What happened
On February 14, 2011, a Beechcraft BE58, registration PR-JHM, was operating a charter flight from Guarulhos International Airport to Brasília International Airport. The aircraft was carrying two pilots and two passengers.
Upon landing on runway 11L at Brasília, the aircraft traveled approximately 300 meters down the runway before the right main landing gear unexpectedly retracted. This sudden retraction caused the wingtip to strike the ground, inducing a rightward rotation. The aircraft eventually came to a stop off the runway, facing the opposite direction of its landing heading. The occupants of the aircraft were uninjured, though the aircraft sustained light damage.
The investigation
CENIPA investigators examined the complex electromechanical landing gear actuation system of the BE58. This system relies on precise adjustments, specifically the Down Lock Tension, to ensure the gear remains extended. The investigation focused on whether recent maintenance or mechanical failures contributed to the gear retraction.
Documentary reviews confirmed that all recent maintenance, including a 50-hour inspection performed one week prior, was conducted according to the manufacturer's manual. No discrepancies were found in the maintenance logs regarding the landing gear mechanism or the Down Lock Tension settings.
However, the investigation revealed significant issues regarding tire pressure. While the left main tire was found to be 12 psi below the manufacturer's recommended pressure, the right main tire was completely deflated. The investigation found that the inner tube of the right tire had been damaged due to the tire slipping against the wheel hub. This condition indicated that the right tire was also underinflated, which likely caused excessive vibration during the landing rollout.
Findings
- The low tire pressure in the right main landing gear caused significant vibration during the landing rollout.
- This vibration was sufficient to overcome the Down Lock Tension, triggering the inadvertent retraction of the right main gear.
- The left main tire was also found to be underinflated by 12 psi, suggesting that pre-flight tire pressure checks were not being consistently performed by the crew.
- Maintenance and management supervision were identified as contributing factors to the overall condition of the aircraft's operational readiness.