Event Description
During the landing roll, the nose gear of the aircraft collapsed. The same aircraft had previously experienced a total electrical failure on an earlier flight. During the approach of the accident flight, the aircraft encountered another total electrical failure. After the first electrical failure, company maintenance personnel replaced the battery and verified the electrical system operation according to manufacturer procedures.
Examination Findings
Post-accident examination disclosed that the output lugs were broken off both alternators. The National Transportation Safety Board conducted a metallurgical examination of the fracture surfaces. The analysis showed no discernable fracture features. Both parts exhibited evidence of electrical arcing, which resulted in significant melting of the separated ends. A subsequent landing gear retraction test was performed, revealing no discrepancies with the landing gear system.
Maintenance and Inspection
The airframe Maintenance Manual inspection checklist includes directives to inspect wiring to the engine and accessories, replace damaged wires and clamps, and inspect terminals for security. Additionally, the section of the maintenance manual that describes servicing the electrical system states: "The security of all electrical connections should be checked." The time elapsed since the last annual inspection was 12.7 hours.