NTSB Identification: SEA82FYK08
14 CFR Part 133: Rotorcraft Ext. Load
Accident occurred Monday, February 22, 1982 in SUTHERLIN, OR
Probable Cause Approval Date: 02/22/1983
Aircraft: KAMAN HH-43F, registration: N4524
Injuries: 1 Minor.

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.

THE HELICOPTER WAS BEING USED ON A LOGGING OPERATION. AFTER RELEASING A LOAD FROM A HOVER OUT OF GROUND EFFECT, THE PILOT BEGAN TO TURN AND ACCELERATE. ABOUT TWO-THIRDS TO THREE-FOURTHS OF THE WAY THROUGH A 180 DEGREE TURN, THE AIRCRAFT BEGAN A SUDDEN, VERY VIOLENT, RAPID VIBRATION. THE PILOT RECALLED BEING THRASHED ABOUT WHILE THE HELICOPTER ROLLED TO THE RIGHT AND CRASHED. AN INVESTIGATION REVEALED THAT ONE OF THE RIGHT ROTOR BLADES HAD FAILED. A 9.5 FT SECTION OF THE OUTBOARD LEADING EDGE ALONG WITH APPROXIMATELY A 3.5 FT PIECE OF THE BLADE TIP HAD SEPARATED. THEY WERE FOUND ABOUT 1/4 MILE FROM THE MAIN WRECKAGE. AN EXAMINATION OF THE BLADE REVEALED THAT THE STAINLESS STEEL CONDUCTOR STRIP, PN K711583-11, HAD BEEN PULLED LOOSE FROM THE BOLT WHICH HELD IT ON THE TOP SIDE OF THE BLADE. THE BOTTOM BOLT HOLE WAS ELONGATED AND THE BOTTOM OF THE STRIP WAS STRETCHED. THE PAINT SHOWED WHIP MARKS RADIATING OUT FROM THE INBOARD ATTACH POINT. A NEARBY TREE HAD NO EVIDENCE OF ROTOR CONTACT.

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

ROTOR SYSTEM,MAIN ROTOR BLADE..FAILURE,TOTAL

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

ROTOR SYSTEM,MAIN ROTOR BLADE..SEPARATION


Contributing Factors

ROTOR SYSTEM..VIBRATION

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