Sherman, TX, USA
N62269
Hughes 269A
A pilot applicant was demonstrating a simulated power failure from a two-foot hover to an FAA inspector when he lost control of the helicopter. The helicopter drifted aft and to the left before it impacted the ground and rolled on its left side. The FAA inspector's attempts to recover the helicopter were unsuccessful. According to the FAA Rotorcraft Flying Handbook, common errors when executing a power failure in a hover are; failing to use sufficient proper antitorque pedal when power is reduced, failing to stop all sideward and backward movement prior to touchdown, failing to apply up-collective pitch properly, resulting in a hard touchdown, failing to touch down at a level attitude, and not rolling the throttle completely to idle. In addition, "A helicopter is susceptible to a lateral rolling tendency, called dynamic rollover, when lifting off of the surface. For dynamic rollover to occur, some factor has to first cause the helicopter to roll or pivot around a skid, or landing gear wheel, until its critical rollover angle is reached. Then, beyond this point, main rotor thrust continues the roll and recovery is impossible. If the critical angle is exceeded, the helicopter rolls on its side regardless of the cyclic corrections made."
On June 1, 2005, at 1050 central standard time, a Hughes 269A single-engine helicopter, N62296, sustained substantial damage during a simulated power loss from a two-foot hover at the Grayson County Airport (GYI), Sherman/Denison, Texas. The airline transport pilot (a Federal Aviation Administration inspector) sustained minor injuries and the private pilot (applicant) was not injured. The helicopter was registered to and operated by an individual. No flight plan was filed for the flight that originated at Grayson County Airport, about 0950. Visual meteorological conditions prevailed for the flight conducted under 14 Code of Federal Regulations Part 91. The purpose of the flight was for the FAA inspector to conduct a practical examination for the addition of a rotorcraft-helicopter rating to the applicant's private pilot (airplane single-engine land) certificate. In a written statement, the FAA inspector reported that the accident occurred while executing the last maneuver of the check-ride, a simulated power failure in a hover. The pilot was instructed to position the helicopter into the wind and establish a skid height of two feet above the ground, which he did. The inspector said, "I prefer to be very close to the flight controls...due to the possibility the applicant's initiation of the maneuver or performance of the maneuver may escalate to a situation that may exceed my abilities to recover the aircraft." The instructor positioned himself close the controls and instructed the applicant to "slowly reduce the throttle, not a snap", and to inform him when he was going to begin the maneuver. The applicant announced that he was going to commence the maneuver, and closed the throttle. The instructor said, "This was totally unexpected. I immediately noticed a left drift and reached for the flight controls...While reaching for the flight controls, I observed the left drift had transitioned to a left aft movement." The left heel of the skid impacted the ground and the helicopter began to roll to the left with a nose-high attitude. The inspector immediately applied full right, forward cyclic, and right antitorque pedal in an effort to level the helicopter, and blocked the collective with his left hand. The left heel of the skid hit the ground again, and the helicopter rolled over on its left side. In a telephone conversation, the applicant stated that wind had shifted during the flight. In preparation for the maneuver, he positioned the helicopter into the wind and established a two foot hover height. The applicant said that when he "chopped" the throttle to initiate the maneuver and as the helicopter descended, a "big" gust of wind pushed the helicopter to the left as rolled on its left side. A witness was standing about 100 yards away from the helicopter when the accident occurred. He said the helicopter was hovering about two feet above the ground into the wind, which were light gusts about 5 to 10 miles per hour. The witness then heard a "sudden" power reduction, before observing the helicopter drift aft and to the left. As it drifted, it descended and the left heel of the skid contacted the ground and bounced three times. Each time the helicopter bounced, it began to roll more to the left until the main rotor blades struck the pavement. An FAA inspector from another Flight Standards District Office (FSDO), performed an on-scene examination of the helicopter. The helicopter came to rest on its left side. All three main rotor blades remained attached to the hub, but were displaced upward and exhibited impact damage. The left side of the fuselage and the windscreen were also damaged. According to the FAA Rotorcraft Flying Handbook (FAA-H-8083-21), page 11-4, it said, "Power failures in a hover...are practiced so that you automatically make the correct response when confronted with engine stoppage or certain other emergencies while hovering. To simulate a power failure, firmly roll the throttle into the spring loaded override position, if applicable. This disengages the driving force of the engine from the rotor, thus eliminating torque effect. As the throttle is closed, apply proper antitorque pedal to maintain heading. Usually, a slight amount of right cyclic control is necessary to keep the helicopter from drifting the left, to compensate for the loss of tail rotor thrust. However, use cyclic control, as required, to ensure a vertical descent and a level attitude...Some of the common errors are: failing to use sufficient proper antitorque pedal when power is reduced, failing to stop all sideward and backward movement prior to touchdown, failing to apply up-collective pitch properly, resulting in a hard touchdown, failing to touch down at a level attitude, and not rolling the throttle completely to idle." In addition, on page 11-8, it said, "A helicopter is susceptible to a lateral rolling tendency, called dynamic rollover, when lifting off of the surface. For dynamic rollover to occur, some factor has to first cause the helicopter to roll or pivot around a skid, or landing gear wheel, until its critical rollover angle is reached. Then, beyond this point, main rotor thrust continues the roll and recovery is impossible. If the critical angle is exceeded, the helicopter rolls on its side regardless of the cyclic corrections made." Weather at the airport at 0945 was wind from 340 degrees at 6 knots, visibility 7 miles, and scattered clouds at 1,600 feet.
The applicant's failure to maintain directional control of the helicopter during a simulated power failure from a hover and the FAA inspector's delayed remedial action resulted in a dynamic rollover.
Source: NTSB Aviation Accident Database
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