History of Flight
On August 31, 2012, about 1045 eastern daylight time, a Bell 407 helicopter, registration N11SP, operated by the New York State Police (NYSP), made a forced landing to wooded terrain near Bath, New York. The helicopter was substantially damaged. The commercial pilot, who was the sole occupant, sustained minor injuries. Visual meteorological conditions prevailed, and a company VFR flight plan was filed for the public use aerial surveillance flight that had departed from a field near Hammondsport, New York, about 1020.
The pilot reported that the helicopter was in cruise flight between 110 and 120 knots at an altitude of about 2,500 feet mean sea level, with the autopilot heading and altitude modes engaged, when it encountered turbulence. He elected to climb to 3,500 feet and reached down to disengage altitude hold, at which point the helicopter began un-commanded excursions in pitch and yaw. The pilot pushed the cyclic forward and left to compensate for nose-up pitch and right yaw. The helicopter then pitched severely nose-down and entered a right spin. The pilot saw a portion of the tail boom, the tail rotor, and the tail rotor gearbox separating from the helicopter. He entered autorotation and completed a power-off landing to wooded terrain. After egressing, he called for assistance on his cellular telephone.
Witnesses reported seeing the helicopter in cruise flight when something fell off, followed by a spin. Others stated the helicopter was spinning before objects fell.
Personnel Information
The pilot held a commercial pilot certificate with rotorcraft/helicopter and instrument helicopter ratings. His most recent FAA second-class medical certificate was issued on April 13, 2012. He had accrued approximately 1,600 total flight hours, with 40 hours in the accident helicopter make and model. A NYSP Trooper, he joined the aviation division on June 7, 2012, and completed Bell 407 Initial Pilot and Ground Training on August 3, 2012. He was designated pilot-in-command for the Bell 407 on August 14, 2012. The accident flight was his second single-pilot mission.
Aircraft Information
The helicopter was manufactured in 2002 and maintained under a Manufacturer's Inspection Program. Its most recent inspection was completed on July 6, 2012, at 2,918.4 total aircraft hours. On the accident day, the helicopter was configured for single-pilot operation with the copilot's cyclic and collective controls removed.
Meteorological Information
At 1153, weather at Elmira/Corning Regional Airport (ELM), 22 miles southeast of the accident site, included clear skies, 10 miles visibility, temperature 26°C, dew point 14°C, and an altimeter setting of 30.03 inches of mercury. Wind was from 240° at 10 knots.
Wreckage and Impact Information
Examination of the wreckage revealed separation of the entire tail boom and substantial damage to the fuselage. The landing skids, main rotor blades, and tail boom had separated during the accident sequence. The fuselage exhibited substantial vertical impact damage, the landing skids had spread and fractured, all four main rotor blades separated in overload near the blade grips, the exhaust duct was crushed downward, and the tail boom separated due to main rotor blade contact. The pilot-side chin bubble was fractured, and the anti-torque pedals were in the full left position. The top of the forward cowling showed extensive main rotor blade rub marks. The tail rotor assembly exhibited no evidence of rotational damage. Fracture surfaces were consistent with overstress. The force trim switch was found in the off position.
Additional Information
During a maintenance test flight approximately one year after the accident, the NYSP chief pilot experienced a similar in-flight upset in a Bell 407 configured for single-pilot operation with the copilot controls removed. While in cruise flight with the force trim switch off, releasing the cyclic caused it to move aft, pitching the nose up and yawing right. He recovered but noted a pitch-up of about 15 to 20 degrees. A subsequent test flight on December 5, 2013, with an NTSB investigator aboard confirmed that in a single-pilot configuration with the force trim off, releasing the cyclic caused it to transition aft, pitching up and rolling right. The manufacturer duplicated these results. It was noted that the autopilot heading and altitude modes function only with the force trim on, but the mode capsules illuminate regardless of the trim position.
Tests and Research
The engine's electronic control unit showed no faults. Swabs from flight control surfaces revealed insect matter but no evidence of a bird strike. Hydraulic fluid analysis indicated high viscosity and silicone content but normal results otherwise. Hydraulic servo actuators, autopilot components, and gyros were tested and showed no anomalies precluding normal operation. Toxicology testing detected no drugs or alcohol in the pilot's blood.