FTW98LA274

The flight instructor lost control of the helicopter while demonstrating the technique for recovering from a loss of tail rotor effectiveness while hovering over a helipad. After assuming the controls for the demonstration, the instructor noticed that the RPM was set too low, at 99 percent. The instructor elected to 'beep up' the RPM by stabilizing the cyclic with his left hand and 'beeping' the RPM with the right thumb. He was unsuccessful in beeping the RPM up on 2 attempts. On his last attempt, while manipulating the cyclic lever with his left hand and the RPM switch with the thumb of his right hand, and keeping his eyes on the engine tachometer, the helicopter assumed a nose high attitude while drifting backwards. The flight instructor was not able to recover the helicopter in time to avoid impact with the ground. The winds at the time of the accidents were reported from the south at 27 knots.

On June 18, 1998, at 1515 central daylight time, a Bell 206L4 helicopter, N8094L, was substantially damaged upon impact with the ground following a loss of control while hovering near Hurst, Texas. The helicopter was registered to and operated by Bell Helicopter Textron, Inc., of Fort Worth, Texas. The flight instructor and the pilot receiving instruction, were not injured. Visual meteorological conditions prevailed and a VFR company flight plan was filed for the Title 14 CFR Part 91 training flight. The local flight originated from the Bell Helicopter training facility in Hurst, Texas, approximately 15 minutes prior to the accident.

The flight instructor provided the following information in a written statement. He was demonstrating the technique for recovering from a loss of tail rotor effectiveness while hovering over Pad 2, at the Bell Helicopter training area. The procedure is demonstrated by establishing the aircraft at a high hover with the nose of the helicopter 90 degrees to the left of the prevailing wind. Once the helicopter is stabilized, the pressure on the left pedal is relaxed and the helicopter rotates 45 degrees. The recovery procedure is to apply forward cyclic while reducing collective pitch approximately 15 to 20 percent. During this demonstration, if the wind is above 10 to 12 knots, the helicopter streamlines and flies away without any additional pedal inputs while losing no more than 10 feet in altitude.

After assuming the controls of the helicopter to demonstrate the procedure, he noticed that the RPM was set too low, at 99 percent. To obtain maximum effectiveness, the instructor elected to "beep up" the RPM by stabilizing the cyclic with his left hand and "beeping" the RPM with the right thumb. The instructor was unsuccessful in "beeping up" the RPM on 2 attempts. On his third and last attempt, the helicopter assumed a nose high attitude while drifting backwards. The instructor was not able to recover and the helicopter in time to avoid impact with the ground.

Subsequently, the helicopter landed hard, resulting in partial separation of the engine mount assemblies and the tail boom. A fire erupted in the vicinity of the engine compartment which alerted the facility's rescue and fire fighting personnel, who responded to the scene of the accident and extinguished the fire.

The reported winds at the DFW International Airport, located 8 nautical miles to the north-northeast of the accident site, were from 180 degrees at 27 knots.

The 4,770 hour flight instructor did not report any mechanical anomalies or problems with the helicopter or systems prior to the event. The 1995 model helicopter had accumulated a total of 241 hours since new.

The FAA inspector confirmed that the helicopter sustained structural damage to the airframe.