What happened
A cargo aircraft flying from Luxembourg to Kano, Nigeria, was operating under IFR flight rules when it encountered severe turbulence while climbing through flight level 320 over the Drôme province. During this period of unstable air, the crew heard a loud double bang, followed by a sudden right roll. The aircraft's engine fire warning system activated, initially indicating a fire on engine number 4, then subsequently reporting a fire on engine number 3. The crew observed that the throttles for these engines had moved forward autonomously.
The first officer reported that the outboard engine on the right side had separated from the wing, and later communicated that both right-side engines were lost. Amidst a cabin depressurization warning and intense cockpit noise, the crew initiated emergency procedures. The flight engineer and a maintenance passenger assisted with gear extension and fuel dumping to reduce weight, while the captain managed the flight controls under difficult conditions.
The crew declared a MAYDAY and diverted toward Marseille. After identifying Istres military airfield as a suitable landing site, the first officer coordinated with air traffic control for a left-hand circuit on runway 15. The captain struggled significantly to maintain control during the final turn. Upon touchdown at 190 kt, the aircraft experienced a burst in the left main gear tires. Due to the lack of hydraulic brakes, the crew utilized the emergency braking system. The aircraft traveled 2,300 meters along the runway before veering off the left side and coming to a halt 250 meters from the runway axis. All five occupants successfully evacuated via cockpit windows and doors.
Findings
The incident was caused by the fracture of the right inboard engine pylon fitting. This structural failure allowed the engine to strike and subsequently tear away the outboard engine. It was noted that existing Airworthiness Directives (AD) regarding the periodic inspection of midspar fittings were not sufficiently effective in preventing this failure.