NTSB Factual Report

On March 30, 2002, at 1525 central standard time, a Mooney M20F single-engine airplane, N9530M, was substantially damaged during a forced landing following a loss of engine power while in cruise flight near Grapeland, Texas. The airplane was registered to and operated by the pilot. The private pilot and his passenger were not injured. Visual meteorological conditions prevailed, and an instrument flight rules flight plan was filed, but not activated for the 14 Code of Federal Regulations Part 91 personal flight. The cross-country flight originated from Livingston, Texas, at 1500, and was destined for Addison, Texas.

The pilot reported in the Pilot/Operator Aircraft Accident Report (NTSB Form 6120.1/2) that approximately 25 minutes after departure, the airplane was in cruise flight at 1,500 feet msl when a "sudden heavy" vibration shook the airplane. He then scanned the engine instruments and everything "appeared to be normal." Subsequently, oil covered the windscreen, which severely limited forward visibility. He then initiated a forced landing to a grass field with the landing gear in the retracted position. During the landing, the airplane bounced, and the left wing "skimmed" across the top of a metal cattle feeder before impacting the ground, and the airplane spun around approximately 450 degrees before coming to rest upright.

Examination of the airplane by the FAA inspector, who responded to the accident site, revealed that the left wing spar was bent and there were two holes in the engine's #2 cylinder.

Further examination of the Lycoming IO-360-A1A engine, serial number L-14690-51A, on July 31, 2002 and August 1, 2002 at Textron Lycoming's facility in Williamsport, Pennsylvania, conducted under the supervision of the NTSB, revealed two holes on the top and bottom of the engine case between the #1 and #2 cylinders. The #2 connecting rod was found sticking out of the top hole and was not attached to the crankshaft. The #2 connecting rod cap was found separated from the connecting rod. The #2 connecting rod cap attachment bolt, nut, and both bearings were missing and not located. The other attachment bolt was found lodged inside the crankcase next to the #3 cylinder opening. The camshaft exhibited impact damage and was fractured in half at the point where the #2 connecting rod was found positioned.

Testing of the #2 connecting rod, bolt and nut was preformed on August 1, 2002 at the Lycoming Materials Laboratory. The bolt and nut fragments were checked for conformance to the engineering drawing criteria related to material and fabrication. There were no material nonconformities found with the connecting rod bolt or the nut. The lab concluded that "the connecting rod had been damaged secondarily. "

Review of the maintenance records revealed the last major engine overhaul was performed on May 18, 1993. On April 21, 2001, at the time of the last annual inspection, the engine had accumulated 997.75 hours since the last major overhaul. Further review indicated that the last entry in the engine logbook was an oil change performed on July 21, 2002, with 1097.4 hours accumulated since the last major overhaul.

NTSB Probable Cause

The loss of engine power due to the #2 connecting rod cap separating from the connecting rod. A contributing factor was the limited forward visibility due to oil on the windscreen.