Though early in the process, investigators probing the 4 November crash of a UPS Boeing MD-11 freighter are zeroing in on the possibility that an engine mount failed moments before the crash.
That is according to a source familiar with the investigation, who says evidence is leading investigators to consider whether a rear mount failure was part of events leading the jet’s left-side GE Aerospace CF6 turbofan to separate from the wing.
It is unclear what factors might have contributed to such a failure.
Three mounts secure each of the MD-11F’s wing-mounted CF6’s to the engines’ pylons, including two forward mounts and one aft mount, according to the source, who declines to be identified due to the sensitive nature of the investigation.
The engine separated during the MD-11F’s take-off from Louisville as flight 2976 to Honolulu. With its left wing in flames, the jet gained only about 100ft of altitude before rolling left and slamming into an industrial neighbourhood immediately south of Louisville’s runway 17R.
The crash killed at least 14 people including those on the ground and three pilots aboard the jet.
Airlines have since suspended operations with the type after the Federal Aviation Administration on 8 November issued an emergency airworthiness directive grounding the aircraft. That order carried the subject component code for nacelles and pylons
The MD-11F’s engine mounts are part of a complex and highly-engineered system designed to allow the engine to break free entirely from the wing in case of some types of catastrophic engine failures.
If the engine was to separate while producing significant thrust, the turbofan would not be expected to drop from the wing, but rather to travel over the top of the wing and away from the aircraft, the source says.
Investigators have not yet uncovered any reason to suggest the position of the jet’s flaps or slats contributed to the crash, the source adds.
The US National Transportation Safety Board (NTSB), which is leading the investigation, did not respond to a request for comment. Neither did Boeing. UPS is deferring comment to the NTSB.
Investigators have already recovered the jet’s cockpit-voce and flight-data recorders, which are being evaluated.
