What happened
On May 10, 2011, at approximately 10:00 a.m., a Piper PA-25-260 (registration HI-191) was conducting local familiarization flights at the Peñuela Aerodrome in the Dominican Republic. The flight consisted of a series of takeoffs and landings as part of a training requirement for new pilots.
During the third landing attempt, ground personnel notified the pilot that the left main landing gear brake assembly had detached. The pilot proceeded with a normal approach to land, aware of the mechanical issue. Upon touchdown, the aircraft traveled approximately 300 meters before veering sharply to the right, completing a 270-degree turn. This excursion caused the left main landing gear to detach completely and resulted in the left wing striking the ground. The pilot was uninjured and able to exit the aircraft safely.
The investigation
The CIAA investigation focused on the mechanical failure of the braking system and the circumstances of the flight. Investigators examined the aircraft's maintenance records, which showed the aircraft had undergone an annual inspection in July 2010 and was compliant with applicable airworthiness directives.
Technical analysis of the wreckage revealed that the left brake caliper had fractured at the mounting bolts. The investigation examined the physical properties of the aluminum alloy used in the caliper, noting its lack of malleability and susceptibility to brittle fracture under stress. The investigation also reviewed the pilot's credentials, noting a valid commercial license and sufficient rest prior to the event.
Findings
- The primary cause of the accident was cyclic metal fatigue within the left brake caliper.
- The fracture occurred at the level of the mounting bolts, causing the assembly to detach from the landing gear.
- The nature of the familiarization flights, which involved repeated high-impact landings, likely exacerbated existing microscopic cracks in the aluminum alloy component.
- The loss of braking capability led to the uncontrolled ground excursion and subsequent wing strike.