Incident Overview
On April 1, 2011, at 1820 central daylight time, a Piper PA-46-350P, registration N146DG, operated by Fountain Blue Management Services LLC, sustained substantial damage to both wings during a precautionary landing at Greenwood-Leflore Airport (GWO), Greenwood, Mississippi. The flight, which was personal under 14 CFR Part 91, had originated from Memphis International Airport (MEM) at 1720 en route to Lakefront Airport (NEW), New Orleans, Louisiana. Visual meteorological conditions prevailed and an instrument flight rules flight plan had been filed. The airline transport pilot and a passenger were not injured.
Sequence of Events
While climbing through 13,000 feet above ground level, the pilot heard a loud "pop" and observed a large reduction in manifold pressure. He declared an emergency with air traffic control and initiated a slow descent toward the nearest suitable airport recommended by ATC. Initially, the pilot inquired about a mechanic at that airport, but none was available. ATC then informed him that Greenwood had a control tower and a mechanic, so he diverted to GWO.
During the descent, the pilot obtained an amended clearance. The passenger visually identified the airport, but the aircraft was high. The pilot planned a downwind leg for runway 18, but as oil pressure dropped to zero and the oil warning light illuminated, he decided to land straight ahead. He lowered the landing gear to lose altitude, then shut down the engine after ensuring he could reach the runway. He raised the gear but airspeed decreased; he then lined up with a grassy area to avoid the instrument landing system and extended gear and flaps. The airplane touched down hard, struck a ditch, and collapsed the nose landing gear.
Aircraft Examination
Examination of the crash site showed three ground scars extending about 300 feet to a drainage ditch, with the aircraft continuing another 615 feet before stopping. The aircraft was recovered to a hangar. The nose landing gear actuator separated from its mount. The propeller assembly remained attached; two blades were undamaged, one blade was separated about 6 inches from the hub.
The right wing remained attached but the main spar was twisted, with diagonal wrinkling of the leading edge skins and wheel well area. The right main gear was extended and canted inboard and aft. The left wing also showed similar damage, with the main spar twisted and wing skins wrinkled. The empennage, vertical fin, rudder, horizontal stabilizers, and elevators were undamaged. Flight control continuity was confirmed.
Engine and Turbocharger Findings
The engine was secure with no external signs of catastrophic failure. Suction and compression were observed on all cylinders, and drive train continuity was confirmed. Oil was noted on cowling pieces near the right turbocharger. The left turbocharger rotated freely; the right turbocharger would not rotate. Examination revealed the shaft was displaced, and blades were broken and bent. Oil was leaking in the hot and compressor sections. The turbocharger was sent for metallurgical examination, which indicated the turbine wheel assembly failed due to a fatigue fracture of one turbine wheel blade, leading to an imbalance.
The cylinders had normal combustion deposits but were wet with oil from the right turbocharger. Spark plugs were wet with oil. The oil filter and propeller governor screen showed no metal or contaminants. The fuel distribution manifold had a trace amount of fuel and was missing a cut-off spring; fuel injector nozzles were clear.
Maintenance Records
The last annual inspection was on September 13, 2010, at 3,358.8 hours total airframe time; at the accident, total time was 3,513.0 hours. The engine had 1,326.6 hours since overhaul. Turbochargers were to be overhauled at engine overhaul or 12 years. The right turbocharger was originally assembled in May 1988, and both were overhauled on March 12, 2008. The left turbocharger was recently installed on March 30, 2011. The right turbocharger had 1,002.7 hours since overhaul.