# NTSB LAX86FVA11: Bell 47G-5, N1316X, Porterville, CA, July 8, 1986

- Type: NTSB accident investigation
- Classification: Accident · Serious injuries · Final report
- Date: July 8, 1986, 09:15 local (16:15 UTC)
- Place: Porterville, CA
- Coordinates: 35.959358, -118.920463 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=35.9594&lon=-118.9205&mi=10
- Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping)
- Highest injury: Serious injuries
- Injuries: 1 serious, 2 uninjured
- Status: Completed, report March 10, 1988
- Report: Approved by Office Director
- NTSB case key (mKey): 24963
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX86FVA11
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/24963/pdf
- Page: https://openairdocs.org/ntsb/LAX86FVA11

## Sequence of events

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

- Airframe/component/system failure/malfunction, maneuvering - turn to reverse direction
  - rotor drive system,tail rotor drive shaft - failure,total (cause)
  - rotor drive system,tail rotor drive shaft - corroded (contributing factor)
  - rotor drive system,tail rotor drive shaft - unapproved part (contributing factor)
- Forced landing, descent - emergency
- In flight collision with object, landing
  - object - building(nonresidential) (contributing factor)

## Analysis

DURING AN AERIAL APPLICATION FLIGHT THE PLT LOST CONTROL OF THE HELICOPTER AND COLLIDED WITH A BUILDING. EXAMINATION REVEALED THAT THE INSIDE DIAMETER OF THE TAIL ROTOR DRIVESHAFT WAS NOT COATED WITH ALUMINIZED LACQUER AS REQUIRED BY THE BELL FINISH PROCESS SPECIFICATION. THE BELL DRAWING REQUIRES TWO #2 SHORT PLUGS TO BE INSTALLED AT A SPECIFIED DISTANCE FROM EACH END OF THE TAIL ROTOR DRIVESHAFT AND THE END OF THE SHAFT TO BE SEALED OFF WITH ADHESIVE TO PROTECT THE SHAFT INSIDE DIAMETER FROM CORROSION. A DIMENSIONAL CHECK OF THE SHAFT REVEALED THAT THE PLUGS WERE NOT INSTALLED AT THE CORRECT DISTANCE FROM THE END OF THE SHAFT AS SPECIFIED IN THE DRAWING.

## Aircraft

- Registration: [N1316X](https://openairdocs.org/deregistered/N1316X-1994-03-16), registration cancelled 1994-03-16, S/N 7827 (OpenAirDocs)
- Reported make and model: BELL 47G-5
- Registry model: [Bell 47G-5](https://openairdocs.org/model/bell-47g-5) (registry code 1181032) (OpenAirDocs)
- Category: Helicopter
- Serial number: 7827
- Airframe hours: 5951
- Engines: LYCOMING VO-435-B1A 260 horsepower reciprocating
- Damage: Substantial damage
- Flight: Aerial application, Part 137
- Registered owner: M&W Flying Service, Inc.
- Airworthiness certificate: Standard, Normal
- Last inspection: Annual, July 1, 1985, 289 hours before

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 57; commercial; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 2, valid medical--w/ waivers/lim; seat: left; flight hours: 10,077 total, 5,000 in this make and model, 9,801 as pilot in command, 110 in the last 90 days

## Weather

- Conditions: Visual (VMC), Day
- Wind: calm
- Visibility: 30 statute miles
- Lowest ceiling: none

## 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 19860708031469A](https://openairdocs.org/incident/19860708031469A), Jul 8, 1986: Bell 47G5, Porterville, CA, Substantial damage. Tail rotor driveshaft failed due to corrosion. Caused uncontrolled spin and crash.

## Other investigations on N1316X (3)

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 LAX88DVM02](https://openairdocs.org/ntsb/LAX88DVM02), Jun 5, 1988: Bell 47G5 (N1316X), Oceano, CA, substantial damage
- [NTSB LAX85LVA03](https://openairdocs.org/ntsb/LAX85LVA03), May 20, 1985: Bell 47-G5 (N1316X), Lindsay, CA, substantial damage
- [NTSB OAK75DVA51](https://openairdocs.org/ntsb/OAK75DVA51), Mar 23, 1975: Bell 47G-5 (N1316X), Porterville, CA, substantial damage

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.