Engine Sudden StoppageWhat is a prop strike? 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 43.13-1A. 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. Teledyne Continental powered aircraft operating under Part 135 of the F.A.R.'s, that have to comply with all manufacturers service bulletins, would have to comply with Service Bulletin 96-11 requiring total disassembly and inspection after any incident that required removal of the propeller for repairs or if the engine physically lost R.P.M.'s during the incident. An aircraft, operating under the same regulations, that is powered by a Textron Lycoming engine, would have to comply with Service Bulletin 475B after a propeller strike of any kind and would also have to comply with A.D.note 91-14-22 if the propeller strike was deemed a sudden engine stoppage. On these Textron Lycoming powered aircraft, it is the responsibility of the inspecting technician to determine if the engine should be removed from service for disassembly and inspection. These are the legal requirements as I see them. There may be other additional requirements mandated by insurance policies or engine manufacturer's and or overhauler's warranties. Either may require additional inspection requirements but neither may negate the inspections required by the F.A.R.'s. Never allow an insurance adjuster to dictate the inspection requirements after an incident. Always rely on the inspecting technician, applicable service data and the F.A.R.'s to dictate how thorough an inspection is necessary to continue the engine in service. After the extent of the inspection has been determined, it is important, as with any major repairs that are accomplished on your aircraft, to find out exactly what is included in the estimate to repair your engine following a prop strike. Are the minimum legal requirements being met? Is the engine being completely disassembled and inspected? What other services or inspections are being performed at the same time as the inspection? If the engine is being disassembled does the estimate include testing after reassembly? Are any of the engine's accessories inspected and if so to what extent? Are there any hidden costs? After finding out the answer to these questions, it's time to discuss with your insurance company what they will pay for and what they won't, before it's a big surprise after the inspection has been completed. Many insurance companies will not pay for any inspection requirements unless damage from the incident is found during that inspection. Others will pay for all costs for the inspection and for any parts needed due to the incident. Still others will only pay for the labor to do the job and will not pay for any parts. Finding out what needs to be done and whether that agrees with what you feel should be done, who's going to do it and who is going to pay for it, should help make the experience of a prop strike as painless as possible.
by Mahlon RussellSend your questions, to Mahlon at mahlon@mattituck.com or Click below for another Article © Mahlon Russell 1997 |