NTSB Identification: FTW98LA404.
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Accident occurred Friday, September 18, 1998 in DUCK CREEK, UT
Probable Cause Approval Date: 12/01/1999
Aircraft: Piper PA-28RT-201T, registration: N8252S
Injuries: 1 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.

The airplane was in cruise flight at 12,500 feet when the pilot noticed the manifold pressure had dropped from 51.8 inches to 25 inches. 'The engine had poor response to throttle movement, and the engine sounded bad when I moved the throttle.' He made the decision not to proceed further due to the remote terrain. As he checked his maps for the nearest airport, the airplane lost altitude. 'The engine did not seem to have much power, and I was about 3,000 feet AGL by this time.' The pilot made a forced landing on a dirt road. During rollout the aircraft struck poles alongside of a cattle guard. According to the salvage company and the FAA inspector who examined the engine, two of the four screws securing the rocker cover on the number 3 cylinder were missing, and oil was leaking out. The rocker cover had a round indention on the outside, and a wear mark on the inside. The exhaust rocker arm studs were also loose. The rear stud was only finger tight. Aluminum was found imbedded in its threads. The front stud was loose, but its nut locking mechanism was still in place.

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

Loose intake valve rocker arm studs that allowed a loss of compression and a loss of oil. A factor was unsuitable terrain on which to make a forced landing and poles next to a cattle guard.

Full narrative available

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