Eveleth, MN, USA
N4079R
Piper PA32
The airplane’s engine lost power during cruise flight, and the pilot executed a forced landing to a wooded area. A postimpact fire ensued, and the airplane was destroyed. Postaccident examination revealed that the engine-driven fuel pump drive shaft had fractured. No other anomalies were found. Further examination of the pump revealed internal corrosion and smeared material on the ends of the pump rotor vanes. The internal bypass spring was missing, but wear marks indicated that the spring had been in place sometime during the life of the pump. The investigation could not determine whether the spring had been removed or was destroyed and consumed internally. Heat discoloration observed on the rotor shaft was consistent with frictional heating of the shaft. Disassembly of the engine-driven fuel pump revealed that the ends of the rotor vanes that interfaced with the pump sidewalls showed evidence of smeared material, transfer marks, and other oxidized particles, which were consistent with ferrous wear debris. Such contamination of the internal pump components likely resulted in increased friction, frictional heating, and the eventual seizure of the pump, which led to the total loss of engine power during the accident flight. The investigation was unable to determine the source of the contamination based on available evidence. The engine driven fuel pump was subject to a Mandatory Service Bulletin. The service bulletin introduced pump design enhancements to improve relief valve housing sealing characteristics. These enhancements included actions to ensure that valve cover screws are tightened to correct torque values. The materials examination of the pump showed the gaskets were consistent with unmodified original components indicating the accident fuel pump had not been modified in accordance with the service bulletin. Had the service bulletin been complied with a visual inspection would have revealed gasket protrusion observed between the valve and the pump housing. This would have led to maintenance or replacement of the pump. Maintenance records were destroyed in the airplane when the accident occurred and hence were not available to substantiate if the service bulletin had been complied with.
On July 5, 2020, about 1200 central daylight time, a Piper PA-32-300, N4079R, was destroyed when it was involved in an accident near Eveleth, Minnesota. The pilot and passenger sustained minor injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot reported that the airplane had about 55 gallons of fuel onboard before the flight began, including 14 gallons in the left-tip tank. The pilot also reported that he started the engine with a main tank and then switched to the left-tip tank for takeoff; he did not recall switching fuel tanks after that. After takeoff, the airplane climbed to 7,500 ft mean sea level and leveled off. Shortly afterward, the engine lost total power. The pilot’s attempts to restart the engine were not successful, so he decided to glide the airplane to the nearest airport. When the pilot realized that the airplane had insufficient altitude to reach the target airport, he executed a forced landing to a wooded area. During the forced landing, both wings separated from the airplane; the fuselage and tail surfaces were impact damaged; and various parts of the airplane, including the cabin section, were damaged by postimpact fire. Postaccident examination of the airplane revealed that the drive coupling on the engine-driven fuel pump had fractured. No other anomalies were found during the examination. Subsequent laboratory examination of the engine-driven fuel pump found that the drive coupling fracture surface had features consistent with torsional overstress. Additional features resembling ratchet marks were observed around the shaft. No evidence of fatigue was noted, but smearing was found on the outer edge of the fracture surface. Disassembly of the pump revealed difficulty rotating the input shaft by hand and that the input shaft, once freed, could only be rotated about 90° before it seized. The disassembly of the pump also revealed that the spring for the bypass valve was missing. Wear marks indicated that the spring had been present at some time during the life of the pump. Material consistent with rust was found on several internal components of the pump. The ends of the rotor vanes that interfaced with the pump sidewalls showed evidence of smeared material, transfer marks, and other oxidized particles, which were consistent with adhesive wear and ferrous wear debris. The rotor shaft had a discolored region consistent with heat discoloration, which was consistent with frictional heating of the shaft. The rotor shaft also had areas of pitting and missing material on the outside edge of the rotor, which was consistent with spalling. The part number identified on the engine-driven fuel pump was subject to Textron Lycoming Mandatory Service Bulletin No. 539A, issued November 22, 2000, which was a reprint of Crane/Lear Romec Service Bulletin No. RG9080-73-001, issued November 29, 1999. The Crane/Lear Romec service bulletin introduced pump design enhancements to improve relief valve housing sealing characteristics. These enhancements included actions to ensure that valve cover screws are tightened to correct torque values. Materials examination of the pump showed the gaskets were consistent with unmodified original components indicating the accident fuel pump had not been modified in accordance with the service bulletin. The pilot reported that the airplane’s maintenance records were in the airplane at the time of the accident. The maintenance records were not subsequently found.
The seizure of the airplane’s engine-driven fuel pump due to internal contamination, which led to a total loss of engine power. The source of the contamination could not be determined based on available evidence.
Source: NTSB Aviation Accident Database
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