Accident Aerospatiale AS-355F-1 N909CH,
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ASN Wikibase Occurrence # 374979
 
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Date:Saturday 31 May 1986
Time:12:30 LT
Type:Silhouette image of generic AS55 model; specific model in this crash may look slightly different    
Aerospatiale AS-355F-1
Owner/operator:Hemmeter Aviation, Inc.
Registration: N909CH
MSN: 5123
Total airframe hrs:731 hours
Engine model:Allison 250-C20F
Fatalities:Fatalities: 0 / Occupants: 5
Aircraft damage: Substantial
Category:Accident
Location:Kameula, HI -   United States of America
Phase: Taxi
Nature:Private
Departure airport:
Destination airport:Maui, HI
Investigating agency: NTSB
Confidence Rating: Accident investigation report completed and information captured
Narrative:
THE PLT RPRTD THAT AS HE 'HOVERED' THE HELICOPTER BTN 5 & 10 FT AFTER LIFT-OFF, HE NOTED A 'SLIGHT LATERAL VIBRATION.' HE LNDD IMMEDIATELY, BUT THE VIBRATION/GROUND RESONANCE (VIB) INCREASED IN SEVERITY, SO HE 'SHUT-OFF' BOTH THROTTLES. THE VIB CONTD TO THE EXTENT THAT HE COULDN'T HOLD ONTO THE CYCLIC CTL STICK. THE TRANSMISSION SEPD FM ITS ATTACH POINT &THE MAIN ROTOR BLADES CONTACTED THE GND BFR THE ENG STOPPED. AN EXAM REVEALED THE TRANSMISSION SUPPORT BARS (TSB'S) HAD FAILED DRG THE ACDNT. THERE WAS EVIDENCE OF OVERLOAD FAILURE OF THE TSB'S, EXCEPT THE LEFT FWD TSB HAD EVIDENCE OF FA- TIGUE ON EITHER SIDE OF THE BUCKLED AREA. A STRIATION COUNT INDCD THE CRACK HAD PROGRESSED OVR AN ESTD TIME OF AT LEAST 1 HR & 15 MIN. ALSO, AN ARM OF THE STARFLEX ASSY (S/A) HAD FAILED. THE S/A HAD 323 HRS SINCE RPLCMNT. CRAZE CRACKS WERE FND ON THE S/A, BUT AN EXAM FAILED TO VERIFY WHETHER THEY HAD FORMED BFR OR DRG THE ACDNT. THE S/A WAS APRX 3% POROUS & HOLES IN THE ENAMEL BARRIER ALLOWED ENVIRONMENTAL BLACKENING OF ITS EDGES. LNDG SKID SHOCK ABSORBERS WERE BADLY DMG.

Probable Cause:

Accident investigation:
cover
  
Investigating agency: NTSB
Report number: LAX86MA238
Status: Investigation completed
Duration: 1 year and 12 months
Download report: Final report

Sources:

NTSB LAX86MA238

Location

Revision history:

Date/timeContributorUpdates
28-Mar-2024 14:54 ASN Update Bot Added

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