Fatigue failure in a bracing structure led to the landing-gear collapse on a Blue Islands ATR 42-320 turboprop as it touched down at Jersey in the Channel Islands last year.
The collapse allowed the wing-tip and propeller to strike the runway but there were no serious injuries among the 40 passengers and three crew members.
UK investigators, having analysed a crack in the brace upper arm on the left-hand main gear, have suggested that the structure might have sustained a "single overload event" at some point in its history.
This initiated a crack which propagated within the structure but remained "undetectable" until it failed during the landing on 16 June 2012, says the Air Accidents Investigation Branch. The aircraft involved (G-DRFC) was one of the earliest ATRs, serial number 7, which was 26 years old.
After a short flight from neighbouring Guernsey it touched down on Jersey's runway 27 in a slight crosswind from the left, which resulted in the left-hand main landing-gear making first contact. But the investigators state that the ATR's rate of descent on approach was "not excessive" and the aircraft did not land hard.
"Evidence provided by the flight data indicates that the landing was not extraordinary and that it was not considered to have been a contributing factor in the collapse of the landing-gear leg," says the inquiry.