HEMS Eurocopter Loss of Power and Hard Landing (Reno, 2010) скачать в хорошем качестве

HEMS Eurocopter Loss of Power and Hard Landing (Reno, 2010)

On January 17, 2010, at 1250 Pacific standard time, a Eurocopter AS350 B3, N904CF, landed hard on the helicopter pad at Renown Regional Medical Center, Reno, Nevada. The helicopter was operated by Air Methods, d.b.a. Care Flight, under the provisions of Title 14 Code of Federal Regulations, Part 91, as a positioning flight. The pilot and the two medical crew were not injured, and the helicopter was substantially damaged. Visual meteorological conditions prevailed, and a company visual flight plan had been filed. The flight originated at the Renown Regional Medical Center. The pilot reported to the Safety Board investigator that the purpose of the helicopter emergency medical service (HEMS) flight was to fly to Humboldt General Hospital, Winnemuca, Nevada, to pick up a patient for an inner facility transfer to Renown Regional Medical Center. He lifted from the Renown helicopter pad and positioned the helicopter in to a high hover, 25 feet, per the normal operating procedures. Just as the pilot was beginning his transition to forward flight he heard a loud bang, and the helicopter experienced a partial power loss. The pilot lowered the collective slightly and landed hard on the helicopter pad. The post-accident airframe examination revealed that the nuts that attach the engine-to-main gear box flex coupling were not present on their respective bolts. The nuts and associated washers were located loose and clumped together just forward of the gimbal ring in the transmission input housing. An examination of the bolts and flex coupling by the Safety Board Materials Laboratory concluded that the nuts most likely had been hand tightened and that cotter pins had not been installed on the bolts. The improper installation lead to the failure of the flex coupling and resulted in a loss of power to the rotor system. Maintenance records showed that 59 flight hours before the accident the engine had been removed, the helicopter painted, and then the engine was reinstalled. The time between the engine removal and the reinstallation was 88 days. The mechanic who removed the engine stated that he removed the bolts to the engine-to-main gear box flex coupling, and then partially reassembled the flex coupling bolts. This action was not in accordance with the AS350 maintenance manual engine removal procedure. The mechanic who installed the engine 88 days later stated that he did not check the flex coupling bolts because the removal of those bolts is not specified in the maintenance manual as part of the engine removal or replacement procedure. The overall maintenance activity involved a 100-hour inspection, which included a visual inspection of the engine-to-main gear box flex coupling. Although a visual inspection of the engine-to-main gear box flex coupling is a required action, the Quality Assurance inspector signed off the maintenance without performing the visual inspection of the flex coupling. The NTSB determined the probable cause of this accident to be the improper installation of the engine-to-main gear box flex coupling, which resulted in the failure of the flex coupling and a loss of power to the rotor system during takeoff. Contributing to the accident was the mechanic who removed the engine's failure to follow the operator’s maintenance procedures. Also contributing was the Quality Assurance inspector's failure to follow the operator’s post-maintenance inspection requirements.