Incident Overview
On December 31, 2010, about 1400 eastern standard time, a Cessna 152, registration N28BA, sustained substantial damage during a forced landing following takeoff from Wimauma Airport (FD77) in Wimauma, Florida. The aircraft was operated by Cirrus Aviation Inc. under 14 Code of Federal Regulations Part 91 as a maintenance flight. Visual meteorological conditions prevailed, and no flight plan was filed for the planned flight to Sarasota/Bradenton International Airport (SRQ) in Sarasota, Florida. The certificated private pilot, who also held an airframe and powerplant mechanic certificate, was not injured.
Preceding Events
During an earlier flight in the accident airplane, another pilot reported a rough running engine and performed a precautionary landing at FD77. That pilot suspected water in fuel as the cause. The accident pilot, acting as a mechanic, advised the other pilot not to fly the airplane back to SRQ. Instead, the mechanic flew to FD77 in another airplane and swapped aircraft with the other pilot. He subsequently performed a thorough inspection and troubleshooting of the engine and fuel system, finding no anomalies. A thorough run-up of the engine also revealed no issues.
The Accident Flight
After the inspection, the pilot/mechanic departed FD77. When the airplane reached about 300 feet above ground level, he heard a loud "bang" followed by a partial loss of engine power. He leveled the nose and confirmed the throttle lever was fully forward, but could not maintain altitude. Deeming the altitude insufficient to return to FD77, he elected to land in a field ahead. During the landing, the airplane struck a fence and a pole, slid across a road, and came to rest upright in a ditch.
Wreckage Examination
A Federal Aviation Administration inspector examined the wreckage and found damage to the nose landing gear, firewall, and forward fuselage. The No. 2 top spark plug and its associated heli-coil had separated from the cylinder. Further examination revealed worn threads on the spark plug and cylinder, and an approximate 2-inch crack originating near the cylinder head threads. The area around the top and bottom spark plug holes showed visual evidence of exhaust gas leakage.
Maintenance History
At the time of the accident, the airframe had accrued about 9,858 total tachometer hours, and the engine about 1,955 hours since major overhaul. The engine was last overhauled on November 15, 2006. The No. 2 cylinder had been removed and replaced with an overhauled cylinder on May 15, 2009, at 1,123.4 tachometer hours since last major overhaul. The engine operated an additional 832 tachometer hours after that replacement until the accident. The most recent 100-hour inspection was completed on October 8, 2010, with approximately 77 tachometer hours flown since then.
Conclusion
The forced landing resulted from a partial loss of engine power due to the separation of the No. 2 top spark plug and associated heli-coil from the cylinder, with evidence of thread wear, a cylinder head crack, and exhaust gas leakage.