The US tomorrow will issue a final airworthiness directive (AD) aimed at preventing Bombardier Q400 landing gear collapses.
The mandate, which requires visual and non-destructive inspections of the aft hinge of the main landing gear forward stabilizer brace for fatigue cracks beyond a certain number of landings, comes more than one month after Canadian authorities issued an emergency directive for the same issue.
That action came after Transport Canada, the certification authority for the Q400, received "several reports" of failures of a hinge on the brace.
"Laboratory examinations have found that the fatigue cracks were initiated from the dowel pin hole at the aft hinge lug of the main landing gear forward stabilizer brace where the stop bracket is attached," Transport Canada had found. "Failure of the stabilizer brace could result in the collapse of the main landing gear," the AD states.
Horizon Air, the largest operator of Q400s in the US, with 37 aircraft in service, had performed checks of 20 Q400s to which the emergency directive applied immediately after Transport Canada issued its mandate in March.
"We're always following developments on our type of aircraft," a Horizon spokeswoman told ATI at the time. "We became aware of the Transport Canada AD and began to inspect our aircraft."
Source: Air Transport Intelligence news
