Frederick, MD, USA
N2549R
Robinson R-22B
During the dual instructional flight, the student pilot was practicing maneuvers in preparation for his helicopter private pilot checkride. The flight instructor briefed a "simulated engine out during takeoff," which the student pilot had not previously performed. The helicopter took off with the student pilot at the controls. About 100 feet and 60-65 knots, the flight instructor advised him that he had a simulated engine failure. The student pilot lowered the collective and rolled off the throttle. He then applied "slight aft cyclic," and raised the collective to slow the descent. The flight instructor attempted to lower the collective while the student pilot continued to raise it. The main rotor rpm deteriorated and the helicopter touched down hard. The main rotor blades flexed, and chopped off the tailboom. The helicopter's height-velocity parameters approximated the "recommended takeoff profile" when the simulated engine failure was initiated. The helicopter manufacturer had written guidelines regarding simulated engine failures, but no written guidance regarding simulated engine failures during takeoff. According to a company representative, the manufacturer taught flight instructors to avoid exposing even high time pilots to simulated power failures during takeoff, since the high power setting could cause a high rotor rpm decay rate.
On September 16, 2002, at 1540 eastern daylight time, a Robinson R-22B, N2549R, was substantially damaged during a hard landing at Frederick Municipal Airport (FDK), Frederick, Maryland. The certificated flight instructor received minor injuries and the certificated student pilot was not injured. Visual meteorological conditions prevailed at the time. No flight plan had been filed for the local instructional flight, which was conducted under 14 CFR Part 91. According to the flight instructor, the student pilot was preparing for his private pilot practical examination. Prior to the accident maneuver, the student pilot had practiced several rapid decelerations (quick stops), slope operations, and running takeoffs and landings. On a flight earlier the same day, the student pilot had also practiced several straight-in autorotations, hovering autorotations, maximum performance take-offs, and steep and normal approaches. The accident occurred during a "simulated engine out during takeoff." The procedure, which was "discussed fully beforehand," called for an autorotation after the helicopter had reached 60-65 knots and 100 feet agl. The helicopter took off with the student at the flight controls. After attaining the desired flight parameters, the flight instructor announced the simulated engine failure. The student pilot lowered the collective and rolled off the throttle. The student pilot then applied "slight aft cyclic," and raised the collective in an attempt to slow down the descent. The flight instructor tried to lower the collective, to maintain rotor rpm, but the student pilot continued to raise it. A cyclic flare was then attempted, to raise rotor rpm, "but the rpm had decayed due to the up collective still being applied by the student pilot." Forward collective was then applied, to level the helicopter before ground contact. The helicopter touched down with "forward movement," and the rotor blades chopped off the tailboom. According to the student pilot, "Despite the briefing that forward cyclic to increase forward airspeed to 65 KIAS would be required, [I] believe that muscle memory took over with decreased collective, aft cyclic, and right pedal, initiating actions like the five quick stops practiced earlier in the flight." He also noted that he had never performed a simulated engine failure during takeoff prior to the accident flight. According to the Robinson R22 height-velocity diagram, the helicopter's flight parameters approximated the "recommended takeoff profile" when the simulated engine failure was initiated. In a letter to the Safety Board, the Robinson Helicopter Company (RHC) head of technical investigations stated that he had looked into available "written advice, cautions, etc. regarding giving students forced landings or autorotations from low levels and low airspeeds," and was unable to find anything that addressed the subject. He also talked to a number of experienced pilots, who were "unanimous in their opinions that giving a student an autorotation during takeoff was a bad idea at best." He further stated that, "RHC teaches flight instructors to avoid exposing even high time pilots to simulated power failures during takeoff, since the high power setting can cause a high rotor rpm decay rate." RHC Safety Notice SN-27, "Surprise Throttle Chops Can Be Deadly," covered many of the safety aspects regarding simulated engine failures. It did not cover a simulated engine failure during takeoff, but stated that when a simulated engine failure was initiated, "manifold pressure should be less than 21 inches." It was also noted that a flight instructor should "always assume that you will be required to complete the autorotation entry yourself. Never wait to see what the student does. Plan to initiate the recovery within one second, regardless of the student's reaction." Weather, recorded at the airport about the time of the accident, included a broken cloud layer at 7,500 feet agl, a temperature of 82 degrees Fahrenheit, a dewpoint of 64 degrees Fahrenheit, and calm winds.
The student pilot's failure to maintain adequate rotor rpm, and the flight instructor's delayed remedial action. A factor was the manufacturer's inadequate written guidance regarding simulated engine failures during takeoff.
Source: NTSB Aviation Accident Database
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