Fatigue cracks found in US cargo plane that crashed on take-off killing 14

Washington: Fatigue cracks and evidence of stress failures were found in key parts of the cargo plane that lost an engine and crashed on take-off in the US state of Kentucky earlier this month, killing 14 people.

In a preliminary report, the US National Transportation Safety Board said it found evidence of fatigue cracks and overstress failure in mechanical structures that attached the left engine to the underside of the wing of the aircraft.

New images from an airport surveillance camera, released by the NTSB overnight, show the left engine and pylon separated from the wing just as the plane began to lift off from the runway in Louisville.

The left engine is seen to detach, catch fire and propel through the air as the wing also ignited, and the plane struggled to climb. It never made it higher than 30 feet above ground level, the NTSB said.

UPS flight 2976, a McDonnell-Douglas MD-11, cleared a blast fence at the end of the runway, but its landing gear hit the roof of a UPS warehouse at the southern boundary of the airport.

“The airplane then impacted a storage yard and two additional buildings, including a petroleum recycling facility, and was mostly consumed by fire,” the NTSB report said.

Three crew members and 11 people on the ground died. Wreckage spread over a 900-metre-long debris field.

The NTSB examined the key engine and wing structures at its Washington laboratory. “On the aft lug, on both the inboard and outboard fracture surfaces, a fatigue crack was observed where the aft lug bore met the aft lug forward face,” it said.

“For the forward lug’s inboard fracture surface, fatigue cracks were observed along the lug bore. For the forward lug’s outboard fracture surface, the fracture consisted entirely of overstress with no indications of fatigue cracking.

“The forward top flange of the aft mount assembly was examined for indications of deformation or pre-existing fractures, but no indications were found.”

Captain Richard Wartenberg and first officer Lee Truitt each had more than 8500 hours of flying experience logged with the Federal Aviation Administration.

Truitt, the pilot flying, had logged nearly 1000 hours on the MD-11 and Wartenberg, the pilot monitoring, had nearly 5000 hours on that model.

The NTSB noted similarities between this accident and American Airlines flight 191 in 1979, a McDonnell-Douglas DC-10 that crashed on take-off from Chicago when the left engine, pylon and about three feet of the wing’s leading edge detached from the plane and fell onto the runway.

With 273 fatalities, that accident remains the deadliest aviation disaster in the US. The NTSB did not comment on the similarities and said its investigation of UPS flight 2976 was ongoing.

UPS said it appreciated the NTSB’s prompt release of preliminary findings and that the company would continue to support the investigation until its conclusion.

The freight company, which runs a worldwide hub at Louisville, grounded its MD-11s in the aftermath of the crash – about 9 per cent of its fleet. Subsequently, the FAA ordered all MD-11s to be grounded until they were inspected and repaired, if necessary.

“We continue to grieve for the lives lost in the tragic accident involving Flight 2976,” UPS said in a statement.

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