NTSB Identification: SEA83FA065.
The docket is stored on NTSB microfiche number 20987.
Accident occurred Friday, March 18, 1983 in LONGVIEW, WA
Aircraft: Fairchild Hiller FH-1100, registration: N26631
Injuries: 1 Serious.

NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.

SEVERAL PERSONS SAW THE HELICOPTER FLYING AT A CRUISING ALTITUDE OF ABOUT 200 TO 300 FT, THEN ENTER A LOOP TYPE OF MANEUVER. THEY LOST SIGHT OF THE HELICOPTER NEAR THE BOTTOM OF THE MANEUVER BEFORE IT CRASHED. THE PLT RECEIVED SERIOUS HEAD INJURIES & COULD NOT RECALL WHAT HAD HAPPENED. AN EXAM OF THE AIRFRAME REVEALED THAT THE TRANSMISSION & MAIN ROTOR HUB ASSY HAD REMAINED PARTIALLY ATTACHED TO THE AIRFRAME THRU THE LEFT & RIGHT LONGITUDINAL TRANSMISSION STRUTS. BOTH THE LEFT & RIGHT VERTICAL AS WELL AS BOTH LEFT & RIGHT LATERAL TRANSMISSION STRUTS HAD SEPARATED NEAR THEIR ATTACH POINTS. A METALLURGICAL EXAM OF THESE PARTS REVEALED THAT FITTING ASSEMBLY, PN 24-61022-6 HAD FAILED AT A FATIGUE CRACK. ADDITIONALLY, CORROSION WAS FOUND WITHIN THE LEFT VERTICAL & LATERAL (ADJUSTABLE) TRANSMISSION STRUTS. PREIMPACT CONTINUITY OF THE CYCLIC PITCH CONTROL WAS VERIFIED.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

ROTOR DRIVE SYSTEM,MAIN GEARBOX/TRANSMISSION..FATIGUE

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

ROTOR DRIVE SYSTEM,MAIN GEARBOX/TRANSMISSION..FAILURE,PARTIAL


Contributing Factors

AIRCRAFT HANDLING..NOT POSSIBLE..PILOT IN COMMAND


Contributing Factors

ROTOR DRIVE SYSTEM,MAIN GEARBOX/TRANSMISSION..CORRODED

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