BELLE VERNON, PA, USA
N55TP
Robinson R22 BETA
The pilot was performing an out-of-ground-effect hover with a 10 knot tailwind in a Robinson R-22. When the pilot raised the collective to maneuver, and the helicopter began to spin to the right. The helicopter spun four times, descended, and impacted the ground. The pilot had about 100 hours of helicopter experience, and about 10 hours of out-of-ground-effect hover experience. After the accident, the pilot told a police officer that he exceeded the limitations of the tail rotor. FAA Advisory Circular (AC) 90-95 stated all single main rotor helicopters were susceptible to loss of tail rotor effectiveness (LTE). The AC advised pilots that when maneuvering between hover and 30 knots to avoid; tailwinds, out of ground effect hover and high power demand such as lowspeed downwind turns. It also advised the pilots to be aware of wind direction and velocity. In 1995, the FAA sent a letter to all U.S helicopter manufactures recommending they include a discussion on LTE in the operator's handbooks and flight manuals. The Robinson Helicopter Company has not complied with that request.
On December 16, 1997, about 1230 Eastern Standard Time, a Robinson R22 BETA helicopter, N55TP, was substantially damaged when it collided with the ground during an uncontrolled descent near Belle Vernon, Pennsylvania. The certificated commercial pilot received minor injuries, and the passenger was fatally injured. Visual meteorological conditions prevailed for the local, aerial photography flight, that departed the Allegheny County Airport (AGC), Pittsburgh, Pennsylvania. No flight plan was filed for the flight conducted under 14 CFR Part 91. According to the pilot, he departed Runway 5 at AGC, where the winds were from the southwest. The pilot proceeded to the area to be photographed, about 15 miles south of AGC. While en route, smoke stacks and the helicopter's crab angle confirmed a southwesterly wind. When the helicopter arrived at the area to be photographed, the pilot entered an out-of-ground-effect (OGE) hover, with an approximate 10 knot tailwind. During the hover, the pilot raised the collective to maneuver for another series of photographs. The helicopter began to spin to the right. The helicopter spun to the right about four times, descended, and impacted the ground with no forward movement. The pilot stated that the helicopter hovered "very easily" with about 21 to 22 inches of manifold pressure, and that he did not experience any problems with the engine or helicopter. The pilot was asked about recovery procedures for a loss of tail rotor effectiveness. He stated the collective should be lowered, and forward speed should be attained to "fly out of it"; or reduce power and perform an autorotation. The pilot reported that he had an approximate total flight experience of 2,000 hours, of which 100 hours were in helicopters. His total helicopter experience was all in the accident make and model. His flight training included about 5 to 10 hours of OGE hover training. The pilot stated that he had conducted an additional 5 to 10 hours of OGE hover work. Examination of the wreckage by a Federal Aviation Administration (FAA) Inspector did not disclose evidence of mechanical malfunctions with the helicopter, nor did the pilot report any. A Rostraver Township Police Officer questioned the pilot after the accident. The pilot stated "I exceeded the limitations on the tail rotor." The Safety Board issued a recommendation to the FAA on September 26, 1994. Number A-94-140 recommended that the FAA: Strongly encourage the manufacturers of single main rotor/anti-torque rotor helicopters to include in the operator's handbook, and flight manual, discussions of the characteristics of, and recovery techniques from the phenomenon know as loss of tail rotor effectiveness (LTE). On April 4, 1995, the FAA sent a letter to all U.S. helicopter manufacturers & European aviation authorities asking them to include in the operator's handbook, and flight manual, a discussion of the characteristics of the phenomenon known as LTE, and appropriate recovery techniques. The FAA issued advisory circular AC-90-95, Unanticipated Right Yaw in Helicopters during February 1995. The AC stated that the loss of tail rotor effectiveness (LTE) was a critical, low-speed aerodynamic flight characteristic which could result in an uncommanded right yaw rate which did not subside of its own accord and, if not corrected, could result in the loss of aircraft control. It also stated, "LTE is not related to a maintenance malfunction and may occur in varying degrees in all single main rotor helicopters at airspeeds less than 30 knots." Paragraph 9 of the AC covered reducing the onset of LTE. It stated: "In order to reduce the onset of LTE, the pilot should: ...b. Maintain maximum power-on rotor rpm. If the main rotor rpm is allowed to decrease, the antitorque thrust available is decreased proportionally. c. When maneuvering between hover and 30 knots: (1) Avoid tailwinds. If loss of translational lift occurs, it will result in an increased high power demand and an additional anti-torque requirement. (2) Avoid out of ground effect (OGE) hover and high power demand situations, such as lowspeed downwind turns. (3) Be especially aware of wind direction and velocity when hovering in winds of about 8 - 12 knots (especially OGE). There are no strong indicators to the pilot of a reduction of translation lift... (6) Stay vigilant to power and wind conditions." A representative from Robinson Helicopter Company was asked about LTE information in the R22 Pilot's Operating Handbook. The representative said that information on LTE would not be found in any Robinson handbook because it is rare to Robinson Helicopters. He further stated that Robinson Helicopter Company has no plans to comply with the FAA's request of April 4, 1995. According to the Safety Board database, there have been three other helicopter accidents between 1992-1997, involving LTE to Robinson helicopters. Three of the four accidents resulted in fatal injuries.
The pilot's improper out-of-ground hover procedure, which resulted in a loss of tailrotor effectiveness.
Source: NTSB Aviation Accident Database
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