An Air Vanuatu ATR-72 regional aircraft that veered off the runway and slammed into two other aircraft at Port Vila had no hydraulic nose wheel steering or brakes.
The aircraft also had limited rudder authority because a switch was not on the appropriate setting, according to a preliminary report into the July 2018 accident by the Paua New Guinea Accident Investigation Commission.
The ATR-72-500 turboprop with 39 passengers and four crew on board had been flying between Tanna and Port Vila when the No. 2 engine began overheating.
Both the crew and the passengers reported hearing loud banging and hissing noises from the right side of the aircraft and passengers reported seeing white flashes in the cabin.
Investigators later determined the noises were a result of the No.2 engine compressor stalling.
The pilots attempted to stabilize the engine temperature but as they were doing so cabin crew alerted them that smoke was entering the cabin.
The pilot-in-command broadcast a MAYDAY as the smoke intensified, prompting the crew to don oxygen masks and setting off alarms in the ATR.
About six minutes after the engine began malfunctioning, the pilots received a low oil pressure alert and subsequently shut down the No. 2 engine.
However, their problems were not over.
“During the landing flare, the aircraft entered an un-commanded pitch up, forcing the PIC to release control of the power levers, and using both hands he pushed the control column forward in order to regain control of the pitch and therefore lowered the nose of the aircraft,’’ the report said.
“The copilot subsequently placed his hands on the power lever controls as the aircraft landed. Flight data analysis showed that one second after touchdown, both power levers were recorded to have been set to max reverse.
“The aircraft did not have hydraulically powered nosewheel steering and main wheel brakes. Rudder authority, for ground aerodynamic steering, was substantially limited because the switch for manual operation was not set to the appropriate setting.
“Reverse thrust was applied during the landing roll, which induced a significant left yaw resulting in the subsequent runway excursion.
“The crew reported that they could neither control, nor stop the aircraft during the landing roll.
“The aircraft diverged off the left side of the runway and crossed a taxiway before colliding with two stationary, unoccupied Britten-Norman Islander aircraft, about 320 metres from where it left the runway.”
Passengers and crew evacuated the aircraft without injury.
Investigators found that the engine failure “was not directly casual to the accident” but the preliminary report, as is usually the case, did not identify contributing factors.
“History has shown that in any accident there is never a single factor that cause(s) accidents,’’ it said.
“ Therefore, the AIC undertook further research and analysis in consultation with the operator and ATR to establish the circumstances that led to the significant runway excursion.
“The investigation found a number of non-contributory safety deficiencies that are being addressed with the issue of Safety Recommendations to those persons or organizations best placed to ensure they are appropriately addressed and result in safety improvements.”