# NTSB ATL89FA130: Bell UH-1E, N118HS, Aiken, SC, April 17, 1989

- Type: NTSB accident investigation
- Classification: Accident · Serious injuries · Field investigation · Final report
- Date: April 17, 1989, 12:05 local (16:05 UTC)
- Place: Aiken, SC
- Coordinates: 33.539249, -81.7191 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=33.5392&lon=-81.7191&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: Serious injuries
- Injuries: 1 serious
- Status: Completed, report September 5, 1990
- Report: Approved by Office Director
- NTSB case key (mKey): 7887
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ATL89FA130
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/7887/pdf
- Page: https://openairdocs.org/ntsb/ATL89FA130

## Probable cause

IMPROPER INSTALLATION OF A TAIL ROTOR PITCH CHANGE CROSSHEAD RETENTION BOLT BY THE COMPANY MECHANIC, WHICH RESULTED IN LOOSENING OF THE BOLT AND EVENTUAL FAILURE OF THE TAIL ROTOR ASSEMBLY/BLADE AND SUBSEQUENT LOSS OF CONTROL.  TREES AT THE CRASH SITE CONTRIBUTED TO HELICOPTER DAMAGE.

## Sequence of events

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

- Airframe/component/system failure/malfunction, cruise
  - rotor system,tail rotor hub pitch change mechanism - not safetied (cause)
  - maintenance,installation - improper, company maintenance personnel (cause)
  - rotor system,tail rotor hub pitch change mechanism - loose (cause)
  - rotor system,tail rotor hub - failure,total (cause)
  - rotor system,tail rotor blade - separation
- Loss of control - in flight, cruise
  - directional control - not possible
- Forced landing, descent - uncontrolled
  - autorotation - attempted
- In flight collision with object, descent - uncontrolled
  - object - tree(s) (contributing factor)

## Analysis

THE HELICOPTER WAS BEING OPERD AT APRX 100 FT AGL WITH A HOPPER EXTDD FROM A CABLE. WITNESSES HEARD A LOUD POPPING SOUND. AS THEY LOOKED IN THE DRCTN OF THE HELICOPTER, THEY NOTED THE TAIL ROTOR WAS NOT TURNING & ONE BLADE APPEARED TO BE HANGING. THE PLT RPRTD THERE WAS NO WARNING OF AN IMPENDING ANTI-TORQUE CONTROL PROBLEM WHEN HE LOST CONTROL OF THE HELICOPTER. THE HELICOPTER THEN COLLIDED WITH TREES & CRASHED. INV REVEALED THE PLT HAD RPRTD AN OIL LEAK FM THE 90 DEG GEARBOX ON 4/11/89. THE COMPANY MECHANIC SUBSEQUENTLY REPLACED THE GEARBOX & A FUNCTIONAL TEST FLT WAS COMPLETED. THE ACDNT OCCURRED AFTER APRX ANOTHER 6 HRS OF OPN. AN EXAM OF THE TAIL ROTOR ASSEMBLY REVEALED THAT 1 OF THE 2 RETENTION BOLTS WERE MISSING FM THE TAIL ROTOR PITCH CHANGE CROSSHEAD. THREADED IMPRINTS WERE FND INSIDE THE RESPECTIVE CROSSHEAD RETENTION THRU-BOLT HOLE. THE RETENTION BOLT, NUT, WASHER & COTTER PIN WERE NOT RECOVERED. BOTH TAIL ROTOR BLADES CONTAINED CHORDWISE MARKS WHICH CORRESPONDED TO MARKS ON THE VERTICAL FIN (OPPOSITE OF THE TAIL ROTOR TIP PATH PLANE).

## Aircraft

- Registration: [N118HS](https://openairdocs.org/deregistered/N118HS-2013-04-02), registration cancelled 2013-04-02, S/N 155341, built 1968 (OpenAirDocs)
- Reported make and model: BELL UH-1E
- Registry model: [Bell UH-1L](https://openairdocs.org/model/bell-uh-1l) (registry code 1181401) (OpenAirDocs)
- Registry engine: [Lycoming T-53 series](https://openairdocs.org/engine/lycoming-t-53-series) (registry code 41552, turbo-shaft) (OpenAirDocs)
- Category: Helicopter
- Serial number: 155341
- Airframe hours: 5414
- Engines: LYCOMING T-53-L-11D 1100 horsepower turbo shaft
- Damage: Substantial damage
- Flight: Other work use, Part 133
- Registered owner: Helicopter Systems
- Airworthiness certificate: Special, Restricted (Special)
- Last inspection: 100 hour, March 7, 1989, 100 hours before

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 42; commercial; airplane ratings: multi-engine land, single-engine land; instrument ratings: helicopter; medical: class 1, valid medical--no waivers/lim.; seat: right; flight hours: 4,000 in this make and model, 39 in the last 90 days, 30 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: calm
- Visibility: 10 statute miles
- Lowest ceiling: none
- Temperature: 81 °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 19890417008259A](https://openairdocs.org/incident/19890417008259A), Apr 17, 1989: Bell UH1E, Aiken, SC, Substantial damage. Tail rotor 90 degrees gear box and tail rotor separated at low altitude. Control lost hit trees.

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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