Component maintenance manuals help eliminate downtime
By Eric Blickley
Strict maintenance of the engine and its components is required to maximize engine performance for a variety of flight conditions. In time these components, as well as the engine, require overhaul. Whether removed for scheduled or unscheduled
maintenance, it is critical to follow the information in the component maintenance manual (CMM) and the Material Safety Data Sheets (MSDS).
Engine flight-hours are the primary reason to remove the engine or engine component. The time between overhauls (TBO) can be found in the engine maintenance manual and in the CMM for the individual components. Many original equipment manufacturers (OEMs) post this information on their web site. Woodward's recommended TBO periods for their propeller governors, pumps, auto feather valves, speed signal generators, and Type I synchronizer components can be found at www.woodward.com/AES/customer/glservbul.cfm .
Surges and fluctuations in engine and/or propeller speeds are often attributed to problems with the control accessories. However, this is not always the case. Internal leakage, rigging, or problems with the propeller may cause these symptoms. Improperly adjusting the settings on propeller controls can also cause overspeed or fluctuations. To save downtime and cost of repairs confirm the cause of engine symptoms before removing any component by following the aircraft troubleshooting recommendations.
Common causes of unscheduled removals for propeller controls include:
- sudden stoppage
- oil contamination
- lightning strike incidents
If the propeller makes contact with any object, it can cause sudden stoppage, which causes stress in the rotating components. The propeller does not have to come to a complete stop. Bird and deer strikes and "gear -up" landings are known causes for sudden stoppage.
Oil contamination can also cause excessive wear on the component and reduces the TBO. Lightning strikes can cause serious damage to the components by arcing the bearings and magnetizing the metal.
Common causes for unscheduled removal of fuel controls include:
- Overboard drain leakage
- Slow start
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