aircraft accident report and executive summary and incidents reports/9445.pdf · 2018. 1. 9. ·...

CA 12-12a 07 FEBRUARY 2017 of 33

Section/division Accident and Incident Investigation Division Form Number: CA 12-12a

AIRCRAFT ACCIDENT REPORT AND EXECUTIVE SUMMARY

Reference: CA18/2/3/9445

Aircraft registration ZS-HCH Date of accident 30 May 2015 Time of accident 0540Z

Type of aircraft Robinson R44 Raven II Type of operation

Private (Part 91)

Pilot-in-command licence type Private Age 58 Licence valid Yes

Pilot-in-command flying experience

Total flying hours 2 194.7 Hours on type 386.2

Last point of departure Vryburg, North West Province

Next point of intended landing Wonderboom Aerodrome (FAWB), Gauteng Province

Location of the accident site with reference to easily defined geographical points (GPS readings if

possible)

Open field next to the Delareyville Golf Course (GPS coordinates: 26°41.650’ South 025°28.048’ East) elevation 4440ft

Meteorological information

Surface wind; Calm, Temperature; 8°C, Dew point; -3°C, Visibility; + 10km

Number of people on board

1 + 2 No. of people injured 2 No. of people killed 1

Synopsis

The pilot, accompanied by his youngest son, flew from their farm near Tosca to Vryburg where

they landed. The pilot’s wife then joined them for a private flight to Wonderboom aerodrome

(FAWB). The pilot’s wife was occupying the left front seat and the son was seated behind her.

Shortly after take-off, the pilot’s wife was having difficulty communicating with them via the headset

she was wearing and requested the pilot to land somewhere in order for her to get another headset

out from underneath her seat. The pilot’s door was also not properly latched at the top and it was

required to be opened and closed again in order to be latched properly. During an approach for

landing the helicopter collided with a large tree, whereupon the pilot lost control and it impacted

with the ground in a steep nose down attitude. The pilot succumbed to his injuries at the scene. His

wife was seriously injured and was flown by air ambulance to Grand Central aerodrome (FAGC)

and was transported from there by road ambulance to a private hospital in Johannesburg where

she underwent surgery. The son suffered a bleeding nose and concussion. The helicopter was

destroyed during the impact sequence. The investigation determined that during the descent the

helicopter collided with a large blue gum tree, the pilot lost control and the helicopter impacted with

terrain approximately 20m beyond the tree.

Probable cause

The helicopter collided with a tree while on the descent for an intended landing whereupon the pilot

lost control of the helicopter before impacting with terrain.

SRP date 8 August 2017 Release date 11 August 2017


Section/division Accident and Incident Investigation Division Form Number: CA 12-12a

AIRCRAFT ACCIDENT REPORT

Name of Owner : Chata Ranch Family Trust

Name of Operator : Private (Part 91)

Manufacturer : Robinson Helicopter Company

Model : R44 Raven II

Nationality : South African

Registration markings : ZS-HCH

Place : Delareyville

Date : 30 May 2015

Time : 0540Z

All times given in this report are Co-ordinated Universal Time (UTC) and will be denoted by (Z). South

African Standard Time is UTC plus 2 hours.

Purpose of the Investigation:

In terms of Regulation 12.03.1 of the Civil Aviation Regulations (2011) this report was compiled in the

interest of the promotion of aviation safety and the reduction of the risk of aviation accidents or incidents and

not to establish blame or liability.

Disclaimer:

This report is produced without prejudice to the rights of the CAA, which are reserved.

1. FACTUAL INFORMATION

1.1 History of flight

1.1.1 On Friday, 29 May 2015, at approximately 0617Z the pilot took-off from his farm

near Tosca in the North West Province and flew to Wonderboom Aerodrome

(FAWB) in Pretoria where he landed at 0922Z. After the helicopter was refuelled,

he took-off at 0959Z and flew back to his farm where he landed at 1223Z.

1.1.2 The next morning the pilot, accompanied by his youngest son, took-off from the

farm at 0426Z and flew to the town of Vryburg where he landed to pick up his wife.

After landing the son relocated to the left aft seat and the pilot’s wife occupied the

left front seat. According to the track data file that was downloaded from the global

positioning unit (GPS),) which was recovered from the accident site, they departed


from Vryburg at 0509Z flying in an easterly-north-easterly direction towards FAWB

(see Figure 1). The official sunrise time on the day for Pretoria was 0445Z.

1.1.3 The GPS track data files were downloaded and the helicopter was observed to be

on the approach for runway 04 at the Delareyville aerodrome (FADL). From the

data gathered it was evident that the pilot commenced with the descent some

distance out and at 0.55 nautical miles (1 kilometre) from the threshold of runway

04 the helicopter collided with a large blue gum tree next to the roadway (R507,

public road between Ottosdal and Delareyville). Following impact with the tree he

lost control and the helicopter impacted with the ground in a steep nose down

attitude and came to rest on its right-hand side approximately 80 metres (m) beyond

the tree in an open field. The cockpit/cabin structure was severely disrupted, the

skid gear broke off and the tail boom was severed by the main rotor blades, which

remained attached to the main rotor head assembly.

1.1.4 The pilot, who was occupying the right front seat, succumbed to his injuries at the

accident scene. The pilot's wife sustained serious injuries to her lower back, neck,

ribs and left ankle, while she was still secured to her seat by the safety belt inside

the wreckage. Her son, who was seated behind her, braced himself prior to impact

and suffered from a bleeding nose and concussion. Following initial medical

observations on site, the pilot's wife was transported by air mercy flight from

Delareyville to Grand Central aerodrome (FAGC) from where she was taken by

road ambulance to a private hospital in Johannesburg. She was admitted to the

intensive care unit (ICU) and underwent surgery to her back and left ankle. The son

was admitted to the same hospital where he was kept overnight for observation, he

was discharged the following day with concussion. Neither of the two surviving

occupants could recall seeing the tree prior to the helicopter colliding with it.

1.1.5 The pilot’s wife was interviewed while she was in hospital in Johannesburg.

According to her she was having problems with her noise reducing headset and

was unable to communicate properly with her husband and son during the flight.

She requested her husband to land en route in order for her to get another headset

out from underneath her seat as they had additional headsets on board. She

further indicated that they had two different brands of headsets on board and was

going to change from the one brand to another. These two different headset brands

were observed on the scene. She further mentioned that the pilot’s door was not

properly latched at the top, which resulted in unnecessary noise, something he

would have attended to after they had landed.


1.1.6 The accident occurred during daylight conditions at a geographical position that was

determined to be 26°41.650’ South 025°28.048’ East at an elevation of 4440 feet

above mean sea level (AMSL).

Figure 1: Google earth overlay of route flown from Vryburg to Delareyville

Figure 2: Google earth overlay illustrate the flight path of the helicopter in relation to the runway

1.2 Injuries to persons

Route flown prior to the accident

Accident site

Threshold Runway 04, Delareyville aerodrome

Route flown by ZS-HCH prior to impact


Injuries Pilot Crew Pass. Other

Fatal 1 - - -

Serious - - 1 -

Minor - - 1 -

None - - - -

1.3 Damage to aircraft

1.3.1 The helicopter was destroyed during the impact sequence.

Figure 3: The main wreckage as it came to rest

1.4 Other damage

1.4.1 Apart from minor damage to vegetation no other damage was caused.

1.5 Personnel information

1.5.1 Pilot-in-command (PIC)


Nationality South African Gender Male Age 58

Licence number 0270130149 Licence type Private pilot

Licence valid Yes Type endorsed Yes

Ratings None

Medical expiry date 31 December 2015

Restrictions Must wear corrective lenses

Previous accidents/

serious incidents

Wheels up landing runway 17 at Grand Central

aerodrome in a Cessna T210L, ZS-PNG, 21 May

2010.

Collided with wires during low level flying in Robinson

R44, ZS-HCH on 20 May 2011.

Collided with wires during low level flying in Robinson

R44, ZS-HCH on 22 August 2012.

(i) The pilot started flying aeroplanes in 1986 and was issued with a private pilot

licence. He then allowed his pilot licence to lapse for a period of thirteen

years and renewed his licence (aeroplane) again on 26 April 2001 after

having redone his training.

(ii) The pilot was the holder of a private pilot licence on helicopters as well as

aeroplanes. He kept both pilot licences valid and owned an aeroplane and

the helicopter at the time of the accident.

(iii) According to available information (CAA pilot file) his first training flight on

helicopters was on 7 September 2010 and he completed his training on 22 March

2011. The required paperwork was submitted the next day to the regulating

authority and he was issued with a private pilot licence (helicopter). His last flight

skills test (helicopter) was conducted on 1 July 2014. It was further noted that all

his helicopter flying hours entered in his logbook was conducted on the helicopter in

question (ZS-HCH), including his flying training. A copy of the pilot’s helicopter

flying logbook was made available in electronic format to the investigator. The last

entry in his logbook was also dated 1 July 2014 with his helicopter flying hours

reflected at the time to be 375.1.

(iv) The flight folio that was recovered from the accident site had only three

entries on page 1 (new book) and portrayed the period 16 to 24 May 2015

where five hours were flown. The GPS information that was downloaded


along with the Hobbs meter reading of the helicopter provided additional

information such that it could be ascertained that the pilot flew several hours

the previous day. The combined flying hours for the flights on 29 and 30

May 2015 were 6.1 flying hours. The helicopter flying hours in the table

below were obtained from the pilot logbook, the helicopter flight folio as well

as the Hobbs meter and GPS data.

NOTE: There was a ten month period where no documented evidence was available on the pilot’s helicopter flying hours.

Flying experience (helicopter)

Total hours 386.2

Total past 90-days 11.1

Total on type past 90-days unknown

Total on type 386.2

Flying experience (aeroplane)

Total hours 1 808.5

Total past 90-days 35.5

Copies of the pilot’s aeroplane flying logbook were obtained, the last entry in his

logbook was dated 8 March 2015. The total flying hours accumulated on the date

was 1773.0. Copies of his aircraft (Cessna 206, ZS-DJB) flight folio were also

obtained, which reflect the hours flown over the period 17 September 2014 until 28

May 2015. It was noted that from 8 March 2015 until 28 May 2015 the pilot had

flown a further 35.5 hours with the aircraft, which brings his total aeroplane flying

hours to 1808.5.

Total flying experience (aeroplane and helicopter)

Total hours on aeroplane 1 808.5

Total hours on helicopter 386.2

Grand total 2 194.7

1.6 Aircraft information

Airframe:


Type Robinson R44 Raven II

Serial number 12363

Manufacturer Robinson Helicopter Company

Year of manufacture 2008

Total airframe hours (at time of accident) 611.1

Last MPI (hours & date) 525.8 29 October 2014

Hours since last MPI 85.3

C of A (Issue date) 21 August 2008

C of A (Expiry date) 20 August 2015

C of R (Issue date) (present owner) 20 April 2011

Operating categories Standard Part 91

Record of

previous

damage to

the helicopter

The helicopter was involved in two previous occurrences;

Collided with wires during low level flying on 20 May 2011.

Collided with wires during low level flying on 22 August 2012.

According to the airframe logbook, page 89, the helicopter was involved in a main

rotor blade wire strike incident that occurred on 20 May 2011 at 183.6 airframe

hours. New main rotor blades and tail rotor assembly were installed following the

occurrence.

According to the airframe logbook, page 91, the helicopter was involved in another

main rotor blade wire strike incident on 22 August 2012 at 338.6 airframe hours.

New main rotor blades were installed following the occurrence.

The flight folio was retrieved from the accident site. It was a new book with only

three entries on page 1. The first entry was dated 16 May 2015, followed by a

second entry on the same day and then an entry on 24 May 2015. The flight on 29

May 2015 from the pilot’s farm near Tosca to FAWB and back to the farm was not

entered in the flight folio, nor was there any record with regard to fuel uplifts with

11.1 hours flown over this period.

Engine:

Type Lycoming IO-540-AE1A5

Serial number L-32934-48E


Hours since new 611.1

Hours since overhaul T.B.O. not yet reached

Main rotor blades:

Type Robinson C016-7

Serial numbers 2450, 2463

Hours since new 272.5

Hours since overhaul T.B.O. not yet reached

1.7 Meteorological information

1.7.1 An official weather report was obtained from the South African Weather Services

(SAWS). The closest SAWS Automatic Weather Station where data was recorded

to the accident scene was at Ottosdal, which was 55 km south-east of Delareyville.

Parameter 0500Z 0600Z

Wind Calm Calm

Temperature 3°C 8°C

Humidity 57% 45%

Dew-point - 5°C - 3°C

Pressure 1024 HPa 1024 HPa

1.8 Aids to navigation

1.8.1 The helicopter was equipped with standard navigational equipment. Also on

board was a Garmin aera 500 GPS portable unit that was recovered from the

accident site.

1.9 Communication

1.9.1 The helicopter was equipped with a standard communication device. The pilot was

flying outside of controlled airspace underneath the terminal control area (TMA)

when the accident occurred.


1.10 Aerodrome information

Aerodrome location Delareyville (FADL)

Aerodrome co-ordinates 26°41’0 South 025°28’0 East

Aerodrome elevation 4495 feet above mean sea level

Runway designations 04/22

Runway dimension 1200m x 45m

Runway used Not applicable

Runway surface Gravel

Approach facilities None

Aerodrome status Licensed

1.10.1 The helicopter crashed onto an open grass field 0.55 nm (1 kilometre) short of the

threshold of runway 04 at FADL.

1.11 Flight recorders

1.11.1 The helicopter was not equipped with a flight data recorder (FDR) or a cockpit voice

recorder (CVR), nor was it required by the regulations to be fitted to this type of

helicopter.

1.12 Wreckage and impact information

1.12.1 The helicopter collided with a large blue gum tree on the eastern side of the R507

roadway when driving in a northerly direction from Ottosdal towards the town of

Delareyville. The helicopter was flying in a north-easterly direction when the

accident occurred. It impacted with the ground to the left of the tree shortly after

making contact with the tree in a steep nose down attitude. The main wreckage

skidded for a distance of 80m before coming to rest on its right-hand side. The tail

boom was severed twice by the main rotor blades and the boom structure came to

rest approximately 80m from the main wreckage. The aft tail boom structure, which

supported the tail rotor assembly, as well as the vertical and horizontal stabilizer,

was found 30m from the main wreckage. The stinger was observed to be bent

upwards and the lower vertical stabilizer displayed evidence of deformation

associated with ground contact. The tail rotor gearbox and head assembly


remained secured to the aft tail boom structure, the two tail rotor blades fractured

near the blade hub. A section of the tail rotor drive shaft was still secured to the

input housing of the tail rotor gearbox and a section of the tail rotor drive shaft was

still secured to the main rotor gearbox output housing. A section of the tail rotor

drive shaft, approximately 2m in length, was located some distance from the main

wreckage. The main rotor drive train was substantially damaged during the impact

sequence. The four drive belts were found to be intact. Although the cockpit

structure was severely disrupted flight control continuity could be established and all

failures were associated with overload mode. The engine that was still contained

with the airframe was removed and subjected to a teardown inspection.

Figure 4: An aerial view of the accident site (photograph courtesy of the SA Police Services)

Main wreckage

The tree that the helicopter collided with

The aft tail section

Tail boom


Figure 5: Shows the main wreckage and the tree that the helicopter collided with,

Figure 6: The arrows indicate tree branches that were severed by the main rotor blades

The tree which the helicopter collided with The main wreckage

The R507 roadway


Figure 7: Two of the tree branches that were severed

Figure 8: A close view of one of the tree branches that was severed


Figure 9: A view of the main wreckage

Figure 10: The main wreckage lower fuselage with the skid gear ripped out

A red 10 litre container that was filled with Avgas was located at the accident site.


The container remained intact. It could not be determined where this container was

placed on board the helicopter during the flight. The main fuel tank was ruptured

during the impact sequence. The auxiliary tank remained intact and was found to

be filled to capacity as can be seen in Figure 11. The photograph was taken after

the main wreckage was placed in an upright position.

Figure 11: Auxiliary fuel tank was filled to capacity (wreckage was placed in up-right position)


Figure 12: The aft tail rotor assembly, vertical fin with a section of the tail rotor drive shaft

Figure 13: A section of the tail boom structure as found on the scene

The destruction to the cockpit/ cabin area can be viewed in Figure 14 below. The


destruction to the right side (looking at the wreckage from behind) can be seen to

be more extensive in relation to the left side. The pilot's three point safety harness

was found to still be latched in position. The red 10L Avgas container that was

recovered on the scene can also be seen.

Figure 14: A view of the main wreckage after it was turned upright

1.13 Medical and pathological information

1.13.1 According to the medico-legal post mortem report the pilot’s cause of death was

due to; “The base of the skull that fractured with primary brain injuries”.

1.14 Fire

1.14.1 There was no evidence of a pre- or post-impact fire.

1.15 Survival aspects

1.15.1 Two of the three occupants on board the helicopter survived the accident. The pilot

was trapped underneath the wreckage as it came to rest on its right-hand side. He


succumbed to his injuries on the scene.

1.15.2 The pilot's wife who was occupying the left front seat suffered severe spinal injury,

she also injured her neck and fractured her left ankle. She was properly secured by

making use of the helicopter equipped three point safety harness. Even though the

cabin structure was severely disrupted, where she was seated, the seat structure

remained secured to the floor structure. She was flown by air ambulance to Grand

Central aerodrome (FAGC) from where she was transferred by road ambulance to a

private hospital in Johannesburg where she underwent surgery. Medical facilities in

the area of the accident were not conducive to such specialised procedures.

1.15.3 The son, who was seated behind his mother, suffered concussion and a bleeding

nose. He was attended to at the scene by medical personnel and was admitted to

the same hospital as his mother for observation purposes. He was discharged the

next day. He was properly secured by making use of the helicopter equipped safety

harness. The seat and associated structure where he was seated remained intact

during the impact sequence.

1.16 Tests and research

1.16.1 The engine, a Lycoming IO-540-AE1A5, serial number, L-32934-48E was removed

from the wreckage after the helicopter was recovered. Due to impact damage it

was not possible to subject the engine to a bench test procedure and a teardown

inspection was conducted on Monday, 6 July 2015. Both magnetos were removed

from the engine and subjected to a bench test at an approved maintenance facility.

Both magnetos provided spark associated with normal operation. The left-hand

magneto was found to be noisier than the right-hand one, and during a partial

dismantle procedure the shaft bearing was found to display some evidence of wear.

An engine teardown report can be found attached to this report as Annexure A.

1.16.2 Garmin aera 500 GPS


Figure 15: This GPS unit was found on the accident scene

A Garmin aera 500 GPS was retrieved from the accident site, the unit was intact

and it was possible to download several flight tracks from it. The track that the pilot

flew from his farm near Tosca to FAWB and back, the day prior to the accident

flight, could be viewed as well as the accident flight until the point of impact.

Observing the track flown on the morning of 30 May 2015 from Vryburg it was noted

that the pilot deviated en route to Delareyville as the direct track to FAWB would

have taken them to the north of the town. He commenced with a slight right turn

and flew in a north-easterly direction with his flight path taking them to the south of

the town where the accident occurred in an open field near the Delareyville golf

course.


Figure 16: Google Earth overlay displaying the approach path that was flown

Figure 17: Google Earth overlay displaying the approach path from a different angle

1.17 Organizational and management information

1.17.1 This was a private flight; the pilot was also the owner of the helicopter.

Runway 04

The approach path that was flown

Approach path


1.17.2 The aircraft maintenance organisation that carried out the last maintenance

inspection on the helicopter prior to the accident flight was in possession of a valid

AMO approval certificate.

1.18 Additional information

1.18.1 None.

1.19 Useful or effective investigation techniques

1.19.1 No new methods were applied.

2. ANALYSIS

2.1 Man (Pilot)

The pilot was the holder of a valid private pilot licence on helicopters as well as

aeroplanes. He flew several hours with the helicopter the previous day and there

was no defects entered in the flight folio that was recovered from the accident site.

From the flight track data as depicted in Figure 1, page 4 of this report, it was noted

that the pilot changed his route after passing the halfway point between Vryburg

and Delareyville. The flight continued normally and was tracking towards the south

of the town of Delareyville. At no stage during the flight was there an unusual or

sudden change in the flight profile of the helicopter, which was observed to be on

final approach for runway 04 at FADL. It was a known fact that the pilot was going

to land en route to FAWB and he most probably opted to do so at FADL, which was

a safe option as it was a licensed aerodrome. Flying a helicopter allows a pilot with

many landing options should the environment be conducive to such a landing as

there could be a risk involved, i.e., a pilot should avoid landing in tall grass as the

exhaust system can set the veld alight, there could also be wires that blend in with

the environment or uneven/rocky terrain that can damage the helicopter.

This was not the first time the pilot had collided with an object aloft while flying this

helicopter. According to available evidence he was involved in two previous


occurrences where he had collided with wires. Both these occurrences are referred

to in subheading 1.5 on page 6 of this report.

According to the two passengers that survived the accident neither of them could

recall seeing the tree prior to contact with it. The possibility that the pilot saw the

tree when he was in close proximity to it could not be ruled out. The tree branches

that were severed by the blades display a substantial angle; this was supported by

the helicopter impacting the ground to the left of the tree. The cutting angle was in

excess of 30°, which indicates a steep bank angle to the left, however with this

amount of bank he was unable to avoid making contact with the tree, which resulted

in a loss of control.

2.2 Machine (helicopter)

The helicopter was maintained in accordance with the approved maintenance

schedule and no reported defects were found entered in the flight folio that was

recovered from the scene. The auxiliary fuel tank was found to be filled with fuel,

the main fuel tank was however, ruptured. The day prior to the accident flight the

pilot flew from his farm near Tosca to FAWB and back, which was a flight of several

hours without any defect being recorded. The AMO that maintained the helicopter

was also located at FAWB, so should there have been any defects the opportunity

was there to attend to the problem. No defect(s) were reported to the AMO on the

day.

Analysing the data that was downloaded from the GPS unit it was noted that the

pilot commenced with a gradual descent flying toward the threshold of runway 04 at

FADL. At no time prior to making contact with the tree was there any sudden

deviation from the flight path that could have been associated with an emergency or

an unusual situation on board the helicopter. The engine was subjected to a

teardown inspection and no mechanical evidence could be found that the engine

was not functioning satisfactorily at the time of impact.

2.3. Environment


The prevailing weather conditions at the time had no influence on the accident.

There were no clouds and visibility was more than 10km.

The terrain between Vryburg and Delareyville was flat and there was ample space

available for an unscheduled or forced landing should that have been required.

2.4 Crash survivability

The pilot incurred severe head trauma during the impact sequence, he was not

wearing a flying helmet. Flying with an approved flying helmet could have provided

him with the necessary protection to such a degree that his chances of surviving the

accident could have been much better. The two occupants that were seated on the

left side of the helicopter survived the accident. The injuries sustained by the front

seated passenger were due to the destruction of the front as well as the lower

fuselage structure, which was manufactured from glass fibre. The pilot's wife or left

front seat passenger remained secured to her seat via the helicopter equipped

three points safety harness.

2.5 Conclusion

The flight was nothing out of the norm for the pilot as he had flown several hours

the previous day with the same helicopter to the same destination, that being

FAWB. The flight folio that was recovered on the scene did not reflect any entry

that could have been associated with a defect on the helicopter prior to the flight. It

was noted that the pilot deviated from the intended flight route while flying from

Vryburg to FAWB by turning right approximately halfway between Vryburg and

Delareyville and was observed flying to the south of the town of Delareyville. The

direct route to FAWB would have taken them to the north of the town.

It could be seen from the GPS data that the pilot was flying towards FADL as the

helicopter was on approach (lined up) for runway 04 when the accident occurred.

The deviation came about due to the pilot’s door not being properly latched at the

top and the left front seat passenger experiencing problems communicating with

them via the headset she was wearing and wanted to change it for another headset,

which was underneath her seat. It would appear that the pilot’s attention became

distracted during a critical phase of the flight and he most probably saw the tree

seconds before colliding with it head on. He banked left in an attempt to avoid

colliding with the tree but the blades and possibly some of the fuselage made

contact with the tree and control was lost and the helicopter impacted with the


ground.

3. CONCLUSION

3.1 Findings

3.1.1 The pilot was the holder of a valid private pilot licence on helicopters as well as

aeroplanes. He had the helicopter type endorsed on his licence.

3.1.2 The pilot was the holder of a valid aviation medical certificate that was issued by a

designated medical examiner. He had to wear corrective lenses while flying.

3.1.3 The pilot had flown the day prior to the accident flight from his farm near Tosca to

FAWB and back to his farm with the same helicopter without any defect being

recorded in the flight folio.

3.1.4 On the day of the accident he flew from his farm accompanied by his youngest son

to Vryburg where he landed. His wife then boarded the helicopter and from there

they departed to FAWB.

3.1.5 The pilot was flying in a north-easterly direction into the rising sun at the time of the

accident.

3.1.6 According to available evidence the pilot had on two previous occasions collided

with an object aloft (wires) while flying the same helicopter.

3.1.7 The pilot was not wearing a flying helmet, he incurred severe head injuries during

the impact sequence.

3.1.8 The helicopter was in possession of a valid certificate of airworthiness.

3.1.9 The last maintenance inspection prior to the accident flight was certified on 29

October 2014 at 525.8 airframe hours. There were no recorded defects entered in

the flight folio.

3.1.10 The main fuel tank was ruptured but the auxiliary tank still contained ample fuel.

3.1.11 No mechanical malfunction was detected during the engine teardown inspection.

3.1.12 The two occupants that were seated on the left side of the helicopter one survived


the accident with minor injuries and the other with serious injuries.

3.1.13 The prevailing weather conditions had no influence on the accident.

3.1.14 Neither of the two occupants that survived the accident could recall seeing the tree

prior to contact with it.

3.2 Probable cause

3.2.1 The helicopter collided with a tree while on the descent for an intended landing,

whereupon the pilot lost control and it impacted heavily with terrain.

3.3 Contributory factor

3.3.1 Failure to keep a proper lookout by the pilot during a critical phase of flight.

4. SAFETY RECOMMENDATION

4.1 The safety message:

Helicopter pilots should keep vigilance when approaching any landing area and

ensure that they have identified or followed the unmanned aerodrome procedures

when landing or taking off from such landing areas or aerodromes.

5. APPENDICES

5.1 Annexure A (Engine teardown report)


ANNEXURE A

The engine, a Lycoming IO-540-AE1A5, serial No. L-32934-48E was removed from

the wreckage after recovery and was taken to an approved engine maintenance

facility where a teardown inspection was performed on Monday, 6 July 2015. The

impact damage was of such a nature that the engine could not be subjected to a

bench test. The sole purpose of the teardown inspection was to assess the

mechanical integrity of the engine. The following observations were made:

The engine prior to the teardown inspection

Engine

Model Lycoming IO-540-AE1A5

Serial No. L-32934-48E

Fuel Injector

Servo,

Precision

Part #

61M23587

Serial #

70CR4403

The fuel injector servo sustained minor impact damage and was

found to be in an overall good condition. A small amount of fuel

was drained from the unit after it was removed from the engine. All

linkages were secured and no anomalies were noted that would

have restricted normal operation.


Fuel pump

The fuel pump was undamaged and was removed from the engine.

The unit still contained a small amount of fuel.

Fuel flow

divider.

Part #

2576526-1

Serial #

4290

The fuel flow divider, with the six fuel lines attached, was found to

be intact and the fuel lines were secured to the fuel nozzles. The

wire locking was cut and the unit was opened. The unit did not

display any internal damage and the diaphragm was found to be

intact (see photograph).


Fuel nozzles

All six fuel nozzles were removed from the engine, inspected and

found to be free of any obstructions.

Spark plugs:

Autolite

UREM-38E

The spark plugs were removed from the cylinders and found to be

in good overall condition displaying a light brownish colour, which is

associated with normal engine operation. The spark plugs on

cylinders 2, 4 and 6 displayed evidence of oil on the electrodes,

which was associated with the fact that the wreckage came to rest

on its right-hand side and was lying in this position for several hours

before it was placed in an upright position.

HT harness

Slick

The high tension harnesses were in good overall condition.

Magnetos

Alpha

Systems

#66B21784

(right side),

#66B21783

(left side)

Both magnetos were still attached to the engine. The units did not

sustain any damage and it was possible to bench test both units.

The units were removed from the engine and were subjected to a

bench test at an approved electrical maintenance facility. During

the bench test both magnetos were found to function satisfactorily,

providing spark over the entire RPM range it was tested.


The left-hand magneto was found to be much noisier than the right-

hand magneto during the bench test procedure. The unit was

dismantled following the bench test and it was found that the shaft

bearing started showing evidence of wear.

The photograph below display one of the magnetos being bench

tested.

Oil filter

The filter was still attached to the engine and did not sustain any

damage.

Gear drive

train

The gear drive train was undamaged.

Cylinders

All six of the cylinders were removed, they showed signs of proper

combustion and carbon deposits found to be normal on this type of

engine.

The #2 cylinder sleeve was found to be scored, which was

attributed to wear caused over an undetermined period of time as a

result of a broken compression ring on the #2 piston.


Pistons &

rings

The pistons were in good condition and displayed evidence of

carbon build-up associated with normal engine operation.

Apart from the #2 piston compression ring (top ring) that failed no

other damage was observed.

The photo below displays the broken compression ring (top ring on

the piston).

Main

bearings &

Big-end

bearings

All the bearings were found to be in good overall condition and

displayed evidence of adequate lubrication.

Connecting

rods

LW-11570

All six connecting rods were found to be in good condition and the

connecting bolts were properly secured.

Crankshaft

The crankshaft was found to be in good overall condition. In the

photo below the connecting rods are still attached to the crankshaft.

Both crankcase assemblies are also visible on the photo.


Camshaft

The camshaft including the gear drive assembly was removed.

Several of the lobes on the camshaft displayed evidence of wear,

with prominent wear evident on the number five lobe (see photo).


Cylinder

head/ valve

assembly

All the rocker covers were intact, the covers were removed and the

valves with their associated valve springs were found to be intact

and in good condition.

Oil cooler

The unit sustained minor impact damage.

Oil pump

The oil pump was found undamaged and in good condition. There

were still several litres of oil inside the engine.


Oil sump The sump sustained some impact damage but no oil leaked from

the sump assembly. The oil pick-up was intact and free of any

obstructions. The colour of the oil was black and had a very distinct

smell.

The black colour of the oil was associated with combustion gases

bypassing the broken compression ring on the #2 cylinder piston.

Starter

The unit was attached to the engine but sustained some impact

damage.

Alternator

The unit was attached to the engine but sustained some impact

damage.

Alternate

observations

The exhaust stacks were inspected and found to display a brownish

colour on the inside, which could be associated with normal engine

operation.

Conclusion

The teardown inspection of the engine did not reveal any pre- or

post-impact mechanical failure that would have prevented the

engine from normal operation.

aircraft accident report and executive summary and incidents reports/9445.pdf · 2018. 1. 9. ·...

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