Accident Overview
On June 23, 2011, at approximately 2021 Pacific daylight time, a Cessna 172S, registered as N222MF, sustained substantial damage during a forced landing near Palo Alto Airport (PAO) in Palo Alto, California. The aircraft was owned by Aviolease LLC and operated by Advanced Flyers under 14 CFR Part 91. The commercial pilot and two passengers were not injured. Visual meteorological conditions prevailed, and no flight plan was filed for the positioning flight from Concord, California, which departed at 2000 with PAO as the intended destination.
Pilot Report
According to the pilot's written statement, after an uneventful return flight, he entered the airport traffic pattern midfield for runway 31. Air traffic control advised him to follow another aircraft. While turning from base to final, the pilot applied 10 degrees of flaps. As the airplane descended through about 700 feet above ground level, the pilot felt the airplane was slightly low. He partially advanced the throttle but the descent rate continued. Applying full throttle yielded no engine response, leading the pilot to realize the engine had lost power. He troubleshooted and attempted a restart without success while continuing toward the runway. Due to low sun on the horizon, he could not see the runway fully. He initiated a forced landing to an open marsh area south of PAO. During the landing roll, the nose wheel dug into terrain, causing the airplane to nose over.
Aircraft Examination
A Federal Aviation Administration (FAA) inspector examined the wreckage. The airplane came to rest in a muddy marsh about half a mile south of PAO. The fuselage was bent and buckled aft of the baggage compartment, and the vertical stabilizer and rudder were structurally damaged. Fuel smell was present at the site. The wreckage was recovered approximately three weeks later due to tidal submersion.
Engine Examination and Test Run
The engine remained attached via all mounts, and all accessories were secure. After removing top spark plugs, the crankshaft was rotated by hand, and thumb compression was obtained on all four cylinders. Spark plugs and ignition leads were reinstalled. An external fuel source was attached to the left wing root fuel inlet line, and external power was connected to the battery leads. A replacement propeller was installed due to impact damage to the original.
The engine started and ran at various power settings for about five minutes before being shut down using the mixture control, with no anomalies noted. A magneto check showed an approximate 100 rpm drop for both magnetos. Full throttle momentarily produced a peak rpm of about 2600.
Maintenance Records
Review of maintenance records indicated the engine was overhauled on March 2, 2007, at a total time of 2,056 hours. The most recent annual inspection was completed on April 1, 2011, at a tachometer reading of 1,565 hours. At the time of the accident, the engine had accumulated 1,639.9 hours since major overhaul.
Conclusion
The reason for the loss of engine power was undetermined.