Piper PA-46-350P N4133G accident near Auburn, Alabama

Probable cause

The airplane owner’s failure to have maintenance personnel comply with an aircraft manufacturer's service bulletin to require engine mount inspections for fatigue cracks, which resulted in an undetected fatigue crack, the engine mount failing, and the nose landing gear collapsing during landing.

NTSB analysis

The pilot reported that, as the nose landing gear contacted the runway during landing, he heard the tire squealing. The airplane veered right, the nose landing gear collapsed, and the airplane departed the right side of the runway. Postaccident examination revealed that the engine mount had a circumferential fracture at the nose landing gear attachment foot and that the fracture exhibited features consistent with failure due to fatigue. A longitudinal fracture was also found extending from the circumferential fracture to the outboard end of the attachment foot. The surface of the fracture area displayed a matte black appearance, in contrast to the glossy black appearance of the adjoining support tubes. In addition, green primer, which displayed features consistent with brush strokes, could be seen through the coating in areas near the weld.

Before the accident, the manufacturer had issued a series of service bulletins (SB) that required recurring inspections for cracks in the engine mounts in the areas of the nose landing gear actuator attachment feet, the most recent of which was SB-1103D. These inspections required that paint be removed from and around the attachment feet and that corrosion prevention compound be applied after the inspection was completed. Although the nonuniform paint coverage and brush marks around the right attachment foot suggested that the paint might have been removed in accordance with the SB's inspection procedures, no corrosion prevention compound was observed on the accident airplane's engine mount, which indicates that full compliance with the SB had not occurred.

Review of the airplane's maintenance log entries revealed that none of the entries referred to compliance with any revision of the SB. The maintenance log entry for the most recent annual inspection, which was performed in July 2011, stated, "Note - SB1103D not performed this date at owner's request." If the airplane owner had maintenance personnel inspect the engine mount in accordance with the SB, the development and propagation of the fatigue cracking at the nose landing gear actuator attachment foot might have been detected and remedied before the accident.

Text from the NTSB. Open the NTSB docket for ERA12LA441 for the full record.