What happened
On December 10, 2018, a Raytheon C90GT, registration PR-SDA, was performing a private passenger transport flight from Belo Horizonte to Guaxupé, Brazil. During the final approach to the Guaxupé Aerodrome (SNGX), the pilot in command (PIC) noticed that the green indicator light for the right main landing gear remained unlit after attempting to extend the gear. Although the red gear lever light extinguished, indicating the extension cycle had completed, the lack of a green confirmation prompted the pilot to perform a go-around.
During the subsequent approach, the pilot cycled the landing gear three times to troubleshoot the system. The pilot also requested a ground observer to visually inspect the gear from a 1,000-foot flyover; the observer reported that all three landing gear legs appeared to be down and locked. Believing the issue might simply be a faulty indicator light, the pilot proceeded with the landing.
Upon touchdown, the aircraft initially appeared stable. However, approximately 80 meters down the runway, the right main landing gear retracted. This caused the right wing to drop and strike the runway surface. The aircraft veered off the right side of the runway, traveling 132 meters onto the adjacent embankment before coming to a stop. All 5 occupants (two crew members and three passengers) escaped the substantial damage to the aircraft without injury.
The investigation
CENIPA investigators examined the aircraft's landing gear actuation system and conducted various tests using both normal and manual extension methods. The investigation identified a malfunction in the down-lock switch of the right main landing gear. Specifically, the switch had a minor contact failure that interrupted the operation of the hydraulic power pack motor before the gear could fully lock. This failure caused the green indicator light to remain unlit and prevented the red warning light from remaining illuminated as required.
Investigators also reviewed the qualifications of the crew. While the PIC held valid multi-engine and instrument ratings, the pilot in the right seat was found to have expired multi-engine and instrument ratings. Additionally, while the aircraft's airworthiness certificate was valid, the aircraft's engine and airframe logbooks were not up to date.
Findings
- A malfunction in the right main landing gear down-lock switch caused the gear to fail to lock and subsequently retract during the landing roll.
- The pilot's decision-making process was a contributing factor, as the pilot elected to land despite the lack of a green gear indication and without performing the manual gear extension procedure prescribed in the aircraft's abnormal procedures checklist.
- The pilot failed to effectively utilize the second crew member to consult the checklist during the emergency.
- The pilot's judgment and attitude regarding the operational parameters of the landing gear system contributed to the outcome.