MIA94LA017

Shortly after takeoff while climbing to cruise, the engine failed. The pilot executed a forced landing in a field and landed hard. Examination of the engine revealed that the crankshaft failed at the connecting rod thrust face just above the rear fillet radius of the no.5 crankpin journal. Metallurgical examination of the crankshaft revealed that it failed due to fatigue. Review of the engine logbooks revealed that the engine was overhauled then during the run-in, a cam follower failed. The engine was disassembled and the crankshaft was magnafluxed. No defects were noted. The engine was overhauled again and had accumulated about 372 hours since the second overhaul.

On November 7, 1993, about 1500 eastern standard time, a Piper PA-32-300, N9000M, registered to Thomas J. and Carol A. Lewis, was substantially damaged during a forced landing about 5 miles north of Plymouth, Florida, while on a 14 CFR Part 91 personal flight. Visual meteorological conditions prevailed at the time and no flight plan was filed. The private-rated pilot, the sole occupant, was not injured. The flight originated about 10 minutes earlier from the Orlando Country Airport, Plymouth, Florida.

The pilot stated that shortly after takeoff while climbing to cruise, the engine began losing power, then failed. He initiated an emergency descent and while attempting a forced landing in a field, the airplane landed hard and collided with fence poles.

The engine was removed for further examination by the manufacturer and an FAA airworthiness inspector. Examination of the engine revealed that the crankshaft failed at the connecting rod thrust face just above the rear fillet radius of the No.5 crankpin journal. Dimensional measurements of all journals revealed that they were within the overhaul manual service limits. Chemical analysis revealed that the crankshaft material conformed to specification requirements. The case depth, case hardness, and core hardness of the crankshaft were determined to conform to the engineering drawing requirements.

Metallurgical examination of the fracture surfaces by the engine manufacturer revealed that the crankshaft failed due to fatigue. Magnetic particle inspection revealed heat cracks at all of the connecting rod thrust faces just above the front as well as rear fillet radii of the crankpin journals. Additionally, severely damaged spots were observed at the crank cheeks and some damaged areas were blended with no nitriding case observed in the blended areas. The metallurgical report states that lack of concaveness of the beach mark patterns at the apparent origin indicate that the fatigue initiated from a surface origin.

Review of the engine logbook revealed that the engine was major overhauled on July 27, 1990, and about 1 hour later during the engine break-in period, a camshaft follower failed. The engine was disassembled and the crankshaft in part was sent to an FAA approved repair station where the crankshaft was magnafluxed. According to the repair station work order, no cracks were detected. The crankshaft was returned and several components of the engine was replaced including both halves of the crankcase. The engine was overhauled, installed, and at the time of the accident had accumulated about 372.07 hours since the second overhaul.

The manufacturer's metallurgical report was reviewed by personnel in the NTSB Materials Laboratory in Washington, D.C., who state that the report adequately documents the factual observations.