Event Description
A pilot, who also served as the airplane's owner and mechanic, prepared for a landing. Prior to touchdown, the left main landing gear failed to extend and lock into position. The pilot proceeded with the landing using the right main and nose landing gear, which were down and locked, while the left main landing gear remained in a "hanging" configuration. Upon landing, the left main landing gear collapsed, causing the airplane to veer off the left side of the runway.
Post-Accident Examination
A subsequent examination of the aircraft revealed that the left main landing gear saddle had fractured. The saddle was a component subject to an Airworthiness Directive. The directive initially required replacement of the saddle, and after 1,200 hours of service on the new part, mandated annual dye-penetrant inspections. A review of the airframe logbook showed that the saddle had been replaced as required, and that annual inspections should have commenced in 1986. However, no records were found indicating that these inspections had ever been carried out.
Laboratory Findings
A laboratory analysis of the fractured saddle identified features consistent with fatigue cracking. Additionally, no trace of dye penetrant was found on the part, suggesting that the required inspections had not been performed.
Conclusion
The investigation determined that the left main landing gear saddle had fractured due to fatigue, and the required dye-penetrant inspections had not been conducted as stipulated by the Airworthiness Directive.