# NTSB MIA89LA229: Bell 47G, N955B, Ponce, PR, August 23, 1989

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: August 23, 1989, 12:09 local (16:09 UTC)
- Place: Ponce, PR
- Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 1 uninjured
- Status: Completed, report September 5, 1991
- Report: Approved by Office Director
- NTSB case key (mKey): 32486
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=MIA89LA229
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/32486/pdf
- Page: https://openairdocs.org/ntsb/MIA89LA229

## Probable cause

FAILURE OF THE AFT TAIL ROTOR DRIVE SHAFT.

## 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 - final approach
  - rotor drive system,tail rotor drive shaft - failure,total (cause)
- Loss of control - in flight, approach - vfr pattern - final approach
  - directional control - not possible
- Forced landing, landing
  - autorotation - performed, pilot in command
- In flight collision with terrain/water, landing

## Analysis

THE STUDENT PLT WAS ON AN APCH TO LAND ON A X-COUNTRY FLT, WHEN THE AFT TAIL ROTOR DRIVE SHAFT (PN: 47-644-187) FAILED AT ABOUT 40' AGL. HE RPRTD THE HELICOPTER BEGAN TO SPIN TO THE RIGHT, SO HE CLOSED THE THROTTLE & THE SPINNING STOPPED. HE PULLED UP ON THE COLLECTIVE TO CUSHION THE LANDING, BUT RAN OUT OF COLLECTIVE PITCH AT ABOUT 10' ABOVE THE GROUND. SUBSEQUENTLY, THE HELICOPTER TOUCHED DOWN HARD, DAMAGING THE TAIL ROTOR & TAIL BOOM. THE TAIL ROTOR DRIVE SHAFT HAD FAILED JUST FORWARD OF THE 90 DEG GEAR BOX.

## Aircraft

- Registration: [N955B](https://openairdocs.org/aircraft/N955B), registered now, S/N 711, built 1954 (OpenAirDocs)
- Reported make and model: BELL 47G
- Registry model: [Bell 47G](https://openairdocs.org/model/bell-47g) (registry code 1181002) (OpenAirDocs)
- Registry engine: [Lycoming VO-435-A1F](https://openairdocs.org/engine/lycoming-vo-435-a1f) (registry code 42200, reciprocating) (OpenAirDocs)
- Category: Helicopter
- Serial number: 711
- Airframe hours: 5837
- Engines: FRANKLIN 6V-350 235 horsepower reciprocating
- Damage: Substantial damage
- Flight: Instructional, Part 91
- Operator: Esteves, Arturo
- Registered owner: Esteves Arturo
- Airworthiness certificate: Standard, Normal
- Last inspection: 100 hour, August 10, 1989, 15 hours before
- Departed: BQN, BORINQUEN, PR
- Destination: PSE
- Flight plan: VFR
- Airport: PSE, Mercedita, runway 12, 5,529 × 100 ft, concrete

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 48; student; medical: class 3, valid medical--w/ waivers/lim; seat: left; flight hours: 116 total, 77 in this make and model, 55 as pilot in command, 22 in the last 90 days, 7 in the last 30 days, 1 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 130° at 20 knots
- Visibility: 15 statute miles
- Lowest ceiling: none
- Temperature: 91 °F, dew point 73 °F
- Altimeter: 29.00 inHg
- Observed at: PSE

## 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 19890823036149A](https://openairdocs.org/incident/19890823036149A), Aug 23, 1989: Bell 47G, Ponce, Puerto Rico, Substantial damage. Tail rotor drive shaft sheared forward of 90 degree gear box. Made hard emergency landing.

## Other investigations on N955B (1)

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.

- [NTSB MIA91LA141](https://openairdocs.org/ntsb/MIA91LA141), May 11, 1991: Bell 47-G (N955B), Aguadilla, PR, destroyed. Probable cause: THE IMPROPER IN FLIGHT PLANNING/DECISION OF THE PILOT-IN-COMMAND TO CONDUCT AN OUT-OF-GROUND-EFFECT HOVER WITH A RIGHT CROSSWIND. THIS RESULTED IN AN IN FLIGHT LOSS OF CONTROL DUE TO SETTLING WITH…

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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