# NTSB LAX86MA238: Aerospatiale AS-355F-1, N909CH, Kameula, HI, May 31, 1986

- Type: NTSB accident investigation
- Classification: Accident · Minor injuries · Major investigation · Final report
- Date: May 31, 1986, 12:30 local (22:30 UTC)
- Place: Kameula, HI
- Coordinates: 20.040784, -155.699996 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=20.0408&lon=-155.7000&mi=10
- Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping)
- Highest injury: Minor injuries
- Injuries: 1 minor, 4 uninjured
- Status: Completed, report May 27, 1988
- Report: Approved by Office Director
- NTSB case key (mKey): 25282
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX86MA238
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/25282/pdf
- Page: https://openairdocs.org/ntsb/LAX86MA238

## Sequence of events

In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf).

- Miscellaneous/other, hover
  - fuselage - vibration
  - precautionary landing - performed
- Airframe/component/system failure/malfunction, landing
  - reason for occurrence undetermined (cause)
  - fuselage,attachment - fatigue
  - rotor system,main rotor hub flapping hinge/stop(s) - failure,total
  - landing gear,skid assembly - overload

## Analysis

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.

## Aircraft

- Registration: N909CH (not matched to a registry record)
- Reported make and model: AEROSPATIALE AS-355F-1
- Category: Helicopter
- Serial number: 5123
- Airframe hours: 731
- Engines: ALLISON 250-C20F 450 horsepower turbo shaft
- Damage: Substantial damage
- Flight: Personal, Part 91
- Operator: Hemmeter Aviation, Inc.
- Registered owner: Hemmeter Investment Company
- Airworthiness certificate: Standard, Normal
- Last inspection: Annual, December 5, 1985, 78 hours before
- Destination: MAUI, HI

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 37; commercial, airline transport; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 1, valid medical--no waivers/lim.; seat: right; flight hours: 2,657 total, 200 in this make and model, 2,040 as pilot in command, 50 in the last 90 days, 22 in the last 30 days, 2 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 60° at 5 knots
- Visibility: 25 statute miles
- Lowest ceiling: none
- Temperature: 93 °F

## FAA reports on this event (1)

The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs).

- [Accident 19860531087019A](https://openairdocs.org/incident/19860531087019A), May 31, 1986: Aerosp AS355F1, Kamuela, HI, Substantial damage. The starflex assembly failed during hover from composite cracking. Design of unit is considered to be causal.

From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model.

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