What happened
On 2/26/2024, a De Havilland Aircraft of Canada DHC-2, registration VH-OHU, departed Hamilton Island, Queensland, for a scenic flight to Whitehaven Beach. The aircraft was carrying the pilot and four passengers. Upon performing a water landing, the aircraft experienced a rightward yaw and subsequently nosed over, becoming submerged in an inverted position. The incident resulted in 5 minor injuries and substantial damage to the aircraft.
The investigation
Investigators examined the landing gear assembly and discovered that the right main gear had failed to retract. While the nose and left main gear had successfully retracted into the floats, the right carriage assembly had seized on the slide tube in a nearly fully extended position. Post-accident analysis revealed advanced corrosion on the right slide tube, specifically where the carriage bushings were located. This corrosion was likely a result of the aircraft being parked on land with the gear extended, combined with potential issues such as insufficient cleaning or inadequate lubrication.
Although the pilot reported seeing four blue 'gear up' lamps illuminated during pre-landing checks, the investigation found that one lamp failed to illuminate during post-accident testing. While the pilot was able to identify the status of the lamps, the investigation noted that any failure of a lamp to illuminate should have prompted troubleshooting. Additionally, the 'check gear' warning was found to be very similar to the advisory signal used for a standard water landing, which may have hindered the pilot's ability to recognize the unsafe configuration.
Findings
- The right main landing gear assembly seized near the fully extended position due to advanced corrosion on the slide tube.
- The pilot did not identify that the right main gear remained in an unsafe configuration prior to landing.
- The similarity between the 'check gear' annunciation and the standard water landing advisory increased the risk of the error going unnoticed.
- The evacuation of passengers was delayed because the rear left door could not be opened while the aircraft was submerged.
- While the aircraft lacked retrofit push-out windows and enhanced egress handles, the pilot's recent underwater escape training was instrumental in the successful rescue of all occupants.