MIA07LA072

While returning to the departure airport, the engine rpm began decreasing and the cylinder head temperature (CHT) began increasing, along with a further decrease in engine rpm. While descending for a forced landing, the airplane collided with a tree then the ground. The pilot was wearing the installed seatbelt but was not wearing the installed shoulder harness, which resulted in a deep laceration to his chin requiring 40 sutures. A total of 37 ounces of oil were drained from the engine. There was no evidence of oil evacuation from the engine. Disassembly of the engine revealed internal engine damage consistent with inadequate oil supply. The engine oil, and a 100-Hour inspection were last performed in March 2006; the airplane had been operated for 2.7 hours since then at the time of the accident.

On April 7, 2007, about 1303 eastern daylight time, an American Aviation AA-1A, N8FA, registered to and operated by a private individual, collided with a tree then the ground during a forced landing near Lakeland, Florida. Visual meteorological conditions prevailed at the time and no flight plan was filed for the 14 Code of Federal Regulations Part 91 personal, local flight from South Lakeland Airport (X49), Lakeland, Florida. The airplane was substantially damaged and the private-rated pilot, the sole occupant, sustained minor injuries. The flight originated about 1200, from South Lakeland Airport.

The pilot stated that the oil quantity was between 5.5 and 5.75 quarts when he started the flight. After takeoff the flight proceeded to a nearby airport where he performed a practice GPS approach. While returning to the departure airport, the engine decreased 100 rpm. He checked the "...fuel pump, [alternate] air, [magnetos], fuel tanks & primer, continued rpm drop." The engine gauges were in the green arc, but the cylinder head temperature began increasing. He notified Lakeland Linder Regional Airport (KLAL) Air Traffic Control Tower (ATCT), and proceeded to make an off airport forced landing. While descending for the forced landing, the airplane impacted a tree then the ground. He was wearing the installed seatbelt but was not wearing the installed shoulder harness. He sustained a cut on his chin which went to the bone; it required 40 sutures.

Postaccident examination of the airframe and engine by several FAA airworthiness inspectors revealed no oil on the exterior surface of the fuselage bottom skin, or out the crankcase breather hose. No oil was noted in the engine compartment, or on the firewall. Only 37 ounces of oil were found remaining in the engine; the oil was thick and had ferrous particles in it. Metal and carbon was noted in the oil screen, which was stuck in the housing. Resistance was noted during attempts to rotate the engine by hand. The No. 3 cylinder was removed and the connecting rod was noted to be "very tight" when attempting to move it. The same cylinder connecting rod bushing was loose in the rod. All cylinder connecting rods and compression rings exhibited evidence of thermal distress. The No. 4 connecting rod bearing exhibited metal transfer, and the piston pin bushing was loose in the rod. The No. 4 cylinder piston "...started to burn on the back side, from the top down thru the piston pin plug." The spark plugs of cylinder Nos. 1, 2, and 3 appeared "OK" but were dark in color, and the spark plugs for No. 4 cylinder exhibited aluminum transfer. All spark plugs appeared to be "low time with correct gap." The internal damage to the engine was consistent with inadequate oil supply.

Review of the maintenance records revealed the engine oil was changed on March 15, 2006, and the engine was last inspected in accordance with a 100-Hour inspection on March 29, 2006; the airplane had not been operated between the oil change and the 100-Hour inspection. The oil change and 100-Hour inspection were performed by the pilot, who is also an airframe and powerplant mechanic; the airplane had accumulated 2.7 hours since then.