Accident Details
On December 30, 2020, about 1600 eastern standard time, a Piper PA-46R-350T, registration N463ST, was substantially damaged when its nose landing gear collapsed during landing at York Airport (THV), York, Pennsylvania. The private pilot and two passengers were not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight.
According to a Federal Aviation Administration inspector, the airplane’s nose landing gear collapsed during landing due to an engine mount failure, resulting in substantial damage to the airframe. During subsequent repair, mechanics noted that the engine mount failed, causing the nose gear actuator to impinge the engine firewall and collapse the nose gear.
Examination Findings
The failed engine mount, Piper part number 89137-041, was sent to the NTSB Materials Laboratory for examination. On the left side of the mount, several tubes near the nose landing gear actuator attachment foot were bent and cut, and one tube was fractured near its weld to the attachment foot. The fracture surface appeared light gray with slant angles, features consistent with a ductile overstress fracture.
The right-side actuator attachment foot was also fractured. Examination of the attachment foot fracture areas showed deposits of resolidified molten metal. The areas around the deposits were tinted brown and black, consistent with local heating from a welding process. The crack was gaped open, with weld metal spanning the space between crack faces. Smaller beads of resolidified metal, consistent with weld spatter, were fused to adjacent surfaces, including exposed crack faces.
Most fracture surfaces on the right attachment foot were obscured or obliterated by post-fracture welding or heavy recontact damage. However, an area of relatively flat fracture features in planes perpendicular to the forward surface, separated by ratchet marks, was observed on the forward side. After additional cleaning, curving crack arrest lines consistent with fatigue fracture were noted.
Maintenance History
Piper Service Bulletin No. 1103F, dated September 1, 2015, required recurring inspection of PA-46R-350T engine mounts unless the mount had been replaced by Piper part number 89137-043. If cracks were found during inspection, the mount was to be replaced; no repairs were permitted. The latest annual inspection, dated July 1, 2020, contained no reference to compliance with the bulletin. The pilot-owner, who purchased the airplane on January 25, 2019, reviewed maintenance logbooks and reported no documentation of an engine mount weld repair. The date of the weld repair remains undetermined.