What happened
On August 26, 2020, a Beechcraft C90A, registration PR-EVA, was performing a private flight from Belo Horizonte to São Paulo. The aircraft, operated by Costa Nobre Transporte Aéreo e Logística Eireli, was carrying a pilot and five passengers.
During the landing roll at Aeródromo Campo de Marte (SBMT), the right main landing gear unexpectedly retracted. This sudden mechanical failure caused the pilot to lose directional control, leading to a significant yaw to the right. As the aircraft decelerated, the right wingtip, propeller, and flaps made contact with the ground. The aircraft traveled 490 meters before coming to a complete stop, with the right wingtip resting in the adjacent grass area. All six occupants escaped the aircraft without injury, though the aircraft sustained substantial damage.
The investigation
CENIPA investigators examined the aircraft's hydraulic and electrical systems to determine why the gear retracted during the landing roll. Testing performed on hydraulic jacks revealed a burning odor near the hydraulic power pack.
Investigators focused on the landing gear indication system, which uses micro-switches to signal when the gear is down and locked. During testing, it was observed that the indicator light for the right main gear remained illuminated even when the gear was in transit. Further technical examination of micro-switch PN 90-361037-3 confirmed that the component was in a short-circuit state. This electrical fault caused the cockpit indicator to erroneously show that the right gear was locked and down, regardless of its actual position.
Findings
- The pilot was properly qualified, licensed, and medically certified for the flight.
- The aircraft was within weight and balance limits and had a valid airworthiness certificate.
- The micro-switch PN 90-361037-3 was in a short-circuit condition.
- The faulty micro-switch provided a false indication of the right main landing gear being locked and down, even while the gear was still in transit.
- Because the system erroneously signaled that the gear was locked, the hydraulic power was interrupted before the right gear could complete its extension cycle.
- The weight of the aircraft during the landing roll caused the unsecured right main gear to retract unexpectedly.