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On May 13, 2006, about 1045 central daylight time, a Robinson R44 Astro helicopter, N442GS, operated by WW Helicopters LLC, and piloted by a commercial pilot, was substantially damaged when it struck a pole during takeoff at the East Troy Municipal Airport (57C), East Troy, Wisconsin. The 14 CFR Part 91 sightseeing flight was operating in visual meteorological conditions without a flight plan. The pilot and three passengers received serious injuries. One passenger received minor injuries. The local flight was originating at the time of the accident.
The pilot reported that he started to lift off to a hover and the helicopter "bolted forward." He stated that attempted to stop the forward movement and at the same time tried to avoid the hangar and the "weather pole" by the hangar. He stated that the main rotor blades struck the pole, "which brought the helicopter down."
A witness to the accident reported that the helicopter took off from the blacktop taxiway that runs in front of the operator's hangar. He reported that the helicopter lifted off, struck a "windsock/radio antenna" pole located adjacent to the hangar, and then crashed to the ground next to the hangar.
Another witness reported that the helicopter lifted off of the ground with the left skid low. He stated that as it gained altitude, the nose pitched down and the helicopter began accelerating forward. He stated that as the helicopter approached the building it turned to the left and then he heard it hit the pole. The witness did not see the impact.
According to police reports, a child was ejected from the helicopter during the accident. The police reports indicate that the child was 2 years and 8 months old and was seated in his fathers lap in the left rear seat of the helicopter. The child was not wearing a seat belt.
The pilot held a commercial pilot certificate with a rotorcraft-helicopter rating. The certificate also listed airplane single engine land and instrument airplane ratings that were limited to private pilot privileges. In addition, the pilot held a certified flight instructor certificate with a rotorcraft-helicopter rating.
According to the pilot's report, he had accumulated 2,350 hours of total flight experience with 2,100 in helicopters and 1,050 in the same make and model as the accident helicopter.
According to the pilot's statements during a telephone interview, the most recent compliance with special federal aviation regulation 73 (SFAR), regarding special training and experience requirements for Robinson R-22 and R-44 helicopters, was in June of 2003. The pilot stated that he was unaware that his compliance with SFAR 73 had expired.
The pilot's most recent second class airman medical certificate was issued on April 6, 2006.
The aircraft was a Robinson model R44 helicopter, serial number 0863. It was a single main rotor type helicopter with a single anti-torque rotor located on an aft mounted boom. The helicopter was powered by a Lycoming O-540-F1B5 engine, serial number L-25489-40A, rated for a maximum continuous power output of 205 horsepower.
At 1055, the recorded weather at the Burlington Municipal Airport (BUU), 8 nautical southeast of 57C, was: wind 340 degrees at 6 knots; visibility 7 statute miles with rain; sky condition 500 feet scattered, 1,100 feet broken, 2,700 feet overcast; temperature 45 degrees Celsius; dew point 45 degrees Celsius; altimeter setting 29.64 inches of mercury.
WRECKAGE AND IMPACT
The helicopter came to rest adjacent to the hangar used by the helicopter's owner/operator. The hangar was located on the north side of runway 08/26 and was adjacent to the taxiway that runs parallel to runway 08/26. The helicopter came to rest in the grass area to the south of the hangar and between the hangar and the runway's parallel taxiway. The hangar door was located on the east side of the building and another north/south taxiway runs along the east side of the hangar. According to witness accounts, this taxiway was where the accident flight originated.
Located at the southeast corner of the building was a pole that was used to mount a windsock, satellite dish and a radio antenna. The pole was about one foot south and one foot east of the corner of the building. The pole was a tapered steel pole about 24 feet in height and it was anchored to the ground with a cement base. The cement base was about 18 inches in diameter and 2 feet deep, and was completely pulled from the ground. About 18 feet from the base, the pole had markings consistent with being struck by the main rotor blades of the helicopter.
TESTS AND RESEARCH
SFAR 73 details special training and experience requirements for pilots operating Robinson R-22 and R-44 helicopters. The SFAR stipulates that a pilot may not act as the pilot in command of a Robinson R-44 helicopter unless the pilot has received a flight review in a Robinson R-44 within the preceding 12 calendar months. The SFAR also details the minimum requirements for the dual instruction to be given during the flight review. The complete text of the SFAR is included in the docket material associated with this report.
14 CFR 91.107 states that each person on-board an aircraft must occupy an approved seat or berth with a safety belt and, if installed, shoulder harness, properly secured about him or her during movement on the surface, takeoff, and landing. The regulation further states that a person who has not reached his/her second birthday may be held by an adult who is in an approved seat or berth.
During a telephone interview, the pilot informed the National Transportation Safety Board investigator that he only performed a weight calculation and did not calculate the center of gravity. He also informed the investigator that he knew it would be a little forward CG, but did not think it would be out of limits.
Weight and balance data for the accident helicopter was obtained from the aircraft records. The loaded weight and balance was calculated using this data and the fuel and passenger weights as understood by the pilot at the time of the accident. These weights were relayed to the investigator in charge of this investigation during a telephone interview. The calculated longitudinal center of gravity using these weights was 90.6 inches aft of datum at a weight of 2,398 pounds.
The actual weights of the passengers were obtained from relatives, police reports, and the FAA, and substituted into the weight and balance calculations. The calculated longitudinal center of gravity using these weights was 90.1 inches aft of datum at a weight of 2,457 pounds.
The R-44 has a maximum allowable gross weight of 2,400 pounds. The allowable center of gravity limits for the R-44, at a gross weight of 2,400 pounds, are between 93 and 98 inches aft of datum.
Regarding center of gravity limits pertaining to helicopter operations, FAA-H-8083-21 - ROTORCRAFT FLYING HANDBOOK states:
"Improper balance of a helicopter's load can result in serious control problems. The allowable range in which the CG may fall is called the "CG range." The exact CG location and range are specified in the rotorcraft flight manual for each helicopter. In addition to making a helicopter difficult to control, an out-of-balance loading condition also decreases maneuverability since cyclic control is less effective in the direction opposite to the CG location."
With regard to a center of gravity which is forward of the prescribed forward limit, FAA-H-8083-21 states:
"A forward CG may occur when a heavy pilot and passenger takeoff without baggage or proper ballast located aft of the rotor mast. This situation becomes worse if the fuel tanks are located aft of the rotor mast because as fuel burns the weight located aft of the rotor mast becomes less.
You can recognize this condition when coming to a hover following a vertical takeoff. The helicopter will have a nose-low attitude, and you will need excessive rearward displacement of the cyclic control to maintain a hover in a no-wind condition. You should not continue flight in this condition, since you could rapidly run out of rearward cyclic control as you consume fuel. You also may find it impossible to decelerate sufficiently to bring the helicopter to a stop. In the event of engine failure and the resulting autorotation, you may not have enough cyclic control to flare properly for the landing.
A forward CG will not be as obvious when hovering into a strong wind, since less rearward cyclic displacement is required than when hovering with no wind. When determining whether a critical balance condition exists, it is essential to consider the wind velocity and its relation to the rearward displacement of the cyclic control."
A video clip was provided by family members that were recording the flight. The video shows the helicopter's takeoff and the impact with the pole. The video shows that as the helicopter began to lift-off it immediately pitched forward and to its left, and then impacted the pole about 4 seconds later. The helicopter lifted off and climbed to a height of about 10 feet before striking the pole. The video clip does not show the helicopter in a hover prior to the forward movement, nor does it show an attempt to abort the takeoff.