# NTSB FTW86FA085: Bell 206B, N27785, Pine Spring, TX, May 12, 1986

- Type: NTSB accident investigation
- Classification: Accident · Fatal · Field investigation · Final report
- Date: May 12, 1986, 17:45 local (23:45 UTC)
- Place: Pine Spring, TX
- Coordinates: 31.739355, -105.079925 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=31.7394&lon=-105.0799&mi=10
- Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping)
- Highest injury: Fatal
- Injuries: 2 fatal
- Status: Completed
- Report: Approved by Office Director
- NTSB case key (mKey): 21903
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=FTW86FA085
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/21903/pdf
- Page: https://openairdocs.org/ntsb/FTW86FA085

## Sequence of events

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

- Airframe/component/system failure/malfunction, approach - vfr pattern - downwind
  - rotor drive system,engine to transmission drive - disconnected (cause)
  - maintenance,installation - improper, other maintenance personnel (cause)
  - improper use of procedure, other maintenance personnel (cause)
- Forced landing, maneuvering - turn to landing area (emergency)
  - autorotation - initiated
- In flight collision with terrain/water, landing
  - weather condition - turbulence (contributing factor)
  - weather condition - gusts (contributing factor)
  - weather condition - high density altitude (contributing factor)
  - rotor rpm - not maintained
  - flare - not possible

## Analysis

THE HELICOPTER WAS ON A FLT TO A SITE NR GUADALUPE PASS, AN AREA KNOWN FOR ERRATIC & GUSTY WNDS. AS THE PLT WAS ON AN APCH TO A HI MEADOW (ELEV APRX 5460'), THE HELICOPTER ENTERED A DSCNT & CRASHED WELL SHORT OF THE INTENDED LNDG AREA. A WITNESS RPRTD THE MAIN ROTOR RPM SLOWED & THE ROTOR BLADES CONED PRIOR TO IMPACT. THERE WAS EVIDENCE THE HELICOPTER IMPACTED IN A LVL ATTITUDE & AT A HIGH RATE OF DSCNT. AN INV REVEALED THAT A COUPLING ON THE ENG-TO-MAIN TRANSMISSION DRIVE SHAFT HAD BECOME DISCONNECTED. THERE WAS EVIDENCE THAT THE MALE DRIVESHAFT COUPLING WAS NOT PROPERLY SECURED TO THE FLANGE ON THE MAIN ROTOR DRIVESHAFT'S ENG END. EIGHT DAYS PRIOR TO THE ACDNT, AN AIR COND SYS WAS INSTALLED ON THE HELICOPTER. THIS WOULD HAVE REQD THAT A DRIVE SHAFT COUPLING BE DISCONNECTED. THERE WAS EVIDENCE THAT THE SELF LOCKING NUTS WERE REUSED WHEN THE COUPLING WAS RECONNECTED.

## Aircraft

- Registration: [N27785](https://openairdocs.org/deregistered/N27785-1999-07-01), registration cancelled 1999-07-01, S/N 2800 (OpenAirDocs)
- Reported make and model: BELL 206B
- Registry model: [Bell 206B](https://openairdocs.org/model/bell-206b) (registry code 1181511) (OpenAirDocs)
- Category: Helicopter
- Serial number: 2800
- Airframe hours: 2415
- Engines: ALLISON 250-C20B 317 horsepower turbo shaft
- Damage: Destroyed
- Flight: Part 135
- Registered owner: Lone Star Helicopters Inc
- Airworthiness certificate: Standard, Normal
- Last inspection: Continuous airworthiness, April 28, 1986, 11 hours before
- Departed: PECOS, TX

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 54; commercial, airline transport, flight instructor; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane, helicopter; medical: class 1, valid medical--w/ waivers/lim; seat: right; toxicology performed; flight hours: 5,400 total, 1,100 in this make and model, 5,230 as pilot in command, 8 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 0° at 16 knots, gusting 34
- Visibility: 50 statute miles
- Lowest ceiling: none
- Temperature: 81 °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 19860512082049A](https://openairdocs.org/incident/19860512082049A), May 12, 1986: Bell 206B, Pine Springs, TX, Destroyed, 1 fatal. The helicopter lost power and was destroyed on landing. The driveshaft had become disconnected from the rotor.

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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