# N261M: Waco BSO - Status: Valid registration - Airframe: [Waco BSO](https://openairdocs.org/model/waco-bso) (registry code 9601204, 3 seats) - Engine: [Lycoming R680E series](https://openairdocs.org/engine/lycoming-r680e-series) (registry code 41545) - Data sheets: [TCDS ATC 168](https://openairdocs.org/tcds/ATC%20168) (The Waco Aircraft Company), [TCDS E-202](https://openairdocs.org/tcds/E-202) (Textron Lycoming AVCO Corporation) (OpenAirDocs) - Serial number: A-159 - Type: Fixed wing single engine - Engine type: Reciprocating - Airworthiness: Experimental, exhibition - Airworthiness date: May 5, 1977 - Certificate issued: November 18, 2014 - Expires: November 30, 2027 - Mode S code: A283C7 - Registered owner: [Old Style Aircraft LLC](https://openairdocs.org/faa-owner/OLD%20STYLE%20AIRCRAFT%20LLC) - Location: [Ellsinore, MO](https://openairdocs.org/faa-place/MO/Ellsinore) - Owner type: LLC - Owner's area on the map: 36.9538° N, 90.7534° W: Placed by OpenAirDocs at the center of ZIP code 63937, 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=261M - Page: https://openairdocs.org/aircraft/N261M 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 Lycoming R680E model are included. ## ADs that may apply (OpenAirDocs): 5 in force ### Matched by airframe (Waco BSO) None in force. ### Matched by engine (Lycoming R680E series) - [AD 2012-03-07](https://openairdocs.org/ad/2012-03-07): Carburetor · Lycoming Engines GO-435, GO-435-C2 (O-435-17), GO-435-C2A and 389 more. Effective Mar 27, 2012 - [AD 2004-10-14](https://openairdocs.org/ad/2004-10-14): Crankshaft gear · Lycoming Engines AEIO-320-D1B, AEIO-320-D2B, AEIO-320-E1A and 642 more. Effective Jun 25, 2004 - [AD 95-26-02](https://openairdocs.org/ad/95-26-02): Aviation Gasoline · Lycoming Engines IO-320-B1A, IO-320-B1B, IO-320-B1C and 182 more. Effective Jan 24, 1996 - [AD 90-04-06 R1](https://openairdocs.org/ad/90-04-06-R1): Propeller Governor External Oil Line · Lycoming Engines AEIO-320-D1B, AEIO-320-D2B, AEIO-320-E1A and 427 more. Effective May 28, 1991 - [AD 66-06-03](https://openairdocs.org/ad/66-06-03): Connecting Rod Assemblies · Lycoming Engines GO-435-C2 (O-435-17), GO-435-C2A, GO-435-C2A2 and 317 more. Effective Jan 16, 1969 ## Information bulletins (advisory) None matched. ## NTSB investigations None matched to N261M. ## FAA accident and incident reports None matched to N261M. ## 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) (17) 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 airframe (Waco BSO) - [STC SA04652CH](https://openairdocs.org/stc/SA04652CH): To allow use of 100R grade aviation fuel meeting Swift Fuel, LLC specification. Swift Fuels LLC - [STC SA01406NY](https://openairdocs.org/stc/SA01406NY): Installation of Airwolf remote mounted engine oil filter kit AFC-K017 on single and multi-engine fixed light aircraft and rotary wing. Airwolf Filter Corporation - [STC SA2693NM](https://openairdocs.org/stc/SA2693NM): Installation of Electronics International digital volt/amp gauges and accessories. Electronics International Inc - [STC SA02033AT](https://openairdocs.org/stc/SA02033AT): Modification to install an air-oil separator to prevent oil from being aspirated from the engine breather line. M-20 Oil Separators LLC - [STC SA2687NM](https://openairdocs.org/stc/SA2687NM): Installation of Truboplus/ Electronics Int'l gauges and switches. Aero Manufacturing Inc - [STC SA1626NM PAGE 2](https://openairdocs.org/stc/SA1626NM%20PAGE%202): Installation of Electronics Int'l Digital EGT/CHT Instruments and accessories. (201 Series). Electronics International - [STC SA2350NM PAGE 2](https://openairdocs.org/stc/SA2350NM%20PAGE%202): Installation of Electronics International Inc digital carburetor/outside air temperature gauges. Electronics International - [STC SA4302NM](https://openairdocs.org/stc/SA4302NM): Installation of Electronics Int'l digital automatic engine analyzer. Electronics International - [STC SA3862NM PAGE 2](https://openairdocs.org/stc/SA3862NM%20PAGE%202): Installation of Electronics International Primary TIT/EGT/CHT instruments, remote switches and associated accessories. Electronics International - [STC SA2190NM PAGE 2](https://openairdocs.org/stc/SA2190NM%20PAGE%202): Installation of electronics International Digital Volt/Amp Gauges and Accessories. Electronics International - [STC SA2350NM](https://openairdocs.org/stc/SA2350NM) (historical): Installation of Electronics International Inc digital carburetor/outside air temperature gauges listed on the attached continuation sheet and the associated accessories. Electronics International ### Approved for the engine (Lycoming R680E 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 R-680-E1 - [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 R-680-E1 - [STC SE2407CE](https://openairdocs.org/stc/SE2407CE): Add the following approved fuel: unleaded automotive gas, 91 minimum antiknock index and leaded automotive gas, 91 minimum antiknock index, (RON+MON)/2. Petersen Aviation Inc. Lists R-680E3 - [STC SE2408CE](https://openairdocs.org/stc/SE2408CE): Add the following approved fuel: unleaded automotive gas, 91 minimum antiknock index and leaded automotive gas, 91 minimum antiknock index, (RON+MON)/2. Petersen Aviation Inc. Lists R-680E1 - [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. Lists R-680 Series - [STC SE128NE](https://openairdocs.org/stc/SE128NE): Use of AMS/OIL 15W 50 synthetic piston aircraft oil in Avco engines. AMS/OIL. Lists R-680 Series ## Related - Other Waco BSO aircraft: https://openairdocs.org/model/waco-bso/aircraft.md - The Lycoming R680E series engine: https://openairdocs.org/engine/lycoming-r680e-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.