NTSB Factual Report

On June 25, 2001, about 0920 central daylight time, a Lockheed P-38L-5LD Lightning, N25Y, registered to a private individual, operating as a Title 14 CFR Part 91 personal flight, executed an emergency landing to a cotton field due to a fire in the left engine in the vicinity of Greenwood, Mississippi. Visual meteorological conditions prevailed and no flight plan was filed. The aircraft received substantial damage and the commercially-rated pilot, the sole occupant, was not injured. The flight originated from Tullahoma, Tennessee, about 1 hour 20 minutes before the accident.

According to the pilot, during in-range descent to Greenwood-Leflore Airport, the left engine backfired, started running roughly, and the cockpit filled with thick black smoke. When the canopy release was eventually activated, he observed that the left engine was on fire and trailing flame was consuming the carburetor air intake scoop and the aluminum skin between the left reserve fuel tank and the left engine cowling. Due to the severity of the fire he decided to put the aircraft on the ground, gear up, as soon as possible. The site was a cotton field about 5 miles southwest of the airport.

According to an FAA inspector, examination of the wreckage site revealed that after touchdown, the aircraft slid about 600 feet in soft dirt at an angle to the furrows of cotton plants. Examination of the aircraft revealed the smoke and flames emanated from a hole in the rear area of the left engine supercharger housing. Both propellers had separated, the left engine upper nacelle and left inboard fuel tank were burned extensively, both engine lower nacelles, the right vertical stabilizer, and the underside of the fuselage sustained major ground impact damage.

According to the crew chief/mechanic for N25Y, a more thorough postcrash examination of the left engine components revealed failure of 4 to 5 supercharger compressor blades. The helix shaped, centrifugal compressor blades failed from the hub, outward, about 1/3 span. When the high rpm operating impeller blades fractured and separated, they penetrated the supercharger housing and a 3/4-inch diameter fuel feed hose to the carburetor, causing 100 octane fuel at 17 to 20 psi to shower the engine inside the nacelle, thus the in-flight fire.

NTSB Probable Cause

the failure and uncontained separation of supercharger impeller blades for undetermined reasons during normal descent, resulting in a punctured fuel line and the subsequent in-flight engine fire and emergency descent and forced landing to a farm field.