# N631LS: Lockheed 18-56

- Status: Valid registration
- Airframe: [Lockheed 18-56](https://openairdocs.org/model/lockheed-18-56) (registry code 5261642, 17 seats)
- Engine: [Wright C9HD series](https://openairdocs.org/engine/wright-c9hd-series) (registry code 67028)
- Serial number: 2404
- Type: Fixed wing multi engine
- Engine type: Reciprocating
- Airworthiness: Standard
- Airworthiness date: August 6, 1958
- Certificate issued: May 9, 2014
- Expires: May 31, 2027
- Mode S code: A8427E
- Registered owner: [Hill Lawrence E](https://openairdocs.org/faa-owner/HILL%20LAWRENCE%20E)
- Location: [Marion, MT](https://openairdocs.org/faa-place/MT/Marion)
- Owner type: Individual
- Owner's area on the map: 48.0444° N, 114.8326° W: Placed by OpenAirDocs at the center of ZIP code 59925, within about 11 miles (OpenAirDocs). The owner's mailing address, not where the aircraft is based
- FAA registry: https://registry.faa.gov/AircraftInquiry/Search/NNumberResult?nNumberTxt=631LS
- Page: https://openairdocs.org/aircraft/N631LS

From the FAA registry file of October 24, 2026. ADs below are matched by the registry's airframe and engine model codes. They may apply; each AD's applicability can narrow it by serial number, part number or installed equipment. This is not a compliance determination. The registry lists only the engine series, so ADs for every Wright C9HD model are included.

## ADs that may apply (OpenAirDocs): 0 in force

### Matched by airframe (Lockheed 18-56)

None in force.

### Matched by engine (Wright C9HD series)

None in force.

## Information bulletins (advisory)

None matched.

## NTSB investigations

None matched to N631LS.

## FAA accident and incident reports (1)

From the FAA Accident/Incident Data System. Reports are matched to registry aircraft by N-number and event date, checked against the reported make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model.

- [Incident 19800528052239I](https://openairdocs.org/incident/19800528052239I), May 28, 1980: Lkheed 18LKHEED (N631LS), Bedford, MA. Engine shut down due to loss of oil pressure. Relief valve was stuck.

## Service difficulty reports

None filed for this aircraft. Matched to this aircraft by N-number and event date, checked against the reported serial number, make and model.

## STCs that may be installed (OpenAirDocs)

None matched to this aircraft's models.

## Related

- Other Lockheed 18-56 aircraft: https://openairdocs.org/model/lockheed-18-56/aircraft.md
- The Wright C9HD series engine: https://openairdocs.org/engine/wright-c9hd-series.md

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