A Trans Maldivian de Havilland DHC-6-300, registration 8Q-MBC performing a charter flight from Male to Kuredhu Island (Maldives) with 15 passengers and 3 crew, was landing at Kuredhu Island's designated but unmarked water runway, touched down but bounced. While the aircraft was still airborne after the bounce the aircraft banked left, the left wing tip dipped into the water and the aircraft veered to the left, the right wing dropped. The aircraft came to a stop with both floats still intact and in an upright position, the aircraft was moved to a buoy with the left hand engine and a dingy. Two crew and a passenger received minor injuries, the aircraft sustained substantial damage.
On Jul 29th 2020 the Maldives Accident Investigation Coordinating Committee released their preliminary report stating the first officer (31, CPL, 1,007 hours total, 768 hours on type) was pilot flying, the captain (31, CPL, 4,436 hours total, 2,774 hours on type) was pilot monitoring.
The AICC summarized the sequence of events:
According to the flight crew, no abnormalities were observed throughout the flight. Descent began 15 mins prior to landing at Kuredhu, and the FO gave the briefing and descent checks were carried out. The FO requested the PIC to standby for the line and when the Kuredhu was visible, the FO also infomed the PIC that this will be Right base for north east bound landing. The FO reported seeing white caps and the waters were choppy but was confident of landing in such rough waters, as having done similar landings even the week before. The FO communicated the line to the PIC and stated in case of goaround we will climb to 500 feet as per the SOP. The PIC advised the FO to keep the aircraft slightly t the left, closer to the reef, just on the lighter blue area, as it was believed that this area was relatively calmer. The FO reported that around 400 feet FO called out for full flap and max rpm, and repeated for a second time that in case of ground we will climb to 500 feet as per the SOP and FO stated that there was no obstruction.
The PIC confirmed landing just outside the lagoon and about 10 degrees into the wind. Landing inside appeared to be more risky to the PIC, due to number of obstructions including boats and buoys, and the landing outside the lagoon was believed to be safer. No circle overhead was carried out due to not realizing the rough conditons.
The aircraft, while landing touched down and bounced, which appeared to be manageable, according to both the flight crew. As soon as the aircraft bounced the FO was advised by the PIC to add power for a go-around. At the same time FO heard the fire alarm. As power was added after the bounce, the aircraft banked to the left with the left wing tip dipping into the water and veering the aircraft to the left.
Once the aircraft bounced, the PIC attempted to intiate a go-around by adding power but the speed bled off and there was a simulataneous left wing drop. The FO tried to level off the aircraft but reported controls extremely heavy.
Immediately after the dip, the PIC attempted to shut down the right engine as the fire bell was continuously ringing, but could not move the fuel levers as it was jammed, and as a precautionary measure subsequently activated the fire extinguisher bottles, and then switched off the fuel shutoff valves and also shut-off the right engine boost pump. The PIC instructed the FO to visually check for a fire in right engine, to which the FO confirmed there was no visible fire, but smoke emanating due to engine exhaust.
The FO recalled continuously checking outside checking for the float damages as usually float damages are associated with heavy landings.
The FO after seeking approval from the PIC, started to follow the evacuation procedure and with the assistance of the cabin crew instructed and assisted the passengers to remove the seat belts. Next passengers were instructed to remove the life jackets from under the seat and all passengers were made to wear the life jackets but was instructed not to inflate the life jackets. The passengers were told to wait for the boat.
FO reported calling the TMA dispatch three or four times and reported an accident and requested for help. A jetski (water scooter) and a speedboat arrived but the jetski declined to tow the aircraft as jetski would not have the capacity to tow the aircraft.
Using the operable left engine and controlling the aircraft using the left engine power lever the PIC attempted to maintain the aircraft. After about 15 minutes the resort dinghy arrived and helped the aircraft to be secured to the buoy.
Once the aircraft was secured the left engine was shut down, the passengers disembarked and baggage was offloaded, after which the crew went to the resort.
A weather station about 34km from Kuredhu Island reported winds from 080 degrees at 13 knots (average), 070 degrees at 23 knots maximum.
The AICC reported damage and tests with respect to the right hand engine:
- Right Hand engine found fully detached from the mount/nacelle, hanging only by the fuel hoses and fuel control rods connected to it
- One of the vibration isolators (inboard) found sheared off
- Nacelle structure to which the vibration isolators (outboard and top) were ripped off
Since it is not common for vibration isolators to sheer in the way it did, Engine vibration isolator assemblies installed on the right-hand engine, at the time of the accident require metallurgy tests to determine the cause of the failure.
These isolators undergo periodic eddy current inspections as called for in Airworthiness Directive No. CAD/2005/01R1 dated 08 April 2007, issued by CAA Maldives. The AD states that past service experience has indicated that Engine Vibration Isolator failures occur occasionally during landing at rough water conditions.