San Juan, PR, USA
N452JM
ROBINSON HELICOPTER R44
After a 1.5-hour flight, while hover taxiing, the pilot initiated a turn to the left when the helicopter pitched up and rolled left, striking the main rotor blades against the ground and eventually coming to rest on its left side. The Puerto Rico Port Authority then moved the helicopter and cleaned up all of the scattered helicopter parts and debris prior to the arrival of a Federal Aviation Administration (FAA) inspector and without any photo documentation of the wreckage. The FAA inspector subsequently took photographs of the wreckage that included the forward left cyclic servo control (push-pull) tube attachment point on the non-rotating swashplate. The control tube was not attached and the swashplate attachment ear had no corresponding attachment hardware. In addition, the control tube rod end was separated from the top of the tube in overload. A search of the wreckage and the crash site by the FAA inspector did not produce the rod end, nor did a subsequent court-ordered search. A detailed examination of the helicopter revealed that the interior bore of the left lateral servo attachment ear had multiple scoring and impact marks consistent with the dimensions and spacing of the attachment bolt threads. The marks also indicated that the rod end attachment bolt had been forcibly pivoted while backing out of the hole, which likely occurred because the retaining nut was missing. During the helicopter's most recent annual inspection the left lateral servo was removed and replaced; however, neither the inspection nor the replacement of the servo required disconnection of the upper servo control tube rod end from the swashplate attachment ear. The pilot's operating handbook required the pilot to ensure that the flight control rod ends were "free without looseness," and that all fasteners were "tight" during preflight inspections. However, it is unknown whether the retaining nut was missing before the flight or if it came off in flight.
HISTORY OF FLIGHT On November 12, 2008, at 1431 Atlantic standard time, a Robinson Helicopter R44, N452JM, was substantially damaged when it impacted a runway, following a loss of control while hovering at Fernando Luis Ribas Dominicci Airport (TJIG), San Juan, Puerto Rico. The certificated commercial pilot received minor injuries, while the passenger was seriously injured. On January 10, 2009, the passenger died from his injuries. Visual meteorological conditions prevailed, and a visual flight rules flight plan was filed for the flight which departed Cyril E. King Airport (TIST), Saint Thomas, U.S. Virgin Islands, about 1300. The personal flight was conducted under the provisions of 14 Code of Federal Regulations Part 91. In a written statement, and also in an interview with a Federal Aviation Administration (FAA) aviation safety inspector, the pilot stated that he completed his approach to runway 9, abeam the U.S. Customs facility on the north side of the runway. He was then instructed by the tower controller to hover-taxi to the U.S. Customs parking ramp. The pilot initiated a hovering turn to the north, when the helicopter pitched up, rolled left, struck the main rotor on the ground, and eventually came to rest on its left side. During a telephone interview, the FAA inspector who responded to the scene reported that the Puerto Rico Port Authority had cleaned up all of the scattered helicopter parts and debris prior to his arrival, without any photo documentation of the wreckage. The inspector photographed ground scars on the runway, the main wreckage as found, and later took photographs of the helicopter after it was placed upright in a hangar. PERSONNEL INFORMATION The pilot held a commercial pilot certificate with ratings for airplane single-engine land, airplane multiengine land, instrument airplane, and rotorcraft-helicopter. His most recent FAA second-class medical certificate was issued in June 2008. The pilot reported 1,700 total hours of flight experience, 800 hours of which were in helicopters, and 530 hours of which were in the Robinson R44. AIRCRAFT INFORMATION According to the pilot and FAA records, the helicopter was manufactured in 2000, and had accrued 510 total aircraft hours. The helicopter’s most recent annual inspection was completed July 17, 2008, at 497.5 aircraft hours. During the annual inspection, the left lateral servo was removed and replaced for a leak repair. In a telephone interview, the mechanic who performed the "pre- and post-inspection" of the accident helicopter stated he would itemize the discrepancies for correction during the annual inspection and then re-inspect the helicopter at the completion of all work. The mechanic stated that he "only saw the helicopter once a year" for its annual inspection. He said that during the pre-inspection, he would find repairs to the helicopter that had been performed since the last inspection, but not documented in the logbooks. Specifically, he remembered a wiring repair in the vicinity of the battery or starter relay where automotive electrical tape was used, and he wrote it up as a discrepancy. The mechanic stated that he did not know who performed maintenance or servicing of the accident helicopter between annual inspections. The mechanic was asked about the procedure to remove and reinstall the left lateral cyclic servo. He stated the removal of the servo required the disconnection of the servo from the bottom of the vertical push-pull tube, and that no convenience or benefit could be gained by disconnecting the push pull tube at the non-rotating swashplate. He stated that the maintenance manual prescribed removal at the bottom of the push-pull tube only. The mechanic further stated that the Robinson annual inspection checklist required the inspection of all flight control attachment points, to include the presence of "torque seal" paint across the attachment hardware of each connection. The mechanic stated that the flight controls were secure and marked with "torque seal." According to the R44 Pilot's Operating Handbook, Daily or Preflight Checks, the pilot ensured the flight control rod ends were "free without looseness" and that all fasteners were "tight." METEOROLOGICAL INFORMATION At 1456, the weather conditions reported at Luis Munoz Marin International Airport (TJSJ), located 6 nautical miles east of the accident site, included few clouds at 3,200 feet, visibility 10 miles, temperature 30 degrees Celsius, dewpoint 22 degrees Celsius, and an altimeter setting of 29.82 inches of mercury. The winds were from 070 degrees at 13 knots. WRECKAGE AND IMPACT INFORMATION Examination of the inspector's photographs revealed that the forward right, forward left, aft, and fixed scissor attachment points of the non-rotating swashplate were visible. All revealed that the respective control tubes and scissor rod-ends were attached, with the exception of the forward left. The forward left attachment ear had no corresponding attachment hardware, and the attachment rod-end was separated from the top of the control tube. The fracture surface appeared consistent with overload. A search of the wreckage and the crash site by the FAA inspector did not produce the rod-end. On January 25, 2010, at Isla Grande Airport, a court-ordered search for the unaccounted-for rod-end was conducted. The rod-end was not recovered. A detailed examination of the helicopter by an FAA inspector revealed flight control continuity throughout, except to the point of the left lateral servo control tube separation. Inspection of the interior bore of the left lateral servo attachment ear revealed marks consistent with the dimensions and spacing of the attachment bolt threads. The helicopter was released to the owner on August 6, 2009. A consultant hired by the owner conducted an inspection of the wreckage on August 12, 2009 under the supervision of two FAA inspectors. The swashplate and support assembly were removed and examined at McSwain Engineering in Pensacola, Florida, on March 11-12, 2010. Detailed photographs were taken and forwarded to the National Transportation Safety Board investigator-in-charge for inspection. Examination of the photographs revealed thread marks consistent with rotational scoring, and multiple impacts. The interior bore of the swashplate attachment ear was wiped with a swab, and the swab recovered a large quantity of metal filings consistent with the interior bore. The photographs were then forwarded to an NTSB Senior Metallurgist, who concurred with the examination. ADDITIONAL INFORMATION Examination of the Robinson Helicopter maintenance manual revealed that removal of the left lateral cyclic servo did not require disconnection of the C121-31 (upper) control tube from the swashplate. The requirement was for the removal of the C121-28 (lower) control tube along with the servo. Examination of the inspection and maintenance items performed during the most recent annual inspection revealed no procedures that required the disconnection of the upper left lateral servo push-pull tube rod end at the swashplate attachment ear.
The detachment of the forward left servo control tube upper rod end attachment bolt during a hover due to separation of its retaining nut for undetermined reasons.
Source: NTSB Aviation Accident Database
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