Following in-flight separation of a large section of a Delta Air Lines Boeing 767 wing-flap, more than 200 of the type worldwide have to undergo emergency inspection. The event occurred on a 27 March approach to Dallas/Forth Worth (DFW) Airport, Texas, and the pilots reported no problems countering the resulting roll with aileron.
The US Federal Aviation Administration has issued an emergency airworthiness directive (AD) requiring flap inspections within two weeks for 767s with more than 25,000h of operation, or 10,000 flight cycles. The AD requires a torque check of the hinge-fitting bolts on the outboard trailing-edge flaps. If a bolt is outside the specified torque range, the AD requires a dye-penetrative inspection to detect cracking. Each inspection is expected to cost $420. Affected US carriers are Delta Air Lines, American, United and Alaska Airlines and UPS.
In the Delta incident, a 5.5m (18ft) section of the outboard trailing-edge flap tore loose and damaged the spoilers during the break-away, although the aircraft was landed safety.
Boeing says that a partial flap loss has not occurred before on the 767, which has accumulated nearly 5.5 million flight cycles to January 1997. An inspection of the inboard carriage-attach fitting revealed that three of six bolts attaching the flap assembly to the fitting showed corrosion and fracture before the event, but the exact failure mode of the bolts is still under investigation.
Source: Flight International
