Incident Overview
A flight instructor and a student pilot were conducting training maneuvers in a practice area before proceeding to a nearby airport for touch-and-go landings. As the aircraft entered the traffic pattern, the student moved the landing gear selector to the down position. The left main gear down light did not illuminate. After recycling the gear, the same indication persisted. A low approach and flyby past the tower confirmed that the gear appeared down.
The instructor elected to return to the home airport rather than land at the current location. During the return flight, the instructor and student inspected the indicator light bulbs and found them functioning properly. They recycled the gear once more, at which point the gear motor circuit breaker popped and a smoke smell was detected in the cockpit. The pilots pulled the landing gear circuit breakers, and the smoke cleared. They then extended the gear using the manual extension checklist, but still received an unsafe gear indication. The instructor yawed the aircraft in an attempt to lock the gear, but the indication did not change.
Upon arrival at the home airport, the instructor performed a soft-field landing technique. As the aircraft decelerated during the landing rollout, the left main landing gear collapsed. The left wing tip and propeller struck the runway surface.
Maintenance Findings
Post-accident examination by Federal Aviation Administration inspectors revealed that the left main landing gear 'A' frame tube had failed. Airworthiness Directive (AD) 97-06-10 requires repetitive inspections of the main landing gear 'A' frame assemblies for cracks and lubrication, and mandates replacement of any cracked assembly. A review of the aircraft's maintenance records indicated that the AD had been complied with during the last 100-hour inspection on June 21, 2006. The aircraft was operated by a flight school, and maintenance records showed that a 100-hour inspection was accomplished approximately every 30 days due to its activity level.
Summary
The left main landing gear collapsed during the landing rollout after a series of gear indication anomalies and manual extension. The failure was attributed to a cracked 'A' frame tube, which had been inspected per AD requirements but subsequently failed.