The Safety Board says it recognizes that the motions of a helicopter following an engine power loss vary greatly from one make and model helicopter to another and from one flight condition to the next. Therefore, the technique required for safely entering an autorotation will vary, and there is no technique of universal applicability. However, in discussions with experienced helicopter flight instructors and test pilots, NTSB investigators found agreement that simultaneous control inputs, as opposed to only lowering the collective, should be used when entering an autorotation and that the critical task when entering an autorotation is to establish airflow upward through the main rotor system. The instructors and test pilots interviewed reported that the Eurocopter AS350 B2 is not unique in requiring simultaneous application of aft cyclic and down collective to safely enter an autorotation at cruise airspeeds; rather this technique is applicable to many, if not all, helicopters with low-inertia rotor systems.
The Safety Board believes that the additional information about autorotation entries provided by Air Methods to its AS350 pilots would be equally valuable to all pilots flying helicopters with low-inertia rotor systems. Therefore, the Board recommended that the FAA inform pilots of helicopters with low-inertia rotor systems about the circumstances of this accident, particularly emphasizing the findings of the simulator flight evaluations, and advise them of the importance of simultaneously applying aft cyclic and down collective to achieve a successful autorotation entry at cruise airspeeds.
The NTSB's review of the guidance on performing autorotations in the FAA's Helicopter Flying Handbook — the primary source of information on helicopter aerodynamics and flight maneuvers published by the FAA — found that it emphasizes lowering the collective as the initial step in entering an autorotation, does not address the use of simultaneous control inputs in response to an engine failure, and contains minimal information on the entry phase of autorotations. Therefore, the Safety Board recommended that the FAA revise the Helicopter Flying Handbook to include a discussion of the entry phase of autorotations that explains the factors affecting rotor rpm decay and informs pilots that immediate and simultaneous control inputs may be required to enter an autorotation.
Air Methods is now providing all of its Eurocopter AS350 pilots with autorotation training and line-oriented flight training in a full-motion Eurocopter AS350 flight simulator. The NTSB believes that use of a flight simulator addresses the lack of practice representative of an actual engine failure at cruise airspeed in the accident pilot's autorotation training because engine failures in a simulator are representative of an actual engine flameout and can be induced unexpectedly in any flight condition.
This accident highlights the value of using simulators and flight training devices (FTD) for helicopter pilot training.
The Safety Board, through the work of its investigators and consultants, reached these conclusions among others:
Although the helicopter's low fuel state was clearly indicated, the pilot missed three opportunities to detect the condition: (1) before departing on the first leg of the mission as a result of his inadequate preflight inspection, (2) before takeoff by failing to properly complete the before-takeoff confirmation checklist and (3) after takeoff when he erroneously reported the fuel level.
The pilot departed on the second leg of the mission despite knowing that the helicopter had insufficient fuel reserves likely in order to avoid delays and other possible negative outcomes that could have resulted from aborting the mission.
Self-induced pressure likely caused the pilot to fixate on his intended refueling point and continue the flight rather than make a precautionary landing as the fuel gauge indication approached zero.