What happened
On 07 November 2007, a B737-200, registration ZS-OEZ, was performing a scheduled domestic departure from Cape Town International Aerodrome (FACT) to O.R. Tambo International Aerodrome. During the take-off roll, as the aircraft reached rotation speed, the crew observed a sudden drop in engine gauges for the right-hand engine, accompanied by significant changes in the aircraft's attitude. The plane experienced uncommanded rolling and yawing motions before the crew stabilized the flight path.
Following the incident, the pilot declared an emergency and requested to return to the departure airfield. While the aircraft was in the circuit, the right-hand engine separated from the wing. The crew managed to maintain a controlled climb and performed a single-engine approach. After air traffic control cleared the runway of debris left by the fallen engine, the aircraft landed safely on Runway 01. All 112 people on board (including 106 passengers and 6 crew) evacuated the aircraft without injury.
The investigation
SACAA AIID investigators examined the wreckage and the engine mounting components. The investigation focused on the failure of the engine attachment hardware and the maintenance history of the aircraft. Metallurgical analysis was performed on the recovered components to determine the nature of the structural failures.
Findings
Technical analysis revealed that the separation was triggered by the failure of the aft cone bolt. This bolt had developed a pre-existing fatigue crack, which investigators attributed to the incorrect installation of the bolt, likely involving improper torque application. This initial failure caused the engine to shift, placing extreme rotational and unbalanced loads on the remaining mounting structures. Consequently, the forward engine mount support fitting failed, and the outboard forward cone bolt fractured due to overload as the engine swung forward and sideways.
Furthermore, the investigation identified significant maintenance and oversight lapses. The operator had failed to comply with mandatory Airworthiness Directives (AD) requiring crack inspections every 700 cycles. There were no verifiable records of such inspections being performed for approximately five years prior to the accident. Additionally, the investigation found that the maintenance organization was operating under an invalid authorization, having been extended via email by a regulator inspector rather than through formal regulatory processes.