York, PA, USA
N463ST
PIPER AIRCRAFT INC PA46R-350T
During the landing rollout at the conclusion of a cross-country flight, the nose landing gear collapsed. A postaccident examination revealed the engine mount had failed, allowing the nose landing gear (NLG) actuator to impinge the firewall resulting in substantial damage. Further examination of the engine mount revealed that the right-side NLG actuator attachment foot failed from fatigue. The area had been previously repaired by welding, and old resolidified metal was found inside the crack surfaces. The previous weld repair was of poor quality and occurred prior to the owner/pilot purchasing the airplane. There was no documentation of the repair in the maintenance records. Inspection of the engine mount was addressed by a service bulletin (SB) issued by the airframe manufacturer, and there was no record of its compliance during the latest annual inspection of the airplane. The SB also called for the replacement of cracked engine mounts as repairs were not permitted.
On December 30, 2020, about 1600 eastern standard time, a Piper PA-46R-350T, N463ST, was substantially damaged when it was involved in an accident 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 (FAA) inspector, the airplane’s nose landing gear collapsed during landing at THV resulting in substantial damage to the airframe. During the subsequent repair of the airplane, mechanics noted that the engine mount failed, resulting in the nose gear actuator impinging the engine firewall and collapsing the nose gear. The failed engine mount was sent to the National Transportation Safety Board Materials Laboratory for examination and analysis. The failed mount was Piper part number (P/N) 89137-041. On the left-side of the mount, several tubes near the nose landing gear (NLG) actuator attachment foot were bent and had been cut, and one tube was fractured near its weld to the attachment foot. Further examination revealed that the fracture surface appeared light gray and was on slant angles; features consistent with a ductile overstress fracture. The right-side NLG actuator attachment foot was also fractured. A closer examination of the attachment foot fracture areas showed deposits of resolidified pools of molten metal. The areas around the deposits were tinted brown and black, consistent with local heating produced by a welding process. The crack in the foot was gaped open, and weld metal deposits spanned and filled the space between the crack faces. Smaller beads of resolidified metal, consistent with weld spatter, were observed fused to adjacent surfaces, including exposed crack faces. Most of the fracture surfaces on the right NLG actuator attachment foot were obscured or obliterated by the postfracture weld process or heavy recontact damage. An area of relatively flat fracture features in planes perpendicular to the forward surface and separated by ratchet marks was observed on the forward side of the right NLG actuator attachment foot; these were features consistent with fatigue fracture. After additional nondestructive cleaning, curving crack arrest lines consistent with fatigue fracture were observed. Piper Service Bulletin (SB) No. 1103F (Engine Mount Inspection), dated September 1, 2015, called for the inspection of PA-46R-350T engine mounts on a recurring basis if the mount had not been replaced by Piper P/N 89137-043. Also, per the SB, if cracks were found during the inspection, the mount was to be replaced; no repairs were permitted. There was no reference in the latest annual inspection, dated July 1, 2020, indicating compliance with the SB. The pilot/owner of the airplane, who purchased it on January 25, 2019, reviewed the maintenance logbooks and reported that there was no documentation of an engine mount weld repair in the records. The date of the weld repair on the engine mount, therefore, could not be determined.
An improper weld repair of the engine mount, which resulted in a fatigue failure of the mount and subsequent nose landing gear collapse. Contributing to the accident was maintenance personnel’s failure to accomplish the manufacturer’s service bulletin pertaining to engine mount inspections.
Source: NTSB Aviation Accident Database
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