# NTSB ATL89LA124: Cessna 172RG, N9688B, Miamisburg, OH, April 10, 1989

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: April 10, 1989, 10:30 local (14:30 UTC)
- Place: Miamisburg, OH
- Coordinates: 39.82088, -84.049697 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=39.8209&lon=-84.0497&mi=10
- Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 1 uninjured
- Status: Completed, report August 22, 1990
- Report: Approved by Office Director
- NTSB case key (mKey): 8011
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ATL89LA124
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/8011/pdf
- Page: https://openairdocs.org/ntsb/ATL89LA124

## Probable cause

INTERMITTANT GROUNDING OF AN ELECTRICAL WIRE TO THE NOSE LANDING GEAR. THE CHAFED WIRE RESULTED IN THE OPENING OF THE LANDING GEAR MOTOR CIRCUIT BREAKER PREVENTING FULL EXTENSION OF THE LEFT MAIN LANDING GEAR. A SECONDARY FAILURE OF THE THROTTLE WARNING SWITCH PRECLUDED A VISUAL OR AURAL WARNING OF THE UNSAFE GEAR POSITION.

## Sequence of events

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

- Gear not extended, landing
  - electrical system,electric wiring - chafed (cause)
  - electrical system,circuit breaker - open (cause)
  - landing gear,gear indicating system - false indication (cause)
  - gear extension - not possible, pilot in command (cause)
- Main gear collapsed, landing - roll

## Analysis

FOLLOWING IFR FLIGHT PIC LANDED AT UNCONTROLLED FIELD. ON LANDING ROLL LEFT MAIN GEAR COLLAPSED. SUBSEQUENT EXAM OF ACFT REVEALED A CHAFED WIRE FOR NOSE GEAR MICRO SWITCH GROUNDED AGAINST AIRFRAME. RESULTED IN GEAR MOTOR CB OPENING & STOPPING GEAR EXTENSION PRIOR TO FULL EXTENSION OF LEFT MAIN GEAR. ALSO, INTERNAL FAILURE OF THROTTLE WARNING SWITCH DID NOT PROVIDE AN UNSAFE GEAR VISUAL OR AURAL WARNING.

## Aircraft

- Registration: [N9688B](https://openairdocs.org/deregistered/N9688B-2024-05-24), registration cancelled 2024-05-24, S/N 172RG0969, built 1981 (OpenAirDocs)
- Reported make and model: CESSNA 172RG
- Registry model: [Cessna 172RG](https://openairdocs.org/model/cessna-172rg) (registry code 2072438) (OpenAirDocs)
- Registry engine: [Lycoming O&VO-360 series](https://openairdocs.org/engine/lycoming-o-vo-360-series) (registry code 41514, reciprocating) (OpenAirDocs)
- Category: Airplane
- Serial number: 0969
- Airframe hours: 1765
- Engines: LYCOMING O-360-F1A6 180 horsepower reciprocating
- Damage: Substantial damage
- Flight: Business, Part 91
- Operator: Dunbar, Lee R.& Jeffrey T.
- Registered owner: Dunbar, Lee R. & Jeffrey T.
- Airworthiness certificate: Standard, Normal
- Last inspection: Annual, January 6, 1989, 20 hours before
- Departed: TOL, TOLEDO, OH
- Destination: MGY
- Flight plan: IFR
- Airport: MGY, Dayton General Arpt South, runway 2, 5,000 × 100 ft

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 50; private; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 3, valid medical--w/ waivers/lim; seat: left; flight hours: 670 total, 235 in this make and model, 580 as pilot in command, 12 in the last 90 days, 8 in the last 30 days, 2 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 10° at 4 knots
- Visibility: 7 statute miles
- Lowest ceiling: none
- Temperature: 28 °F, dew point 12 °F
- Altimeter: 30.00 inHg
- Observed at: DAY, 15 nm away

## 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 19890410007659A](https://openairdocs.org/incident/19890410007659A), Apr 10, 1989: Cessna 172RG, Dayton, OH, Substantial damage. Left main gear collapsed on landing. Chafed micro switch wire shorted and stopped gear motor with gear not locked.

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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