ATL93LA149

The pilot reported that the engine RPM began to decay during the initial climb after takeoff. Unable to maintain altitude, he maneuvered the aircraft to a nearby field. He force landed the aircraft in high grass, the landing gear collapsed, and the airframe received structural damage. An inspection of the engine revealed that the number 2 and 3 cylinder spark plugs were fouled, and would not produce a spark. A compression check showed no compression on the numbers 1 and 4 cylinders.

On September 4, 1993, at about 1455 central daylight time, an American AA-1, N5765L, was substantially damaged following a forced landing near Tuscaloosa, Alabama. The private pilot had minor injuries. The aircraft was operated under 14 CFR Part 91 by the pilot. Visual meteorological conditions prevailed at the time, and no flight plan was filed for the personal flight to Montgomery, Alabama. The flight was originating at the time of the accident.

The pilot reported the following: During ground operations, he performed a magneto check, and noted a 100 rpm drop (both left and right magnetos). During the initial climb after takeoff, the engine rpm dropped from 2,500 to 2,300. After checking the magnetos and carburetor heat once again, the rpm continued to decay to about 1,200 rpm. Unable to make it back to the airport, he maneuvered the aircraft towards the closest field. He force landed the airplane in a field of high weeds. All three landing gear broke off during the landing roll, and structural damage to the airframe resulted.

An inspector with the Federal Aviation Administration examined the aircraft following the accident. He reported the following: Clean, contaminant-free fuel was found in the fuel tanks, fuel lines, and carburetor. The electric fuel boost pump and engine driven fuel pump worked properly. The induction system tubes were sealed, and the air filter was clean. A compression check was performed on the engine; the numbers 1 and 4 cylinders would not develop compression. An examination of the spark plugs revealed that the numbers 1 and 4 cylinder plugs had dry, black soot deposits on the electrodes. The numbers 2 and 3 cylinder plugs were lead fouled, and would not produce a spark. These plugs were also carbon-fouled.