Primary finding
Probable cause
The loss of engine power during cruise due to the number two cylinder piston connecting rod failure for undetermined reasons.
Investigator assessment
Analysis narrative
The pilot reported that he noticed the engine oil temperature indicator read too high during cruise. He opened the cowl flaps, reduced engine power, and enriched the mixture. He stated that the oil temperature decreased. However, he determined that it was still too high for safety purposes. The engine stopped and oil covered all but the far left side of the windshield. He declared an emergency, started gliding, and lowered the gear on approach. He said, “On final it became clear that I had circled to[o] wide to make the runway, but maintained best glide until striking the garage.” An examination of the airplane indicated that the number two cylinder piston connecting rod failed and fractured the top of the engine case. The cause of the piston rod failure was not determined.
Source record
Factual narrative
On July 31, 2009, about 1058 central daylight time, a Cessna 177RG, N2108Q, encountered a loss of engine power while in cruise flight en route to the Wittman Regional Airport (OSH), near Oshkosh, Wisconsin. The pilot performed a forced landing and the airplane sustained substantial damage when it impacted a garage. Visual meteorological conditions prevailed at the time of the accident. Of the three on board, the private pilot and one passenger were uninjured. The other passenger sustained minor injuries. The 14 CFR Part 91 personal flight was operating on an activated visual flight rules flight plan. The flight originated about 0930 from the Flying Cloud Airport, near Minneapolis, Minnesota, and was destined for OSH. The pilot’s report stated that he noticed the engine oil temperature indicator read too high. He opened the cowl flaps, reduced engine power, and enriched the mixture. He stated that the oil temperature decreased. However, he determined that it was still too high for safety purposes. According to the pilot, the "engine failed and oil covered all but the far left side of the windshield." He declared an emergency, started gliding, and lowered the landing gear on approach. He said, “On final it became clear that I had circled to[o] wide to make the runway, but maintained best glide until striking the garage.” Federal Aviation Administration inspectors examined the wreckage. An inspector indicated that the number two cylinder piston connecting rod failed and fractured the top of the engine case. The connecting rod fracture ends sustained post-separation damage. The pilot stated the aircraft was equipped with a digital engine monitor and warning light. He said that with “the warning light I was assured of more time to decide what course of action to take.”