Bridgeville, DE, USA
N5691Y
Enstrom F28
The commercial pilot had performed numerous local sightseeing helicopter flights the day of the accident. During the accident flight lift off from the field with power lines and farm equipment nearby, the pilot increased the throttle to the maximum engine and rotor rpm and began a climbing left turn toward power lines, during which he noticed the rotor rpm slowing. He slightly decreased collective pitch and further increased the throttle, but the rotor rpm did not increase. The pilot then increased collective pitch even farther as the helicopter cleared the power lines, which exacerbated the low rotor rpm state and was contrary to guidance published in the helicopter's pilot's operating handbook. The pilot's power management allowed the rotor rpm to decay below a point at which sustained flight was possible. Subsequently, the helicopter descended and impacted an open field hard, which resulted in substantial damage to the tailboom and tail rotor. The pilot did not report any preimpact mechanical malfunctions or failures with the helicopter, which was confirmed by a postaccident examination and test run of the helicopter's engine. The pilot's mismanagement of collective pitch control led to the helicopter entering a low rotor rpm state and its subsequent inability to maintain flight.
On October 7, 2018, at 1340 eastern daylight time, an Enstrom F-28C helicopter, N5691Y, was substantially damaged when it impacted terrain shortly after takeoff from a field in Bridgeville, Delaware. The commercial pilot and three passengers were not injured. The helicopter was operated by J&J Shop HeliAir LLC., as a local sightseeing flight conducted under the provisions of Title 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed, and no flight plan was filed for the local flight.According to the pilot, during takeoff with power lines and farm equipment nearby, he increased the throttle to the maximum engine and rotor rpm, and began a climbing left turn, where he subsequently noticed a "slight decaying of rotor rpm." While headed toward the power lines, he "slightly" reduced the collective, while increasing the throttle, in effort to increase rotor rpm, but his corrections did not increase the rotor rpm. Nearing the power lines, he reported that he "pulled collective" which further degraded the low rotor rpm state, as the helicopter cleared the power lines. After clearing the power lines, the helicopter was about 50 to 75 ft above ground level, and the engine and rotor rpms were "well below minimums." With the helicopter sinking, the pilot pulled "full collective" just prior to impact with terrain, and the helicopter touched down hard. The pilot reported that he had previously flown 12 flights with passengers prior to the accident flight and did not notice any abnormalities with the helicopter, nor was he aware of any "mechanical issues" with the helicopter during the accident flight. According to a Federal Aviation Administration (FAA) inspector who examined the helicopter at the accident site, it impacted terrain about 1,000 ft northeast of the departure point in an upright configuration. The tail boom had separated from the fuselage, which resulted in substantial damage to the tail rotor drive shaft, tail boom, and tail rotors. Control continuity was established for the throttle, cyclic, and collective controls. A subsequent engine examination and test run did not reveal evidence of any preimpact mechanical malfunctions or failures that would have precluded normal operation. The operator held an FAA Letter of Authorization to conduct commercial air tour operations under Title 14 CFR Part 91.147. The operator reported that their policy was to conduct flights with a maximum of two passengers, however, the accident flight commenced with three passengers. Following the accident, the operator reiterated to all company pilots and staff that flights cannot have more than two passengers. According to FAA airman records, the pilot held a commercial pilot certificate with ratings for helicopter and instrument helicopter. His most recent second-class medical certificate was issued in September 2018. He reported a total of 1,864 flight hours, 74 hours of which were in the accident helicopter make and model. According to FAA airworthiness records, the helicopter was powered by a Lycoming HIO-360-E1AD, 205-horsepower engine, and had 3 seats. The most recent annual inspection was completed in August 2018. At 1332, the weather conditions reported at Dover Air Force Base, Dover, Delaware, about 25 miles from the accident site, included wind from 240° at 6 knots, visibility 10 statute miles, scattered clouds at 2,400 ft above ground, temperature 28°C, and dew point 22°C. The pilot's operating handbook stated in part: MAXIMUM POWER TAKEOFF FROM CONFINED AREAS Conditions may occur in which the helicopter must be operated from confined areas in which take-off distances (from hover to best rate of climb speed) are not sufficient to clear obstacles that may be in the flight path (trees, buildings, wires, etc.). In order to clear such obstacles safely, the climb portion of the take-off must utilize the best angle of climb airspeed (30 MPH safe side of height velocity curve). This angle of climb will substantially shorten the distance required to clear obstacles. To accomplish this type of take-off, hover helicopter at 3 to 5 feet altitude and 2900 RPM. Apply forward cyclic smoothly. As the helicopter begins to accelerate forward, apply collective and throttle until 36.5 inches of manifold pressure is obtained at 2900 engine RPM. Do not increase collective beyond this point (over pitching) as this will cause engine and rotor RPM to decrease. Maintain 3 to 5 feet altitude by use of cyclic control. As translational speed is reached (15-20 MPH) apply aft cyclic to seek climb angle that will maintain 30-35 MPH (refer to height ~ velocity diagram in flight manual). After clearing all obstacles at this airspeed, apply forward cyclic and readjust collective and throttle as desired for further flight.
The pilot's mismanagement of collective pitch control during takeoff from an area with numerous obstacles, which resulted in the helicopter entering a low rotor rpm state and a forced hard landing.
Source: NTSB Aviation Accident Database
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