What happened
On July 21, 2007, a Piper PA 34-200T Seneca II, registered OO-MLF, was conducting a student pilot proficiency check at Charleroi Airport (EBCI). The flight, operated by a Belgian flight school, proceeded normally for approximately one hour before the aircraft returned for landing on Runway 25.
While the touchdown itself was reported as normal and not excessively heavy, the aircraft's "Gear Unsafe" warning activated shortly after contact with the runway. Within seconds, the right landing gear light extinguished, and the aircraft began to bank toward the right. In response to the sudden instability, the instructor switched off both engines. The aircraft eventually came to a halt 795 meters from the end of the runway, having drifted 5 meters from the lateral centerline. Both the student pilot and the instructor escaped without injury.
The investigation
Investigators from AAIU(Be) examined the wreckage and discovered significant structural damage to the aircraft. The right wing spar, landing gear compartment, and wing surfaces sustained serious damage, and the right propeller tip was damaged following ground contact.
Detailed inspection of the right main landing gear revealed that the gear leg had separated from its support fittings. The forward support fitting, which had been replaced as a new part from the manufacturer only 131 flight hours prior, was found to have failed in a brittle manner. Metallurgical analysis of this specific component revealed a critical manufacturing defect: the silicon content was approximately 14%, nearly double the standard A356 alloy specification of 6.5% to 7.5%. This high silicon content, combined with visible porosities, rendered the part extremely fragile.
Findings
- The primary cause of the accident was the failure of the right main landing gear due to the initial breakage of the forward support fitting.
- The failure of the forward fitting was driven by an out-of-specification metal composition that significantly weakened the component.
- The breakage of the forward fitting subsequently placed an unsustainable overload on the aft support fitting, causing it to fail as well and resulting in the detachment of the landing gear leg.
- While the aircraft had undergone recent maintenance inspections, the specific nature of the metallurgical defect was not detectable through standard 50-hour or 100-hour inspection protocols.