NTSB Identification: NYC06LA038.
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Accident occurred Saturday, November 26, 2005 in Lincoln Park, NJ
Probable Cause Approval Date: 03/26/2007
Aircraft: Piper PA-24-180, registration: N6858P
Injuries: 2 Serious.
NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.
During climb-out from the departure airport, the pilot noticed the engine "felt off balance" and began to "misfire." The pilot initiated a return to the airport, and shortly thereafter the engine "backfired" and lost all power. The pilot initiated a forced landing, during which the airplane impacted trees and was substantially damaged. Examination of the engine revealed that a helicoil was cross threaded in the number 3 cylinder head, and metallic particles were adhered to the cylinder head and top of the piston. Thirteen days earlier, the pilot reported difficulty clearing one of the spark plugs, and he removed the number 3 cylinder bottom spark plug as a result. A mechanic then cleaned the spark plug hole, assured there were no steel particles in the cylinder, replaced the helicoil, installed a new spark plug, and ran the engine. The mechanic who installed the helicoil was non-certificated, and at the time the work was performed, a certificated mechanic was not present. According to Textron Lycoming Service Instruction No. 1043A, if a spark plug Helicoil insert replacement is performed with the cylinder assembled on the engine, "some provision must be made for preventing the aluminum shavings from entering the combustion chamber."
The National Transportation Safety Board determines the probable cause(s) of this accident to be: The improper installation of the helicoil by the non-certificated mechanic, and the inadequate inspection of the installation by the certificated mechanic. Full narrative available
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