NTSB Identification: LAX97LA163.
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Accident occurred Friday, April 18, 1997 in TUCSON, AZ
Probable Cause Approval Date: 05/04/1998
Aircraft: Piper PA-28R-201T, registration: N2847F
Injuries: 2 Uninjured.

NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.

At 300 feet agl in the takeoff initial climb the engine ran roughly for a moment, then smoothed out for a short time at a low power output. The pilot stated that the engine power was insufficient for flight, and, he did not feel that he had sufficient altitude or vehicle energy to return to the runway. The pilot therefore elected to land on a dirt road. The right wing contacted trees during the landing rollout. An engine overhaul was completed on April 3, 1997, and it was reinstalled on the airframe on April 17th, 2 hours prior to the accident. The overhaul facility performed work on only the core engine. The operator's maintenance facility reinstalled all accessories, including all fuel system components, on the engine prior to installing it on the airframe. External visual examination of the engine noted blistered, missing, and discolored paint on the No. 2 cylinder, which had no compression. No valve lash was observed at the No. 2 cylinder intake valve, and air leakage was noted from that area. Exhaust gas residue was noted in all intake tubes during their removal from the engine. The No. 2 cylinder bottom spark plug electrode was damaged, with deposits of what appeared to be molten metal particles. The plugs for cylinders 1, 3, and 4 exhibited sooting. All fuel injection nozzles, including the No. 2 cylinder, were unobstructed. Bench flow tests confirmed normal postaccident flows for the distributor, nozzles, and lines. The No. 2 cylinder was removed from the engine. The piston and combustion chamber were burned. The intake valve stem and back face were burned, and the head was distorted into a tulip configuration. The valve length was stretched. No other internal abnormalities were noted with the engine.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

The partial blockage of the No. 2 cylinder injection line/nozzle by a transient contaminant, which induced an excessively lean mixture in that cylinder, and the subsequent overheating of the cylinder and intake valve. The engine power loss was due to the open intake valve allowing hot exhaust gasses into the induction system. The contamination was due to inadequate installation/inspection procedures used by the operator's maintenance organization when the fuel system was reinstalled on the engine following the overhaul.

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