How Allied Air’s aircraft collapsed as crew attempted to maintain control – NSIB

The Nigerian Safety Investigation Bureau (NSIB) has released preliminary report of accident involving a Boeing 737-400 Freighter aircraft with nationality and registration marks 5N-JRT operated by Allied Air, Limited, which occurred at Nnamdi Azikiwe International Airport (DNAA) Abuja, Nigeria on 11 December 2024.

The report released on Saturday, explained how the aircraft collapsed despite efforts by the crew to maintain control.

The report stated that the accident occurred in the first sector, and there was no cargo on the flight.

The report noted that the flight crew stated that during the Final Approach, flap 30 was selected, but the flaps did not move to the commanded position; they stopped at flap.

The flight crew reported hearing a bang from the aircraft’s right side as the wheels touched down on the runway surface. The aircraft collapsed to the right when the crew attempted to maintain directional control, the report stated.

According to the report, the right main landing gear assembly detached from the aircraft, and as the landing roll continued, the engine number 2 nacelle dragged on the runway surface
until the aircraft veered off to the right of runway 22 centerline and came to a stop
on the grass verge.

“After landing, debris was observed falling from the rear side of the aircraft’s
undercarriage. The Abuja Tower immediately alerted Aerodrome Rescue and Fire Fighting Services (ARFFS) of the occurrence.

“The No.3 and No.4 Main Wheel Tyres bust.The post-occurrence inspection did not reveal evidence of a Hard Landing.
15. The FDR data indicated that from 01 November 2024 to the day of occurrence, the aircraft had performed a total of 101 landings out which 85 were flap 15 landings,” the report disclosed.

The report however stated that the
flight crew held valid, current Licence and were qualified to conduct the flight and the  aircraft had a valid Certificate of Airworthiness.

“The aircraft came in from Doula, Cameroon, on the day of the occurrence and there were no snags logged in the aircraft technical logbook.

“The flight was a cargo revenue flight.
The aircraft was scheduled for six sectors: Lagos-Abuja, Abuja-Sokoto, SokotoAbuja, Abuja-Yola, Yola-Abuja, and Abuja-Lagos. The same flight crew would operate the flights,” the report stated.

For its safety recommendation, the NSIB stated that the Nigeria Civil Aviation Authority should inspect all Allied Air aircraft for potential mechanical
and structural vulnerabilities, including Flap and Landing Gear Systems.

Further investigation show that detailed inspection and examination of the right main landing gear assembly is needed. It also revealed that  there is a need to test and inspect the flap drive system components, including the transmission
assemblies (transmission gearboxes, universal joints, ball nuts, flap tracks,
jackscrew actuators, etc.)

NSIB also noted that further inspection and testing of the aircraft main wheel tyres is also needed.