Accident Details
On April 25, 2008, at approximately 1123 central daylight time, a Beech C90 (registration N21SP) was substantially damaged when the right main landing gear collapsed during the landing roll at Baton Rouge Metropolitan Airport (BTR), Baton Rouge, Louisiana. The commercial pilot and five passengers were not injured. The airplane was owned by Southwest Aviation Specialties LLC and operated by the United States Marine Corps (USMC) as a Title 14 Code of Federal Regulations Part 91 public-use flight. The local flight originated from BTR at approximately 1030. Visual meteorological conditions prevailed, and a visual flight rules (VFR) flight plan was filed.
During the landing roll on runway 13, the pilot reported feeling the airplane shake "as if we hit a pothole." The airplane then began to shimmy, the right wing dropped, and the airplane slid. After coming to a halt, the pilot and passengers egressed without assistance.
Investigation Findings
The responding Federal Aviation Administration (FAA) inspector determined that the upper torque knee on the right main landing gear had failed, leading to the collapse. Examination of the failed upper torque knee revealed a preexisting fracture with discoloration indicative of corrosion. A separate fracture on the same component appeared shiny and showed no corrosion.
Maintenance Records
Airworthiness Directive (AD) 2002-01-10, issued on January 22, 2002, mandated inspections of the main landing gear upper and lower torque knees for fatigue cracks. The initial inspection was required at the next 100-hour inspection and subsequently at intervals not exceeding 1,000 hours time in service. A review of the aircraft logbooks showed that the last recorded inspection of the torque knees occurred on January 3, 2003, when the airframe had accumulated 9,327.7 hours. On July 27, 2007, a logbook entry recorded the airframe time as 10,306.8 hours. After that entry, the only verifiable flight hours came from the USMC pilot's logbook. The pilot's logbook recorded flights in N21SP from October 1 to October 23, 2007, totaling over 23 hours. This operation required compliance with AD 2002-01-10, but no subsequent record of compliance was found despite continued operation. The airplane owner had leased the aircraft to a company that provided the airplane and maintenance under contract to the USMC.