# N21973: 1939 Porterfield CP-50 - Status: Valid registration - Airframe: [Porterfield CP-50](https://openairdocs.org/model/porterfield-cp-50) (registry code 6480114, 2 seats) - Engine: [Continental A50 series](https://openairdocs.org/engine/continental-a50-series) (registry code 17002) - Data sheets: [TCDS E-190](https://openairdocs.org/tcds/E-190) (Continental Aerospace Technologies, Inc.) (OpenAirDocs) - Serial number: 559 - Year built: 1939 - Type: Fixed wing single engine - Engine type: Reciprocating - Airworthiness: Standard - Airworthiness date: October 22, 1956 - Certificate issued: June 2, 2015 - Expires: June 30, 2028 - Mode S code: A1DE5A - Registered owner: [Western Antique Aeroplane & Automobile Museum](https://openairdocs.org/faa-owner/WESTERN%20ANTIQUE%20AEROPLANE%20%26%20AUTOMOBILE%20MUSEUM) - Location: [Hood River, OR](https://openairdocs.org/faa-place/OR/Hood%20River) - Owner type: Corporation - Owner's area on the map: 45.6068° N, 121.6023° W: Placed by OpenAirDocs at the center of ZIP code 97031, within about 7 miles (OpenAirDocs). The owner's mailing address, not where the aircraft is based - FAA registry: https://registry.faa.gov/AircraftInquiry/Search/NNumberResult?nNumberTxt=21973 - Page: https://openairdocs.org/aircraft/N21973 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 Continental A50 model are included. ## ADs that may apply (OpenAirDocs): 1 in force ### Matched by airframe (Porterfield CP-50) None in force. ### Matched by engine (Continental A50 series) - [AD 69-09-01](https://openairdocs.org/ad/69-09-01): Eisemann Magnetos · Eisemann Magnetos, 2A4-45-B2, 2A4-49-B2 and 158 more ## Information bulletins (advisory) (2 in force) - [SAIB NE-16-13](https://openairdocs.org/saib/NE-16-13): Powerplant - Prohibited use of sealant. Issued Mar 8, 2016 - [SAIB NE-13-04](https://openairdocs.org/saib/NE-13-04): Continental Motors, Inc. (CMI) Connecting Rod Piston Pin Bushing Inspection. Issued Oct 31, 2012 ## NTSB investigations (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 SEA67D0141](https://openairdocs.org/ntsb/SEA67D0141), Aug 6, 1966: Porterfield CP-50 (N21973), Yamhill, OR, substantial damage ## FAA accident and incident reports None matched to N21973. ## Reports on N21973 not matched to an aircraft (1) They name N21973, but no registry record covers the date, the aircraft registered then was built later, or the report describes another aircraft. - [Incident 19930311017309I](https://openairdocs.org/incident/19930311017309I), Mar 11, 1993: Cessna U206 (N21973), California City, CA, 1 fatal. Chutist pulled his main chute at a low altitude. Did not open. Not enough time for reserve chute. Impacted ground. ## 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) (12) Approved for this aircraft's airframe or engine model, in force first, then newest. The registry doesn't record which STCs an aircraft has; its records do. ### Approved for the engine (Continental A50 series) - [STC SE04651CH](https://openairdocs.org/stc/SE04651CH): To allow use of l00R grade aviation fuel meeting Swift Fuel, LLC specification SPEC-l00R-22. Swift Fuels LLC. Lists A-50-1 - [STC SE2932SW](https://openairdocs.org/stc/SE2932SW): Install carburetor air temperature indicator. Approved for Aircooled Motors (Franklin Engine Co.) equipped with float carburetors. Model eligibility included here may not be inclusive. Alcor LLC. Lists A-50-1 - [STC SE208SO](https://openairdocs.org/stc/SE208SO): Installation of ice indicator in the carburetor. LegacySTC.com - [STC SE03232CH](https://openairdocs.org/stc/SE03232CH): Installation of Engine Preheat Kit p/n TA2925-1 for 115 volt application. Hartzell Propeller Inc. Lists A-50-1 - [STC SE01966WI](https://openairdocs.org/stc/SE01966WI): Use of GAMI G100UL High Octane Unleaded Avgas in spark ignition piston aircraft engines. General Aviation Modifications Inc. Lists A-50-1 - [STC SE01943CH](https://openairdocs.org/stc/SE01943CH): Add the following approved fuels: unleaded automotive gasoline 87 minimum antiknock index, per ASTM Specification D-439 or D-4814 of any volatility class, A through E, or 82UL AVGAS per ASTM D-6227. Experimental Aircraft Association Inc. Lists A-50-1 - [STC SE634GL](https://openairdocs.org/stc/SE634GL): Superseded by STC SE01943CH. Add the following approved fuel: unleaded automotive gasoline, 87 minimum antiknock index. EAA Aviation Foundation - [STC SE09513SC](https://openairdocs.org/stc/SE09513SC): Installation and usage of Exxon 20W50 Multigrade aircraft engine oil conforming to Exxon Oil Formulation WS-3013. Exxon Company USA - [STC SE1-201](https://openairdocs.org/stc/SE1-201): Installation of the Richter Aero Equipment Type B-4 or B-5 Temperature Probe. (O-360 SERIES (excl. A1C, C2B, C2D)). MidContinent Instru Co Inc - [STC SE5879SW](https://openairdocs.org/stc/SE5879SW): Use of Phillips X/C II 20W-50 and25W-60 oil (OSS 55875) in all Avco reciprocating aircraft engines from 65 to 450 BHP. Phillips Petroleum Co - [STC SE80NE](https://openairdocs.org/stc/SE80NE): Installation and usage of Bel-Ray synthetic aviation oil, Bel-Ray Aero 1, (nonsupercharged), horizontally opposed direct drive, aircraft engines of 350 hp. or less. Bel-Ray Company, Inc - [STC SE44WE](https://openairdocs.org/stc/SE44WE): Use of Kling Aviation Oil, Specifications KL-100, KL-200 and KL-300 in Continental and Lycoming engines. Kling Oil Company ## Related - Other Porterfield CP-50 aircraft: https://openairdocs.org/model/porterfield-cp-50/aircraft.md - The Continental A50 series engine: https://openairdocs.org/engine/continental-a50-series.md --- 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.