Accident Details
On February 29, 2012, about 1715 Pacific standard time, a Eurocopter AS 350-B3, registration N341HP, made a hard landing at Napa County Airport, Napa, California. The helicopter was substantially damaged during the landing. The commercial pilot, who held a certified flight instructor (CFI) certificate, was providing instruction to a second pilot holding a commercial pilot certificate. Neither pilot was injured. The California Highway Patrol (CHP), Sacramento, California, owned and operated the public use helicopter. The flight was conducted under 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed, and no flight plan was filed for the local area instructional flight that originated from Napa about 1600.
Sequence of Events
According to CHP management personnel, at the time of the accident, the CFI was handling the flight controls. While hovering about 3 feet above ground level, the CFI performed an autorotation demonstration for the second pilot. The CFI raised the collective to arrest the descent prior to landing, but the helicopter made a firm touchdown. The CFI reported no mechanical malfunctions or failures with the helicopter prior to impact. The CFI stated that his total flight experience was 2,783 hours, of which 409 were accumulated as a flight instructor.
Post-Accident Examination
During a subsequent examination of the tail boom, numerous dimples in the skin were noted near the area where the tail boom attaches to the fuselage. The tail boom was removed from the helicopter and transported to Eurocopter's Texas facility for repair.
The Federal Aviation Administration Rotorcraft Flying Handbook describes techniques for practice autorotation maneuvers. For hovering autorotations, it instructs the pilot to firmly roll the throttle to the engine idle position and apply proper antitorque pedal to maintain heading. It advises not adjusting the collective pitch on entry. When the helicopter settles to approximately 1 foot AGL, the pilot should apply upward collective pitch control while holding the throttle in the idle detent position to slow the descent and cushion the landing. The manual lists a common error as failure to apply up-collective pitch properly, resulting in a hard touchdown.