NTSB Factual Report

HISTORY OF FLIGHT

On October 22, 2003, at 1515 Pacific daylight time, an American AA-1, N5968L, collided with the ground during a forced landing at South County Airport, San Martin, California. The forced landing was precipitated by a loss of engine power during the initial takeoff climb. The student pilot/owner was operating the airplane under the provisions of 14 CFR Part 91. The pilot and passenger were seriously injured, and the airplane was substantially damaged. Visual meteorological conditions prevailed, and a flight plan had not been filed.

The pilot stated in the Pilot/Operator Accident Report, that at 300 feet (agl) the engine became rough, lost power, and he could not maintain altitude. The pilot directed the airplane to an open area that was a county vehicle depot, and struck the depot boundary fence after making the landing. Damage to the airplane included the collapse or shearing off of the tricycle landing gear and leading edge damage to both wings.

An aircraft airframe and power-plant mechanic examined the airplane under the supervision of an FAA Inspector. The mechanic reported that the carburetor air filter was not present, the number 4 top spark plug was leaded and sooty, all gaps on the bottom spark plugs were wide, the number 2 and 4 cylinders had measured compression ratios of 5/80 and 0/80 psi respectively, and the piston wrist pins had been scraping on the cylinder walls of the number 2 and 4 cylinders.

The pilot, who was also the airplane's mechanic, reported that the Lycoming O-235-C2C engine had been installed on July 27, 1978, with at total time of 1510.57 hours and that the engine had not been overhauled since installation. The pilot provided copies of pages from the engine logbook that showed the last annual inspection on the engine was done on March 1, 2003, at a total time of 2157.5 hours. The airframe maintenance log book records a aircraft total time of 3343.4 hours on March 1, 2003, during its last airframe annual inspection.

PERSONAL INFORMATION

A review of FAA airman records revealed that the pilot held a student pilot certificate issued on June 10, 2003. He was issued a third class medical certificate on June 10, 2003, with the restriction that he posses glasses for near and intermediate vision.

ADDITONAL INFORMATION

Manufacturers Recommended Time Between Overhaul Periods (TBO)

Lycoming Service Instruction 1009AQ, affecting all Lycoming piston aircraft engines, states that "all engines that do not accumulate the hourly period of time between overhauls specified in this publication are recommended to be overhauled in the twelfth year". The specified time between overhauls (TBO) for the O-235-C2C engine is 2,400 hours.

NTSB Probable Cause

The absence of compression in two of the airplane's four cylinders, and the pilot/mechanic's failure to maintain the engine in an airworthy condition, which resulted in a loss of engine power during takeoff-initial climb, and subsequent forced landing.