Accident Overview
On November 20, 2009, at approximately 1130 eastern standard time, a Piper PA-28-151 (registration N41765), operated by Universel Technologies/Unitec, Inc., experienced a partial loss of engine power during a local personal flight under 14 CFR Part 91. The airplane was substantially damaged during a subsequent forced landing in a wooded area near Port Charlotte, Florida. Visual meteorological conditions prevailed, and no flight plan was filed. The flight originated from Charlotte County Airport (PGD) in Punta Gorda, Florida, about 1100.
Pilot Actions and Sequence of Events
The pilot, a certificated commercial pilot, reported that after takeoff and while flying over Port Charlotte, he heard a loud "pop" sound followed by a substantial loss of engine power. Attempts to restore engine power were unsuccessful, and the engine was not producing enough power to sustain flight. The pilot announced on the PGD common traffic advisory frequency his intention to perform a forced landing and activated the emergency locator transmitter. During the descent, the airplane collided with small trees short of a clearing. Subsequently, the right wing contacted elevated terrain, causing the airplane to yaw 180 degrees to the right. The airplane came to rest upright, and all three occupants exited without injury.
Postaccident Inspection
A postaccident inspection of the engine by a Federal Aviation Administration airworthiness inspector revealed that the bottom spark plug from the No. 3 cylinder was not secured to the cylinder. The spark plug had remained attached to the engine only by the ignition lead. A helicoil threaded insert was found attached to the threaded portion of the spark plug, but the insert was unwound.
Maintenance Records
Review of the maintenance records indicated that the engine was overhauled in 1992. The overhaul entry documented that two repaired cylinders were installed, and the other two cylinders were reconditioned. Serviceable tags for the two repaired cylinders showed no indication that a helicoil was installed. No determination was made regarding when the helicoil was installed in the bottom spark plug position of the No. 3 cylinder. The engine had accumulated approximately 2,142 hours since major overhaul.