WPR09LA057

With the engine started and at flight idle, the ground crewman/mechanic disconnected the ground power cart from the helicopter's external power unit plug. As the ground crewman/mechanic was walking away from the helicopter, the pilot detected that a gust of wind was lifting the aircraft up off of its right main landing gear. The pilot applied full right cyclic to counter the uplifting condition; however, the wind gust continued lifting the helicopter to the left and nose down until the aircraft came to rest inverted. As the helicopter was rolling over, the main rotor blades impacted a fueling truck and struck the ground crewman/mechanic. There was no postcrash fire. The pilot noted that the winds were generally light and variable at the time of engine start, and estimated that the gust was from the east-southeast at up to 15 knots. He further reported that gusty, unpredictable wind conditions were not uncommon in the area. The closest aviation weather reporting station was 22 miles south east of the accident site and was reporting winds from 030 degrees at 7 knots. According to the Kaman K-1200 flight manual, the maximum right quartering tailwind condition for takeoff and landing is from 17 knots to 25 knots. The winds at the accident site most likely exceeded the maximum wind allowed with reference to the helicopter's prevailing wind envelope, which resulted in the helicopter lifting to the left and rolling over.

On December 17, 2008, about 0930 Pacific standard time, a Kaman Aerospace Corporation, K-1200 helicopter, N267KA, sustained substantial damage after being upset by a wind gust while standing with engines and rotors operating near Santa Clarita, California. The certificated commercial pilot, the sole occupant, was not injured, while a ground crewman was killed. Visual meteorological conditions prevailed at the time of the accident, and a flight plan was not filed. The proposed flight was planned to operate in accordance with 14 Code of Federal Regulations (CFR) Part 91, with Whiteman Airport (WHP), Los Angeles, California, the reported destination. In a statement submitted to the NTSB investigator-in-charge (IIC), as well as in a telephone conversation with the IIC, the pilot reported that about 30 seconds after starting the helicopter's engine and while in ground idle, the mechanic disconnected the auxiliary power unit (APU). The pilot stated "...then the helicopter began to lift on the right side. I applied full right cyclic to counter the lifting. I ran out of cyclic and was on the stops. The aircraft was still lifting to the left. The right wheel then came off the ground and the tail of the aircraft lifted over the nose." The pilot revealed that the [main rotor] blades impacted a fuel truck, then departed the [helicopter] before striking the mechanic. The helicopter subsequently flipped over and came to rest inverted. The pilot stated that the helicopter was facing a north-northwest direction and the wind was from the east-southeast at a velocity of between 10 to 15 knots. The pilot further stated that the helicopter's main rotor blades were destroyed and that the tail boom was bent and twisted about 90 degrees to the right of the aircraft's longitudinal axis. There was no post crash fire. The pilot stated that gusty wind conditions in the area were not uncommon. According to the Kaman K-1200 Federal Aviation Administration (FAA) Approved Flight Manual, page 5-12, Figure 5-9, Prevailing Wind Envelope, the maximum right quartering tailwind condition for takeoff and landing is from 17 knots to 25 knots. (Refer to the attached Prevailing Wind Envelope.)