NTSB Factual Report

On November 9, 2004, at 1731 central standard time, a Bell 206L1 helicopter, N1075P, was substantially damaged when it impacted terrain following a loss of control while in cruise flight near Sapulpa, Oklahoma. The commercial pilot, a paramedic, and a flight nurse sustained minor injuries. The helicopter was owned and operated by Air Evac Life Team, Inc., of West Plains, Missouri, a Part 135 on-demand air ambulance operator. Visual meteorological conditions prevailed throughout the area for the 14 Code of Federal Regulations Part 91 positioning flight for which a company visual flight rules (VFR) flight plan was filed. The flight refueled at and departed from the Richard Lloyd Jones Jr. Airport (RVS), near Tulsa, Oklahoma, approximately 1720, with the Cushing Regional Hospital Heliport (OK65), near Cushing, Oklahoma, as its intended destination.

In a written statement, the 2,000-hour pilot reported that after an uneventful departure from RVS, he switched to the company dispatch frequency to open his company flight plan. Shortly after, while at an altitude of approximately 500-800 feet and an airspeed of 90 knots, the pilot heard a loud "bang." Following this "bang," the "engine noise increased and the flight controls were stiff." The pilot also stated that "he had no pedal control, and there were no warning or caution lights." The helicopter then made an extremely fast, uncommanded left yaw, and tail rotor effectiveness was lost. The helicopter was then in a nose-down attitude, such that the pilot was looking at the ground through the top portion of the co-pilot's window. Subsequently, the pilot lowered the collective and manipulated the flight controls to level the helicopter and maintain controlled flight.

The pilot reported that as the helicopter was descending rapidly, he spotted a field and guided the helicopter toward it. He added that it was dusk, and as he descended behind a tree line, it was difficult to determine his altitude for deceleration and cushion. The pilot reported that the helicopter did not yaw until just prior to the hard landing.

Following touchdown, the pilot shut-off the fuel and battery and told the passengers to exit the aircraft. The helicopter came to rest on its left side, and there was no post-impact fire.

Examination of the wreckage by the FAA inspector, who responded to the accident site, revealed that some of the fly-away items and some medical supplies, normally stored in the baggage compartment, were found scattered along the route of flight short of the main wreckage. Examination of the baggage compartment door revealed that both door latches were unlatched, and the door was partially open.

Further examination of the tail rotor drive shaft revealed a torsional fracture of the tail rotor drive shaft. Frayed fibers and material consistent with clothing or a blanket were found throughout the tail rotor assembly and tail rotor hub. The baggage compartment door latches were examined and appeared to be undamaged and fully functional. The helicopter was released to the operator for recovery to a secure location.

The pilot reported that prior to the flight's refueling stop at RVS, the helicopter had been at Tulsa Regional Medical Center, which was the last time that the baggage compartment door had been opened. The pilot recalled that when leaving Tulsa Regional Medical Center, all three crewmembers approached the helicopter on its left side and recalled that the baggage compartment door was closed at that time. The pilot added that there were two oxygen containers in the cargo compartment that were stacked on one another and reached approximately the same height as the latch release button on the interior side of the baggage compartment door.

NTSB Probable Cause

The loss of tail rotor drive as a result of a blanket coming in contact with the tail rotor blades, after the baggage compartment door unlatched during flight. A contributing factor was the "dusk" light condition that prevailed at the time of the accident.