What happened
On 19 January 2022, a Beechcraft C90, registration PT-OSO, took off from Pampulha - Carlos Drummond de Andrade Aerodrome in Belo Horizonte, Brazil, bound for Varginha. The flight was conducting a medical transport mission with two crew members and one passenger on board.
Shortly after takeoff, the aircraft's landing gear failed to lock in the retracted position. The crew decided to return to the departure aerodrome and attempted to deploy the gear using the emergency manual extension system. Despite these efforts, the cockpit indicators continued to show that the gear was not locked in the extended position. During the subsequent landing roll, the main landing gear retracted, causing the aircraft to veer off the right side of the runway. The aircraft sustained minor damage to the underside of the fuselage, but the crew and passenger were unharmed.
The investigation
CENIPA's investigation focused on the mechanical state of the landing gear and the crew's ability to execute emergency procedures. Investigators discovered that a set screw securing a tension nut had not been properly safety-wired, leaving it in a loose state. This allowed the tension nut to rotate while the clutch housing remained stationary, preventing the gear from moving correctly.
Furthermore, the investigation revealed that a manufacturer-mandated instructional placard, which detailed the emergency extension steps, was obscured by a decorative tapestry installed in the cabin. This tapestry covered the area near the throttle pedestal where the procedure instructions were located.
Findings
- Lack of training: The pilots were forced to perform an emergency procedure they had not been specifically trained for in a real-world scenario.
- Organizational culture: A misconception existed within the operator's organization that practicing manual gear extension would necessitate post-flight maintenance, leading the operator to exclude the procedure from the official training program.
- Maintenance oversight: A screw in the landing gear system was not properly safety-wired, which likely interfered with the gear's ability to lock.
- Obscured instructions: An instructional placard containing emergency procedures was hidden beneath a cabin tapestry.