# NTSB ANC83LA138: Hughes 369D, N1106Z, Mcgrath, AK, August 5, 1983

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: August 5, 1983, 12:45 local (20:45 UTC)
- Place: Mcgrath, AK
- Coordinates: 63.609722, -154.779556 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=63.6097&lon=-154.7796&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 1 uninjured
- Status: Completed
- Report: Approved by Office Director
- NTSB office: Alaska Regional Office
- NTSB case key (mKey): 4150
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC83LA138
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/4150/pdf
- Page: https://openairdocs.org/ntsb/ANC83LA138

## Sequence of events

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

- Loss of engine power(total) - mech failure/malf, cruise - normal
  - engine assembly,valve,intake - leak (cause)
  - combustion assembly,combustion liner - distorted (contributing factor)
  - turbine assembly,nozzle - overtemperature (contributing factor)
- Forced landing, landing
  - autorotation - performed, pilot in command
- Hard landing, landing - flare/touchdown
  - terrain condition - mountainous/hilly (contributing factor)

## Analysis

THE PLT STATED THAT HE WAS FLYING STRAIGHT & LEVEL AT APRX 700 FT AGL, WHEN THE ENG-OUT LIGHT ILLUMINATED. HE BEGAN AN AUTOROTATION TO A RIDGELINE. DURING THE LANDING, THE MAIN ROTOR BLADES CONTACTED THE TAIL BOOM & SEVERED IT FROM THE MAIN FUSELAGE. AN INVESTIGATION REVEALED THAT THE ENG BURNER DRAIN VALVE HAD AN AIR LEAKAGE OF 3000 CC/MIN. THE MAX ALLOWABLE OHM LIMIT WAS 800 CC/MIN (AT 20 PSI). THE COMBUSTION LINER HAD EXCESSIVE HEAT DISTORTION ADJACENT TO THE LARGE DIAMETER HOLE ON THE RIGHT SIDE OF THE SKIRT. THE 1ST STAGE TURBINE NOZZLE HAD SEVERE HEAT DISTRESS ON 14 TRAILING EDGE VANES & 11 LEADING EDGE VANES. THE FUEL NOZZLE HAD HEAVY CARBON DEPOSITS ON THE SPRAY TIP & AIR SHROUD. ALSO, A WHITE RESIDUE WAS FOUND IN THE ENG & A FUEL SAMPLE REVERSED 425 PARTS PER MILLION OF PHOSPHORUS.

## Aircraft

- Registration: [N1106Z](https://openairdocs.org/aircraft/N1106Z), registered now, S/N 210900D, built 1981 (OpenAirDocs)
- Reported make and model: HUGHES 369D
- Registry model: [Hughes Helicopters HUGHES 369D](https://openairdocs.org/model/hughes-helicopters-hughes-369d) (registry code 4470706) (OpenAirDocs)
- Registry engine: [Allison 250 SER 250HP](https://openairdocs.org/engine/allison-250-ser-250hp) (registry code 03002, turbo-shaft) (OpenAirDocs)
- Category: Helicopter
- Serial number: 210900D
- Airframe hours: 1617
- Engines: ALLISON 250-C20B 375 horsepower turbo shaft
- Damage: Substantial damage
- Flight: Business, Part 91
- Registered owner: Temsco Helicopters
- Airworthiness certificate: Standard, Normal
- Last inspection: 100 hour, July 31, 1983, 24 hours before
- Departed: MCG, MCGRATH, AK

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 29; commercial; airplane ratings: single-engine land, single-engine sea; instrument ratings: airplane; medical: class 2, valid medical--no waivers/lim.; seat: left; flight hours: 3,640 total, 2,310 in this make and model, 3,640 as pilot in command, 375 in the last 90 days, 4 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 260° at 12 knots, gusting 14
- Visibility: 10 statute miles
- Lowest ceiling: 1,500 ft overcast
- Temperature: 45 °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 19830805042429A](https://openairdocs.org/incident/19830805042429A), Aug 5, 1983: Hughes 369D, Mcgrath, AK, Substantial damage. Crash occurred during autorotation landing after engine flamed out for unknown reasons.

## Other investigations on N1106Z (1)

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.

- [NTSB SEA91LA023](https://openairdocs.org/ntsb/SEA91LA023), Nov 26, 1990: Hughes 369D (N1106Z), Mulina, OR, substantial damage. Probable cause: IN-FLIGHT COLLISION WITH A REBOUNDING LONG-LINE, WHICH CAUSED MAIN-ROTOR RPM DECAY AND TAIL-BOOM SEPARATION, COMPROMISING THE PILOT'S ABILITY TO SUCCESSFULLY ACCOMPLISH AN ATTEMPTED AUTOROTATION.

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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