Occurrence
On 8 September 2022, at 21:42 UTC, a Boeing 747-400 cargo aircraft operated by Air Atlanta Icelandic departed from Liège Airport (EBLG) on a flight to Malta (LMML). During initial climb, the left-hand core cowl of engine No. 4 detached and fell in an urban area in Waremme, Belgium. A local resident heard the noise of a low-flying aircraft followed by a loud thud, and the next morning discovered the cowling in their garden along with damage to the garage roof. The aircraft continued to Malta, where a post-flight inspection revealed the missing cowl and a deformed right-hand core cowl. The detached cowling was identified as the left-hand core cowl of the rightmost engine (engine No. 4).
Maintenance and Pre-Flight Inspections
Earlier that day, maintenance was performed on engine No. 4, including replacement of the fan air modulating valve. This task required opening and closing the engine cowls. Multiple technicians completed the work, and job cards were signed off. A certificate of release to service was issued. Between completion of maintenance at approximately 15:00 and departure at 21:42, no additional maintenance was performed. A walkaround inspection was conducted by both maintenance staff and the flight crew, including the captain. The captain reported no findings. The walkaround took place at night, with non-optimal lighting conditions; the captain noted it was dark but the area around the aircraft was lit. After takeoff, the crew requested a right turn from the standard instrument departure to avoid weather. Shortly after, the loose cowl was torn away. No abnormal engine indications were noted during the flight.
Damage
The aircraft sustained minor damage: the left-hand core cowl of engine No. 4 was missing, the right-hand core cowl was deformed, and a flap track fairing was damaged. On the ground, garage roof tiles and slats were damaged. No injuries occurred.
Contextual Information
The aircraft was a Boeing 747-412F (manufactured 1994), registered in Iceland, with 104,418 total flight hours and 18,962 cycles. The engine was a Pratt & Whitney PW4056. The maintenance facility in Liège was well-kept, with qualified technicians holding current licences. The technicians had received initial and recurrent training, including on walkaround inspections. Weather at the time of the walkaround and departure was dark and rainy. The sun had set at 20:08, and METAR reports indicated rain and low clouds.
Similar Events
Past occurrences on various aircraft types have involved engine cowl doors opening in flight due to improper latching after maintenance, with the unlatched condition not identified during pre-flight inspections.