History of Flight
On Sunday, 9 June 2024, a De Havilland Canada DHC-6-300 Twin Otter floatplane, registration 8Q-TMO, operated by Trans Maldivian Airways, departed its main base at Velana International Airport (MLE) for a multisector flight. The aircraft completed the first sector to Miriandhoo water aerodrome (FIN) without incident. For the second sector, it departed FIN at 1508 hours local time with seven passengers and three crew, landing at Westin Maldives water aerodrome (WST) at 1511 hours. The takeoff mass was 11,067 lbs, well below the maximum of 12,500 lbs, and fuel onboard was 750 lbs. Sea conditions at the aerodrome were calm.
Upon landing and application of reverse thrust, the flight crew heard a thud from outside, and the aircraft began tilting to the right. The first officer observed that the right float was no longer upright and the wing was drooping. The pilot-in-command shut down both engines to prevent propeller damage from the detached float. Rescue launches and dinghies arrived quickly; all passengers disembarked safely and were taken to the resort. The crew remained onboard while the aircraft was towed to the beach, where it partially submerged before being secured.
Injuries
No injuries were reported among the two flight crew, one cabin crew, or seven passengers.
Damage to Aircraft
A post-incident survey revealed that the right rear spreader bar attachment point was completely detached, with the attachment bolt sheared. The right propeller impacted the float, causing damage to the propeller and fuselage. The forward spreader bar remained attached to the floats, but flywires were damaged and the jury strut detached from the fuselage. The right-hand stairs detached, likely during beaching. The left float strut cover was damaged due to float spreading. Wing fairings and sling points remained secure. The right aft attachment was broken and the forward point cracked.
Probable Cause
The investigation determined that the right rear spreader bar attachment bolt failed due to fatigue fracture, leading to detachment of the right float. Contributing factors included intergranular stress corrosion cracking (IGSCC) on the bolt, which reduced its fatigue life.