Testing After Install
After installation of a propeller, the engine must be ground run in order to check the propeller for correct function and operation. Aircraft propeller installations vary considerably, and no set testing procedure would be satisfactory for all aircraft. It is imperative, therefore, that any particular installation should be tested in accordance with the approved AMM procedure, which will normally include the following general requirements:
- The engine should normally be fully cowled, and the aircraft should be facing into wind before starting an engine run. It is sometimes recommended that the pitch change cylinder should be primed with oil before starting, by operation of the feathering pump.
- The safety precautions appropriate to engine ground running should be taken, the controls should be set as required, and the engine should be started.
- As soon as the engine is operating satisfactorily, and before using high power, the propeller should be exercised in the manner specified in the Maintenance Manual, to establish that the pitch change mechanism is operating.
- The checks specified in the Maintenance Manual to confirm satisfactory operation of the propeller system, including constant speed operation, feathering, operation of the propeller pitch change throughout its range, synchronisation with other propellers on the aircraft, and operation of associated warning and indicating systems, should be carried out.
- Engine running time should be kept to a minimum consistent with satisfactory completion of the checks, and a careful watch should be kept on engine temperatures to avoid overheating. With turbine engines, changes to operating conditions should be carried out slowly, to avoid rapid engine temperature changes, and to conserve engine life.
- When all checks have been successfully carried out, the engine should be stopped, and a thorough inspection of all propeller system components should be carried out, checking for security, chafing of pipes and cables, and signs of oil leaks.
- Don't forget to complete all paperwork related to the maintenance activity, including Duplicate Inspections.
Note: If vibration was experienced during the engine run, the hub retaining nut should be re-tightened after the engine shaft has cooled down.