WPR15LA249

The commercial pilot reported that, after returning from a noneventful personal flight and during the approach for landing, he noticed erratic cyclic control movements. He attempted an emergency landing, but the cyclic continued to move erratically counter-clockwise, and the helicopter subsequently landed hard. Postaccident examination of the helicopter revealed that a main rotor damper had disbonded, which would have resulted in the degradation of its damping capability and excessive main rotor vibrations and oscillations. This would have caused substantial damage in the main rotor mast supporting structure and aft cabin bulkhead before the landing and the erratic cyclic control movements reported by the pilot. Further examination of the helicopter and engine did not reveal any additional evidence of a mechanical malfunction or failure that would have precluded normal operation.

On August 23, 2015, about 1645 mountain standard time, a Schweizer 269C, N315TV, sustained substantial damage during a hard landing, at the Falcon Field Airport (FFZ) Mesa, Arizona. The helicopter was registered to Canyon State Aero LLC., and operated by the pilot under the provisions of Title 14 Code of Federal Regulations Part 91. The commercial pilot was not injured and the passenger sustained minor injuries. Visual meteorological conditions prevailed and no flight plan was filed for the personal flight. The local flight originated at FFZ about 1615. The pilot reported that during the approach to the ramp area in front of the operator's hangar, he noticed erratic cyclic control movements, and during the landing, the helicopter landed hard. Initial examination of the helicopter by a Federal Aviation Administration (FAA) inspector revealed that the main rotor blades and tail boom were substantially damaged. The helicopter was recovered to a secured local storage facility for further examination. Further examination by the National Transportation Safety Board (NTSB) investigator-in-charge (IIC), an FAA inspector, and a representative from Sikorsky, revealed the helicopter was sitting upright on its skids with the tail boom separated. All three main rotor blades were attached to the main rotor head. The main rotor mast was observed to be tilted. The flight control system was generally intact. All rods and bellcranks were appropriately attached at all their respective points. Flight control continuity with the cyclic and collective was established with the cockpit controls. Continuity to the tail rotor was established from the cockpit pedals to the forward end of the control rod where a facture was observed; and from that fracture point to the tail boom. The electric cyclic trim system was operated and was fully functional with no anomalies noted. The helicopter main rotor mast support structure including the lower transmission housing sustained damage and resulted in the main rotor mast being tilted. Scratches and marks were observed on the mast indicating its movement. Further damage was sustained to the aft cabin bulkhead. The main rotor head was intact and attached to the drive shaft. The swashplate was also intact, and the rotor head rotated freely in the mast bearing. The pitch housings remained attached to the main rotor hub and were correctly installed. The main rotor head dampers were removed and examined, and all three dampers exhibited compression contact marks on the interior of the barrel end caps, which indicated excessive lead lag motion. Additionally, the dampers had internally separated. Further examination of the dampers revealed that one had become dis-bonded and would result in the degradation of its damping capability. The engine was observed to be intact but had been slightly displaced due to the damage to the mast and main gear box mounting. Continuity with all the engine controls was established. When the engine starter wasengaged, the engine rotated normally with suction observed on the cylinders and fuel servo inlet. Examination of the helicopter did not revealed any additional evidence of a mechanical malfunction that would preclude normal operation. A review of the maintenance records revealed that the last annual inspection was on June 14, 2015, at 2,368 hours. The dampers were determined to be the original units. The main rotor damper inspection would have been complied with during the August 28, 2011, inspection, at 2,319 hours. Although not required, no specific results of the damper check dimensions were documented.