Incident Details
On March 7, 2010, at approximately 1400 Central Standard Time, a Tecnam P92 Light Sport airplane, registration N323BR, experienced a landing gear collapse during landing at RWJ Airpark (54T) in Baytown, Texas. The aircraft was registered to 323 BR, Inc. and operated by the Flying Tigers Flight School. The flight instructor and student pilot on board were not injured. Visual meteorological conditions prevailed at the time of the accident. The flight had departed Ellington Field (EFD) in Houston, Texas, around 1230.
The flight instructor reported that they were performing a full stop landing on runway 08. He stated the landing was smooth, but as the airplane decelerated, the right-main landing gear collapsed. The right wing then impacted the runway surface. After shutting down the engine, fuel, and electrical master switch, both occupants exited the aircraft.
Investigation
An on-site inspection of the airplane found that the three bolts securing the right-main landing gear had failed. The bolts were sent to the National Transportation Safety Board Materials Laboratory in Washington, D.C., for detailed examination.
The Materials Laboratory Factual Report indicated that the two outboard bolts exhibited crack arrest markings consistent with fatigue cracking originating from multiple points. The third bolt, located inboard, displayed necking and bending of the grip diameter, with fracture characteristics consistent with an overstress separation. The bolts submitted for analysis appeared to be UNI 5737 bolts.
Service Bulletins
Tecnam had issued Service Bulletin P92/001 on August 7, 2007, requiring an inspection of the landing gear bolts within 10 flight hours for proper torque. If replacement was necessary, the bulletin specified bolts conforming to MS specifications instead of the UNI specifications.
Additionally, Tecnam released Service Bulletin SB 004-CS, which recommended that owners replace the original bolts with MS bolts. However, this bulletin was not mandatory, and it did not apply to N323BR due to its serial number.