# NTSB FTW91LA061: Cessna 150D, N4437U, San Ygnacio, TX, April 6, 1991

- Type: NTSB accident investigation
- Classification: Accident · Serious injuries · Limited investigation · Final report
- Date: April 6, 1991, 10:55 local (16:55 UTC)
- Place: San Ygnacio, TX
- Coordinates: 27.129774, -99.330749 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=27.1298&lon=-99.3307&mi=10
- Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping)
- Highest injury: Serious injuries
- Injuries: 2 serious
- Status: Completed, report March 24, 1993
- Report: Approved by Office Director
- NTSB case key (mKey): 23319
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=FTW91LA061
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/23319/pdf
- Page: https://openairdocs.org/ntsb/FTW91LA061

## Probable cause

POWER LOSS DUE TO CARBURETOR ICE AND A MALFUNCTIONING CARBURETOR HEAT CONTROL AND THE PILOT'S LOSS OF CONTROL OF THE AIRPLANE.

## Sequence of events

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

- Loss of engine power, maneuvering
  - weather condition - carburetor icing conditions
  - carburetor heat control - failure,partial (cause)
- Forced landing, descent - emergency
- Loss of control - in flight, maneuvering
  - aircraft control - not maintained, pilot in command (cause)
- In flight collision with terrain/water, descent - uncontrolled

## Analysis

THE PIC ASKED THE PASSENGER RIDING IN THE LEFT SEAT IF HE WANTED TO SEE HOW THE AG PILOTS FLEW. HE REDUCED POWER TO IDLE AND DOVE DOWN TOWARD AN OPEN FIELD. AFTER TRAVERSING THE FIELD THE PILOT ADDED POWER AND THE PASSENGER HEARD A 'POP OR BANG' NOISE FROM THE ENGINE AND THE PILOT SAID 'OH MY GOD'. THE AIRPLANE SUBSEQUENTLY IMPACTED IN THE FIELD IN A SHALLOW NOSE DOWN ATTITUDE AND A SLIGHT LEFT BANK AND CART-WHEELED. INVESTIGATION REVEALED THAT CONDITIONS WERE PRESENT FOR CARBURETOR ICING AND THAT THE CARBURETOR ACCELERATOR PUMP WAS NOT ACTUATING SMOOTHLY. THE CARBURETOR HEAT CONTROL WAS FOUND JAMMED TO THE FULL ON POSITION FOLLOWING THE ACCIDENT; HOWEVER, IT COULD NOT BE DETERMINED IF THAT WAS THE CONDITION PRIOR TO IMPACT.

## Aircraft

- Registration: [N4437U](https://openairdocs.org/deregistered/N4437U-2013-09-16), registration cancelled 2013-09-16, S/N 15060437, built 1964 (OpenAirDocs)
- Reported make and model: CESSNA 150D
- Registry model: [Cessna 150D](https://openairdocs.org/model/cessna-150d) (registry code 2071810) (OpenAirDocs)
- Registry engine: [Continental 0-200 series](https://openairdocs.org/engine/continental-0-200-series) (registry code 17020, reciprocating) (OpenAirDocs)
- Category: Airplane
- Serial number: 15060437
- Airframe hours: 3266
- Engines: CONTINENTAL O-200-A 100 horsepower reciprocating
- Damage: Destroyed
- Flight: Personal, Part 91
- Operator: Juan A. Guevera, Sr.
- Registered owner: Jose M. Garza
- Airworthiness certificate: Standard, Normal
- Last inspection: Annual, March 18, 1990, 114 hours before
- Departed: NONE, ZAPATA, TX

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 59; commercial; airplane ratings: multi-engine land, single-engine land; medical: class 2, valid medical--w/ waivers/lim; seat: right; flight hours: 384 total, 384 as pilot in command, 1 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 10° at 6 knots
- Visibility: 8 statute miles
- Lowest ceiling: 3,500 ft overcast
- Temperature: 68 °F, dew point 57 °F
- Altimeter: 30.00 inHg

## 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 19910406058799A](https://openairdocs.org/incident/19910406058799A), Apr 6, 1991: Cessna 150D, San Ygnacio, TX, Destroyed. Made low pass over field to simulate aerial spray run. Engine quit. Crashed. Carb heat jammed in off position.

## Other investigations on N4437U (1)

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 FTW66D0001](https://openairdocs.org/ntsb/FTW66D0001), Feb 18, 1965: Cessna 150 (N4437U), Washburn, TX, destroyed

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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