ERA12LA373

According to the pilot/owner/builder of the experimental amateur-built helicopter, he had recently finished performing maintenance on the helicopter, which included tracking its rotor system. He then positioned the helicopter in front of his hangar and proceeded to perform an operational check, before attempting to hover the helicopter. Immediately upon entering the hover, the pilot felt a large amount of vibration in the cyclic control and the helicopter began moving to the left. The pilot pushed the cyclic control right in an effort to stop the left movement of the helicopter, but the control input was ineffective. The pilot then increased the helicopter's altitude to avoid a collision with nearby obstacles and attempted to maneuver to an open grass area. Realizing that the rotor rpm had decayed, he reduced the collective pitch and increased engine power. The helicopter then entered a settling-with-power flight condition and impacted a taxiway located between two hangars. During a telephone interview conducted about 2 weeks after the accident, the pilot stated that the loss of control that precipitated the accident was most likely due to improper tracking of the helicopter's main rotor blades, related to the method of leveling the blades he had used during the helicopter's most recent maintenance. A postaccident examination of the wreckage revealed that the cyclic control cross tube had separated from its attachment point at the left side of the fuselage, adjacent to a break in a repair weld of the fuselage's tubular frame. Detailed examination of the fracture surface revealed that while the weld was of a generally poor quality, the fracture exhibited features consistent with a failure in bending overload. Given the nature of the failure, it is most likely that the weld fractured during the impact sequence.

On May 30, 2012, about 2010 eastern daylight time, am experimental amateur-built Rotorway Exec 162F, N8707E, was substantially damaged during a hard landing at Smoketown Airport (S37), Smoketown, Pennsylvania. The commercial pilot/owner/builder of the helicopter incurred minor injuries. Visual meteorological conditions prevailed, and no flight plan was filed for the local flight. The personal flight was conducted under the provisions of Title 14 Code of Federal Regulations Part 91. According to the pilot, he had recently finished performing maintenance on the helicopter, which included tracking its rotor system following removal of the main rotor blades. He then positioned the helicopter in front of his hangar and proceeded to perform an operational check before attempting to hover the helicopter. Immediately upon entering the hover, the pilot felt a large amount of vibration in the cyclic control and the helicopter began moving to the left. The pilot pushed the cyclic control right in an effort to stop the left movement of the helicopter, but the control input was ineffective. The pilot then climbed the helicopter to avoid a collision with several nearby posts and the hangar, and attempted to maneuver to an open grass area. Realizing that the rotor rpm had decayed, he reduced the collective pitch and increased engine power. The helicopter then entered "settling with power" and impacted a taxiway located between two hangars. Federal Aviation Administration inspectors examined the helicopter following the accident. During the examination the inspectors found that the helicopter's tubular steel frame had fractured in two locations. Each location was the site of a weld repair, which according to the pilot, were performed following a previous hard landing in 2006. The inspectors also found that the cyclic control cross tube had disconnected from its pivot point on the left side of the fuselage frame, just aft of one of the previously observed separations in the frame. The inspectors reported no other evidence of any pre-impact mechanical malfunctions or failures. The portions of the tubular frame encompassing the fractures were sectioned from the wreckage and forwarded to the NTSB Materials Laboratory for detailed examination. The first two halves of tubular frame pieces examined were located adjacent to the left front skid attachment point. The tube pieces exhibited a branched circumferential fracture that followed several external porous weld deposits, arc strikes, areas of burn-through, and two cross-drilled holes. The tube weldment exhibited fracture features consistent with a failure in bending overstress. The second set of structural tubing was recovered from the engine mount area, and was fractured through the filet weld deposit where a square tube was joined to a round tube. The thermal discoloration of the paint and the morphology of the weld deposit in the vicinity of the fracture were consistent with weld deposit overlay over an existingfilet weld. The weld deposit in the region of the fracture exhibited undercut, incomplete fusion, overlap, insufficient throat, burn-through, and poor filet formation. The fracture of the weld exhibited features consistent with failure due to bending overstress. During a telephone interview conducted by a Federal Aviation Administration (FAA) inspector several weeks after the accident, the pilot stated that he believed that the loss of control that had precipitated the accident was due to improper main rotor blade tracking, and specifically, related to the method of leveling the blades he had utilized during the helicopter's most recent maintenance.