Auburn, AL, USA
N4133G
PIPER PA-46-350P
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.
On July 6, 2012, approximately 1455 central daylight time, a Piper PA-46-350P, N4133G, sustained substantial damage when the nose landing gear collapsed during landing at Auburn University Regional Airport (AUO), Auburn, Alabama. The commercial pilot was not injured. Visual meteorological conditions prevailed, and an instrument flight rules flight plan was filed for the flight, which departed Booneville/Baldwyn Airport (8M1), Booneville, Mississippi, approximately 1340. The personal flight was conducted under the provisions of Title 14 Code of Federal Regulations Part 91. The pilot stated that the flight from 8M1 was uneventful, and that the approach for landing was normal. As the airplane touched down on the runway, the pilot held the control yoke back and allowed the nose landing gear to "ease down." As the nose landing gear contacted the runway, the pilot heard the sound of a "squealing tire." The airplane veered to the right, the nose landing gear collapsed, and the airplane exited the right side of the runway, where it came to rest in the grass, resulting in substantial damage to the engine firewall and left wing. Postaccident examination of the airplane revealed a fracture of the engine mount at the right nose landing gear actuator attach foot. The engine mount was subsequently diasassembled, and the fractured components were sent to the NTSB Materials Laboratory for further examination. The pilot held a commercial pilot certificate with ratings for airplane single-engine land and airplane multiengine land, as well as instrument airplane. He reported 4,013 total hours of flight experience, of which 1,098 hours were in the accident airplane make and model. His most recent Federal Aviation Administration third-class medical certificate was issued in April 2012. The airplane was manufactured in 1998 and purchased by the pilot in February 1999. Review of the airplane's maintenance logs indicated that from 1999 through October 2004, the airplane accumulated 557.3 total flight hours. Between December 2004 and August 2006, there were no entries made in the airplane's maintenance log. The maintenance log indicated that the airplane was inspected in preparation for a ferry flight in August 2006, at a total aircraft time of 606.0 hours. An annual inspection was subsequently performed in November 2006 at a total aircraft time of 606.5 hours. The next entry was an annual inspection dated April 2, 2010 at a total aircraft time of 639.6 hours. The most recent annual inspection was completed on July 10, 2011 at a total time of 661.1 hours. The pilot reported that the airplane had accumulated 700 total flight hours at the time of the accident. The airplane's engine mount was of a welded tubular construction, and the attachment feet were positioned at the aft end of the engine mount. The attachment foot was welded to three support tubes, which extended forward and down, and were welded to the engine mount. The right attachment foot was fractured in the circumferential direction inboard of the support tubes. There was also a longitudinal fracture that extended from the circumferential fracture to the outboard end of the attachment foot. The circumferential fracture exhibited features consistent with failure due to fatigue. In the area of the weld and fracture, the surface displayed a matte black appearance, in contrast to the glossy black appearance of the adjoining support tubes. In addition, there were areas in the vicinity of the weld where green primer could be seen through the coating, which displayed features consistent with brush strokes and non-uniform coverage. Beginning in April 2002, the manufacturer issued a series of mandatory service bulletins (SB 1103, with subsequent revisions A, B, C, and D) requiring inspections for cracks in the areas of the nose landing gear actuator attachment feet welds. Inspections were to take place at the next regularly scheduled maintenance event upon reaching 290 hours time in service, and thereafter on a recurring basis, at a frequency interval not to exceed 100 hours. If cracks were found, the engine mount was to be replaced with a new design, which featured a one-piece landing gear actuator attachment. Replacement of the engine mount with the new design would not have alleviated the repetitive inspection requirement. The most recent revision of the service bulletin required that the paint be removed prior to fluorescent dye penetrant inspection. After inspection, the area where the paint was removed was to be coated with a corrosion prevention compound, specified in the service bulletin as Dinitrol/ARDROX AV8 and AV30. At the next inspection, these compounds are removed with an organic solvent and reapplied at the conclusion of the inspection. According to the manufacturer information, the compounds are transparent and brown in color. AV30, the final coating material, is firm, waxy, and tack-free. These compounds were not observed on the accident airplane's engine mount. Review of the airplane's maintenance log entries revealed that none of the entries referred to compliance with any revision of the service bulletin, with the exception of the most recent annual inspection, performed in July 2011. The maintenance log entry for that inspection stated, "Note – SB1103D not performed this date at owner's request."
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.
Source: NTSB Aviation Accident Database
Aviation Accidents App
In-Depth Access to Aviation Accident Reports
