Accident Sequence
During the takeoff roll at Sana'a International Airport, the crew noticed a loud bang and vibrations when the aircraft reached a speed of 95 knots. The captain decided to abandon the takeoff and initiated an emergency braking maneuver. The aircraft decelerated and came to a stop on the runway.
Damage and Evacuation
After stopping, the right wing of the aircraft was on fire. All 124 occupants evacuated the aircraft safely, with two passengers sustaining minor injuries. The aircraft was assessed as damaged beyond repair.
Investigation Findings
The official investigation determined that the accident resulted from an uncontained explosion of the first stage high pressure turbine disk of the right engine. The disk fracture originated from a low cycle fatigue crack on one of the embossments of the disk rim. This crack existed prior to the accident and was not detected during inspections conducted at the operator's workshops. These inspections followed the method defined by the manufacturer and the requirements of the airworthiness authority.
The investigation also revealed the need to reduce the intervals between inspections of these disks and to conduct two independent sequential inspections. Additionally, a design modification and progressive replacement of the disks with a new type were recommended. The limit life validation methods in use at the time were considered insufficient regarding the probability of crack detection.