On Saturday 19 May 2001, at 1450, Boeing 767-319 ZK-NCH was on approach to land at Auckland International Aerodrome when a section of a wing flap deflection control track separated from the aeroplane. The 3 kg section penetrated the roof of an occupied warehouse and fell to the floor without causing personal injury. The crew of ZK-NCH were unaware of the event and continued with a successful landing.
The flap control track failed owing to a fatigue crack. The failure of the track was accelerated by the coincidental inclusion of slag during manufacture and extended aircraft operations at very low temperatures but still within its flight envelope.
The safety issue identified was the fatigue life of the flap control track. As a result of the incident other Boeing 767 maintenance organisations were informed and the operator initiated an additional regular inspection of the flap control track. The manufacturer subsequently reviewed the operation of the flap control track and began developing an inspection schedule to enable a cracked track to be identified before failure.
