EMS Helicopter Fuel Exhaustion

By Richard N. Aarons
Source: Business & Commercial Aviation

The Board concluded, “. . . the pilot's personal texting activities likely degraded his decision-making performance when he decided to continue the mission. The pilot's texting, which occurred (1) while flying, (2) while the helicopter was being prepared for return to service and (3) during his telephone call to the communication specialist when making his decision to continue the mission, was a self-induced distraction that took his attention away from his primary responsibility to ensure safe flight operations. Further, although there is no evidence that the pilot was texting at the time of the engine failure, his texting while airborne violated the company's cell phone use policy.”

Following the accident, Air Methods modified its policy on the use of cell phones. The new policy states, in part, the following:

“In compliance with FAA regulations and to prevent distractions, the PIC shall not allow cellular phones/portable electronic devices to be used or turned on during ground operations including taxi and hover operations, takeoff, en route, approach and landing. . . . In the interest of safety, this is a zero tolerance policy.”

Autorotation Guidance

The pilot's awareness of the helicopter's low fuel status and the near zero indication on the fuel gauge as the flight continued should have given him ample warning of the impending engine failure and provided him with the opportunity to prepare to execute an autorotation. Apparently, that didn't happen.

Simulator flight evaluations conducted during the investigation demonstrated that it was possible to maintain rotor rpm and execute a successful autorotation from low-level cruise flight with touchdown occurring about 25 sec. after engine failure. However, a successful autorotation was only possible if simultaneous flight control inputs of down collective and aft cyclic were made within about 1 to 2 sec. after the engine failure. If these flight control inputs were not promptly made, the result was a rapid decay in rotor rpm and impact with terrain in a nose-down attitude in an average time of 4 to 5 sec. after the simulated engine failure.

The pilot was required to demonstrate competency in performing autorotations during his Part 135 initial and recurrent training. The practice autorotations that Air Methods pilots performed were done at airspeeds of about 80 kt. This was consistent with traditional flight training for autorotations that is typically done at airspeeds below cruise and emphasizes immediate lowering of the collective as the first pilot action in response to a loss of engine power. However, Eurocopter AS350 B1 certification flight test data suggest that following a simulated engine failure at cruise speeds comparable to the accident scenario, the pilot may need to make a substantial aft cyclic input within 1.5 sec. of engine failure to achieve a successful autorotation entry.

The simulator flight evaluations also showed that the helicopter tended to pitch down rapidly following a simulated engine failure at 115 kt., requiring immediate use of aft cyclic to enter the autorotation and avoid an unrecoverable decay in rotor rpm. Pilots might not be able to initiate the appropriate flight control inputs (aggressive aft cyclic, down collective and left antitorque pedal) within such a short period of time unless they have received extensive practice in similar flight conditions. “Thus, the pilot's autorotation training was not representative of an actual engine failure at cruise speed and did not optimally prepare him to respond appropriately to such a scenario,” said the Safety Board.

When the pilot received his training in the Eurocopter AS350 B2, the Air Methods AS350 Flight Training Maneuvers Manual listed “smooth, positive reduction” of the collective to the full down position as the first step in performing a practice autorotation. This was consistent with the emergency procedure in the AS350 B2 RFM and with the general guidance provided by the FAA in the Helicopter Flying Handbook and the Helicopter Instructor's Handbook.

Following the accident, Air Methods changed the guidance on autorotations in its Eurocopter AS350 pilot training program to emphasize the importance of applying simultaneous control inputs when entering an autorotation. “It is imperative that the pilot take immediate action to change to an autorotative attitude; i.e., simultaneously applying aft cyclic, lowering the collective to maintain rotor rpm and trimming the aircraft. Failure to apply aft cyclic while lowering the collective will result in a nose-low attitude; this condition may be unrecoverable at low altitudes.”

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