# NTSB MKC89LA184: Dormoy TKD Bathtub, N812SS, Carlisle, MN, August 21, 1989

- Type: NTSB accident investigation
- Classification: Accident · Minor injuries · Limited investigation · Final report
- Date: August 20, 1989, 20:00 local (Aug 21, 1989, 01:00 UTC)
- Place: Carlisle, MN
- Coordinates: 46.280204, -96.060462 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=46.2802&lon=-96.0605&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: Minor injuries
- Injuries: 1 minor
- Status: Completed, report June 18, 1990
- Report: Approved by Office Director
- NTSB case key (mKey): 34852
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=MKC89LA184
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/34852/pdf
- Page: https://openairdocs.org/ntsb/MKC89LA184

## Probable cause

FAILURE OF THE MIXTURE CONTROL CABLE AND INADEQUATE MAINTENANCE (REPAIR) BY THE PILOT.  THE TERRAIN CONDITIONS WERE CONSIDERED TO BE CONTRIBUTING FACTORS.

## 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, cruise - normal
  - mixture control,cable - failure,total (cause)
  - maintenance - inadequate, pilot in command (cause)
- Forced landing, descent - emergency
- In flight collision with terrain/water, landing
  - terrain condition - none suitable (contributing factor)
  - terrain condition - rough/uneven (contributing factor)

## Analysis

THE PLT SAID THAT DURING FLT, THE ENG OF THE HOME BUILT ACFT LOST POWER OVER ROUGH TERRAIN. DURING AN EMERGENCY LANDING, THE ACFT ENCOUNTERED TALL GRASS, ROCKS, GOPHER MOUNDS & DOWNWARD SLOPING TERRAIN, AND WAS DAMAGED. AN INVESTIGATION REVEALED THE MIXTURE CONTROL CABLE (PIANO WIRE) HAD FAILED AT A BOLT WHERE IT ATTACHED TO THE MIXTURE CONTROL LEVER. THIS WAS THE 2ND FAILURE DURING THE FLT FROM FARGO, ND TO FERGUS FALLS, MN. THE 1ST FAILURE OCCURRED ABOUT 15 TO 20 MIN INTO THE FLT. THE PLT MADE A SUCCESSFUL FORCED LANDING AFTER THE 1ST FAILURE, THEN BORROWED SOME TOOLS & REPAIRED THE CABLE. THE 2ND FAILURE OCCURRED ABOUT 10 TO 15 MIN AFTER HE TOOK OFF TO CONTINUE THE FLT.

## Aircraft

- Registration: [N812SS](https://openairdocs.org/deregistered/N812SS-1991-06-18), registration cancelled 1991-06-18, S/N 1 (OpenAirDocs)
- Reported make and model: DORMOY TKD BATHTUB (TKD BATHTU)
- Registry model: [Thompson Harrison C TKD BATHTUB](https://openairdocs.org/model/thompson-harrison-c-tkd-bathtub) (registry code 056133D) (OpenAirDocs)
- Category: Airplane, amateur-built
- Serial number: 1
- Airframe hours: 122
- Engines: FRANKLIN 2A-120-B 60 horsepower reciprocating
- Damage: Substantial damage
- Flight: Personal, Part 91
- Registered owner: Thompson, Harrison C.
- Airworthiness certificate: Special, Experimental (Special)
- Last inspection: Annual, June 23, 1989, 12 hours before
- Departed: FAR, FARGO, ND
- Destination: FFM, FERGUS FALLS, MN

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 46; commercial; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 2, valid medical--no waivers/lim.; seat: center; flight hours: 2,400 total, 122 in this make and model

## Weather

- Conditions: Visual (VMC), Day
- Wind: 20° at 7 knots
- Visibility: 15 statute miles
- Lowest ceiling: none
- Temperature: 68 °F, dew point 55 °F
- Altimeter: 29.00 inHg
- Observed at: FFM, 10 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 19890821030829A](https://openairdocs.org/incident/19890821030829A), Aug 21, 1989: Carlisle, MN, Substantial damage. Piano wire mixture control broke. Landed and reattached. Departed engine quit again same reason. Crashed on landing

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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