# NTSB DEN91LA025: Grumman AA1B, N1638R, Roswell, NM, December 15, 1990

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: December 15, 1990, 10:11 local (17:11 UTC)
- Place: Roswell, NM
- Coordinates: 33.639911, -104.379737 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=33.6399&lon=-104.3797&mi=10
- Phase of flight: [Initial climb](https://openairdocs.org/ntsb-phases/350) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 1 uninjured
- Status: Completed, report December 8, 1992
- Report: Approved by Office Director
- NTSB case key (mKey): 18060
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DEN91LA025
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/18060/pdf
- Page: https://openairdocs.org/ntsb/DEN91LA025

## Probable cause

LOW CYLINDER COMPRESSION AND FOULED SPARK PLUG.

## Sequence of events

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

- Loss of engine power(partial) - mech failure/malf, takeoff - initial climb
  - powerplant - low compression (cause)
  - ignition system,spark plug - fouled (cause)
- Forced landing, descent - emergency
- Hard landing, landing - flare/touchdown

## Analysis

THE PILOT SAID THAT AFTER TAKEOFF, AT AN ALTITUDE OF APPROXIMATELY 150 FEET, THE ENGINE STARTED RUNNING ROUGH. HE SAID THAT ENGINE PERFORMANCE CONTINUED TO DETERIORATE AND HE HAD TO MAKE A FORCED LANDING. THE AIRCRAFT STRUCK THE GROUND HARD AND SUSTAINED SUBSTANTIAL DAMAGE TO THE ENGINE COWLING AND THE MAIN LANDING GEAR. SUBSEQUENT EXAMINATION OF THE ENGINE REVEALED ONE CYLINDER HAD FOULED SPARK PLUGS AND ALL CYLINDERS EXCEPT ONE HAD LOW COMPRESSION.

## Aircraft

- Registration: [N1638R](https://openairdocs.org/deregistered/N1638R-1993-06-09), registration cancelled 1993-06-09, S/N AA1B0638 (OpenAirDocs)
- Reported make and model: GRUMMAN AA1B
- Registry model: [Grumman American Avn. AA-1B](https://openairdocs.org/model/grumman-american-avn-aa-1b) (registry code 3960103) (OpenAirDocs)
- Category: Airplane
- Serial number: AA1B0638
- Engines: LYCOMING O-235-L2C 108 horsepower reciprocating
- Damage: Substantial damage
- Flight: Personal, Part 91
- Operator: Guffey, Jerry D.
- Registered owner: Unknown
- Destination: ALM, ALAMOGORDO, NM
- Flight plan: VFR/IFR
- Airport: ROW, Roswell Indust. Air Cntr.

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 26; commercial; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 1, valid medical--no waivers/lim.; flight hours: 800 total, 150 in this make and model, 760 as pilot in command, 150 in the last 90 days, 70 in the last 30 days

## Weather

- Conditions: Visual (VMC), Day
- Wind: 20° at 3 knots
- Visibility: 40 statute miles
- Lowest ceiling: none
- Temperature: 46 °F, dew point 27 °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 19901215054339A](https://openairdocs.org/incident/19901215054339A), Dec 15, 1990: Gulstm AA1B, Roswell, NM, Substantial damage. Engine lost power on climbout. Landed short of runway trying to return. Low compression and fouled sparkplugs.

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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