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    Blade Assembly Procedure

    Introduction

    This document outlines the recommended procedure for installing blade assemblies in the propeller hub.

    The instructions assume that

    • the hub and blade assemblies have been lubricated, prior to assembly
    • all parts should be inspected for damage or corrosion.
    • the hub should be inspected for nicks and burrs at each propeller bore.
    • each blade retention assembly, including the thread on the retention nuts and thrust bearing elements should be inspected for any sign of damage.

    Note

    The instructions in this part assume that the propeller hub is already installed on the aircraft. This is the recommended procedure, however in some cases operators may find it easier to assemble the propeller before installing it on the aircraft.

    Note

    The manufacturer will have already lubricated the pitch change drive spindle and nut inside the hub. Ensure these items are adequately lubricated with grease.

    Note

    Park the pitch change mechanism at the coarse pitch limit for easier blade assembly


    Step 1  Locate & Insert Blade into Hub

        • Insert one blade assembly into the corresponding mounting bore number of the hub, while carefully aligning the cam-follower to locate into the slot of the pitch change slide.

    Note

    Each blade assembly is marked with a single digit number that corresponds to a matching bore of the propeller hub. This number is stamped on the side of the cam plate.

     

    Step 2  Align Blade

        • Take care with the alignment of the blade assembly to ensure that the alignment bearing slides completely into the lower bore of the hub.
        • When the correct alignment is achieved the blade assembly will seat completely into the hub by applying a gentle downwards force.

    Note

    By holding the blade assembly retention nut with one hand while moving the tip of the blade slightly from side to side, the correct alignment is easily found

     

    Step 3  Tighten Retention Nut

        • Use C-spanner to firmly tighten the blade retention nut to 130% of final torque value (see Step 4), so that any excess grease which may cause improper blade seating is expelled.

    Caution

    The retention nut should wind in smoothly. If resistance is met when tightening, stop and unwind to remove the blade; then reattempt blade assembly with the correct alignment.

     

    Step 4  Back off Retention Nut

      • Loosen the blade assembly retention nut a 1/4 turn.
     

    Step 5  Torque Retention Nut

    • Re-tighten the retention nut with a torque wrench to achieve pre-load torque setting.

    Attention

    Torque wrench 3/8in drive.  Ensure handle of torque wrencth is 90deg to the handle of the retention nut tool

    Note

    If torque wrench acts parallel with the C-spanner a higher torque than that of the wrench will be applied. This torque may be calculated if the length of the wrench is known using the ratio of levers method, as used with a crow’s foot extension or torque adapter

     

    Attention

     3 Series4 Series5 Series6 Series7 Series
    Pre-Load Torque 10Nm (8ftlb) 15Nm (12ftlb) 20Nm (12ftlb) tbd tbd

    Step 1  Blade Seating Check

    • Check Blade Retention nut is flush with hub face.

    Caution

    If Retention Nut is proud of hub this may indicate that excess grease packed in the Thrust-Bearing bore is causing the blade to seat improperly. Remove blade from hub and inspect grease applied in this region in accordance with lubrication instructions, remove excess.

     

    Step 2  Blade Assembly Check 1

    • Apply a moderate force side-to-side at the blade tip with one hand only and monitor the movement produced.
    • No movement should be evident between the blade assembly and hub (ignore the deflection due to the bending of the blade itself).

    Caution

    If blade assembly rocks within the hub this may indicate that excess grease packed in the Thrust-Bearing bore is causing the blade to seat improperly. Remove blade from hub and inspect grease applied in this region in accordance with CHAPTER 5.4.2, Lubrication, remove excess.

     

    Step 3  Blade Assembly Check 2

    • Apply a moderate torque by twisting blade with one hand only and monitor the movement produced.
    • No movement should be evident between the blade and the ferrule into which it is mounted.

    Note

    A slight perceptible movement between the ferrule and the hub is acceptable, which is due to backlash in the pitch change mechanism.

    Note

    The reduction gearbox on the Rotax engines has a discernible backlash. Do not confuse this backlash with movement of the blade within the hub.

     

    Step 1  Retention Nut Plate

    • Fit retention nut securing plate (P0442).
    • Check alignment between the screw holes in the hub and any two holes in the plate. Further tightening of the retention nut in the hub may be required to achieve correct alignment.
    • Secure retention plate with two philister-head screws and secure with lock-wire.

    Attention

    Slotted Screwdriver, Torque 2.0Nm

    Attention

    Twist Pliers, 0.025” SS Lock-wire

     

    Repeat procedure to assemble remaining blades (for propeller hubs using 4+ blades, perform blade installation in sequence of opposing pairs).

    Note

    After the propeller is run for the first time, operators may observe seepage of yellow jointing compound from the blade root area of the blade assembly. This compound is used during manufacture and such seepage is normal for the first few runs. Minor grease expulsion is also acceptable during first run. The blades should be wiped clean with a rag, which may be moistened with kerosene or methylated spirits if necessary.

    Parts Required

    ItemQtyPart #DescriptionImage
    1. 1  AB-xxx Airmaster Blade Assy   
    2. 1 AH-xxx Airmaster Hub Assy

     

    Tooling

    ItemQtyPart #DescriptionImage
    1. 1  AT-x  Blade Assembly Tool (C-Spanner)   
    2. 1 - Torque Wrench
    3. 1 - Lockwire Pliers

     

    Consumables

    ItemQtyPart #DescriptionImage
    1. as required   0.025” SS Lock-wire