# NTSB LAX87FA173: Hughes 369E, N5200W, Palm Desert, CA, April 11, 1987

- Type: NTSB accident investigation
- Classification: Accident · Serious injuries · Field investigation · Final report
- Date: April 11, 1987, 07:35 local (14:35 UTC)
- Place: Palm Desert, CA
- Coordinates: 33.700004, -116.39933 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=33.7000&lon=-116.3993&mi=10
- Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping)
- Highest injury: Serious injuries
- Injuries: 1 serious, 1 minor
- Status: Completed, report June 7, 1989
- Report: Approved by Office Director
- ADs cited in the narratives: [AD 86-20-07](https://openairdocs.org/ad/86-20-07) (OpenAirDocs)
- NTSB case key (mKey): 25397
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX87FA173
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/25397/pdf
- Page: https://openairdocs.org/ntsb/LAX87FA173

## Sequence of events

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

- Airframe/component/system failure/malfunction, maneuvering
  - rotor drive system,tail rotor gearbox(90 deg) - incorrect (cause)
  - maintenance,compliance with ad - improper, other maintenance personnel (cause)
  - rotor drive system,tail rotor gearbox(90 deg) - fatigue (cause)
  - rotor drive system,tail rotor gearbox(90 deg) - separation
- Loss of control - in flight, maneuvering
- Forced landing, descent - emergency
  - autorotation - attempted, pilot in command
- Hard landing, landing

## Analysis

THE HELICOPTER DSCNDD UNCONTROLLED & CRASHED IN A RESIDENTIAL AREA. AFTER THE ACDNT, THE PLT SAID HE AGREED TO ORBIT THE RESIDENCE OF HIS PAX. AT THE APRX 135 DEG POINT OF A LEFT ORBIT, HE FELT 'A BANG & SEVERE VIBRATION IN THE TAIL.' THE PLT LOST DRCTNL CTL & THE HELICOPTER BEGAN SPINNING TO THE RIGHT. AN EXAM OF THE TAIL ROTOR GEAR BOX (T/R GB) ASSY REVEALED 3 OF 4 T/R GB MOUNTING STUDS HAD FAILED FROM CYCLIC FATIGUE DUE TO BENDING WHICH HAD RESULTED FROM A LOSS OF CLAMP-UP TORQUE. SUBSEQUENTLY, THE LOWER RIGHT EAR OF THE T/R GB (AT THE LCTN OF THE 4TH STUD) FAILED FROM OVERLOAD & THE T/R GB SEPD. FURTHER INVESTIGATION REVEALED THAT 3 WASHERS HAD BEEN INSTALLED ON EACH OF THE MOUNTING STUDS, BUT ONLY ONE WAS PERMITTED. THE WASHERS WERE INSTALLED DURING COMPLIANCE WITH AD 86-20-07, 78 FLT HRS BEFORE THE ACDNT.

## Aircraft

- Registration: [N5200W](https://openairdocs.org/aircraft/N5200W), registered now, S/N 0025E (OpenAirDocs)
- Reported make and model: HUGHES 369E
- Registry model: [Hughes Helicopters 369E](https://openairdocs.org/model/hughes-helicopters-369e) (registry code 4470707) (OpenAirDocs)
- Registry engine: [Allison 250-C20 series](https://openairdocs.org/engine/allison-250-c20-series) (registry code 03020, turbo-prop) (OpenAirDocs)
- Category: Helicopter
- Serial number: 0025E
- Airframe hours: 333
- Engines: ALLISON 250-C20B 270 horsepower turbo shaft
- Damage: Substantial damage
- Flight: Personal, Part 91
- Registered owner: Kensrue Development Corp.
- Airworthiness certificate: Standard, Normal
- Last inspection: 100 hour, January 9, 1987, 35 hours before
- Departed: UDD, BERMUDA DUNES, CA
- Destination: 17L, HEMET, CA

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 65; commercial; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 2, valid medical--w/ waivers/lim; seat: left; flight hours: 6,000 total, 111 in this make and model, 5,075 as pilot in command, 16 in the last 90 days, 2 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 210° at 3 knots
- Visibility: 40 statute miles
- Lowest ceiling: 18,000 ft broken
- Temperature: 57 °F, dew point 36 °F
- Altimeter: 29.00 inHg
- Observed at: TRM, 6 nm away

## 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 19870411009089A](https://openairdocs.org/incident/19870411009089A), Apr 11, 1987: Hughes 369E, Paln Desert, CA, Substantial damage. Loud bang,began spin to right and crashed into city street. Tail rotor gear box separated after attach bolts failed

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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