One of two engines in the Duke Life Flight helicopter that crashed Sept. 8 showed signs of “overheating and lack of lubrication,” investigators from the National Transportation Safety Board say.
A bearing in the engine also was “worn down to the surface of the bearing race,” the investigators said in their preliminary report on an accident that killed all four people on the helicopter. Inspectors also noted that the transmission of the crashed aircraft, a separate assembly, “could not be rotated by hand.”
Witnesses reported seeing the craft trailing smoke before it went down. One heard a “popping noise,” and then watched it turn twice and descend before it disappeared from sight.
That witness thought the helicopter’s pilot, Jeff Burke, was still “in control” and that its rotors were still turning.
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Burke died in the crash, along with flight nurses Kristopher Harrison and Crystal Sollinger, and their patient, Mary Bartlett.
The helicopter was bringing Bartlett, a cancer patient, to Duke University Hospital from the Sentara Albemarle Medical Center in Elizabeth City.
It went down 15 miles from Elizabeth City hospital, in Perquimans County amid the Amazon Wind Farm U.S. East.
The wind farm is marked on navigational charts, as some of its rotors stand about 500 feet tall.
NTSB investigators say tracking data from the Eurocopter EC145 showed that after takeoff, Burke initially took it to an altitude of about 1,000 feet above sea level, then turned west and climbed to about 2,500 feet.
After about eight minutes, the craft turned toward the south, slowed and dropped down to about 1,200 above sea level. That was still well above the posted height of the wind farm, 515 feet above sea level.
Aviators typically use sea level as a reference point for altitude reporting and decisions. The coastal area near Elizabeth City is relatively low-lying, charts showing that landing fields near the crash site are no more than about 15 feet above sea level.
The NTSB report didn’t say exactly where the helicopter began descending, though eight minutes was enough time for it to reach the vicinity of the crash site given its roughly 138 mph initial cruise speed. A westerly heading lines up with the direct path between the hospitals’ helipads. A southerly or southeasterly heading doesn’t.
An aviation attorney and helicopter pilot based in Raleigh, Jim Crouse, said the report suggests to him that by the time the last altitude data point was recorded, “something was happening” that prompted Burke to begin “slowing down and descending rather rapidly.”
“I suspect with a crash of this nature they’re going to find mechanical and equipment indications of what happened,” added Crouse, a Duke School of Law graduate who represented the family of another Duke Life Flight pilot who was killed in a crash in 2000.
In looking at the wreckage of the Sept. 8 crash, NTSB investigations noted that “all the major components of the helicopter were present” at the crash site.
None of the blades of the craft’s main or tail rotors showed signs of damage to their leading edges, and all them were still attached to it after the crash.
One witness investigators talked to told of seeing the helicopter “hovering” and “not traveling forward,” while it was “a couple hundred feet” above the wind turbines.
The helicopter had an “on-board audio and video recording system,” the NTSB said. It suffered heat damage – a fire burned the cabin after the crash – but its “memory device” remained intact and was sent to an NTSB lab for study.
Mechanics check the airworthiness of Duke’s helicopters daily, and the one involved in the Sept. 8 crash had gone through a regulation-mandated “30-hour” inspection Aug. 15. It also had undergone “several additional inspections” during scheduled maintenance Sept. 1.
Federal Aviation Administration records obtained by The Herald-Sun show mechanics in early March installed a structural reinforcement of the helicopter’s tail boom suggested by Airbus Helicopters, now the corporate parent of its manufacturer.
The boom “remained largely intact” after the crash and the tail rotor’s drive shaft was still attached to the transmission, the NTSB said.
Before leaving Elizabeth City, the crew radioed its operations center and reported it had about two hours’ worth of fuel on board. That was the last radio communication from the craft. A Colorado company, Air Methods Corp., supplies Duke Life Flight’s pilots and mechanics.
The 2000 crash happened while Duke Life Flight was working with an entirely different helicopter operator, CJ Systems Aviation Group. It went down because of a mechanical failure, a broken main rotor gearbox.
The NTSB’s probe of the 2000 crash faulted a mechanic’s checks of the aircraft following an oil-pressure warning light. But subsequent litigation suggested the gearbox had failed several post-overhaul bench tests and shouldn’t have been certified as airworthy by the U.S. arm of Eurocopter.