# NTSB CHI88DEC05: Bell 47D1 (OH-13E), N12087, Stockbridge, MI, July 11, 1988

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Final report
- Date: July 11, 1988, 10:10 local (14:10 UTC)
- Place: Stockbridge, MI
- Coordinates: 42.450557, -84.170555 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=42.4506&lon=-84.1706&mi=10
- Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 1 uninjured
- Status: Completed, report June 10, 1991
- Report: Approved by Office Director
- NTSB case key (mKey): 13848
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CHI88DEC05
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/13848/pdf
- Page: https://openairdocs.org/ntsb/CHI88DEC05

## Sequence of events

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

- Airframe/component/system failure/malfunction, maneuvering
  - rotorcraft flight control - disconnected (cause)
- Forced landing, landing
  - run on landing - attempted, pilot in command
- Loss of control - in flight, landing
  - aircraft control - not possible
- In flight collision with terrain/water, landing

## Analysis

THE PLT WAS SPRAYING AN ONION FIELD WHEN HE NOTED A VIBRATION, FOLLOWED BY A LOUD NOISE & SEVERE SHAKING OF THE HELICOPTER. HE ATTEMPTED A FORCED LANDING, BUT THE HELICOPTER WAS UNRESPONSIVE TO CYCLIC & COLLECTIVE INPUTS. SUBSEQUENTLY, THE RIGHT SKID DUG INTO THE GROUND & COLLAPSED DURING TOUCHDOWN, THEN THE MAIN ROTOR BLADES STRUCK THE GROUND. A POST ACDNT INSPN REVEALED THE BOLT, WHICH CONNECTED THE DRIVE LINK TO THE COLLECTIVE SCISSORS ARM, WAS MISSING.

## Aircraft

- Registration: [N12087](https://openairdocs.org/aircraft/N12087), registered now, S/N 734 (OpenAirDocs)
- Reported make and model: BELL 47D1 (OH-13E) (47D1 (OH-1)
- Registry model: [Bell 47D1](https://openairdocs.org/model/bell-47d1) (registry code 1180802) (OpenAirDocs)
- Registry engine: [Franklin 6A4200 series](https://openairdocs.org/engine/franklin-6a4200-series) (registry code 27027, reciprocating) (OpenAirDocs)
- Category: Helicopter
- Serial number: 734
- Airframe hours: 7951
- Engines: FRANKLIN 6V4-200-C32 200 horsepower reciprocating
- Damage: Substantial damage
- Flight: Aerial application, Part 137
- Registered owner: Allied Helicopter Services Inc
- Airworthiness certificate: Special, Restricted (Special)
- Last inspection: Annual, April 21, 1988, 113 hours before

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 62; commercial; airplane ratings: single-engine land; medical: class 2, valid medical--w/ waivers/lim; seat: left; flight hours: 12,877 total, 12,697 in this make and model, 12,807 as pilot in command, 135 in the last 90 days, 47 in the last 30 days, 1 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 230° at 9 knots
- Visibility: 5 statute miles
- Lowest ceiling: none
- Temperature: 79 °F, dew point 66 °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 19880711026589A](https://openairdocs.org/incident/19880711026589A), Jul 11, 1988: Bell 47D1, Stockbridge, MI, Substantial damage. Loud noise vibration and loss of cyclic during spray run. Crash landed. AN17432 bolt missing causing control loss.

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.