MOBILE, AL, USA
N5197W
KAMAN HH-43B/F
THE HELICOPTER WAS BEING USED FOR EXTERNAL LIFT, LONG-LINE LOGGING OPERATIONS. AFTER LIFTING A LOAD OF LOGS, THE PILOT EXPERIENCED CONTROL PROBLEMS WITH THE HELICOPTER. THE LOAD, AND THEN THE LONG LINE, WERE JETTISONED, AND AN EMERGENCY DESCENT WAS BEGUN TO THE REMOTE, TEMPORARY LOG HELIPORT. AS THE PILOT ATTEMPTED TO SLOW THE HELICOPTER'S DESCENT RATE, CONTROL WAS LOST. POWER WAS REDUCED, A LEVEL ATTITUDE REGAINED, AND THE MAIN ROTOR BLADES CONTACTED THE GROUND. THE FUSELAGE THEN LANDED HARD. THE WRECKAGE WAS EXAMINED, WHICH REVEALED THAT THE COTTER PIN FOR THE RIGHT ROTOR HEAD TEETER PIN RETAINING NUT WAS ABSENT. ABSENCE OF THE COTTER PIN WOULD ALLOW THE TEETER PIN RETENTION NUT TO LOSE TORQUE, AND EVENTUAL SEPARATION OF THE ROTOR HEAD FROM THE HELICOPTER.
On December 29, 1993, at about 1655 central standard time, a Kaman HH-43B/F, N5197W, collided with the ground during an emergency descent near Mount Vernon, Alabama. The helicopter was operated by Scott Paper Company under 14 CFR Part 133, and visual flight rules. Visual meteorological conditions prevailed. A flight plan was not filed for the external lift, long-line, logging flight. The commercial pilot was not injured, and the helicopter was substantially damaged. The local flight had departed a logging work area at an unspecified time. The pilot reported a partial loss of rotor system control, after lifting an external load of logs. The external load was jettisoned. Control of the helicopter could be maintained while in straight and level flight, with the collective at its lowest pitch setting. As the pilot attempted to slow the helicopter's descent rate for a landing, control was lost. The collective was lowered, and the helicopter collided with the ground. The rotor system contacted the ground and shattered, and the fuselage landed hard. The operator examined the wreckage and discovered that the cotter pin for the right rotor head teeter pin retention nut was absent. Both rotor hub assemblies had been replaced because of normal maintenance action on December 13, 1993. The operator stated that a maintenance action checklist would be developed to supplement the Maintenance Manual to preclude a similar oversight in the future.
AN INADEQUATE MAJOR REPAIR BY COMPANY MAINTENANCE PERSONNEL WHO FAILED TO INSTALL THE COTTER PIN WHICH SECURED THE RETAINING NUT OF THE RIGHT MAIN ROTOR HUB TEETER PIN.
Source: NTSB Aviation Accident Database
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