# NTSB NYC90LA125: Hughes 369HS, N8315F, Brookville, PA, June 5, 1990

- Type: NTSB accident investigation
- Classification: Accident · Serious injuries · Limited investigation · Final report
- Date: June 5, 1990, 09:15 local (13:15 UTC)
- Place: Brookville, PA
- Coordinates: 41.159538, -79.080329 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=41.1595&lon=-79.0803&mi=10
- Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping)
- Highest injury: Serious injuries
- Injuries: 1 serious, 2 minor
- Status: Completed, report March 17, 1992
- Report: Approved by Office Director
- NTSB case key (mKey): 36658
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=NYC90LA125
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/36658/pdf
- Page: https://openairdocs.org/ntsb/NYC90LA125

## Probable cause

WORN TAIL ROTOR PITCH CONTROL ASSEMBLY, DUE TO IMPROPER MAINTENANCE/INSTALLATION, AND SUBSEQUENT FATIGUE FAILURE OF THE TAIL ROTOR SWASHPLATE.

## Sequence of events

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

- Airframe/component/system failure/malfunction, maneuvering
  - rotorcraft flight control,tail rotor control - worn (cause)
  - maintenance,installation - improper, other maintenance personnel (cause)
  - rotorcraft flight control,tail rotor control - fatigue (cause)
- Loss of control - in flight, maneuvering
  - directional control - not possible
- Forced landing, descent - emergency
  - autorotation - attempted, pilot in command
- In flight collision with object, descent - uncontrolled
  - object - wire,transmission
- In flight collision with terrain/water, descent - uncontrolled

## Analysis

DURING A POWER LINE PATROL FLT OVER WOODED TERRIAN, AT ABOUT 60 TO 85 FT AGL, TAILROTOR CONTROL OF THE HELICOPTER WAS LOST. THE HELICOPTER BEGAN TO SPIN TO THE RIGHT AND THE PLT ATTEMPTED A HOVERING AUTOROTATION. THE HELICOPTER BEGAN SPINNING FASTER. SUBSEQUENTLY, IT SETTLED ONTO THE POWER LINE, THEN CRASHED TO THE GROUND. AN EXAM REVEALED THAT THE TAIL ROTOR SWASHPLATE HAD FAILED FROM FATIGUE. THE SWASHPLATE OUTER DIAMETER WAS WORN WITH EVIDENCE OF SPALLING, THE BEARING INNER DIAMETER WAS LIGHTLY SCORED, THE SWASHPLATE THREADS WERE SEVERELY WORN WITH EVIDENCE OF SPALLING DUE TO RELATIVE MOTION WITH THE MATING THREADS OF THE LOCKNUT, AND THE LOCKWASHER TANG HAD WORN A SIGNIFICANT PATTERN IN THE SWASHPLATE KEYWAY.

## Aircraft

- Registration: [N8315F](https://openairdocs.org/deregistered/N8315F-2020-07-27), registration cancelled 2020-07-27, S/N 360801S (OpenAirDocs)
- Reported make and model: HUGHES 369HS
- Registry model: [Hughes 369HS](https://openairdocs.org/model/hughes-369hs) (registry code 4470728) (OpenAirDocs)
- Category: Helicopter
- Serial number: 801S
- Engines: ALLISON 250-C20 278 horsepower turbo shaft
- Damage: Destroyed
- Flight: Aerial observation, Part 91
- Operator: Helicopter Minit Men, Inc.
- Departed: DUBOIS, PA
- Flight plan: Company VFR

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 60; flight instructor, commercial; airplane ratings: single-engine land; instrument ratings: helicopter; medical: class 2, valid medical--no waivers/lim.; flight hours: 11,500 total, 1,000 in this make and model, 11,000 as pilot in command, 60 in the last 90 days, 60 in the last 30 days, 1 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 225° at 5 knots
- Visibility: 10 statute miles
- Lowest ceiling: none
- Temperature: -0 °F, dew point -0 °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 19900605018529A](https://openairdocs.org/incident/19900605018529A), Jun 5, 1990: Hughes 369S, Brookville, PA, Destroyed. Began uncontrolled right spin on powerline patrol,struck powerline and ground. Tail rotor pitch control 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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