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Manual No. E492A

O P E R AT I O N AN D M AI N T E N AN C E M AN U A L

February 2012

HO-V343()-()

Three bladed lightweight Constant Speed Propeller

HO-V343()-S

Three bladed lightweight Constant Speed and Feathering

Propeller

Hoffmann Propeller GmbH & Co. KG

Küpferlingstraße 9

D-83022 Rosenheim

Phone: +49-(0)8031-1878-0

Fax: +49-(0)8031-1878-78

Email: [email protected]

Internet: http://www.hoffmann-prop.com

mailto:[email protected]

http://www.hoffmann-prop.com/

HOFFMANN PROPELLER

INTRO PAGE I E492A February 2012

Warning

People who fly, or are operating a propeller driven vessel, should recognize that different types of risks are

involved, and they should take all possible precautions to reduce them, because they cannot be eliminated

entirely. The propeller is a vital component of the aircraft or the propeller driven vessel. A mechanical failure

could cause a forced landing or create vibrations sufficiently severe to damage the aircraft or vessel possibly

causing it to become uncontrollable.

All propellers are subject to constant vibration stresses from the engine and airstreams, which are added to

high bending and centrifugal stresses.

Before a propeller is certified as being safe to operate on an airplane or a propeller driven vessel an

adequate margin of safety must be demonstrated. Even though every precaution is taken in the design and

manufacture of a propeller, history has revealed rare instances of failures, particularly of the fatigue type.

It is essential that the propeller is properly maintained according to the recommended service procedures

and a close watch is exercised to detect impending problems before they become serious. Any grease or oil

leakage, loss of oil pressure, unusual vibration or change in operation behavior should be investigated and

repaired very carefully as it could be a warning that something serious is wrong.

Hoffmann strongly recommends reading this manual thoroughly. It contains a lot of information about your new propeller.

The propeller is among the most reliable components of your airplane, or the propeller driven vessel. It is

also among the most critical to flight safety. It therefore deserves the care and maintenance called for in this

Manual. We kindly ask you please give it your attention, especially the section dealing with Inspections and

checks.

We like to thank you very much for choosing Hoffmann Propeller. Properly maintained it will give you many

years of reliable service.

Your Hoffmann Crew.

HOFFMANN PROPELLER

PAGE II DESCRIBTION E492A February 2012

For operator of non certified or experimental aircraft, or the propeller driven vessel, even a greater level of vigilance is required in the maintenance and inspection of the propeller. Experimental installation often uses propeller- engine combinations that have not been tested and approved. In these cases, the stress on the propeller and, therefore, safety margin is not known. Failures could be as severe as loss of propeller or propeller blades and cause loss of propeller control and / or loss of aircraft or the propeller driven vessel.

Hoffmann Propeller GmbH follows the EASA regulations for propeller certification on certified aircraft. Experimental aircraft may operate with unapproved engines or propellers or engine modifications to increase horsepower, such as unapproved crankshaft damper configurations or high compression pistons. These issues affect the vibration output of the engine and the stress levels on the propeller. Significant propeller life reduction and failure are real possibilities.

Frequent inspections are strongly recommended if operating with a non-certificated installation; however, these inspections may not guarantee propeller reliability, as a failing device may be hidden from the view of the inspector. Propeller overhaul is strongly recommended to accomplish periodic internal inspection.

Visually inspect the wooden propeller blades for cracks. Inspect the hubs, with particular emphasis on each blade arm for cracks. Eddy current equipment is recommended for hub inspection. Since cracks are usually nor apparent.

Hoffmann Propeller will not be responsible for any translation of this manual. In case of doubt only the original English version of this manual will be valid and accepted.

HOFFMANN PROPELLER

INTRO PAGE III E492A February 2012

Warnings, Cautions and Notes

Throughout the next in this manual, Warnings Cautions and Notes pertaining to the procedures being accomplished are included. These adjuncts to the text are used to highlight or emphasis important points. Warning and Cautions precede the text they pertain to, and Notes follow the text they pertain to.

Warning: Calls for attention to use of materials, methods, processes, procedures or limits which must be followed precisely to avoid injury and/ or death to persons.

Caution: Calls attention to methods and procedures which must be followed to avoid damage to equipment.

Note: Calls attention to methodes which will make the job easier.

Personnel Requirements

Personnel performing any work or maintenance to the propeller assembly are expected to have sufficient knowledge and training to accomplish the required work in a safe and airworthy manner.

HOFFMANN PROPELLER

PAGE IV DESCRIBTION E492A February 2012

Airworthiness Limitations

If each prescribed service is accomplished, there is no restriction of the airworthiness of this propeller. For the current valid TBO(Time Between Overhaul) refer to SB E1.

HOFFMANN PROPELLER

INTRO PAGE V E492A February 2012

Table of Contents and Revisions

Chapter Pages Revision Date

1 Description 1-1 to 1-4 A July 2011

2 Construction 2-1 to 2-2 A July 2011

3 Installation 3-1 to 3-4 A July 2011

4 Operation 4-1 to 4-4 A July 2011

5 Adjustment 5-1 to 5-5 A July 2011

6 Maintenance and Cleaning 6-1 to 6-5 A July 2011

7 Trouble Shooting 7-1 to 7-3 A July 2011

8 Shipping and Storage 8-1 to 8-1 A July 2011

9 Specials 9-1 to 9-1 A July 2011

10 Drawings and Tables 10-1 to 10-6 A July 2011

HOFFMANN PROPELLER

PAGE VI DESCRIBTION E492A February 2012

Record of Revisions to this Manual

Rev. No.

Description of Revision

Date

A Feathering Propeller HO-V343()-S incorporated. New document-structure and new drawings.

Feb 12

HOFFMANN PROPELLER

INTRO PAGE VII E492A February 2012

Service Documents

Warning: The following list shows the Service Documents which are applicable at the date of issue of this document. A complete up-to date list of Service Documents is available at the Hoffmann Homepage: http://www.hoffmann-prop.com.

Service Bulletins

SB E1 SB E11 SB E13 SB E14 SB E15 SB E17 SB E18 SB E20 SB E21 SB E22

Service Advisories

SA E3

Service Instructions

SI E4 SI E6 SI E7 SI E8

Service Letters

SL E3

SL E4

SL E12

SL E13

SL E14

http://www.hoffmann-prop.com/

HOFFMANN PROPELLER

DESCRIBTION PAGE 1-1 E492A February 2012

1. Description

1.1 Introduction The Propeller HO-V343()-() is a three bladed single acting fully hydraulically controlled constant speed

propeller.

The pre-selected Propeller RPM will be kept constant in the normal operating range by a Propeller

Governor. The travel of the Propeller Blades is limited by internal mechanical adjustable hard stops.

1.1.1 HO-V343(); HO-V343()-F The Propeller uses Oil pressure to increase pitch. In the event of an oil pressure failure the propeller

blades automatically return to the mechanical low pitch stop and the Propeller can be used as a

fixed pitch unit. The Propeller RPM has to be adjusted and controlled by the throttle only, but the

flight may be continued.

1.1.2 HO-V343()-V

The Propeller uses Oil pressure to decrease pitch. Counter Weights are used to turn the Propeller

Blades toward high pitch. In the event of an oil pressure failure the propeller blades automatically

return to the mechanical high pitch stop and the Propeller can be used as a fixed pitch unit. The

Propeller RPM has to be adjusted and controlled by the throttle only, but the flight may be

continued.

1.1.3 HO-V343()-S The Propeller uses Oil pressure to decrease pitch. Counter Weights are used to turn the Propeller

Blades toward high pitch. In the event of an oil pressure failure the propeller blades automatically

turn to the feathering position.

The Propeller will be kept in a starting position by mechanical stops, if the engine was shot down

with the Propeller Lever at low pitch (high RPM).

It is possible to feather the propeller by shot down the engine with a high pitch setting.

Optionally an unfeathering accumulator can be installed to unfeather the Propeller during flight. The

installed Propeller Governor must be equipped with an accumulator port.

The Propeller RPM has to be adjusted and controlled by the throttle only, but the flight may be

continued.

HOFFMANN PROPELLER

PAGE 1-2 DESCRIBTION E492A February 2012

1.2 Designation

1.2.1 Designation of the Hub

HO - V 34 3 K () - () - () /Blade Model 1 2 3 4 5 6 7 8

1 Hoffmann GmbH & Co. KG 2 Propeller model

V: Variable Pitch E: Ground adjustable Pitch

3 Number of basic Model 4 Number of blades 5 Designation of Flange F: ARP 502 Type 1 K: AS 127D (SAE 2 Mod) 3/4” bushings 1/2”-20 UNF bolts L: AS 127D (SAE 2 Mod) 5/8” bushings 7/16”-20 UNF bolts B: AS 127D (SAE 1) 6 Number of hub extension from blade center to flange Blank: 180mm (7.1inch) 1 135mm (5.3inch) 2 233.3mm (9.2inch) – with spacer 3 280mm (11.0inch) – with spacer 4 280mm (11.0inch) 5 250mm (9.8inch) 6 200mm (7.9inch) – with spacer 7 100mm (3.9inch) 8 188.3mm (7.4inch) – with spacer 9 235mm (9.3inch) – with spacer 10 155mm (6.1inch) – with spacer Depending on the Flange designation, not every hub extension will be

available. 7 Hydraulic pitch change Blank Oil pressure to increase pitch, no counterweights F Oil pressure to increase pitch, counterweights V Oil pressure to decrease pitch, counterweights S Oil pressure to decrease pitch, counterweights, feathering position 8 Minor changes not affecting interchangeability

HOFFMANN PROPELLER

DESCRIBTION PAGE 1-3 E492A February 2012

1.2.2 Designation of the Blade

() 183 GY - () () () ± () 9 10 11 12 13 14 15

9 Rotation Mode, Position Pitch Change Pin and Tipping Blank Right-hand, tractor D Right-hand, pusher L Left-hand, tractor LD Left-hand, pusher V Pitch Change Pin for oil pressure to decrease pitch S Pitch Change Pin for feathering C PU-Erosion tipping, type C 10 Basic diameter in cm 11 Designation of blade design 12 Designation of blade twist 13 De-Icing Blank Non De-Icing B Electrical De-Icing 14 Material of blade Blank Compreg scarfed with lighter wood P Compreg 15 Decrease (-) or increase (+) of basic diameter in cm

On a decal on each blade the designation of the hub assembly and serial number, as well as the designation

of the blade and blade serial number are printed. The serial number of the blade is additionally stamped into

the blade retention nut and the blade ferrule (at the blade ferrule the stamp isn’t visible from the outside).

The complete designation of a variable pitch propeller is a combination of the designation of the hub

assembly and the blade assembly. Both designations are separated by a slash mark.

Example: HO-V343K/183GY

The serial number of the hub is considered to be the serial number of the complete propeller assembly.

Figure 1-1: Blade Decal (Example only)

HOFFMANN PROPELLER

PAGE 1-4 DESCRIBTION E492A February 2012

1.2.3 Design Data Following data are standard values only. For installation purposes only the data given in the Type Certificate

Data Sheet (TCDS) No. 32.130/90 of the German Luftfahrt – Bundesamt (LBA) or the Type Certificate Data

Sheet (TCDS) No. P12BO of the Federal Aviation Administration (FAA) are valid.

Pmax 190kW (260hp) nmax 2700 1/min Number of blades: 3 Diameter: about 190cm Pitch change range max: about 80° Weight: 18kg (40lbs) Weight of the spinner: 1.7kg (3.75lbs) Polar moment of inertia: About 1.8kgm² (6150lbsin²) Governor: Woodward 210xxx series,

McCauley, Hartzell, Jihostroj

HOFFMANN PROPELLER

CONSTRUCTION PAGE 2-1 E492A February 2012

2. Construction

The HOFFMANN variable pitch propeller and the ground adjustable pitch propeller consist of 4 sub-

assemblies:

- Hub assembly

- Blade assembly

- Spinner assembly (if applicable)

- Counterweight assembly (if applicable)

2.1 Hub assembly The one piece hub is made from aluminum and mounted to the engine flange with bolts or studs. The pitch

change cylinder and the piston are mounted on the front of the hub, or inside the back part of the hub. Axial

movement of the piston is transferred to the pitch change pin by a fork and pitch change blocks, whereby the

blade angle is changed. The pitch change range is limited by internal mechanical stops.

2.2 Blade assembly The HOFFMANN composite blade is a joint construction. The blade root is made of highly compressed

hardwood and the blade part is made of light wood (spruce). Blades may also be manufactured of

compressed wood only. Special lag screws connect the compressed wood of the blade to a metal ferrule.

For erosion protection of the blade leading edge, three different types of Hoffmann proved leading edge

protection could be used:

Type A is a brass metal strip soft soldered to a bronze fabric and glued to the blade FRP cover.

Type B is a special aluminum strip glued directly to the wooden core of the blade.

Type C is a special PU-strip (Polyurethane) blade tipping and also glued directly to the wooden core. Due to

the material the leading edge is not painted.

Picture 2-1: Leading edge protection Type A(left) and Type B/C(right)

HOFFMANN PROPELLER

PAGE 2-2 CONSTRUCTION E492A February 2012

To increase torsional stiffness and provide a good erosion protection the blade is covered with fibre

reinforced epoxy (FRP). Fatigue failures due to vibration are unlikely with such blades because the internal

damping of the material is considerably higher than that of duralumin.

Several layers of special polyurethane paint (PU- paint) are sprayed onto the fibre reinforced epoxy covering

and the erosion tipping (with the exception of the Type C erosion tipping); this assures a high resistance to

atmospheric conditions. This polyurethane paint shows also high resistance against erosion and mechanical

damage. Colored paint is required to protect the wood against UV-rays. The thrust side is painted dull black

to avoid reflection of sunlight. For safety reasons the tips are painted with a different color to make the

transparent propeller disc visible when the propeller is running.

An axial needle bearing absorbs the centrifugal force of the blade. The bearing races are made of steel. The

needle cage is a one piece bearing. After repair or overhaul it can be split into two halves to allow exchange

of the cage without removing the blade ferrule.

The blade ferrules are made of aluminum alloy or steal. The blades are installed into the hub by a retention

ring (blade nut), made of aluminum alloy. The torque of the retention ring adjusts the necessary pre-load of

the blade bearing. The blade retention rings are sealed against water from outside with silicone rubber

between the retention nut and the hub. The blade shaft is sealed against water from the outside with silicone

rubber between the blade and the ferrule. The blade ferrule is sealed against water from the outside with a

lip seal between the ferrule and the retention nut.

2.3 Spinner assembly The spinner dome is one piece and made of Aluminum alloy. It is screwed to the spinner bulkhead. The

spinner bulkhead is made of an Aluminum- sheet and mounted to the hub or the starter gear, or clamped

between engine and propeller flanges. A front spinner support is used to support the spinner dome.

2.4 Counterweights Models using oil pressure to decrease pitch including feathering require counterweights. However, small

counterweights may also be used to reduce the pitch change force of the blades on models with oil pressure

to increase pitch. The counterweights are fixed to the blade ferrule by clamps and screws.

HOFFMANN PROPELLER

INSTALLATION PAGE 3-1 E492A February 2012

3. Installation

Warning: Before performing any work on the propeller follow the safety precautions given in the aircraft flight manual.

Warning: The mating surface of the engine- and propeller flange must be absolutely clean and dry before installing the propeller.

Caution: Propeller installation is subject to an immediate inspection by a licensed engineer.

(1) Carefully clean the propeller- and engine flange with solvent. Engine torque is mainly transferred by

friction; therefore the surfaces have to be smooth and clean.

(2) Check if both O-rings (H3.1, H3.2) are installed in the center ring (H3.3) if applicable. Place center

ring in the hub, if not yet installed (refer to Picture 3-1 or 3-2).

3.1 Installation the K, L and B – Flange Propeller Refer to Picture 3-1

Warning: Do not install an additional O-ring on the engine flange.

(1) Installing the spinner bulkhead on the starter gear ring or between engine- and propeller flange if

applicable that one blade axis is aligned with a flange bushing, which does not protrude through the

engine flange.

(2) Insert all 6 flange bolts (H3.4) with the washers (H3.5) in the bores of the propeller flange.

Caution: Take care not to damage the o-ring.

(3) Slightly oil the O-ring (H3.1) in the center ring. Carefully slide the propeller on the engine flange.

Caution: To apply the correct torque the running torque of the bolt has to be determined.

Caution: To apply the torque a calibrated torque wrench has to be used.

(4) Always screw in two opposite flange bolts by hand. Slightly relieve the propeller weight while doing

so. Torque flange bolts equally crosswise and wire lock 2 bolts together using stainless steel wire

with a diameter of 0.8 mm. (For the right torque see torque table Chapter 10)

HOFFMANN PROPELLER

PAGE 3-2 INSTALLATION E492A February 2012

3.2 Installing the F – Flange Propeller Refer to Picture 3-2

Warning: Do not install an additional O-ring on the engine flange.

(1) Apply a thin coat of oil to the O-ring (H3.1)

Caution: Take care not to damage the o-ring.

(2) Slide propeller carefully onto the engine flange. Check the correct position of the dowel pins if

applicable.

(3) Slide washers (H3.6) onto the bolts (H3.8). Install new stop nuts (H3.7) and torque them equally

crosswise.



(4) Torque the stop nuts equally crosswise (For the correct torque values see torque table Chapter 10).

3.3 Dynamic Balancing

Dynamic balancing is recommended in order to reduce vibrations caused by the rotating system of the aircraft. Dynamic balancing will prolong the life of the airframe, engine, propeller and the whole equipment. To accomplish the dynamic balancing ask your aircraft service station.

3.4 Spinner installation Refer to Picture 3-3

(1) Install the distance ring (H3.15) on the cylinder.

(2) Apply a thin coat of oil to the O-rings (H3.9, H3.10) in the front spinner support (H3.11) if applicable

and slide it onto the cylinder.

(3) Apply a coat of oil to the O-ring mating surface of the spinner dome (H3.12) and install the dome

according the markings.

(4) Use plastic washers (H3.13) and screws (H3.14). Torque the screws (For the correct torque values

see torque table Chapter 10).

The removal of the Spinner has to be done in the opposite sequence than installation.

3.5 Propeller removal

Warning: Before performing any work on the propeller follow the safety precautions given in the aircraft flight manual.

Caution: Before removing the Propeller drain the oil from the Propeller into a bucket.

The removal of the propeller has to be done in the opposite sequence than installation. After loosening the

self-locking nuts (H3.7) or the bolts (H3.4) and before removing the propeller allow the oil of the propeller to

drain into a bucket.

HOFFMANN PROPELLER


Picture 3-1: Installation K, L and B – Flange Propeller

HOFFMANN PROPELLER


Picture 3-2: Installation F – Flange Propeller

Picture 3-3: Spinner Installation

(Example: HO-V373K-V)

HOFFMANN PROPELLER


4. Operation

4.1 Propeller Pitch Change The pitch change force of HOFFMANN composite blades is much lower than that of metal blades. This

means a lower pitch change force is required to change the blade angle and the pitch changes much faster

than with metal blades.

Warning: Prior operating the propeller, make sure every screw, bolt or stop nut has the correct torque and everything in front of the Propeller is clean and secured. Take precautions according the craft’s manual.

Caution: Always move propeller and / or power lever slowly and smoothly. Do not operate the levers abruptly..

Rapid movement of the levers may cause over speeding until the governor is able to stabilize.

4.1.1 Models using oil pressure to increase pitch To increase pitch oil pressure works against the natural centrifugal twisting moment of the blades. On -F

models small counterweights are installed on the blade to reduce the natural centrifugal twisting moment of

the blades. During idle or on ground with the propeller rotating the pitch change mechanism reaches the

internal low pitch stop. The maximum high pitch is also limited by an internal hard stop.

4.1.2 Models using oil pressure to decrease pitch Blade centrifugal twisting moment acts to move the blades to low pitch, but the installed spring and the

counterweights overcome this force. The oil pressure against the hydraulic piston opposes the counterweight

and spring and moves the blades to the low pitch. The internal hard stops for high and low pitch remains as

described in paragraph 4-1.1.

4.1.3 Models using oil pressure to decrease pitch with feathering

The pre-selected propeller RPM will be kept constant in the normal operating range by a propeller governor.

This propeller uses oil pressure to decrease pitch and counterweights and a spring force to increase pitch till

feathering. In the event of oil pressure failure the propeller blades automatically go to the feathering position.

The travel of the propeller blades is limited by internal mechanical adjustable hard stops.

The internal hard stops for feathering and low pitch remain as described in paragraph 4-1.1. If the propeller

rotational speed is below 700RPM, the Start-locks are active and allow a maximum blade angle of about 4°

higher than the low pitch position (Start-position). If the propeller rotational speed is higher than 800RPM, the

Start-locks are unlocked, and not active, higher pitch and feathering is possible.

HOFFMANN PROPELLER


4.2 Governor A gear type oil pump in the governor uses engine oil to produce the necessary oil pressure. The rotating

flyweights and a spring will operate the pilot valve in the governor. According to the situation oil is directed to

or from the propeller or the oil flow is blocked. The governor is single acting and produces oil pressure in

only one direction (either increasing or decreasing pitch). Movement of the propeller blades in the opposite

direction will be achieved in different ways.

4.3 Propeller Governing The paragraphs 4-3.1 to 4-3.3 describe a Governor model “oil pressure to increase pitch”. Governor model

“oil pressure to decrease pitch” works similar following exceptions:

I Supply of pressure oil at Under-Speed condition

II Drain of oil at Over-Speed condition

Nearly all propeller systems for acrobatic flight use governor model “Oil pressure to decrease pitch “or an oil

accumulator which provides servo pressure to the propeller if the oil supply from the engine to the governor

is interrupted for a short time.

4.3.1 On-Speed condition

In this condition, the forces acting on the engine-governor-propeller combination are in balance. The speed

adjusting control arm has been set by the pilot to obtain the desired engine rpm. The propeller blades are at

the correct pitch to absorb the power developed by the engine. The centrifugal force of the rotating flyweights

exactly balances the force of the speeder spring with the flyweights in the vertical position. The pilot valve is

positioned in the drive gear shaft so that the control ports from the oil pump and to the propeller pitch

changing mechanism are covered. Pressure oil from the gear pump is circulated through the open governor

relief valve back to the inlet side of the pump.

4.3.2 Over-Speed condition

This condition occurs when air speed or power is increased and engine rpm increases above the rate called

for by the setting of the speed adjusting control arm. The rotating flyweights pivot outward as their increased

centrifugal force overcomes the force exerted by the speeder spring. The flyweight toes raise the pilot valve

plunger, uncovering ports in the drive gear shaft that permit pressure oil to flow to the propeller pitch change

mechanism. As the propeller blades increase pitch, load on the engine is increased and engine rpm is

reduced. This, in turn, lessens the centrifugal force of the flyweights. The speeder spring returns the

flyweights to a vertical position and the pilot valve plunger once more covers the ports in the drive gear shaft,

blocking flow of pressure oil to or from the pitch change mechanism of the propeller.

4.3.3 Under-Speed condition An under- speed condition occurs when the air speed or horsepower is decreased and engine rpm falls

below the rpm setting of the speed adjusting control lever. The decrease in the centrifugal force of the

rotating flyweights causes them to pivot inward under the force exerted by the speeder spring. The pilot

valve plunger is forced downward, uncovering the ports in the drive gear shaft, thus allowing oil to flow from

the pitch change mechanism of the propeller to sump. This permits the natural twisting moment of the blades

to decrease propeller pitch. This relieves the load on the engine, thereby increasing engine speed and the

centrifugal force developed by the rotating flyweights. As the flyweights return to the vertical position, the

flyweight toes lift the pilot valve plunger to cover the control ports.

HOFFMANN PROPELLER


4.4 Operational Test (Static run up)

Warning: When operating the Propeller without the spinner dome remove the front spinner support.

Warning: Before starting the engine take safety precautions given by the aircraft flight manual!

Caution: After Propeller installation and before first flight a day, a static run up has to be performed.

Caution: Perform engine run up on paved and clean surfaces only.

(1) Engine and propeller manufacturers do not recommend using high rpm during ground operation for

a long time because the engine can be overheated and the propeller be damaged by foreign objects.

(2) Start engine according to the flight manual and warm it up (oil temperature in the green).

Caution: Trapped air in the propeller hydraulic system can cause the pitch control not working correctly and may cause surging.

(3) After warm up use the power lever to adjust the propeller rpm to about 1800 rpm. Slowly pull the

governor control in the cockpit to obtain a propeller rpm decrease of at least 200 rpm.

(4) Slowly push governor control forward and observe rpm increase. The time required for the pitch

change should be about the same in both directions (rpm increase and decrease).

(5) Repeat this procedure at least three times. The flight manual may contain additional information.

Note: The mechanical pitch stops have been set at the factory to meet the aircraft / engine specifications.

Caution: While performing the next step be careful not to overspeed the engine.

Caution: While performing the next step there should be NO wind or only wind from 90 degrees left or right.

(6) Slowly apply full power using the power lever and hold it for a few seconds.

(7) The maximum static rpm shall be limited by the low pitch stop to 80 - 120 rpm below the maximum

propeller take off rpm. In flight the maximum propeller rpm has to be limited by the governor. Chapter

5.2 “Maximum Propeller RPM” describes how to find out whether the propeller or the governor limits

the static rpm.

(8) After the static run up inspect the blade retention system for grease leaks and the propeller hub

assembly for oil leaks. NO oil leaks are allowed.

Note: New or overhauled propellers can show small grease traceson the blade. This will stop after a few operating hours.

HOFFMANN PROPELLER


4.5 Feathering Propellers

Caution: Depending on the Aircraft and the Engine, some procedures describet below are not possible or are restricted. Refer to the Aircraft manual to find out, which procedures are applicable.

4.5.1 Engine Shut Down When the engine is stopped on the ground, it is undesirable to feather the Propeller, as the high blade angle

inhibits engine starting. To shut down the engine with the Propeller in Start-lock position, reduce the

Propeller rotational speed below 700 RPM. Move the Propeller lever to the low pitch (high RPM) position and

hold the propeller rotational speed below 700 RPM. Now the Start-locks will be locked and hold the Propeller

below the Start-lock position.

To check, if the Start-locks are locked, it is possible to slowly move the propeller lever to the high pitch stop.

If the propeller stops changing the Pitch after a small pitch change (about 4° degree), the Start-locks are

locked.

Shut down the Engine as described in the aircraft manual.

4.5.2 Feathering the Propeller

Caution: Feathering the Propeller during high rotational speed will result in a high torque on the engine and a high load on the whole Propeller.

The air resistance of a feathered propeller is much lower as the air resistance of an unfeathered propeller.

This will result in a better gliding performance of the aircraft.

To feather the Propeller reduce the Propeller rotational speed to about 900RPM. Slowly move the Propeller

lever to the feathering position, and hold the rotational speed above 800RPM. At this lever position oil will

drain from the Propeller and return to the engine sump and the propeller feathers.

Shut down the Engine as described in the aircraft manual.

4.5.3 Unfeathering without hydraulic accumulator

Caution: Starting the Engine on ground with the Propeller in feathering position can reduce the lifetime of the engine starter.

To unfeather the Propeller during flight, move the Propeller lever in a normal flight (governing) range and

restart the Engine. The pitch of the Propeller will decrease. The Propeller begins to windmill and increases

the Engine rotational Speed. Warm up the engine before increasing the power.

4.5.4 Unfeathering with a hydraulic accumulator Some aircrafts are equipped with a hydraulic accumulator which stores a supply of oil under pressure. To

unfeather the Propeller with the accumulator, move the Propeller lever to the low pitch position. This will

open a check valve in the governor and pressurized oil will flow to the Propeller and decrease the blade

angel below the Start-lock position. The Start-locks will prevent the propeller to return to feathering position.

During flight the Propeller will start to windmill by this procedure. Now the engine can be started as described

in the aircrafts manual.

HOFFMANN PROPELLER


4.6 Parking Position Hoffmann strongly recommends that the Propeller is not left outside the hanger with one propeller blade in

the vertical up position, but in the down position to avoid water accumulation in the spinner dome. The water,

or ice in the wintertime, may cause vibrations and corrosion.

4.6.1 Feathering Propellers with accumulator It is strongly recommended to park Propellers with feathering and accumulator in the Start-lock position. The

check valve for the accumulator can be a little bit leaky and discharge the accumulator slowly. Starting the

Engine with the Propeller in feathering position can reduce the lifetime of the engine starter.

HOFFMANN PROPELLER


5. Adjustment The hard high and low pitch stops of the propeller and propeller governor have been set at the factory to

meet the aircraft / engine specifications. Therefore a readjustment of the hard stops of more than +/- 100rpm

should not be necessary.

Warning: Before performing any adjustment to the propeller make sure the engine develops its full power and the rpm indicator is correct.

Warning: Before starting the engine take safety precautions given in the aircraft flight manual!

Caution: Propeller installation and adjustments may be performed only by qualified mechanics and are subject to immediate inspection by a licensed engineer.

Caution: Perform engine run up on paved and clean surfaces only.

5.1 Static RPM (RPM is propeller RPM) With the Propeller and Governor adjusted correctly, the maximum static rpm on ground (without wind, or

perpendicular to the wind) should be 80-120 rpm below the maximum take off rpm. The static rpm has to be

limited by the mechanical hard low pitch stop of the propeller and not by the governor. This can be checked

as follows:

(1) Push governor control lever full forward (rpm increases).

(2) Slowly open throttle until maximum rpm is reached.

(3) Slowly pull governor control lever back until rpm decreases by at least 25 rpm.

(4) If a considerable movement of the governor control lever is necessary to obtain a reduction of about

25 rpm, the static rpm is limited by the low pitch stop in the Propeller. If the maximum static rpm is

decreasing immediately when pulling the governor control lever, the static rpm is limited by the

governor. In this case readjust the governor as described in the governor manual.

(5) If the static rpm is limited by the propeller, but too high or too low, readjust the Propeller low pitch

stop as described below.

HOFFMANN PROPELLER


5.1.1 Adjustment of the low pitch stop – Propellers without feathering (Refer to Picture 5-1)

Warning: To adjust the pitch stops the spinner dome and the front spinner support have to be removed.

Warning: Do not turn the stop nut.

(1) Bend lock washer away from the check nut.

(2) Mark the position of the inner check nut.

(3) Loosen check nuts using wrench PV-999.

(4) Change pitch with the check nut.

(5) Turning clockwise (cw) facing the nut increases low pitch (rpm decrease).

(6) Turning counterclockwise (ccw) facing the nut decreases low pitch (rpm increase).

Note: Turning the check nut about 120° changes the low pitch stop about 1 degree or about 100 rpm.

(7) Tighten check nuts again

(8) Check static rpm.

(9) Lock Check nuts again with the lock washer.

Picture 5-1: Adjustment low pitch stop Propellers without feathering

HOFFMANN PROPELLER


5.1.2 Adjustment of the low pitch stop Propellers with feathering (Refer to Picture 5-2)

Warning: To adjust the pitch stops the spinner dome and the front spinner support have to be removed.

(1) Change pitch with the Low Pitch Stop Screw.

(2) Turning clockwise (cw) facing the screw increases low pitch (rpm decrease).

(3) Turning counterclockwise (ccw) facing the screw decreases low pitch (rpm increase).


(4) Check static rpm

Picture 5-2: Adjustment low pitch stop Propellers with feathering

HOFFMANN PROPELLER


5.2 Maximum Propeller RPM

Caution: The maximum propeller RPM has to be checked in flight.

Check the maximum Propeller RPM during climb or cruise. Slowly move the Propeller lever to the low pitch

position (high RPM). Take care not to over speed the engine by doing this. If the maximum RPM is too high

or too low the governor has to be readjusted as described in the governor manual. If the governor setting is

correct check the maximum RPM during descent. If the RPM increases during descent the Propeller high

pitch stop is set too low. Readjust the high pitch stop at described below.

5.2.1 Adjustment of the high pitch stop (Refer to Figure 5-3)

Caution: Propellers with feathering got no high pitch stop. If a feathering propeller increase rpm during descent contact HOFFMANN.

(1) Remove the propeller from the engine according chapter 3.

(2) Change the pitch with the high pitch stop nut.

(3) Turning clockwise (cw) facing the nut decreases high pitch (rpm increase).

(4) Turning counterclockwise (ccw) facing the nut increases high pitch (rpm decrease).


(5) Reinstall the propeller to the engine according chapter 3.

Picture 5-3: Adjustment high pitch stop

HOFFMANN PROPELLER


5.3 Feathering Adjustment During flight with the Engine down and the Propeller in feathering position, the Propeller shout not rotate, as

long as the aircraft speed is on or below the maximum allowed feathering speed.

If the Propeller turns under this condition, the feathering position of the Propeller has to be readjusted. This

occurs very seldom on piston engines.

5.3.1 Adjustment of the feathering pitch stop (Refer to Picture 5-4)

Caution: It could be, the Propeller turn in the wrong direction during feathering. Check first the direction of the Propeller.

(1) Remove the 4 Hexagonal Head Screws and the washers as shown on the Figure 5-4.

(2) Remove the Low Pitch Stop Cap.

(3) Change the pitch with the feathering pitch stop screw.

(4) Turning clockwise (cw) facing the nut decreases feathering pitch.

(5) Turning counterclockwise (ccw) facing the nut increases feathering pitch.

Note: If the Propeller turns in the wrong direction decrease pitch otherwise increase pitch. Change the pitch only in small steps about an half rotation of the nut.

(6) Put back the Low Pitch Stop Cap on the Propeller.



(7) Reinstall the 4 washers and Hexagon Head Screws and torque them (For the correct torque values

see torque table Chapter 10).

HOFFMANN PROPELLER


Picture 5-4: Adjustment feathering pitch stop

HOFFMANN PROPELLER


6. Maintenance and Cleaning

6.1 Inspection

6.1.1 Daily inspection

Warning: Before performing any work on the propeller follow the safety precautions given in the flight manual.

Check blade installation. No blade shake is allowed. Blade angle play up to about 1° is permitted. Check the

propeller for loose screws and safety wires, the blades and the propeller spinner for cracks and damage.

Turn blades by hand to check for smooth pitch change. Check the correct position of counterweights, if

installed.

6.1.2 100 hour inspection

To be carried out every 100 hours until TBO(Time Between Overhaul) is reached.

(1) Remove spinner dome. Perform daily inspection. Check flange bolts or stop nuts for correct torque by applying the required torque only. (Do not loosen the bolts or nuts before.) Check for oil and grease leakage. Check the sealing of the blade retention nuts. If damaged, repair with silicone rubber.

6.1.3 Inspection of the blades

To be carried out every daily and 100 hour inspection.

Inspection of wooden composite blades is easy and gives reliable results. Critical conditions will show early

as surface cracks in the paint. Therefore correct judgment of such cracks is very important.

(1) Clean the blades.

(2) Erosion on the leading edge of the blades is normal and not critical. Metal propellers erode too. On a

composite propeller the erosion sheet (Type A or B) becomes visible under the paint.

Picture 6-1: Normal erosion (no matter of concern)

HOFFMANN PROPELLER


(3) The area around the blade root between blade body and metal ferrule is sealed with silicone rubber.

NO cracks in the silicone rubber and NO separation from the metal ferrule or the blade are

permitted. A crack might indicate that the blade got loose in the ferrule. The propeller has to be

removed from service IMMEDIATELY

Picture 6-2: Blade root

(4) The erosion tipping (Type A) of the propeller blades ends in the inner third of the blade. Fine cracks

in the paint along the tipping are no reason of concern.

Picture 6-3: Erosion tipping Type A

(5) The erosion tipping (Type B and C) ends in the inner third of the blade. Fine cracks in the paint along

the tipping are no reason of concern. Cracks in the tipping perpendicular to the blade axis are not

dangerous as long as the tipping does not lift off from the blade body. Slide your fingernail along the

leading edge from the hub to the tip. If the tipping lifts off from a crack, remove propeller for repair.

Picture 6-4: Erosion tipping Type B and C

HOFFMANN PROPELLER


(6) Fine cracks in the paint or the tipping across the blade axis, especially in the outer third of the blade,

are indications of bending vibration. In an advanced stage the tipping may break or come off piece

by piece. Notches in the tipping support this procedure. If such cracks occur, contact the factory or a

service station, which is authorized by Hoffmann.

Picture 6-5: Fine Cracks in the paint or the tipping

(7) Cracks in the paint or in the blade, starting from the blade tip and extending parallel or at any angle

to the blade axis, are indications for torsional vibrations. Such cracks occur very seldom. If such

cracks occur, contact the factory or a service station authorized by Hoffmann.

Picture 6-6: Cracks in the paint or blade

(8) Hair-cracks in the paint of the blade, starting from the blade tip and / or in the blade root area and

extending in any direction are indications of vibrations or overload of the propeller blade. They are

unimportant as long as they will be paint cracks only. If they start growing quickly and penetrating

into the fibre cover contact the factory or a service station authorized by Hoffmann.

Picture 6-7: Hair-cracks in the paint

HOFFMANN PROPELLER


(9) Any damage in the paint in the area behind the metal- or PU- blade tipping has to be repainted

immediately after occurrence. There must not be a joint between metal- or PU- leading edge and the

blade body.

Picture 6-8: Damage in the Paint behind Blade tipping B or C

(10) Normal stone nicks in the fibre cover are unimportant as long as the wooden core is protected.

(11) Air bubbles or any other bubbles under the fibre cover, with a maximum diameter of 1.5 cm (0.6

inch) are unimportant, if size does not increase during operation.

(12) Scratches and nicks in the fibre cover should be protected with water resistant paint during routine

maintenance.

6.1.4 Additional periodic inspections

New propeller-engine-aircraft combinations may require additional periodic inspections between overhaul,

such as partial disassembling and inspection of the thrust bearings. These inspections have to be carried out

in the factory or a service station authorized by Hoffmann.

6.1.5 Overhaul The TBO(Time Between Overhaul) is normally the same as for the engine, but should not exceed the figures

of HOFFMANN Service Bulletin No. E 1() (latest edition). Overhaul must be carried out in the factory or a

service station authorized by Hoffmann.

6.1.6 Special inspections (1) Special inspection is required if the max. rated propeller rpm, according the EASA "TCDS", has been

exceeded by more than 10%. If the overspeed was above 20% of the max rated propeller rpm the

propeller has to be removed from service. Repair is not possible. These propellers have to be

marked as rejected.

(2) Special instructions may be necessary for unconventional installations. A conventional installation is

a tractor installation on a single engine aircraft.

6.2 Cleaning

The paint on HOFFMANN composite blades is resistant against fuel, oil and nearly all solvents. The propeller should periodically be cleaned with any gentle detergent or equivalent and protected with car polish that does NOT contain silicone. The surface protection (paint and epoxy fibre glass) should be completely sealed to prevent penetration of moisture into the wooden core. In special case contact an inspector with appropriate license to assure safe operation.

HOFFMANN PROPELLER


6.3 Repair

6.3.1 Minor damage on the blades

Minor damage (small scratches etc.) can easily be repaired. Prior to repair check that there is NO fiberglass covering and / or wooden core damage. The materials required for repair can be obtained from HOFFMANN. Proceed as follows:

(1) Clean damaged area with solvent and polish with emery cloth # 220.

(2) If required, apply filler of epoxy resin to fill the bulges. Do not apply too much filler.

(3) Allow filler to dry. Polish the hardened surface with emery cloth # 220.

(4) Apply paint (white, grey, black, blue, red or yellow). It is highly recommended to use original paint, because resistance and bonding of other paints cannot be guaranteed. Observe the curing time if several layers of paint have to be applied.

6.3.2 Repair of HOFFMANN composite blades

Presently repair of HOFFMANN composite blades can only be carried out in the factory or by Hoffmann

approved facilities.

Blade tips can be repaired if 90% of the blade remains free of cracks. Trailing edges can be repaired; the

fibre reinforced epoxy covering and the erosion tipping can be replaced.

6.3.3 Leading edge Type B or C

Caution: The leading edge protection has, depending on the type a thickness of 2mm up to 7mm only. Do not file to deep..

If the leading edge Type B or C shows sharp nicks or becomes jagged then it should be blended using a fine

file or sand paper. Should the leading edge become eroded close to the wooden core or it starts cracking

and small pieces come off the propeller should be returned for repair.

Picture 6-9: Rework leading edge Type B or C

HOFFMANN PROPELLER


7. Trouble Shooting Trouble Probable cause Remedy

Blade shake Blade bearing loose Contact Hoffmann or a Hoffmann approved service station.

Sluggish pitch change on ground

1. Cold oil 1. Run engine until a sufficient oil temperatur is reached.

2. Friction of the internal pitch change mechanism

2. Move pitch change mechanism by turning the blades by hand. If excessive friction is revealed, contact Hoffmann or a Hoffmann approved service station.

3. Oil sludge in the internal pitch change mechanism

3. Contact Hoffmann or a Hoffmann approved service station.

Surging RPM 1. Trapped air in the propelller

1. Move the propeller control several times over the complete pitch change range to release air.

2. Oil sludge in the pitch change system


3. Wrong governor 3. Contact Hoffmann or a Hoffmann approved service station.

4. Wrong pitch setting of propeller


5. Abrupt movement of propeller control lever

5. Move lever slowly and smoothly.

6. Wrong carburetor 6. Contact a Hoffmann approved service station.

7. Oscillation of tachometer drive

7. Contact a approved service station for Repair.

Differences in RPM during climb, cruise and dive at the same RPM setting (Up to ±50 RPM is normal)

1. Friction in propeller 1. Contact Hoffmann or a Hoffmann approved service station.

2. Friction in governor 2. Contact Hoffmann or a Hoffmann approved service station.

3. Tachometer malfunction

Contact a approved service station for Repair.

HOFFMANN PROPELLER


Trouble Probable cause Remedy

RPM increase during normal operation without moving the governor control lever on Models using oil pressure to increase pitch or decreasing RPM on propeller models using oil pressure to decrease pitch

1. Oil leakage, visible from outside


2. Leakage in internal oil system between governor and propeller causes blade pitch change

2. Contact engine repair station (oil transfer to propeller shaft may be faulty or supply of engine oil to governor is insufficient).

3. Internal leakage in the propeller


4. Malfunction of governor drive or relief valve

4. Contact Hoffmann, exchange governor.

Attention: If oil leakage appears suddenly during flight, take care to minimize oil pressure for pitch change. Accomplish as follows:

Models using oil pressure to increase pitch:

I Set govenor control lever at max. RPM.

II Move power lever back to decrease RPM by at least 100 RPM continue flight to the next airfield.

Models using oil pressure to decrease pitch:

I Pull governor control lever completely black.

II Reduce power as much as possible to continue flight to the next airfield.

RPM decrease during normal operation without moving the governor control lever on propeller models using oil pressure to increase pitch

1. Failure of governor speeder spring or sticking plunger in the governor


2. Malfunction or failure of connection between governor control lever in cockpit and lever on the governor

2. Contact an approved service station.

Attention: Flight may be continued to the next airfield with considerably decreased power to aviod high manifold pressure. RPM stays low.

Extremely sluggish pitch change after moving the governor control lever. (RPM changes with flight speed like a fixed pitch prpeller)

1. Oil lines between governor and propeller are closed

1. Contact engine repair station to clean the pipes.

2. Oil sludge in the prop cylinder


3. Failure of internal pitch change mechanism of propeller

3. Contact Hoffmann or a Hoffmann approved service station. Failure may occer suddenly.

To 1. and 2.: This malfunction does not appear abruptly. Function worsens slowly. It should be found during the propeller check before the flight.

HOFFMANN PROPELLER


Trouble Probable cause Remedy

Oil leakage visible from outside

Internal sealing damage

Contact Hoffmann or a Hoffmann approved service station.

Attention: Flight may be continued to the next airfield with considerably decreased power to avoid high manifold pressure. RPM stays low.

Vibration or rough running engine

1. Unbalance 1. Perform dynamic balancing

2. Propeller remains in high pitch. Indicated by high manifold pressure and/or low RPM


HOFFMANN PROPELLER


8. Shipping and Storage

8.1 Shipping Careful packing is the best protection to avoid damage during shipping. Therefore HOFFMANN provides

special wooden or cardboard boxes, which are re-useable if they will be treated carefully. The blade tips,

leading and trailing edges have to be protected sufficiently.

8.2 Storage No propeller should be stored standing on the blade tips. The best is to store the propeller in the original

packing.

Special preservation of HOFFMANN composite blades is not necessary; the existing surface protection is

sufficient. Also the hub does not need preservation if the propeller is stored in a dry room. The propeller

should not be stored near heating systems or in rooms with extreme temperature changes.

Note: For the maximum storage time, plese refer to SB (E)1()

HOFFMANN PROPELLER


9. Specials There are no special instructions for the HO-V343 Propeller.

HOFFMANN PROPELLER


10. Drawings and Tables

Drawing/ Table Pages

Drawing HO-V343(K/L/B) 10-2

Drawing HO-V343F 10-3

Drawing HO-V343()-V 10-4

Parts List HO-V343()-() 10-5

Torque Table 10-6

HOFFMANN PROPELLER


10.1 HO-V343(K/L/B) - Drawing

Picture 10-1: HO-V343(K/L/B)

HOFFMANN PROPELLER


10.2 HO-V343F - Drawing

Picture 10-2: HO-V343F

HOFFMANN PROPELLER


10.3 HO-V343()-S

Picture 10-3: HO-V343()-S

HOFFMANN PROPELLER


10.4 Parts List HO-V343()-()

Pos. Qty. Part Name Part-No. Remark

1.2 1 O-Ring PRP231-N70 K/L/B- Flange

1.8 6 Washer VP20-528 B- Flange

1.9 6 Flange Bolt AN76-12 B- Flange

1.29 2 Groove Nut VP20-749

1.30 1 Safety Washer DIN462-20x1

1.43 1 Center Ring VP20-517 K/L/B- Flange

1.44 1 O-Ring PRP228-N70 K/L/B- Flange

1.45 6 Flange Bolt VP20-1353 K– Flange

1.46 6 Washer VP20-618 K- Flange

1.49 6 Flange Bolt B6489-25 L– Flange

1.50 6 Washer B6526-7 L- Flange

1.62.5 6 Stud A-2429-4 F- Flange

1.62.6 2 Dowel Pin A-4001 F- Flange

1.63 6 Washer NAS1149F0863P F- Flange

1.64 6 Stop Nut A-2044 F- Flange

1.67 1 O-Ring PRP233-N70 F- Flange

1.68 1 Center Ring VP20-1147 F- Flange

1.109 1 Low Pitch Stop Cap VP20-1885+ HO-V343()-S

1.110 1 Low Pitch Stop Screw VP20-1893 HO-V343()-S

1.111 4 Washer DIN433-2-8,4 HO-V343()-S

1.113 4 Hexagonal Head Screw DIN912-M8x45-8.8-Zn HO-V343()-S

3.2 *) Spinner Screw MS51958-62

3.3 *) Plastic Washer A-1020

*) Quantity depends on the Spinner installed.

HOFFMANN PROPELLER


10.5 Torque Table

Caution:.To apply the torque the running torque of the nut or bolt has to be determined, and added to the nominal value.


Caution: The values are for dry threads.

Description Thread diameter Torque nominal

Flange Bolt K- Flange 1/2”-20UNF 80-90Nm (765-780 inlbs)

Flange Bolt L- Flange 7/16” -20 UNF 55-60Nm (480-525 inlbs)

Flange Bolt B- Flange 3/8” -24 UNF 35-41Nm (310-365 inlbs)

Stop Nut F- Flange 1/2”- 20 UNF 80-90Nm (765-780 inlbs)

Spinner Screw No.10-32 UNF 2.5-3.0Nm (22-27 inlbs)