Accident Details
Probable Cause and Findings
FOULED SPARK PLUGS ON THE NUMBER 2 AND 3 CYLINDERS, AND A LACK OF COMPRESSION ON THE NUMBER 1 AND 4 CYLINDERS, WHICH RESULTED IN A LOSS OF ENGINE POWER. A FACTOR WAS THE HIGH VEGETATION AT THE FORCED LANDING SITE.
Aircraft Information
Registered Owner (Historical)
Analysis
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.
Data Source
Data provided by the National Transportation Safety Board (NTSB). For more information on this event, visit the NTSB Records Search website. NTSB# ATL93LA149