I can't remeber where I found the below artice, but it is very good and explain prop strikes.
A prop strike is? Is it a sudden engine stoppage regardless of the cause? Is it an occasion when a prop blade strikes a foreign object and the engine continues to run? Is it hitting a rock or other loose object with a prop blade while operating on a runway or taxiway? Is it when something or someone impacts a prop blade when the engine isn't running?
The only pertinent F.A.A. definition that I have been able to find is in Advisory Circular 43.13-1B. It defines a sudden engine stoppage as; stopping an engine in one revolution or less for any reason, be it from propeller impact or from an engine failure of some sort. Both major engine manufacturer's have service literature that explains the desired course of action after accidental propeller damage and, in the case of Teledyne Continental, defines what their interpretation of a propeller strike is.
T.C.M.'s Service Bulletin 96-11, in a nutshell, says that if a propeller must be removed from the aircraft to be repaired following a propeller blade impact of any sort or if the engine physically lost R.P.M.'s from the incident, then the engine has experienced a propeller strike and it should be removed from service and completely disassembled and thoroughly inspected for damage from the incident.
Textron Lycoming, in their Service Bulletin 533, takes the approach that the safest procedure is to take the engine apart for inspection following any incident involving propeller blade damage. However, they have the caveat that the inspecting mechanic may override that position and return the engine to service without disassembly and inspection if he feels that it is the prudent and responsible thing to do.
Textron Lycoming has also published Service Bulletin 475B which requires, 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. Compliance with this service bulletin is mandatory in the eyes of the F.A.A. by A.D. note 91-14-22, if and only if, the engine has experienced a sudden engine stoppage not a propeller strike. It should be noted that to comply with A.D. note 91-14-22, the engine does not need to be completely disassembled and that access to the accessory gear train can be accomplished, in most cases, with the engine still installed in the aircraft.
What this all boils down to is that in the case of any accidental damage to a propeller installed on a aircraft operating under Part 91 of the F.A.R.'s, it is up to the inspecting technician to determine if the engine should continue in service without total disassembly and inspection. A Textron Lycoming engine, that is being operated on a Part 91 aircraft, that had a sudden engine stoppage, not a propeller strike, must comply with A.D. note 91-14-22 and Service Bulletin 475B at a minimum.
