Helikopter - Dramatisk video av havari i en "preventable accident", slik FAA uttrykker det - Curt Lewis

Flight For Life helicopter crash in Frisco that killed pilot was caused by hydraulic issue, NTSB finds

• Pilot Patrick Mahany, of Silverthorne, had started as a Flight for Life pilot in 1987

The July 2015 crash in Frisco of a Flight for Life helicopter that left the pilot dead and two passengers seriously hurt was probably caused by a preventable hydraulic issue that stemmed from a preflight maintenance check, the National Transportation Safety Board said Tuesday.


Federal investigators also found that the fiery crash was survivable, but that since the helicopter wasn't equipped with a crash-resistant fuel system, a post-impact blaze made it lethal.

The NTSB also said that if the pilot, 64-year-old Patrick Mahany, had completed a "hover check" - as is procedure - while lifting off from the ground, "he would have identified the (hydraulic issue) at an altitude that could have afforded a safe landing."

The NTSB released its findings during a hearing in Washington, D.C. The helicopter reached an estimated altitude of about 100 feet before it went down and immediately burst into flames, all in about 30 seconds.

Mahany, of Silverthorne, had started as a Flight for Life pilot in 1987. He served as a scout helicopter pilot in the Vietnam War in 1971 and was awarded the Bronze Star and Purple Heart.

Paramedic and flight nurse David Repsher and flight nurse Matthew Bowe were critically hurt in the July 3, 2015, crash. Attorneys for the pair say Repsher had 90 percent of his body burned in the post-crash fire while Bowe suffered severe internal injuries and permanent disabilities.

The two have sued the helicopter's operator, Air Methods Corporation; the manufacturer, Airbus Helicopters S.A.S; and the distributor, Airbus Helicopters. The helicopter that crashed was an AS350 that was built in 2013.

According to the NTSB, the crash stemmed from a preflight hydraulic check in which Mahany turned off a switch, cutting hydraulic pressure to the tail rotor hydraulic circuit.

Federal investigators say they determined he "most likely did not return the ... switch to its 'On' position before takeoff, resulting in no hydraulic pressure in both the tail rotor servo control and the yaw load compensator accumulator, a lack of hydraulic boost to the pedals and significantly increased pedal loads."

A video shows the helicopter lifting off and then yawing - or twisting - to the left nearly one full rotation before rising out of view. The craft, still out of view, continued rotating counterclockwise several times and, about 30 seconds later and back in view, crashed into a nearby recreational vehicle. The aircraft then burst into flames as its mangled wreckage was strewn across a parking lot.

The NTSB says it found several safety issues that, if addressed, could have prevented the crash, including a lack of a cockpit warning to alert the pilot of the hydraulic issue. The agency also said there is a need for changes in the helicopter's tail rotor flight controls to "ensure pedal control hydraulic assistance" in the case of pilot error.

Federal investigators also highlighted that, going forward, the type of Airbus helicopter involved in the crash needs to have better crash-worthiness protections, including spill-resistant fuel tanks. Most choppers certified after 1994 were required to have fuel system protections, but because of a loophole, the accident helicopter was not, the NTSB says.

After the crash, the NTSB issued a safety recommendation to the Federal Aviation Administration to require that all newly manufactured helicopters have crash-resistant fuel systems. The FAA is still working to implement the regulation, officials say.

"This accident involved multiple issues that together led to the results we have before us today," Acting NTSB Chairman T. Bella Dinh-Zarr said in presenting the agency's findings. "It is likely the helicopter's system that provides boost to the pedals was misconfigured prior to takeoff. The design of the accident helicopter did not provide an alert to the pilot of this misconfiguration."

NTSB's recommendations

To the FAA:

Require that existing Airbus Helicopters dual-hydraulic AS350-series helicopters be equipped with a visual and an aural alert for the loss of hydraulic boost to the pedal controls, which would result in increased pedal loads.
Require operators of Airbus Helicopters dual-hydraulic AS350-series helicopters to incorporate changes to the dual hydraulic system to both ensure pedal control hydraulic assistance and mitigate the possibility of pilot error during any check of the hydraulic system.
To Airbus Helicopters:

For newly manufactured dual-hydraulic AS350-series helicopters, assess and implement changes to the dual hydraulic system that would both ensure pedal control hydraulic assistance and mitigate the possibility of pilot error during any check of the hydraulic system.
For existing dual-hydraulic AS350-series helicopters, assess and implement changes to the dual hydraulic system that would both ensure pedal control hydraulic assistance and mitigate the possibility of pilot error during any check of the hydraulic system.
To the Association of Critical Care Transport:

In collaboration with the Association of Air Medical Services and the Air Medical Operators Association, establish a working group to develop and distribute guidelines, for those who purchase, lease and contract for helicopters, regarding the equipment and systems that would enhance the helicopters' crashworthiness, including, at a minimum, a crash-resistant fuel system and energy-absorbing seats.
To the Association of Air Medical Services and the Air Medical Operators Association:

Work with the Association of Critical Care Transport to establish a working group to develop and distribute guidelines, for those who purchase, lease and contract for helicopters, regarding the equipment and systems that would enhance the helicopters' crash worthiness, including, at a minimum, a crash-resistant fuel system and energy absorbing seats.