Kearny, NJ, USA
N210MH
BELL 206L-3
The pilot reported that, during a 20-ft hover, the helicopter spun right. The pilot made left pedal inputs; however, the helicopter then rotated three times to the right. The pilot decreased the throttle and increased the collective before the helicopter landed hard. Postaccident examination of the helicopter revealed that the No. 5 tail rotor driveshaft tube had separated from its bonded flange adapter, where it had been secured by adhesive. The driveshaft tube had been freshly painted. When some of the paint was removed, hand written markings in red ink reading "X," ".004," and ".024" were noted on the tube. The numbers were on either end of the tube and were likely measured runout values for the shaft, and, because they exceeded the maximum runout requirement of .003 inch, the "X" mark was made to indicate that the tail rotor shaft was unairworthy. However, at some point after the red markings were made, the unairworthy shaft was repainted by unknown personnel, which obscured the markings. It is likely that the driveshaft became imbalanced because it was beyond its runout tolerance, which led to the overstress separation of the tube from the bonded flange adapter. A representative of the current owner reported that the owner had recently purchased the helicopter. About 5 years before the purchase, the helicopter had experienced a hard landing, and it had not been flown during the subsequent 5 years. The current owner received the helicopter with the driveshaft freshly painted. When he inquired about the fresh paint, the previous owner told him that the driveshaft was purchased at auction. The current owner did not receive serviceable tags with the driveshaft but did receive an auction invoice; however, no serial numbers were listed on the invoice. The serial number format found etched on the driveshaft did not match any known records. Therefore, the investigation could not determine if the separated driveshaft was the same driveshaft that was installed on the helicopter when it experienced the hard landing. As a result of the accident examination, the helicopter manufacturer submitted a suspected unapproved parts report to the Federal Aviation Administration.
On May 20, 2015, about 1030 eastern daylight time, a Bell 206L-3, N210MH, registered to Meridian Helicopters LLC and operated by New York Helicopter, was substantially damaged during a hard landing, following a loss of control in a hover at Helo Kearny Heliport (65NJ), Kearny, New Jersey. The commercial private pilot was not injured. The positioning flight was conducted under the provisions of 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed and no flight plan was filed for the planned flight to Downtown Manhattan/Wall Street Heliport (JRB), New York, New York.The pilot reported that he fueled the helicopter at 65NJ and planned to position it to JRB. He entered a 20-foot hover prior to departure, in order to contact air traffic control (ATC) for clearance into the overlying airspace. Before he could radio ATC, the helicopter started to yaw to the right. The pilot attempted to correct the yaw with left pedal input; however, the helicopter spun three revolutions to the right. The pilot decreased throttle and increased collective, before the helicopter landed hard on the helipad while still yawing to the right. During the hard landing, the tail rotor contacted the ground and the main rotor contact the tail boom. Subsequent examination of the helicopter by a Federal Aviation Administration (FAA) inspector revealed that a section of the tail rotor driveshaft had separated. The inspector also noted damage to the tail boom, tail rotor blades, left vertical fin, and vertical stabilizer. Review of maintenance records revealed that the operator had recently leased the helicopter. Prior to that, it had experienced a hard landing in Chile in 2010 and had not flown until the current registered owner recently purchased it. On April 28, 2015, a hard landing inspection was completed on the helicopter, followed by an annual inspection on April 30, 2015. As the helicopter was received by the registered owner partially disassembled, the accident tail rotor driveshaft was installed after the hard landing inspection, but before the annual inspection. The helicopter had been operated for about 26 hours from the time of those inspections, until the time of the accident. The separated section of tail rotor driveshaft was examined at the manufacturer's facility under the supervision of an FAA inspector. The examination revealed that the No. 5 tail rotor driveshaft tube separated from its bonded flange adapter, where it had been secured by an adhesive. Due to the shaft tube spinning in the adapter after separation, the amount of adhesive remaining at the time of failure could not be determined to compare against the required amount of .003 inch bond line thickness. The remaining adhesive appeared disbonded and discolored, consistent with heat generated by the separated spinning driveshaft tube. Additionally, the separated section of driveshaft had been painted at some point after manufacture as the finish was different than what was applied during manufacture. When some of the paint was removed from the driveshaft tube, a red "X" was noted near the middle of the tube along with red numbers .004 and .024 on either end of the tube, consistent with runout numbers that were in exceedance of the manufacturer's maximum runout requirement of .003 inch. The examination also revealed areas where corrosion had been removed. Further, the format of the serial number (BTMK 00777) found etched on the driveshaft did not match any known records. A representative of the registered owner of the helicopter reported that when he recently purchased the repaired helicopter from Marks Aviation Group, the driveshafts were received freshly painted. He further stated that when he inquired about that, he was told by the previous owner that the driveshafts were purchased at auction. The current owner did not receive serviceable tags with the driveshaft, but did receive an auction invoice; however, no serial numbers were listed on the invoice. As such, the investigation was unable to determine if the separated driveshaft was the same driveshaft that was on the helicopter when it experienced a hard landing in 2010. As a result of the examination, the helicopter manufacturer submitted a suspected unapproved parts report to the FAA.
The deliberate concealment and reuse of an unairworthy tail rotor driveshaft by unknown personnel, which resulted in an overstress separation at a bonded flange adapter as a result of driveshaft imbalance.
Source: NTSB Aviation Accident Database
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