# NTSB SEA91LA012: Christen Industries A-1, N9609G, Afton, WY, November 4, 1990

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: November 4, 1990, 16:40 local (23:40 UTC)
- Place: Afton, WY
- Coordinates: 42.720329, -110.920501 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=42.7203&lon=-110.9205&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 1 uninjured
- Status: Completed, report November 23, 1992
- Report: Approved by Office Director
- NTSB case key (mKey): 41359
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=SEA91LA012
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/41359/pdf
- Page: https://openairdocs.org/ntsb/SEA91LA012

## Probable cause

AN IMPROPER MAINTENANCE MODIFICATION TO DISABLE THE CARBURETOR HEAT CONTROL BY UNKNOWN PERSONNEL.

## Sequence of events

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

- Loss of engine power(total) - nonmechanical, cruise - normal
  - carburetor heat control - inoperative
  - maintenance,modification - improper, unknown (cause)
  - weather condition - icing conditions (contributing factor)
- Forced landing, descent - emergency
- Forced landing, descent - emergency
  - terrain condition - ditch

## Analysis

DURING A CROSS COUNTRY FLIGHT, THE AIRPLANE EXPERIENCED A LOSS OF ENGINE POWER. THE PILOT INITIATED A FORCED LANDING, DURING THE LANDING ROLL, THE AIRPLANE STRUCK A DITCH AND NOSED OVER. INSPECTION OF THE ENGINE REVEALED THAT THE CARBURETOR HEAT VALVE HAD BEEN SECURED IN THE COLD OR OFF POSITION. THIS MODIFICATION DID NOT ALLOW FOR THE CARBURETOR HEAT TO BE APPLIED. AT THE TIME OF THE ENGINE FAILURE, THE AIRPLANE WAS OPERATING IN ICING CONDITIONS. THERE WERE NO OTHER MECHANICAL FAILURES OR MALFUNCTIONS FOUND.

## Aircraft

- Registration: [N9609G](https://openairdocs.org/deregistered/N9609G-1991-04-19), registration cancelled 1991-04-19, S/N 1156 (OpenAirDocs)
- Reported make and model: Christen Industries A-1
- Registry model: [Christen Industries A-1](https://openairdocs.org/model/christen-industries-a-1) (registry code 221020X) (OpenAirDocs)
- Category: Airplane
- Serial number: 1156
- Engines: LYCOMING O-360-C1G 180 horsepower reciprocating
- Damage: Substantial damage
- Flight: Business, Part 91
- Operator: Heiner, Mark G
- Registered owner: Unknown
- Departed: BFF, SCOTTSBLUFF, NE

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 41; commercial; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 2, valid medical--w/ waivers/lim; flight hours: 1,632 total, 365 in this make and model, 1,632 as pilot in command, 154 in the last 90 days, 67 in the last 30 days, 9 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Visibility: 10 statute miles
- Lowest ceiling: 5,400 ft overcast

## 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 19901104052139A](https://openairdocs.org/incident/19901104052139A), Nov 4, 1990: Chris A1, Afton, WY, Substantial damage. Engine quit en route. Force landed on road. Hit ditch on curve. Carb heat control broken and wired too off position

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.