Piper PA 46 350P N640BD incident near Tallahassee, Florida

Probable cause

The failure of the nose landing gear (NLG) actuator attachment bolt due to fatigue for reasons that could not be determined during postincident examination, which resulted in the NLG collapsing during landing.

NTSB analysis

After a normal takeoff for the business flight, the airline transport pilot retracted the landing gear; however, the red landing gear warning annunciator light remained illuminated. The pilot chose to divert the airplane to its base airport for landing. During the precautionary landing, the nose landing gear (NLG) collapsed, and the airplane sustained minor damage.

Postincident examination of the NLG components revealed that the aft NLG actuator bolt had fractured at the upper attachment fitting from reverse-bending fatigue, which led to the subsequent collapse of the NLG. The head of the bolt was missing, which precluded verification of the bolt part number. However, the bolt had a drilled shank, which was inconsistent with the specified part number bolt. Although the bolt was not the correct part number, the bolt diameter in the grip and the hardness and material composition conformed to the required specifications; therefore, use of the incorrect part number bolt likely did not cause the fatigue cracking. The fracture and wear patterns on the bolt were consistent with some level of torque having been applied during installation; however, the preincident level of applied torque could not be determined; therefore, it could also not be determined whether inadequate torque on the bolt resulted in the fatigue initiation. Lastly, a tug was frequently used to move the airplane during ground operations, which would have placed additional stress on the NLG attachment; however, the effect of tug usage on the incident bolt could not be determined.

Text from the NTSB. Open the NTSB docket for ERA14IA019 for the full record.