NYC94LA174

The pilot and passenger were on the second leg of a cross country flight. Thirty minutes into the flight a vibration began, followed by oil seeping from the engine cowling. A few seconds later the engine failed and oil covered the airplane windshield. The pilot performed a forced landing to an open field with no forward visibility due to the oil. The pilot was unable to stop the airplane before it struck trees at the end of the field. Examination revealed that the number two cylinder had separated from the engine. Seven of the eight cylinder studs had sheared. The stud not sheared was intact and undamaged. An upper stud was rusted partially across, with the remainder of the stud sheared cleanly. The engine had been overhauled 362 tach hours before the failure by a local engine overhaul facility.

On September 10, 1994, at 1300 eastern daylight time, a Piper PA-24-250, N55GV, owned by O&A Aircraft Modifications, Inc., and piloted by Joseph S. Grabin, was substantially damaged during a forced landing to an open field near North Anson, Maine. The pilot and passenger were not injured. Visual meteorological conditions prevailed, and no flight plan had been filed for the flight operating under 14 CFR Part 91.

This was the second leg of a cross country flight that originated in Factoryville, Pennsylvania, the same day. Mr. Grabin and his passenger departed the Oxford County Regional Airport, Oxford, Maine, at approximately 1230 for the last leg to Greenville, Maine.

In the NTSB Form 6120.1/2, the pilot stated:

"...thirty minutes into the flight a vibration began in the engine. A few seconds later I noticed a small bit of oil seeping up at the rear of the cowling. I turned direct to Central Maine Airport. Thirty seconds or so later, more oil came out and covered half of the window. A few seconds later the engine let go followed by more oil in the slip stream, which completely covered the windshield...looking out the side window I turned sharp and slipped into the field with no forward visibility. Touched down was good, but I was unable to stop before the end, and went into the trees."

In the Federal Aviation Administration (FAA) Inspector's report, he stated that an inspection of the engine revealed that the number two cylinder had separated from the engine case. The top of the cylinder did not show any evidence of damage, except where it had punctured the left hand engine cowl. He further stated:

"...All damage appeared to be the result of the cylinder separating from the case. Seven of the eight cylinder mounting studs were sheared off, while the eighth stud (lower forward position) was intact...the absence of paint on this stud's threads would indicate that the nut had been originally installed when the engine was painted during overhaul...the #2 cylinder lower side of the mounting flange and the corresponding case surface showed evidence of fretting...the initial evidence indicated an undertorque situation which could have propagated into the loss of the lower forward stud mount nut. This may have resulted in the failure of the upper forward mount stud over a period of time as suggested by the rusting found on this stud...With the failure of this stud and lack of holding power from the lower forward stud, the stress on the remaining studs conceivably would cause their failure..."

The engine was installed on November 2, 1990. It had been overhauled by a company no longer in business, the Windham Aircraft Engines, Inc., of Willimantic, Connecticut. The engine had accumulated approximately 362 hours since installation.