogan on the back cover ofthe January 1970 edition of AVIATIONChart 1

DIGEST which states: Safety is likecastor oil-hard to take, but results areassured. Most of our personnel realizethe long term benefit of safety, likecastor oil; however, there are a fewwho express their opinions of safetyas being more like the immediate resultsof the medication. These nearsightedindividuals have modified the simileto express their own opinions: Safe tyand castor oil both give me Hopefully the influence of magazines suchas AVIATION DIGEST will help to bringthese misinformed members into thefold. Captain R. W. SlaughterStaff Officer 2 Flight SafetyTraining Command HeadquartersCanadian Forces Base WinnipegManitoba, Canada

Thanks for the letter, captainit'll either bring 'em into the fold orwipe 'em out.Sir:I was very interested to read thearticle The Kiowa Joins Up byMajor Robert S Fairweather in theNovember 1969 issue. I was particularly interested in his comment thatthe fun and enthusiasm that markedthe OH-23 versus the OH-13 unitrivalry can now be applied to twonewer contenders: the OH-6A Cayuse

and the OH-58A Kiowa. MAJ Fairweather presents some performancecomparisons between the OH-6A andthe OH-58A. As one who has beenheavily involved in the developmentof the OH-6A, I feel MAJ Fairweatherpresented the performance comparisonin a form that is biased toward theOH-58A. So, in the spirit of friendlyrivalry, I am taking this opportunity tocompare the performance of the twoships in a more realistic manner.

Two items of performance in MAJFairweather's comparison table give anerroneous impression. These are hisdata on Vne and rate of climb. Vneis a structural limit airspeed and is notnecessarily related to maximum cruisespeed capability, which is the importantspeed characteristic. The followingnumbers compare the maximum cruisespeed capability of the two helicopters(chart 1).As you can see, the cruise speed ofthe OH-6A is 10 to 16 knots fasterthan that of the OH-58A. Minor ratingchanges in the commercial version ofthe OH-6A have further increased itscruise speed. These rating changes arecurrently being offered to the U. S.Army.The rate of climb comparison presented in MAJ Fairweather's articlewas for sea level standard conditions.Under more realistic altitude and/ortemperature conditions the rate of climbcomparison is as shown in chart 2.As you can see, under realistic ambient conditions the rate of climb ofthe OH-6A is 10 to 40 percent higherthan that of the OH-58A.Kenneth B AmerAssistant DirectorAeronautical Engineering DivisionHughes Tool Company,Aircraft DivisionCulver City, Calif. 90066

Chart 2COMPARISON OF MAXIMUM CRUISE SPEED R TE OF CLIMB COMPARISON

OH6A Cayuse* OH58A KiowaSea level standard

Scout 118 110Observation 120 111Sea level 95 F

Scout 110 97Observation 115 99

From TM 551520214-10 Figures 145 and 1421)From TM 55152022810 Figure 1418)

APRIL 1970

OH6A Cayuse* OH58A Kiowa * *Sea level 95 F

Scout 1,350 980Observation 1,550 1,0625,000 feet standardScout 1,320 1,230

Observation 1,500 1,310From TM 551520214-10 Figures 1416 and 1420)From TM 55152022810 Figures 1412 and 14-4)

15


18/68

16

Aloser ot

The Writ

Much has been written and said against the annual writ butthe fact remains that year after year a large percentage ofArmy aviators continue to fail the exam on the first attempt.It might be to the advantage of those who took the test toolightly last year to take a closer look at the writ this year

Major James G Moreau



19/68

A CLOSER LOOK at thisyear s Annual Writ StudyGuide by most aviators seems tobe in order in view of the statisticswhich were compiled on the 1969examination: 43 percent of those who tookthe test qid not know that bothceiling and visibility minimumsare required for circling approaches. 12 percent failed the E-6Bcomputer questions even thoughthe problems were computed atround number increments. 8 percent failed to identifythe right type of transponder onDD Form 175. 17 percent of fixed wing aviators did not know copilot requirements. 31 percent of all examineesfailed the examination on the firsttry.What most aviators don t realizeis that the annual writ is notan examination as its official title

would indicate. In its true form itis a review and updating of theaviator s knowledge. Most of the21,000 aviators who annually takethe exam look upon it as a copyof the previous writ. Most likelythis is because questions that constantly appear are the ones that aremissed most frequently by the examinees. For example, an analysisof the 1969 examination showedthat 48 percent of the aviatorsAPRIL 1970

answered the questions concerning approach minimums incorrectly. Therefore, questions pertaining to approaches or relatedquestions are incorporated into thecurrent examination. For instance,one question that has appeared onthe last four annual written examinations in one version or anotheris: hen flying from a high pres-sure area to a low pressure areayour true aircraft altitude wouldbe . This type questionwill appear on this year s annualwrit because 18 percent of theaviators last year answered thequestion incorrectly.Over the years numerous articlesand suggestions have been writtenconcerning Army aviation s annual writ. Many of the articlescondemn the writ and call for itselimination on the grounds thatit is outdated, not fair or does notwarrant the time and expense. Yeta large percentage of Army aviators continue to fail the examination the first time around. Thefailure rate would probably behigher if the tests were graded ata central point as are MOS (military occupational specialty) tests,OED (general education development) and other Army-wide examinations.An analysis of last year s writis applied to all questions in thecurrent examination. As regulations and procedures change, theyalso are incorporated into theexam. f a regulation or a procedure is changed that pertains to aquestion that has a high failurerate on the writ, the question isrephrased or rearranged to coverthe change or procedure. Becauseof this, many questions concerning communication procedures areasked on the examination. The1970 exam covers this area ingreat detail due primarily to thefailure rate and situations that areencountered in a radar and nonradar environment.

From the professional view-

point, Army aviation attempts toupdate the aviator s knowledgeannually. For many aviators, especially staff officers and thoseon Category B assignments, theannual writ and study guide arethe only ways to stay current withchanges in the professional Armyaviation field.To keep the annual writ andstudy guide as current as possible,changes in procedures and regulations are made available to thewriter of the examination 6 to 12months in advance of their distribution to the field. Changes inflight procedures that are relatedto FAA or FLIP policies are coordinated through the U. S. ArmyAeronautical Service Office. Draftcopies of aViatIOn regulations

which would affect the annualwritten examination are madeavailable by the Assistant Chief ofStaff for Force Development, Department of the Army. Close coordination by the U. S. Army Aviation School with the two aboveagencies guarantees that the latestand most current information isutilized on the annual written examination.Each year a study guide is available to every Army aviator whois required to complete the annual written examination. Anyaviator who conscientiously completes the study guide, which is inprogramed text format, shouldencounter no difficulty passing thewrit. Some 43 percent of the annual writ examinees did not knowthat both ceiling and visibilityminimums are required for circlingapproaches as stated in AR 95-2,paragraph 3-9g 2), and another36 percent felt that a ceiling minimum was needed for a straightin approach. Failing to look up allthe answers contributed to mostof the other misses. Remember,the writ covers changes-not memories. f you disregard the studyguide you are throwing away atleast 50 correct answers.

17


20/68

Aviators beware of commercially available sunglasses. They refine for girl watching but often can present problems on anapproach to a pinnacle. Stick to the recommended N-15 sunglasses

To the air crewman: A noteworthy incident pertainingto impairment of vision recently was reported by a rotary winginstructor pilot. The IP was performing a check ride on a studentin a oH I. Sunset was fast approaching with the wind coming~ r o the west. During an approachto a pinnacle landing the IP, noting the student was having difficulty, recovered and completedthe landing. Upon questioning,the student complained he couldn'tsee well enough through his sunglasses. He was wearing commercially acquired sunglasses whichmay not have permitted the transmission of adequate light underdusky conditions. The IP waswearing Army issue N-15 sunglasses (in aviator spectacleframes). Under the prevailing conditions he experienced no visualdifficulty.The N-15 sunglass is a neutraldensity filter that transmits approximately 15 percent of the lightreaching its surface. The wavelength (color) of light transmittedis fairly uniform ( all colors aretransmitted equally well) . Thisprevents color distortion. Othersunglasses, not produced to meetArmy specifications, may transmitless than 10 percent of light and doso with excessive color distortion.This problem was discussed atsome length in an article entitledRose Colored Glasses in theOctober 1969 issue of theAVIATION DIGEST.Every effort should be made toensure utilization of the recommended N-15 sunglasses. Avoidcommercially available glasses.They are usually designed forbeaches, sun bathing and fashion,not flying. The aviator spectacleframes provide the advantage ofminimum interference with field ofvision due to their wire construction. Other frames, horn-rimmedand the like, frequently obscurethe field of view. While no Army

8 U. S ARMY AVIATION DIGEST


21/68

Provided by th Societyof U S Army Flight Surgeons

PRIL 1970

regulation prohibits the use ofother than the N-15 sunglasses, itis apparent that the safest courseof action is to recommend theiruse at the exclusion of all others.the flight surgeon: New pos

sibilities are being consideredin the area of visual protection. Over the past few years thecle r helmet visor has been recommended for routine use with the aircrewman s protective helmet. Thisprovides maximum protection ofthe eyes against fragmentary missiles and flash fires during bothday and night flights. During daylight the N-15 sunglasses wererecommended for use in conjunction with the clear visor. For nightmissions the clear visor alone isused. The problem that arises isthat the N -15 sunglasses (in avi-ator spectacle frames) often donot integrate comfortably with theAPH-5 or other helmet.A recent study undertaken willevaluate the use of lightweight,durable, plastic lenses with appropriate coatings in conjunctionwith special frames designed tointegrate comfortably with theSPH-4 helmet and other crewman s equipment. Another solution to this problem is the dualvisor, but this usually adds undesirable weight to the helmet,thereby reducing its safety duringcrash force decelerations. Eitherw y we must find the optimal wayof protecting the air crewman seyes both day and night. Do your

~ r e in promoting eye protectionat your unit or station: Encourage the use of N -15sunglasses with aviator spectacle

frames during exposure to brightlight or glare. Discourage the use of unapproved or unknown quality sunglasses. Promote the use of the clearvisor to protect against fragmentary missiles and potential crashor flash fires both day and night.

19


22/68

ETERNAL VIGILANCE is theprice of a good reputation.That may sound a bit lofty, butnone the less it is quite a significantstatement i you care what othersthink of your professional capabilities.I m sure most of us have founda safety improperly installed or acotter pin missing on a preflight.So, we consider ourselves fairlyalert-and under normal conditions I suspect we are. Normalconditions ,are the exception, however, and circumstances may conspire against you if you let yourguard down for a minute.All of this professional reputation talk wouldn t be much good, without an example to analyze. Ido have one which serves to illustrate my point that eternal vigilance is a personal responsibility.It began with a twofold mission:to drop off medical personnel atpoint A, and then proceed topoint B for adjustments on therigging of the left engine of ourU-21A.My copilot an old hand, asenior Army aviator qualified inmost fixed wing aircraft, includingthe C-45 and C-47 but not the

U-21A. He had flown with us inthe U-21 on several flights andhad helped , on preflight inspections. Through his own efforts hehad familiarized himself with theaircraft until his presence was anadvantage.

As for myself I had been flyingmore years than I like to admit(16) and have averaged about 350hours per year. I had flown theU-21A for two years and hadmore than 300 hours in the aircraft. So, we had an experiencedcrew that should have had an easyflight.

We dropped off the medicalpeople and arrived at point Babout 1530 hours. After briefingthe factory technical representativeon the rigging problems of the engine, I turned the aircraft over to20

the local maintenance crew and retired to the BOQ for the night.The next morning I was on theflight line at 0800 to give whatassistance I couid. After talking tothe tech rep I decided to depart at1230 for home base. I asked themaintenance sergeant to tum theaircraft around before refueling,as it was parked heading downhilland I expected a long 3 hour and45 minute flight home.

The flight plan was filed for9,000 feet and I was pleased thatthe weather guesser gave me adifferent wind figure from theearlier forecast. The new figurewould give me about 3 + 20 enroute. The copilot and I went outabout 1100 to preflight and loadthe aircraft.Just as we arrived the fuel truckwas pulling away and I noticedthat the aircraft had not beenturned around as I had requested.But due to the reduced enroutetime, plus a good forecast at destination, I accepted the fuel loadas it was.I started my preflight by ohecking the installation of the cowlingwhich had been reinstalled. While

I was making this check I notedmy copilot preflighting the engines.I asked the sergeant who wasreplacing a missing screw i heknew how much fuel had beenput in. He said he didn t, but didknow that they had not added anyoil. I completed the preflight byclosing all four fuel caps and weprepared to depart. The enginerunup was very smooth due to thererigged left engine and we brokeground at 1235 hours.

The climbout was without incident and after leveling off at9,000 feet I trimmed the aircraftand turned it over to the copilotso he could practice ADF tracking. Within five minutes we raninto a deck of strato cumuluswhich proved to e quite choppy,sn I asked control for a higheraltitude.

As we started to climb I sweptthe engine panel and was surprisedto see rhe oil pressure on the rightengine drop off the 80-poundmark, then the 70 and finally sitfluctuating at 60 pounds. To saythat I was surprised would be aslight understatement. I was watching the rerigged left engine like ahawk and felt slightly betrayedwhen the right engine started behaving in a peculiar manner.Let me go quickly and lightlyover the next 20 minutes. I won tbore you with a recount of the discussion which went on in thecockpit. We asked for and received clearance back to point BAs the oil pressure dropped we

watched the oil temperature gauge,but it did not rise. When the pressure got to 25 pounds (low red tline is 40) I decided that I couldno longer depend on the temperature gauge to give me an accurate reading, so I shut the engine ,down to avoid damaging it.Then I declared an emergencyand descended point Bandlanded.We taxied to the ramp and shutdown the other engine. When weopened the cowling you might



23/68

Don t let a mistake ruin your reputation as a professional Only througheternal vigilance can you hope to earn the respect of your contemporaries

guess what we found the oil dipstick was left open and the stickhad been pushed up about threeinches allowing oil to escape. Wehad lost seven quarts, not enoughto hurt the engine but enough todo a lot of damage to my ego andreputation.How did it happen? I let my-self be deluded by my knowledgeof the skill and experience of mycopilot. I believed that he hadpulled a thorough preflight on theengines. This, plus the fact thatno oil had been added to theengines, led me to fail to adequately perform the preflight. I shouldhave checked the oil and capsmyself I was the aircraft commander; I was the one responsible

APRIL 1970

to take the time and' put out theeffort needed to ensure a goodpreflight.So there you have it. Not thewhole story because that still hasyears to go years in which I willimagine that everyone I meet willbe saying to himself, Cates?Isn't he the guy that left the oilcap off the U-21?

CW3 Norman F Cates

I realize that an occurrence suchas I've described here would notin itself be overly damaging toone's professional reputation. Buti a person becomes associatedwith too many incidents his reputation will suffer. To avoid this, onemust e prepared to pay the priceof e t ~ m l vigilance.

21


24/68

Dear Danny: On several occasions while flyingChinooks here in Vietnam, I have turned on theventilation blower to cool down the cockpit andreceived a blast of air mixed with dust, grass andother particles directly in my eyes. As you know,we fly in and out of many dusty LZs and all sortsof trash collects in the lower chin bubbles. Canyou give any help in this area?CW2 H. V. G., RVNDanny's answer: Your comment coincides with others that have been received here. At the last CH-47publications conference, action was taken to preventthis potentially dangerous situation from happeningto Chinook pilots. In soon to be published changes,caution notes will be added under paragraph 6-19of TM 55-1520-227-10 and paragraph 6-22 of TM55-1520-209-10 stating that the cockpit air controlknobs should be closed prior to starting the ventilation blower, and opened slowly afterwards. Thankyou for your interest and for your letter.

* * *ear Danny: I m having maintenance problems withsome OH-6 components and I am wondering ifthey are due to the aircraft being flown faster thanthe maximum allowed. I've heard it said by somepilots that these little machines will do an easy 140knots. Since that's above the red line by almost20 knots, I m suspecting that some damage is done.Can you help me by cautioning pilots of the OH-6to observe the red line? M l L. S F.Danny's answer: Consider it done. Page 7-3, chapter7 of the OH-6 operator's manual (dash 10) shows121 knots as vne (velocity never exceed) at 2,400pounds gross weight. That speed is for a densityaltitude of zero. Look a bit further to page 7-6 andcheck for a density altitude of 4,000 feet at 2,400pounds gross weight. Vne under these conditionsis 103 knots. Quite a difference Exceeding Vnewill cause damage to the aircraft. The damage maynot show its ugly head the next hour, day or weekand may even go undetected until a catastrophicfailure occurs.

* * *ear Danny: Chapter 11 of the CH-54A operator'smanual defines the CH-54 crew as one pilot, onecopilot and a crew member. We're using a crewof four in our unit (pilot, copilot, flight engineer22

C/Jollie ond DonnyIF YOU DON T WANT TO

WIND UP LIKE THIS GUYYOU LL BE INTERESTED IN ONEOF THIS MONTH S LETTERS.

and crew chief). How about changing the manualto require a crew of four?CPT B C.

Danny's answer: The crew of three called for in theCD-54 operator's manual is a minimum requirement. t does not restrict the use of additional crewmembers for some operations. The fourth crewmember may be added at the commander's discretion.

* * *ll DA 2028 forms arriving at the central maildesk at the U. S Army Aviation Systems Command,St. Louis, Mo., are routed to the 2028 control desk.At the control desk they are assigned a four digitcontrol number and then based on place of origin(CONUS, Europe or SEA) the necessary copiesare made and sent to the applicable action office.The action office is given 20 working days to acton the recommendation. At present the policy isto give a 2028 originating in SEA first priority,fonowed by Europe and then CONUS, unless it isa safety of flight item or expedite action has beenrequested.U. S ARMY AVIATION DIGEST


25/68

RECOMMEHDED CHAHGES TO PUBLICATIOHS u. P a rt 11 ( r vers Bide) for Re pair Parts and [ATE, thl& 0 # AR 31 () 1 ; the p'oponent o,ene, Spec i a l Too l U s t s (RPSTL ) and Supp ly Ca t ... 15 Apr 70logs / Supply Manual . (SC / SM ).a Th. 'lIjut.ft' Ge e,.I'. Offlc .

iTO , ( onIIud 10 propon ent 1 pub ll at lon) nClu e Z IP Code ) FROM: (Ac t ivi ty en d loc . t lon ) Inc lude Z IP Code)Coumanding General Eva1 Div. DOl. USAAVNSU. S. Army Av ia t ion Sys tems COlDIUand ATTN: AJRDI-ER: B ~ ~ Z 9 ~ l : l a Of f iceSt. Lou i s , M ssour i 63166 Fort Rucker. Alabama 36360PART I ALL PUBLICATIONS EXCEPT RPSTL AND SC I SM

Nu B < H DAT E IT IT LETM 55 - 1510-201-10 / 5 Feb 69 Operator 's Manual U-S FITE M P AGE P All A LI NE F IGUIIE TA B L E IIECOMM E ND E D CH N GES AND IIE ASONNO. NO . GR AP K NO. ' NO. NO. (Ex e cI wor d ln , of recommend .d ch an4e m u.t be , v e n)

1 14-12 14-7 Add: Takeo f f distance char t f or minimum runtakeo f f .Reason: Takeo f f d i s tance for mi n i mUlll r un takeoffi n recoumended conf ig ur at ion i . e 65%flaps) is not av a i lab le in th is tuanual.

-- - - - - -- - - Re fe rence to lin e num bers w ith in he paragrsph or $ubpa raSrsph .

TYP E D NAME. G RAD E. O il TITLE r G N ~ ~ ~ ? ~ OHN P. JONES, GS-13Eva1 Div, DOl, USAAVNSFORMDA .Dc 2028

The action office for 2028s concerning the operator's manual (dash 10) and the pilot's checklist(dash CL) is the Directorate of TDC&S (TechnicalData Cataloging and Standardization). When acopy of the 2028 arrives at TDC&S a determinationis made as to who will be involved in the staffing.I f the recommendation affects publications only(format, etc.) it is staffed by the Technical Publications Division of TDC&S. I f it concerns chapters3, 4, 6, 10 or 11 of the operator's manual (dash 10)or the pilot's checklist (dash CL), a copy is forwarded to the U. S. Army Aviation School at Ft.Rucker, Ala., for staffing. A recommendation involving the remaining chapters of the operator'smanual is sent to the applicable aircraft office within systems engineering. The office assigned to staffthe recommendation is given a suspense date thatfalls within the original 20 working days (in theevent that a considerable amount of coordination isinvolved the suspense date may be increased). Whenthe staffing is completed and the recommendationsare sent back to TDC&S a reply is sent to theoriginator on DA Form 200. I f the change or recommendation affects safety of flight or a significanterror in a maintenance or operational procedure,APRIL 1970

R E PL AC ES OA ~ O M 2:02 8. 1 A.PR eA. AND - 0 ' FORM l D l ,A OE C 5 5 , WH IC H WILL . a US I' D .

action is immediately taken to correct the discrepancy via an in-house change to the manual.Adoptable items which do not fall into this categoryform part of the material to be included in thenext scheduled change or revision to the applicablemanual.

* * *ear Danny: The CH-54A maintenance manualcontains a warning about applying excessive collective friction and its affect on AFCS (automaticflight control system) operation. Shouldn't this warning be pointed out to all CH-54 pilots?CW3 G. P.Danny's answer: That's a roger. Look for the following caution in a future change to the CH-54manual: CAUTION-Excessive friction on the collective pitch control will prevent proper operationof AFCS. Above is an example of how a suggestionis to be submitted on a DA Form 2028.Remember-keep those cards and letters coming.

23


26/68

L IT S THAT TIM AGAINCaptain Hubert J Bell Jr

M:*-.p , .

24 U S ARMY AVIATION DIGEST


27/68

No it s not quitting time, but if you re a Vietnam returnee it may be time torenew your instrument ticket. In fact, it might be that time is running out

AY, GEORGE, my birthdayis coming up next month.Doesn't my tac card expire then?That's right, and you have torenew it right away.O.K., but what are the requirements for renewal?I don't know; you'll just haveto look that up somewhere.f these two aviators are typicalVietnam returnees after an initialaviation assignment there, theyprobably don't know the requirements and procedures for renewal

of a tactical instrument rating. Thisis especially true since the publication of a new AR 95-63, whichwas effective 1 July 1969.An aviator must reestablish instrument qualification within 60days of date of expiration, or within 90 days from the date of reporting for duty if maintenance ofqualification was not required inhis previous assignment. Normally an instrument card is renewedduring the 90-day period preceding

the aviator's birthday, but whenthis is not accomplished the abovecriteria apply. An exception tothese rules is granted to individuals returning from Southeast Asia (Laos, Vietnam andThailand). These aviators whoseinstrument cards expired while assigned in SEA are granted sixmonths in which to reestablishtheir instrument qualification.f an aviator does not reestablish his instrument qualification

yvitl lfi the appropriate time period,he will be temporarily suspendedfrom flying status and placed before a flight evaluation board.The requirements for renewalof a tac rating are specified in

AR 95-63. The applicant musthave successfully completed theannual written examination for theAPRIL 1970

current fiscal year before an examiner is allowed to conduct theflight examination.Uncertainty regarding the content of the tac renewal checkrideseems to cause a great deal of confusion and apprehension. Below isa summary of the required procedures: Flight planning-usingATC or FOC procedures,whichever is appropriate, theapplicant is required to plana flight under simulated or

actual instrument conditions. Equipment check-theapplicant must determine thatall instruments and equipment installed in the aircraftand considered necessary forIFR flight are functioningsatisfactorily. Airway traffic controlthe applicant must obtainsimulated or actual airwaytraffic clearance. Enroute navigation-theapplicant must demonstrateability to navigate betweenradio facilities, determineposition, locate proper frequencies and tune and use allradios required during theflight. Navigational facilitiesthe applicant must demonstrate proficiency in the following procedures for ADFand GCA only: establish hisposition using designated navigational aids of examiner'schoice; follow assigned bearing or course after intercepting it at an appropriate angle;identify arrival at, or passageof, a station or fix; enter aspecified holding pattern onany prescribed fix; executeADF and GCA approaches;perform appropriate low visi-

bility approach procedure. Recovery from unusualattitudes-the applicant mustreturn the aircraft promptly tolevel flight using emergencypanel (no gyro heading or attitude indicator). Autorotation-the applicant is required to follow correct procedures for the helicopter being utilized.Autoratations and recoveryfrom unusual attitudes will be performed only under simulated in

strument conditions, and omission of these items will not meanthe checkride is incomplete. Thereshould be no absolute criteriaestablished for determining an applicant's proficiency, but finaldetermination of applicant's qualification is based on the examiner'sjudgment that he can safely pilotan aircraft under instrument conditions.When the checkride has beencompleted satisfactorily, the tactical instrument rating will beawarded and appropriate entriesmade on the individual's DAForms 759 and 66. f the aviatorfails the renewal ride, he mustsuccessfully complete a reexamination within a 60-day period fromthe date of the original failure orbe placed before a flight evaluation board to determine future fly-ing status.

The tactical instrument concept,properly implemented, has madean important contribution to Armyall-weather tactical capability. Thiscapability is enhanced when theindividual and his commander cooperate in ensuring that the taccard holder reaches the appropriate level of instrument flyingproficiency not just once a year,but maintains it throughout theyear.

25


28/68

A s s i g n enl :V ie l na


29/68

Army aviators assigned to the Republic of Vietnam will find a placementsystem which gives individual attention to each man as well as a choiceof assignments More improvements to this system and an upgrading offacilities at each replacement battalio n are scheduled in order to ensure fast

efficient and considerate handling of aviator replacements

THE u s ARMY S largest andmost varied aircraft inventoryis located in the Republic ofVietnam. The aviation personnelpopulation required to operate andmaintain this vast fleet is constantly changing with daily arrivals anddepartures.One of the many tasks of theU. S Army Vietnam AdjutantGeneral is to ensure that the correct number of qualified aviationpersonnel arrive to meet the replacement requirements. This article will outline officer assignment procedures and hopefullywill provide answers to the questions regarding aviator personnelpolicies which are asked mostoften.

The replacement system hasbeen improved during the pastfew years to expedite processingthrough the replacement battalionand to provide a choice of assignments. Additional improvementsare scheduled which should further streamline the processing procedures and significantly upgrade thefacilities at each replacement battalion.Replacement aviators are assigned by the Aviator AssignmentBranch which includes two fieldgrade aviators. The Chief of theA viator Assignment Branch historically has been an officer whoserved a recent tour with the Officer Personnel Directorate atDepartment of the Army andprovides current information regarding assignment requirementsand career planning. Continuousliaison is maintained with the Executive for Army Aviation OfficerAPRIL 1970

Lieutenant Colonel illy E Rutherford

Personnel Directorate Headquarters Department of the Army bytelephone letter and message.USARV assigns aviators directlyto divisions groups and otherseparate major subordinate commands.Each aviator arrives assigned tothe USARV Transient Detach

ment for further assignment to bedetermined upon arrival. TheTransient Detachment is merelya strength accounting unit and isnot in fact a unit with a commander and troops. Correspondence addressed to the Commanding Officer of the TransientDetachment is forwarded to theUSAR V AG section for reply. TheIn-country Designator Code (IDC)is shown on the special orders andindicates the arrival location inVietnam. IDC 1 is Cam Ranh Baywhere the 22nd Replacement Bat-

talion is located. IDC 4 is BienHoa. Personnel arriving at BienHoa are processed at the 90th Replacement Battalion at Long Binh.All field grade aviators and themajority of the company gradeaviators arrive at Bien Hoa.Processing: Immediately afterarrival at the replacement battalion initial processing begins.All aviators are asked to complete an avtatLon qualificationsheet. Company grade officers andwarrant officers will complete anassignment preference sheet. Forthose aviators processing at the90th Replacement Battalion DAForm 66s preference sheets andqualification sheets are handcarried to the Aviator AssignmentBranch. For aviators arriving atCam Ranh Bay this informationis teletyped to the Aviator Assignment Branch. While the assign-

ecent light school graduates who satisfy most o the replace-ment requirements in Vietnam benefit from the improved assign-ment system which h s gone into operation during the past years

27


30/68

ment is being processed the centralissue facility at each replacementbattalion will issue field equipment ,tropical fatigues, jungle boots,drawers, T-shirts, handkerchiefs,socks and towels. Nomex flightsuits, gloves, leather boots andweapons are issued by the unitsupply at ultimate destination.Assignments: The Aviator Assignment Branch receives the DAForm 66 or teletype sheet from thereplacement battalion and beginsthe process of matching the replacement aviators to unit requirements. Assignments for lieutenantcolonels and majors are made toa specific unit approximately 60to 90 days prior to the officer sprogramed arrival date. For thisreason these two grades are notrequired to complete an assignment preference sheet. The assignment officer will call the replacement battalion and have all fieldgrade officers and CW3s andCW4s paged and discuss theirspecific assignment. For companygrade officers and warrant officersthe preference sheet is receivedand compared with the existingrequirements. Every effort is madeto assign aviators to one of thefive units which may be listed onthe assignment preference sheet.

The 1st Aviation Brigade has

60 percent of the aviators so itreceives a like percentage of thereplacements. The airmobile 1stCavalry and 101st Airborne divisions receive the second largestnumber. Small units such as artillery groups and separate brigadesusually require only one or twoaviator replacements a month.Once the assignments are made,the DA Form 66 and assignmentinstructions are returned or a teletype message dispatched to the replacement battalions. This assignment information is posted to abulletin board and the good or badnews known. In the event an aviator wants to discuss his assignment, he may call the assignmentofficer by using one of the telephones available at the replacement battalion. The 22nd Replacement Battalion at Cam Ranh Bayhas a direct line to the USARVDirector of Replacement Operations.Transportation: The goal of thereplacement battalion is to processall officers and have them on theway to their units in less than 24hours. f the unit is close to thereplacement battalion, the unitwill pick up replacements by vehicle. In the case of more distantlocations, Air Force aircraft areused to transport personnel.

After the aviator arrives and issettled in his \lnit he may haveadditional questions about otherareas which will affect his assignment while in Vietnam. A few ofthese areas are:I n country transition training:OH 6 and OH 58 transition training is conducted in USARV. Anaviator assigned to fly these aircraft will receive transition training at his unit or a formal courseconducted by a USARV trainingteam. The USARV Cobra trainingteam conducts AH l G transitioning for approximately 400 aviatorseach year. Aviators are selected bytheir units to attend and must havesix months remaining in Vietnamto be eligible. Transition trainingin the AH l G is only authorizedin the formal course conducted byUSARV. Unit transition training isconducted as required in U-6, U lan d U -21 aircraft.

In country transfers: Normallyall company grade officers and warrant officers spend their full toursin their initial unit of assignment.In-country transfers are usuallymade only when necessary to adjust the number of personnel rotating from a unit in a specific monthor in conjunction with a six-monthextension of foreign service tour.

Aviation personnel management in the epublic of Vietnam means a constantly changing personnel population for the largestArmy aircraft inventory in the world The size of this giant inventory grew with the concept of mass airmobile operations

28 U. S ARMY AVIATION DIGEST


31/68

One of the many tasks of the U S Army Vietnam Adjutant General is to ensure that the correct number of qualified aviationpersonnel arrive to meet replacement requirements Every effort is made to assign an aviator to the unit of his choiceField grade officers usually changejobs at least once during their tour,particularly those who are programed for command.Ground duty: USARV Regulation 614-10 authorizes aviators tobe assigned to Category B positions. Aviators assigned to Category B positions after arrival inVietnam remain charged againstthe aviator strength of the unitand a nonaviator or aviator replacement cannot be requisitioned.In view of this restriction, the number of aviators in Category Bpositions is very limited.Aircraft commanders: Eachmajor subordinate commander hasestablished minimum criteria fordesignating aircraft commanders inthose aircraft which require aircraft commanders. The requirements are generally based on fly-ing hours and duty performance.Foreign service tour (FST) extensions: USARV has approvingauthority to act on requests forPST extensions if the individual

PRIL 1970

has not completed eight months ofhis FST and is not on D orders.Otherwise the request must be forwarded to the appropriate careerbranch at DA. Under a recent Dprogram aviation warrant officersserving on their initial obligatedvolunteer tour may extend theirFST for six months and be releasedfrom active duty upon their returnto CONUS. All personnel extending their FST for six months areeligible for a 30-day leave inCONUS or other location of theirchoice.One of the bright spots in thepicture of Army aviation in Vietnam today is that TOE gradeauthorizations and actual fill arenearly identical. Gone are thosebleak days when majors occupiedmost of the key slots in an airmobile company. Some may grimly recall a pair of companies thathad two platoons of majors. Thecurrent officer-warrant officer mixis very close to the ratio desiredby DA. Only in extreme and un-

usual cases will an officer be assigned to a TOE position which isauthorized a lower grade.In Army aviation we are veryfortunate to have the finest aviation training program in theworld. On numerous visits and discussions with commanders throughout Vietnam, aviation personnelcontinue to be highly commendedfor their performance of duty andprofessionalism. Nothing can substitute for the actual conditionsencountered in flying combat missions; however, the newly assignedaviator becomes a combat veteranin a very short time. You are the

n w uy on the first day only-the replacement flow is continuousand the time goes quickly. t iswith a tremendous amount of pridethat we who are in Vietnam watchour young aviators accept the challenge of combat flying and supportof ground units with unequaleddedication and professionalism.Our motto Above the Best hasnever been challenged.

29


32/68

SONICN LYSISS Blair Poteate Jr.

Chief, Aircraft Support SystemsU S Army

Aviation Materiel Laboratories

NEW CONCEPT in rmyaviation maintenance-a sonic analyzer designed to listento engines and transmissions anddetect malfunctions and anomalies-currently is being field tested atthe U. S. Army Aviation MaterielLaboratories (A VLABS), theArmy s aviation research center atFt. Eustis, Va. Potential savingsthrough the use of such devicescould amount to millions of dollars per year.

The present AVLABS programis designed to establish correlationbetween the condition of helicoptercomponents as established by thesonic analyzer and the actualmechanical condition of thosecomponents.

In this program, UH-l helicopters at Ft. Stewart/HunterAAF, Ga., are subjected to a sonicanalysis when they come in forpower train component removalfor overhaul.

The sonic analyzer built forAVLABS by Curtiss-Wright Corporation is believed to be capable30

of monitoring mechanical condition of the rotating elements in theengine, transmission, shafting andtail rotor gearboxes by comparingthe acoustic patterns of the components in question with theacoustic patterns of componentsknown to be in good mechanicalcondition. Comparisons can bemade in order that various faultsmay be isolated.While the magnitude of savingspossible with such a system inactual operation is impossible . tocalculate, the following gives agood idea: at present, UH-l maintransmissions are scheduled forremoval for overhaul every 1,100hours. A very large percentageof these components which areremoved because they have reachedtheir time between overhaul

(TBO) are found to have no me-chanical discrepancies upon tear-downThe cost of this overhaul procedure for the UH-l main transmission is approximately $2,500. tis the desire of the Army to beable to extend this time betweenoverhaul substantially, or eliminateit altogether, and by use of suchdevices as the sonic analyzer establish that the power train components are in good working order

at any given time.In addition to TBO removals.pilot/crew complaints about aircraft performance anomalies alsogenerate many engine teardowns,inspections and reassembly operations which , with the proper monitoring and diagnostic equipment,could usually be eliminated or at



33/68

least the problem isolated so thatcomplete teardown would be unnecessary.A word of caution: The sonicanalyzer is not an operationalmaintenance tool. I t is still in theresearch stage and there are questionable and unknown areas whichmust be resolved.To determine the potential ofthis system, AVLABS engineersare evaluating a fairly large sampleof UH-1D helicopters about 100)at Stewart/Hunter.In an effort to establish the accuracy of the sonic analysis, thecomponents removed for overhaulare being followed through themechanical teardown and inspection process at overhaul to provideinformation on their actual mechanical condition for correlation.APRIL 1970

aintenance Through SoundThis teardown and inspectionprocess takes place at the U SArmy Aviation Depot MaintenanceCenter ARADMAC) at CorpusChristi, Tex., where Army andBell Helicopter Company engineersare gathering data.Some of the features of theanalyzer, either existent or anticipated, are: Simplicity three microphonesare located on the aircraft whileit is running at approximatelyground idle for about 10 minutes. The entire power train isanalyzed at one time. The systems discretionaryability-expectations are that theanalyzer will be able to detectcomponent malfunction at a veryearly stage, which will allow maintenance personnel to be aware ofan impending problem and monitor its progress.The last point above is extreme-

ly crucial in that it will allow continuing flight operation for a largenumber of hours if experience hasshown the identified anomaly willnot progress to a catastrophic condition within that number of hours.

To verify this and to establish