HILO, HI, USA
N369LA
HUGHES 369D
A SEARCH WAS INITIATED WHEN THE HELICOPTER DID NOT ARRIVE. IT WAS FND 2 DAYS LATER WHERE IT CRASHED DRG AN AUTOROTATION IN A RAIN FOREST. DRG THE FLARE/TOUCHDOWN, VEGETATION HAD CAUGHT ON A TUNDRA PAD ON THE L SKID & THE ACFT ROLLED OVER. AN EXAM REVEALED THE LWR BENDIX COUPLING ON THE ENG-TO-TRANSMISSION DRIVE SHAFT, PN 369A4410, & THE UPPER R ENG MOUNT, PN 369H8017, HAD FAILED. UNAPPROVED MOD/REPAIRS HAD BEEN MADE TO BOTH THE DRIVE SHAFT & OVERLYING COVER PANEL. A STEEL REINFORCING ROD HAD BEEN INSTALLED INSIDE THE COVER PANEL. DUE TO PRESSURE OF CARGO (LARGE WTR BUCKET), THE STEEL ROD HAD BEEN FORCED ONTO THE DRIVE SHAFT. THERE WAS EVIDENCE OF ANGULAR MISALIGNMENT & LATER FAILURE OF THE DRIVE SHAFT. A METALLURGICAL EXAM OF THE ENG MOUNT REVEALED LOW CYCLIC FATIGUE IN THE THREADED ROD AREA OF THE ADJUSTING SCREW. THE FRACTURE AREA OF THE DRIVE SHAFT WAS TOO BADLY DAMAGED TO DETERMINE THE MODE OF FAILURE. ACFT PREV OPERD IN CANADA, REG C-GVTJ. ANNUAL INSPN & U.S. AIRWORTHINESS CERTIFICATE ISSUED DESPITE UNAPPROVED MOD. DATE OF MOD UNKNOWN.
Source: NTSB Aviation Accident Database
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