# NTSB BFO90FA079: Hughes 269C, N1094D, Jefferson, MD, September 25, 1990

- Type: NTSB accident investigation
- Classification: Accident · Fatal · Field investigation · Final report
- Date: September 25, 1990, 10:35 local (14:35 UTC)
- Place: Jefferson, MD
- Coordinates: 39.359714, -77.529579 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=39.3597&lon=-77.5296&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: Fatal
- Injuries: 1 fatal
- Status: Completed, report December 14, 1992
- Report: Approved by Office Director
- NTSB case key (mKey): 11559
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=BFO90FA079
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/11559/pdf
- Page: https://openairdocs.org/ntsb/BFO90FA079

## Probable cause

THE FAILURE OF THE TAIL ROTOR DRIVE TRANSMISSION SYSTEM DUE TO A WORN TAIL ROTOR SPLINED DRIVE SLEEVE, AND INADEQUATE MAINTENANCE AND/OR INSPECTION BY THE OPERATOR. CONTRIBUTING TO THE LOSS OF CONTROL WAS THE STUDENT PILOT'S FAILURE TO MAINTAIN ADEQUATE ROTOR RPM DUE TO INEXPERIENCE.

## Sequence of events

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

- Airframe/component/system failure/malfunction, cruise
  - rotor drive system - failure,partial (cause)
  - rotor drive system,tail rotor drive shaft coupling - worn (cause)
  - maintenance,inspection - inadequate, company maintenance personnel (cause)
- Loss of control - in flight, cruise
  - rotor rpm - not maintained, pilot in command (contributing factor)
  - lack of total experience, pilot in command (contributing factor)

## Analysis

ACCORDING TO WITNESSES THE ACFT CAME APART IN THE AIR. RADAR DATA SHOWS THE ACFT AT 2600 FT WHEN IT TURNED ABOUT 35 DEGREES RIGHT IN ABOUT 4 SECONDS. THE ACFT SUSTAINED GENERAL DISINTEGATION. EXAMINATION REVEALED THAT THE SPLINES OF THE TAIL ROTOR SPLINED DRIVE SLEEVE WERE EXCESSIVELY WORN, RENDERING LOSS OF TRANSMISSION OF TORQUE TO THE TAIL ROTOR. TWO OTHER HU-269 ACFT HAD SIMILIAR WEAR OF THE SPLINED SLEEVE. 300-HR INSPECTION REQUIRES THAT THE UPPER PULLEY ASSEMBLY BE REMOVED AND INSPECTED, AND BEARINGS LUBRICATED. SCHWEIZER ACFT CORP HAD ISSUED SERVICE BULLETIN N-219 A MONTH BEFORE THE ACCIDENT WHICH REQUIRED RETORQUING OF THE SPLINE RETAINING NUT. HOWEVER, THE ACFT WAS WITHIN THE REQUIRED COMPLIANCE TIME, AND THE BULLETIN WAS NOT DONE.

## Aircraft

- Registration: [N1094D](https://openairdocs.org/deregistered/N1094D-1990-12-07), registration cancelled 1990-12-07, S/N 600935 (OpenAirDocs)
- Reported make and model: HUGHES 269C
- Registry model: [Hughes 269C](https://openairdocs.org/model/hughes-269c) (registry code 4470504) (OpenAirDocs)
- Category: Helicopter
- Serial number: 600935
- Engines: LYCOMING HIO-360-D1A reciprocating
- Damage: Destroyed
- Fire: On-Ground
- Flight: Instructional, Part 91
- Operator: New Horizon Aviation, Inc.
- Registered owner: White Ox Enterprise Inc.
- Airworthiness certificate: Standard, Normal
- Departed: W16, WINCHESTER, VA
- Destination: FDK, FREDERICK, MD

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 39; student; medical: unknown, unknown; toxicology performed; flight hours: 27 total, 27 in this make and model, 10 as pilot in command, 14 in the last 90 days, 3 in the last 30 days

## Weather

- Conditions: Visual (VMC), Day
- Wind: 190° at 10 knots
- Visibility: 15 statute miles
- Lowest ceiling: none
- Temperature: 66 °F, dew point 52 °F
- Altimeter: 29.79 inHg
- Observed at: IAD, 27 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 19900925042309A](https://openairdocs.org/incident/19900925042309A), Sep 25, 1990: Hughes 269C, Jefferson, MD, Destroyed, 1 fatal. Lost tailrotor drive at cruise due to worn sp line sleeve. Inadequate maintenance and inspection contributed.

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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