To comply with AD 2004-10-14, if it applies to your engine, the engine does not need to be completely disassembled and access to the accessory gear train can be accomplished, in most cases, with the engine still installed in the aircraft. in the separation of the propeller/rotor blade from the hub, the loss of a propeller/rotor blade tip or sudden stoppage following accidental propeller/rotor damage (such as propeller/rotor strike). Any decision to operate an engine which was involved in a sudden stoppage, propeller/rotor strike or loss of propeller/rotor blade or tip without such an inspection must be the responsibility of the agency returning the aircraft to service. Inspect all engine driven accessories in accordance with the manufacturers maintenance instructions. Prior to any ground operation of the engine assure that the propeller flange and the crankshaft flange area are free of any crack indications in addition to the engine component inspection. Lycoming's Service Bulletin 475B requires that in the event that the engine has experienced a propeller strike, inspection and possible rework of the accessory gear train as well as the rear of the engine's crankshaft is required. Nitride hardened cranks have a greater tendency to crack, since the nitride hardened materials resist bending. There may be other additional requirements mandated by insurance policies or engine manufacturer and/or overhauler warranty.
Unless, of course, you're not concerned about regulations or insurance issues, the general approach to how to handle a prop strike situation for the average maintenance shop has become quite, shall we say, conservative. This is not restricted to propeller strikes againstthe ground. Are the minimum legal requirements being met? 0000008269 00000 n O-435, and TIO-541 series engines being exempt. Some reports are quite specific about a recent prop strike in the engines history. Second, any time foreign object damage requires propeller removal for repairs other than the minor dressing of the blades as mentioned above, the incident is considered a propeller strike and must be inspected as outlined in SB 96-11B.
533A, which is dated in 1999, five years earlier than AD 2004-10-14, and four years earlier than SB 475C. Never allow an insurance adjuster to dictate the inspection requirements after an incident. Note the recurring theme of the loss of rpm or sudden stoppage of the engine runs as a key criteria for an internal inspection among the makers as well as the FAA. Any decision to operate an engine, which was involved in a sudden stoppage, propeller/rotor strike or loss of propeller/rotor blade or tip without such an inspection must be the responsibility of the agency returning the aircraft to service. 0000018430 00000 n Accessories can take quite a kinetic hit, and while it is specifically mot mentioned in the above AD, that is more of a focus issue. Compliance with this service bulletin is mandatory per AD 91-14-22. Also, some engines with a gear-driven alternator have a large, relatively thin and very vulnerable gear bolted to the forward end of the crankshaft. Lycoming's new SB seems to generalize the term propeller strike and sudden stoppage to be quite inclusive.
This dream price just may be the cast off of a prop-strike incident that has been covered up or minimized in some way-or a prop with blades that are out of spec from metal removed from previous overhauls. This damage can result in catastrophic engine failure. Not every prop strike results in sudden stoppage, but it doesn't take much to damage some of these accessories. Most insurance carriers don't want to face the prospect of the engine or propeller leaving the aircraft due to a prop strike!". This is a minor or major prop repair issue, but not a potential engine tear down issue. In this case however, there is an existing AD for quite a few differentLycoming engines that specifically mentions prop strikes and mandates some degree of tear down, but not necessarily a full tear down, and only if it is a prop strike as opposed to a sudden stoppage.