NYC07MA073

The failure of maintenance personnel to properly tighten (torque) the flight control servo lower attachment clevis, and reinstall a functioning lock washer, which resulted in a flight control disconnect and a complete loss of helicopter control. Contributing to the accident was the operator's failure to ensure its maintenance program was being executed in accordance with Federal regulations.

The helicopter was returning from a sightseeing flight when the pilot contacted the dispatcher and announced, "I'm having hydraulic problems, and I'm probably going to have to do a run-on landing." The language he used to describe his situation changed from "hydraulic problem" to "hydraulic failure" as the flight proceeded. The pilot did not immediately land at the approach end of the runway; instead, he continued to the departure end, where the passenger terminal was located. The helicopter approached the mid-point of the runway, and as it neared the surface, the dispatcher heard the pilot state, "Okay we're done." Then, the sound of the rotor changed pitch and the helicopter impacted the ground. Postaccident examination of the helicopter revealed that the left lateral flight control servo became disconnected in flight at the transmission. Further examination revealed that the lower clevis of the left lateral servo was still attached to the transmission case, but was no longer attached to the servo. The threads on the clevis, as well as the threads on the inner diameter of the servo, appeared undamaged. The jam nut, lock nut washer, and safety wire were still attached to the clevis threads and rotated freely. The lock washer was severely worn and the locking tang was missing. Metallurgical testing and torque testing of the accident servos revealed that the jam nut, washer, and piston rod were able to easily rotate off of the clevis if no torque was applied and with the locking tang missing. Under normal loads, the main hydraulic flight control servos experience slight twisting that could contribute to the servo rotating off the clevis bolt (without an intact and functioning locking washer installed). Therefore, the investigation revealed that the servo attachment nut was not torqued during maintenance about one month prior to the accident, and the lack of torque, coupled with the installation of a severely worn lock washer, allowed the servo to rotate off of the clevis during the accident flight, resulting in a complete disengagement of the servo from its mounting clevis on the transmission. Examination of the company maintenance program revealed that none of the mechanics at the helicopter's base had received factory training, and that the maintenance manuals they used were three revisions out of date. Mandatory quality control inspections of maintenance actions, as well as post-maintenance test flights prescribed in the General Operator's Manual and the manufacturer's maintenance manuals (that included the replacement of the flight control servo), were not performed. (This report was modified on June 16, 2009)

HISTORY OF FLIGHT On March 8, 2007, at 1502 Hawaii standard time, an Aerospatiale AS350BA helicopter, N354NT, operated by Heli-USA Airways, Inc., was substantially damaged when it collided with terrain following a loss of control while landing at the Princeville Airport (HI01), Princeville, Hawaii. The certificated airline transport pilot and three passengers were killed, and three passengers were seriously injured. Visual meteorological conditions prevailed for the local air tour flight that departed the Princeville Airport about 1415, and was conducted under 14 Code of Federal Regulations (CFR) Part 135. According to the company dispatcher, the helicopter departed for a 45-minute sightseeing flight. When the pilot contacted the company base by radio about 1455, the dispatcher anticipated a routine radio call announcing his return. Instead, the pilot announced, "I'm having hydraulic problems, and I'm probably going to have to do a run-on landing." The dispatcher took her hand-held radio, ran to the hangar area, and notified the base operator and the maintenance supervisor of the pilot's intentions. She stated that as the conversation with the pilot continued, the language he used to describe his situation changed from "hydraulic problem" to "hydraulic failure." She continued to monitor the frequency as the helicopter neared the airport. As the helicopter approached the ground, she heard the pilot state, "Okay we're done." Then, the sound of the rotor changed pitch and the helicopter impacted the ground. In interviews, several employees of the company explained how they prepared for the helicopter's arrival and heard it approaching. Some of the employees saw the helicopter "low" over the approach end of the runway, as they stood at base operations near the departure end of the runway. The helicopter then disappeared from their view, and shortly thereafter, they heard the sounds of impact. Another witness, who worked at the terminal building at the center of the airport and had an unobstructed view of the helicopter through her office window, watched the helicopter approach. She noticed that the helicopter was not approaching the runway faster than usual, but it was flying lower than usual. The helicopter slowed over the runway at less than 10 feet above the ground, then turned slowly towards the grassy area on the left side of the runway. The witness wondered what the helicopter was doing, because the helicopter was moving slowly in a level attitude seeming as though it would land in the grass. Then, "...all of a sudden, the nose went down and [the helicopter] hit the ground." She described the entire series of events as happening "slowly." When asked about the landing gear floats, the witness stated that they were not deployed prior to the accident. PERSONNEL INFORMATION The pilot-in-command, age 59, was current and qualified to fly the accident helicopter in accordance with CFR Parts 135 and 91. A review of Federal Aviation Administration (FAA) airman records revealed that the pilot held an airline transport pilot certificate with a rotorcraft-helicopter rating, a commercial pilot certificate with a rotorcraft-helicopter rating, and a rotorcraft-helicopter flight instructor certificate. The pilot had accrued 10,471 total hours of flight experience, with about 3,500 hours in the accident make and model helicopter. The airline transport pilot certificate was issued on August 20, 1977; the commercial certificate was issued on November 19, 1971 and the flight instructor certificate was issued on August 10, 1975. The original issuance of the FAA commercial pilot certificate was based on the pilot's previous military flight training and experience. The pilot's most recent FAA second-class medical certificate was issued on January 24, 2007. The certificate carried a limitation that required the pilot to have correcting lenses available for near vision correction. The pilot completed primary helicopter flight training with the U.S. Army in September of 1968. The primary flight training was conducted in a TH-55A Osage (Hughes Model 292). He later flew combat missions, and was an instructor in the UH-1 Iroquois. A copy of the pilot's resume was obtained and reviewed. The following synopsis is a chronological summary of the pilot's employment history as a helicopter pilot: 1967 - 1971 Pilot/Instructor US Army 1975 - 1977 Pilot Bell Helicopters - Instructor (Esfahan, Iran) 1977 - 1980 Pilot Rocky Mountain Helicopters - EMS operations 1980 - 1981 Pilot Windward Helicopters - Oil support and external load 1982 - 2000 Pilot Rocky Mountain Helicopters - EMS Ops and Safety Manager 2004 - 2007 Pilot Heli USA Airways, Inc. - Air tour operations The pilot's most recent Airman Competency/Proficiency Check was successfully completed on February 25, 2007. The pilot was also a company check airman per Special Federal Aviation Regulation 71, "Special Operating Rules for Air Tour Operations in the State of Hawaii." AIRCRAFT INFORMATION The Aerospatiale AS350BA helicopter was powered by a single Turbomeca Arriel 1B turboshaft engine, with a three bladed main rotor system, and a conventional two bladed tail rotor for anti-torque and heading control. The helicopter had a seating capacity of 6 passengers plus a pilot and had 2 doors on each side of the helicopter. The helicopter was manufactured in France in 1979. The AS350 series helicopters were made by Aerospatiale, Inc., a French company that later changed its name to Eurocopter, Inc., with a merger of Aerospatiale and Messerschmitt-Boelkow-Blohm (MBB), a German helicopter company. The helicopter had accrued 21,706 total hours of operation and its most recent 100-hour inspection was completed on February 22, 2007, at 21,642 hours. An engine change was performed on February 28, 2007, at 21,665 aircraft hours. A postaccident weight and balance estimate conducted by Eurocopter using the published weights of the pilot (145 pounds), a fuel load of 183 pounds, and a combined passenger weight of 1,085 pounds indicated that, at the time of the accident, the helicopter's approximate weight was 4,397 pounds, which was less than the certificated maximum allowable gross weight limit of 4,630 pounds. Company Maintenance Program The company was authorized by the FAA to conduct CFR Part 135 flight operations and maintenance in accordance with its FAA issued operations specifications (ops specs). The ops specs allowed the company to conduct maintenance on its helicopters as prescribed by the original equipment manufacturer (OEM) maintenance programs and were tracked by a computer database. The company maintained its helicopters in accordance with a maintenance program that consisted of regularly scheduled inspections, component changes, parts replacements, heavy checks (such as 100 or 500 hour inspections), unscheduled maintenance, maintenance check flights after specific types of maintenance, such as flight controls, hydraulic servos, main/tail rotor blade replacement and engine changes. The accident helicopter was maintained using compact disks (CDs) provided by Eurocopter and Turbomeca. The company General Operating Manual (GOM) was an FAA accepted, company written manual of standard operating procedures. Chapter 13 of the GOM outlined maintenance requirements, mechanics responsibilities, instructions for training of company mechanics, as well as a list of Required Inspection Items (RII). The RIIs called for separate inspections and signed logbook entries by mechanics that did not perform the actual work on the helicopter. The initial mechanic signed the logbook to indicate that the work was completed and a different mechanic stamped and signed the logbook to indicate that the work was inspected and approved for return to service. Maintenance Record Review for the Accident Helicopter A review of the maintenance logbook for the 30 days prior to the acciden