# NTSB NYC85LA005: Bell 47G3-B1, N401GC, Moultonboro, NH, October 7, 1984

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: October 7, 1984, 17:55 local (21:55 UTC)
- Place: Moultonboro, NH
- Location: 43.7548° N, 71.3967° W: Placed by OpenAirDocs: center of Moultonborough, NH, within about 6 miles (OpenAirDocs)
- Nearby events: https://openairdocs.org/map.md?lat=43.7548&lon=-71.3967&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 3 uninjured
- Status: Completed
- Report: Approved by Office Director
- NTSB case key (mKey): 35629
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=NYC85LA005
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/35629/pdf
- Page: https://openairdocs.org/ntsb/NYC85LA005

## Sequence of events

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

- Loss of engine power(total) - mech failure/malf, climb
  - engine assembly,valve,intake - disabled (cause)
- Forced landing, descent - emergency
  - autorotation - performed, pilot in command
- In flight collision with terrain/water, landing
  - terrain condition - mountainous/hilly (contributing factor)
  - terrain condition - high vegetation (contributing factor)
  - object - tree(s) (contributing factor)

## Analysis

ACFT WAS CLIMBING THROUGH A MOUNTAIN SADDLE WHEN THE ENGINE BEGAN TO BACKFIRE AND LOSE POWER. PLT ENTERED AUTOROTATION & SETTLED INTO TREES ON AUTOROTATIVE FLARE. ENGINE INSPECTION REVEALED #3 CYLINDER INTAKE VALVE SPRINGS BROKEN.

## Aircraft

- Registration: [N401GC](https://openairdocs.org/deregistered/N401GC-1990-04-04), registration cancelled 1990-04-04, S/N 3568 (OpenAirDocs)
- Reported make and model: BELL 47G3-B1
- Registry model: [Bell TH-13T](https://openairdocs.org/model/bell-th-13t) (registry code 1180813) (OpenAirDocs)
- Category: Helicopter
- Serial number: 3568
- Airframe hours: 5822
- Engines: LYCOMING VO-435-A1F 270 horsepower reciprocating
- Damage: Substantial damage
- Flight: Part 135
- Registered owner: Vermont Travelers, Inc.
- Airworthiness certificate: Standard, Utility; Standard, Normal
- Last inspection: 100 hour, February 27, 1984, 89 hours before
- Departed: HN08, MOULTONBORO, VT
- Airport: Moultonboro

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 44; commercial; instrument ratings: helicopter; medical: valid medical--no waivers/lim.; seat: left; flight hours: 2,229 total, 295 in this make and model, 1,996 as pilot in command, 245 in the last 90 days, 6 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Visibility: 12 statute miles
- Lowest ceiling: none
- Temperature: 52 °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 19841007076179A](https://openairdocs.org/incident/19841007076179A), Oct 7, 1984: Bell TH13T, Moultonboro, NH, Substantial damage. Settled into trees after power loss during cruise flight. Intake valve springs broken, spark plug electrodes worn.

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.

---
OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.