Flight and Incident
On 5 February 2000, an ATR42-300 (registration G-ORFH) operated a scheduled passenger flight from Teesside Airport to Paris. After takeoff from Runway 23 at 0719 UTC, the aircraft climbed to 19,000 feet. Approximately 20 minutes later, the cabin crew reported that a passenger had noticed a panel missing from the No 1 engine. The cabin crew member also recalled hearing a noise during takeoff, which she originally attributed to baggage movement.
From the flight deck, the crew observed that part of the No 1 engine outboard cowl door had broken off. They decided to return to Teesside, informing air traffic control of a technical problem. The crew limited airspeed to 180 knots to minimize further damage and declined to declare an emergency, though ATC placed airport emergency services on local standby. During final approach, the crew spotted a panel on Runway 23 near its threshold. The aircraft overflew the panel and landed without further incident.
Aircraft Examination
Examination revealed that the recovered panel was the lower three-quarters of the left cowl door of the No 1 engine bay. A longitudinal fracture from gross overload had separated this portion from the remainder, which stayed attached to the door hinges. The door mounting beam fasteners had failed due to overload. The left door was found with the forward and lower latch operating handles open, while the aft latch handle and catch were closed.
The detached door had struck the airframe, causing a 5-inch split in the left wing leading edge, shattering the outer pane of the left No 7 cabin window (and damaging the inner pane), scrape damage to the fuselage left side below the No 10 cabin window, and impact damage to the left sponson hydraulic reservoir access door, which tore off its hinges. Minor impact damage to the left hydraulic reservoir filler cap and battering damage to the left sponson composite fairing also occurred.
No evidence suggested the door, latches, or latchplates were defective or damaged before the incident. Markings did not conclusively indicate any latch was incorrectly engaged. Checks on the similar No 2 engine door indicated that incorrect latching would leave the door noticeably proud of the nacelle, and unlatched handles would protrude.
Maintenance and Pre-Flight Inspection
The aircraft arrived at Teesside at 1725 hours the previous day. A licensed aircraft engineer (LAE) employed by the operator conducted a weekly check from 1725 to 1845 hours, after dark on the apron. The weather was good with no precipitation. The LAE used an A-frame stepladder for access and reported completing the inspections normally, believing he had fastened the latches.
At 0650 hours on the day of the flight, the captain performed a pre-flight walk-round inspection using a torch. He believed all engine bay doors were flush with surrounding panels but could not confirm latch engagement due to the doors' height above ground.
Discussion
Evidence indicated the left cowl door had not been restrained by its latches and hinged open under propeller slipstream when engine power increased at the start of the takeoff run. Aerodynamic loads failed the door mounting beam fasteners and fractured the door. No latch failure occurred, and no reason for disengagement was found. The most likely cause was that the door was inadvertently not latched after the weekly check and not detected during the pre-flight walk-round. This condition would normally be noticeable (door proud, handles protruding), but both the check and inspection were conducted in darkness, with the aircraft positioned so the left side was shadowed from apron lights, potentially causing dazzle.
Previous Cases
No similar ATR42 engine bay door losses were found. However, the event closely followed the loss of a fan cowl door from a UK-registered Airbus A320 during takeoff from Gatwick Airport (G-VCED, AAIB Bulletin 7/2000). At least seven previous A319/A320/A321 fan cowl door losses attributed to inadvertent failure to latch occurred between 1992 and 1999, typically at rotation. In the year since this accident, four further similar cases were reported.
Recommendations
Although the damage was not severe, it was extensive and could have had more serious consequences. The aircraft had climbed to an appreciable altitude before the crew was informed of damage, and the door debris posed a hazard to other runway users.