Investigators have concluded that on-ground jet blast contributed to the gradual failure of elevator cables in the Air Moorea de Havilland Canada Twin Otter that crashed in French Polynesia in 2007.
France's BEA investigation agency has recommended a ban on stainless steel cables on the type, as well as better awareness of the potential risk of jet blast.
The BEA had already determined that the Twin Otter crashed, killing all 20 occupants, after the pitch-up control cable failed shortly after departure from Moorea on 9 August 2007. But in a final report into the accident it attributes the failure to a chain of events centred on three phenomena.
These comprised significant wear on the cable's outer strands, on-ground failure of several strands - probably from heavy aircraft jet blast - and in-flight loading of the elevator when the flaps were retracted after take-off.
Six new safety recommendations are included in the final report, including those on the steel cable ban and jet-blast risk awareness.
BEA says crews lacked information and training on loss of pitch control and that the manufacturer and aviation authorities failed to take full account of the wear phenomenon. It adds that the operator omitted special inspections of the aircraft.