The pilot reported that, during the postmaintenance test flight, the turboprop engine lost power. The
airplane was unable to maintain altitude, and the pilot conducted a forced landing, during which the
airplane was substantially damaged.
The engine had about 9 total flight hours at the time of the accident. A teardown of the fuel pump
revealed that the high-pressure drive gear teeth exhibited wear and that material was missing from them,
whereas the driven gear exhibited little to no visible wear. A metallurgical examination of the gears
revealed that the damaged drive gear was made of a material similar to 300-series stainless steel instead
of the harder specified M50 steel, whereas the driven gear was made of a material similar to the
specified M50 steel. Subsequent to these findings, the airplane manufacturer determined that the gear
manufacturer allowed three set-up gears made from 300-series stainless steel to become part of the
production inventory during the manufacturing process. One of those gears was installed in the fuel
pump on the accident airplane, and the location of the two other gears could not be determined. Based
on the evidence, it is likely that the nonconforming gear installed in the fuel pump failed because it was
manufactured from a softer material than specified, which resulted in a loss of fuel flow to the engine
and the subsequent loss of engine power.
Category: Maintenance Flight
The airplane had not been flown for about 5 months and the purpose of the accident flight was a maintenance test flight after both engines had been replaced with higher horsepower models. Witnesses observed the airplane depart and complete two uneventful touch-and-go landings. The airplane was then observed to be struggling to gain altitude and airspeed while maneuvering in the traffic pattern.
The Beech King Air had undergone maintenance that included a landing gear disassembly and inspection in preparation for the airplane’s sale. Following the landing gear inspection, the left main landing gear strut was overfilled to an extension that exceeded maintenance specifications due to the strut not being able to maintain the manufacturer’s specified pressure/extension.
The pilot was landing the twin-engine, turboprop airplane on a 3,000-foot-long, 70-foot-wide, asphalt runway, when he encountered a high sink rate. He applied engine power; however, the engines did not respond quickly enough to prevent a hard landing. During the hard landing, the main landing gear separated and the left landing gear struck the vertical stabilizer. The pilot subsequently performed a go-around and landed on a grass runway, without further incident. The pilot stated that he did not experience any mechanical malfunctions. He reported 5000 hours of total flight experience, which included 500 hours in the same make and model as the accident airplane.
The airplane had not been flown for about 5 years prior to the accident, and was undergoing maintenance in preparation of a ferry flight. A mechanic reported that he had asked the pilot to conduct some engine run-ups as close to full power as possible. The pilot taxied to runway 35, a 2,470 foot-long, 35 foot-wide, gravel and turf runway; where he performed two high speed engine run-ups.