# Lycoming IO-320-C1A

- Type: Engine model (FAA registry)
- Registry code: 41913
- Manufacturer (registry): LYCOMING
- Model: IO-320-C1A
- Engine type: Reciprocating
- Power: 160 hp
- Data sheet: [TCDS 1E12](https://openairdocs.org/tcds/1E12) (OpenAirDocs)
- Holder: Lycoming Engines
- Installed in: 7 registered aircraft
- Page: https://openairdocs.org/engine/lycoming-io-320-c1a

Model codes come from the FAA registry's reference file.

## ADs that may apply (OpenAirDocs)

Matched to this engine model by model name and maker. Each AD's applicability may narrow it by serial number, part number or equipment.

- [AD 2026-04-11](https://openairdocs.org/ad/2026-04-11): Engine (Reciprocating) · Lycoming Engines AEIO-320-D1B, AEIO-320-D2B, AEIO-320-E1A and 605 more. Effective Apr 8, 2026
- [AD 2015-19-07](https://openairdocs.org/ad/2015-19-07): Fuel injector fuel lines · Lycoming Engines AEIO-320-D1B, AEIO-320-D2B, AEIO-320-E1B and 187 more. Effective Nov 3, 2015
- [AD 2012-03-06](https://openairdocs.org/ad/2012-03-06): Fuel servo diaphragm · Continental Motors 6-260-A, 6-285-A, 6-285-B and 482 more. Effective Feb 24, 2012
- [AD 2010-07-08](https://openairdocs.org/ad/2010-07-08): Turbochargers · Kelly Aerospace Energy Systems HIO-360-E1AD, HIO-360-E1BD, HIO-360-F1AD and 137 more. Effective Apr 19, 2010
- [AD 2009-26-12](https://openairdocs.org/ad/2009-26-12): Cylinder assemblies · Engine Components Reciprocating Engine Cylinder Assemblies, AEIO-320-D1B, AEIO-320-D2B and 264 more. Effective Feb 4, 2010
- [AD 2009-02-03](https://openairdocs.org/ad/2009-02-03): Fuel injection servos · Lycoming Engines AEIO-320-D1B, AEIO-320-D2B, AEIO-320-E1A and 261 more. Effective Feb 9, 2009
- [AD 2006-12-07](https://openairdocs.org/ad/2006-12-07): ECi cylinder assemblies · Aerostar AEIO-320-D1B, AEIO-320-D2B, AEIO-320-E1A and 386 more. Effective Jul 11, 2006
- [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 2003-14-03](https://openairdocs.org/ad/2003-14-03): Rotary fuel pumps · Lycoming Engines AEIO-540-D4A5, AEIO-540-D4B5, AEIO-540-D4C5 and 262 more. Effective Aug 14, 2003
- [AD 98-02-08](https://openairdocs.org/ad/98-02-08): Crankshaft · Lycoming Engines AEIO-320-D1B, AEIO-320-D2B, AEIO-320-E1A and 216 more. Effective Mar 30, 1998
- [AD 97-15-11](https://openairdocs.org/ad/97-15-11): Cylinder kits · Lycoming Engines AEIO-320-D1B, AEIO-320-D2B, AEIO-320-E1A and 538 more. Effective Aug 12, 1997
- [AD 96-23-03](https://openairdocs.org/ad/96-23-03): High pressure fuel pumps · Lycoming Engines AEIO-320-D1B, AEIO-320-D2B, AEIO-320-E1A and 174 more. Effective Dec 23, 1996
- [AD 96-09-10](https://openairdocs.org/ad/96-09-10): Oil pump · Lycoming Engines AEIO-320-E1A, AEIO-320-E1B, AEIO-320-E2A and 334 more. Effective Jul 15, 1996
- [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 92-12-05](https://openairdocs.org/ad/92-12-05): Piston Pins · Lycoming Engines AEIO-320-D1B, AEIO-320-D2B, AEIO-320-E1A and 532 more. Effective Jul 10, 1992
- [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 87-10-06 R1](https://openairdocs.org/ad/87-10-06-R1): Rocker Arm Assembly · Lycoming Engines IO-360-B4, IVO-360-A1A, O-340-A1A and 243 more. Effective Sep 1, 1989
- [AD 80-06-05](https://openairdocs.org/ad/80-06-05): Magnetos · Lycoming Engines AEIO-320-D1B, AEIO-320-D2B, AEIO-320-E1A and 254 more. Effective Mar 28, 1980
- [AD 79-04-05](https://openairdocs.org/ad/79-04-05): Regulator Diaphragm Stem Assembly · Lycoming Engines AEIO-320-D1B, AEIO-320-E1A, AEIO-320-E1B and 215 more. Effective Sep 26, 1979
- [AD 78-23-10](https://openairdocs.org/ad/78-23-10): Center Body Bellows Seal Assembly · Lycoming Engines AEIO-320-D1B, AEIO-320-E1A, AEIO-320-E1B and 218 more. Effective Nov 7, 1978
- [AD 75-08-09](https://openairdocs.org/ad/75-08-09): Oil Pump Drive Shaft · Lycoming Engines AEIO-360-A1B, AEIO-360-A1B6, AEIO-360-A1C and 365 more. Effective Aug 18, 1977
- [AD 73-23-01](https://openairdocs.org/ad/73-23-01): Piston Pin Assembly · Lycoming Engines AIO-360-A1A, AIO-360-A1B, AIO-360-A2A and 215 more. Effective Jan 13, 1977
- [AD 75-09-15](https://openairdocs.org/ad/75-09-15): Fuel Starvation To The Engine · Lycoming Engines AIO-320-A1A, AIO-320-A1B, AIO-320-A2A and 130 more. Effective Apr 30, 1975
- [AD 73-10-02](https://openairdocs.org/ad/73-10-02): Bendix Fuel Injectors · Bendix Fuel Injectors, AIO-320-A1A, AIO-320-A1B and 88 more. Effective May 16, 1973
- [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
- [AD 67-22-06](https://openairdocs.org/ad/67-22-06): Fuel Injectors · Lycoming Engines HIO-360-A1A, HIO-360-B1A, HIO-360-B1B and 28 more. Effective Aug 9, 1967
- [AD 66-20-04](https://openairdocs.org/ad/66-20-04): Oil Filter Adapter Gasket · Lycoming Engines IO-320-A1A, IO-320-A2A, IO-320-B1A and 121 more. Effective Aug 27, 1966

Historical (superseded or no longer in force):

- [AD 2024-21-02](https://openairdocs.org/ad/2024-21-02) (historical): Engine (Reciprocating) · Lycoming Engines AEIO-320-D1B, AEIO-320-D2B, AEIO-320-E1A and 548 more. Effective Dec 5, 2024
- [AD 2011-26-04](https://openairdocs.org/ad/2011-26-04) (historical): Externally mounted fuel injector fuel lines · Lycoming Engines AEIO-320-D1B, AEIO-320-D2B, AEIO-320-E1B and 186 more. Effective Jan 25, 2012
- [AD 2011-15-10](https://openairdocs.org/ad/2011-15-10) (historical): Fuel servos · Lycoming Engines AEIO-320-D1B, AEIO-320-D2B, AEIO-320-E1A and 256 more. Effective Aug 16, 2011
- [AD 2008-19-05](https://openairdocs.org/ad/2008-19-05) (historical): Parallel Valve'' reciprocating engines · Engine Components Reciprocating Engine Cylinder Assemblies, AEIO-320-D1B, AEIO-320-D2B and 262 more. Effective Oct 20, 2008
- [AD 2008-14-07](https://openairdocs.org/ad/2008-14-07) (historical): Externally mounted fuel injector fuel lines · Textron Lycoming, AVCO AEIO-320-D1B, AEIO-320-D2B, AEIO-320-E1B and 185 more. Effective Aug 14, 2008
- [AD 2008-08-14](https://openairdocs.org/ad/2008-08-14) (historical): Fuel injection servo plugs · Superior Air Parts AEIO-320-D1B, AEIO-320-D2B, AEIO-320-E1A and 242 more. Effective Apr 29, 2008
- [AD 2008-06-51](https://openairdocs.org/ad/2008-06-51) (historical): Fuel injection servo plugs · Lycoming Engines AEIO-320-D1B, AEIO-320-D2B, AEIO-320-E1A and 235 more
- [AD 2005-26-10](https://openairdocs.org/ad/2005-26-10) (historical): ECi cylinder assemblies. · Lycoming Engines AEIO-320-D1B, AEIO-320-D2B, AEIO-320-E1A and 413 more. Effective Jan 31, 2006
- [AD 2002-26-01](https://openairdocs.org/ad/2002-26-01) (historical): Fuel injector fuel lines · Textron Lycoming, AVCO IGO-480-A1B6, IGO-540-B1A, IGO-540-B1C and 178 more. Effective Jan 31, 2003
- [AD 98-18-12](https://openairdocs.org/ad/98-18-12) (historical): Fuel Pump · Textron Lycoming, AVCO AEIO-540-D4A5, AEIO-540-D4B5, AEIO-540-D4C5 and 249 more. Effective Sep 28, 1998
- [AD 81-18-04 R2](https://openairdocs.org/ad/81-18-04-R2) (historical): Engine Oil Pump Driven Impeller and Shaft · Textron Lycoming, AVCO AEIO-320-D1B, AEIO-320-D2B, AEIO-320-E1A and 376 more. Effective Jun 7, 1982

## Information bulletins (advisory) (7)

- [SAIB NE-19-08](https://openairdocs.org/saib/NE-19-08): Reciprocating Engine Cylinder Section - Lycoming Engines Parallel Valve Cylinders. Issued May 2, 2019
- [SAIB NE-08-32R1](https://openairdocs.org/saib/NE-08-32R1): Propeller Governor  Idler Gear Shaft Set Screw. Issued May 13, 2016
- [SAIB NE-14-13](https://openairdocs.org/saib/NE-14-13): Reciprocating Engine - Cylinder Mounting Studs. Issued Mar 24, 2014
- [SAIB NE-13-06](https://openairdocs.org/saib/NE-13-06): Pushrod Shroud Spring Retainers, Engine Components Part No. AEL14995, for Lycoming Engines 320, 360, and 540 Series Engines. Issued Nov 21, 2012
- [SAIB NE-09-04](https://openairdocs.org/saib/NE-09-04): Fuel Control/Reciprocating Engines. Issued Jan 10, 2009
- [SAIB NE-06-32R1](https://openairdocs.org/saib/NE-06-32R1): Reciprocating Engine - Crankshaft. Issued Sep 10, 2008
- [SAIB NE-08-32](https://openairdocs.org/saib/NE-08-32) (historical): Propeller Governor Set Screw. Issued Jul 3, 2008

## Registered aircraft (7)

- [N111PL](https://openairdocs.org/aircraft/N111PL): [Columbia Asset Trust Corp Trustee](https://openairdocs.org/faa-owner/COLUMBIA%20ASSET%20TRUST%20CORP%20TRUSTEE), [Wichita, KS](https://openairdocs.org/faa-place/KS/Wichita), built 1969, S/N 301929
- [N160ML](https://openairdocs.org/aircraft/N160ML): [Lindsey Roy M](https://openairdocs.org/faa-owner/LINDSEY%20ROY%20M), [Thorsby, AL](https://openairdocs.org/faa-place/AL/Thorsby), built 2022, S/N 22807
- [N7224S](https://openairdocs.org/aircraft/N7224S): [Cunningham Russell A](https://openairdocs.org/faa-owner/CUNNINGHAM%20RUSSELL%20A), [Zimmerman, MN](https://openairdocs.org/faa-place/MN/Zimmerman), built 2021, S/N 281
- [N8203Y](https://openairdocs.org/aircraft/N8203Y): [Mn98 LLC](https://openairdocs.org/faa-owner/MN98%20LLC), [Belview, MN](https://openairdocs.org/faa-place/MN/Belview), built 1966, S/N 30-1322
- [N843G](https://openairdocs.org/aircraft/N843G): [R & B Aircraft Holdings LLC](https://openairdocs.org/faa-owner/R%20%26%20B%20AIRCRAFT%20HOLDINGS%20LLC), [Denham Springs, LA](https://openairdocs.org/faa-place/LA/Denham%20Springs), built 1969, S/N 30-1766
- [N84TD](https://openairdocs.org/aircraft/N84TD): [Bailey Dennis](https://openairdocs.org/faa-owner/BAILEY%20DENNIS), [Kernersville, NC](https://openairdocs.org/faa-place/NC/Kernersville), built 1969, S/N 30-1951
- [N8897Y](https://openairdocs.org/aircraft/N8897Y): [Avion LLC](https://openairdocs.org/faa-owner/AVION%20LLC), [Lewes, DE](https://openairdocs.org/faa-place/DE/Lewes), built 1970, S/N 39-54

## NTSB investigations

None matched to aircraft with this engine model.

## FAA accident and incident reports

None matched to aircraft with this engine model.

## Service difficulty reports (8)

As reported by operators and repair stations, by the model named in the report.

- [SDR 2015FA0000339](https://openairdocs.org/sdr/2015FA0000339), Jun 15, 2015: SOLENOID VALVE. CONTAMINATED. INSUFFICIENT FUEL FLOW TO ENGINE FROM AUXILIARY AND TIP FUEL TANKS. DEBRIS IN SOLENOID VALVE, OBSTRUCTING, JAMMING OPERATION. THE PLUG IS IN A LOCATION PERMITTI
- [SDR 2005FA0000358](https://openairdocs.org/sdr/2005FA0000358), Mar 7, 2005: CAMSHAFT. BROKEN. WHILE CLIMBING OUT OF 4,000 FT, RT ENGINE (2-23-05) SHUTTERED AND BEGAN VIBRATING EXCESSIVELY. RETURNED TO AIRPORT. INSPECTION REVEALED THE CAMSHAFT HAD BROKEN 
- [SDR AUS20021019](https://openairdocs.org/sdr/AUS20021019), Sep 2, 2002: SPAR CAP. CORRODED. (AUS) LH AND RH WING LOWER FORWARD SPAR CAPS CONTAINED SEVERE EXFOLIATION CORROSION IN AREA LOCATED AT WS 62 DUE TO ENGINEEXHAUST GASSES. AT LEAST 10% OF THE SP
- [SDR 2002FA0000054](https://openairdocs.org/sdr/2002FA0000054), Jan 14, 2002: CYLINDER. CUT. ENGINE WAS INSTALLED ON THE AIRCRAFT AND RUN UP. AN OIL LEAK WAS NOTICED IN THE LOWER SPARK PLUG BOSS AREA OF NR 1 CYLINDER. FURTHER EXAMINATION REVEALED THAT S
- [SDR 2002FA0000055](https://openairdocs.org/sdr/2002FA0000055), Jan 14, 2002: CYLINDER. LEAKING. ENGINE WAS INSTALLED ON THE AIRCRAFT AND RUN UP. AN OIL LEAK WAS NOTICED IN THE LOWER SPARK PLUG BOSS AREA OF NR 1 CYLINDER. FURTHER EXAMINATION REVEALED THAT S
- [SDR CA000222003](https://openairdocs.org/sdr/CA000222003), Feb 10, 2000: WIRE. FAILED. (CAN) PILOT REPORTED LOST GLIDESCOPE ON APPROACH AFTER LANDING GEAR WOULD NOT RETRACT. GEAR SWUNG, ELECTRICAL WIRING INSPECTED, BATTERY REPLACED, VOLTAGE REGULA
- [SDR AU960913](https://openairdocs.org/sdr/AU960913), Jun 3, 1996: FUSELAGE. CORRODED. (AUS) AIRFRAME STRUCTURE CONTAINED NUMEROUS TYPES OF CORROSION IN ALL AREAS
- [SDR AU960499](https://openairdocs.org/sdr/AU960499), Apr 11, 1996: DRIVE UNIT. MALFUNCTIONED. (AUS) ENGINE STARTER MOTOR DRIVE LOCKED IN THE ENGAGED POSITION

## STCs that may be installed (OpenAirDocs) (41)

Approved for this engine model: the STC's model list names it on its data sheet, or a series that includes it. In force first, then newest. The registry doesn't record which STCs an aircraft has.

- [STC SE00825WI](https://openairdocs.org/stc/SE00825WI): Installation of Specialty Products Spin-on oil filter on Lycoming Engines. B & C Specialty Products Inc
- [STC SE04349CH](https://openairdocs.org/stc/SE04349CH): Installation of SureFly electronic ignition. SureFly Partners Ltd
- [STC SE01954SE](https://openairdocs.org/stc/SE01954SE): Installation of engine crankcase seal. Ly-Con Rebuilding Company
- [STC SE02352CH](https://openairdocs.org/stc/SE02352CH): Installation of Challenger cleanable oil filter assembly. Challenger Aviation Products Inc
- [STC SE00939WI](https://openairdocs.org/stc/SE00939WI): Installation of B&C Specialty Products Model BC 315-( ) Starter on Lycoming engines. B & C Specialty Products Inc
- [STC SE2452CE](https://openairdocs.org/stc/SE2452CE): Installation of B&C Specialty Products lightweight (10.2 pounds) engine starter PN BC315-100-1(12 volt) or PN BC315-100-3(24 volt) on engines with ring gears having 122 teeth and PN BC315-100-2 (12 volt) or PN BC315-100-4 (24 volt) on engines with ring gears having 149 teeth. B & C Specialty Products Inc. Lists IO-320 Series
- [STC SE03232CH](https://openairdocs.org/stc/SE03232CH): Installation of Engine Preheat Kit p/n TA2925-1 for 115 volt application. Hartzell Propeller Inc
- [STC SE14WE](https://openairdocs.org/stc/SE14WE): Installation of one Rajay Turbocharger P/N RJ 0325, RJ 0326, RJ 0326-1, or RJ 0326-2. TALCO Aviation
- [STC SE04577CH](https://openairdocs.org/stc/SE04577CH): Install an electronic engine ignition system. Electroair Acquisition Corp
- [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
- [STC SE8628SW](https://openairdocs.org/stc/SE8628SW): Installation of oil nozzles for lubrication of cam and filters. Cygnet Aerospace Corp
- [STC SE09445SC](https://openairdocs.org/stc/SE09445SC): Installation of fuel injector nozzles. General Aviation Modifications Inc. Lists IO-320 Series
- [STC SE03215CH](https://openairdocs.org/stc/SE03215CH): STC for the conversion of Lycoming O-320-A, B, C, D, E; IO-320-A, B, C, D, E, F; AIO-320-A, B; AEIO-320-D, E to increase engine displacement to 340 cubic inches by installation of a crankshaft with a longer stroke. Continental Motors, Inc
- [STC SE1339SW](https://openairdocs.org/stc/SE1339SW): Modify pistons to Drawings 11007 and 11015; piston rings. Continental Motors, Inc
- [STC SE4408SW](https://openairdocs.org/stc/SE4408SW): Miscellaneous engine cylinder replacement parts. Continental Motors, Inc. Lists IO-320 Series
- [STC SE8776SW](https://openairdocs.org/stc/SE8776SW): Installation of coated cylinders and piston rings. Continental Motors, Inc. Lists IO-320 Series
- [STC SE00218NY](https://openairdocs.org/stc/SE00218NY): Replacement of Lycoming starter with SKY-TEC 12 volt starter installed. Hartzell Engine Technologies, LLC. Lists IO-320 Series
- [STC SE00226NY](https://openairdocs.org/stc/SE00226NY): Replacement of Lycoming starter with SKY-TEC 24-volt starter Models 149-24HT and 122-24HT. Approval limited to 24-volt DC source available to the starter. Hartzell Engine Technologies, LLC
- [STC SE00357NY](https://openairdocs.org/stc/SE00357NY): Replacement of Lycoming starter with SKY-TEC 24-volt starter installed. Hartzell Engine Technologies, LLC. Lists IO-320 Series
- [STC SE2901NM](https://openairdocs.org/stc/SE2901NM): Lycoming valve cover gasket. Real Gaskets Tennessee
- [STC SE02409AK](https://openairdocs.org/stc/SE02409AK): Installation of the Superior Air Parts Cold Air Induction System (CAIS). Wattum Aircraft Services
- [STC SE00590DE](https://openairdocs.org/stc/SE00590DE): Installation of modified Lubricated Camshaft. Centri-Lube Technologies LLC
- [STC SE02555AT](https://openairdocs.org/stc/SE02555AT): Consolidated Fuel Systems 201F series fuel pump assembly on various Textron Lycoming engine models. Kelly Aerospace Energy Systems LLC
- [STC SE01524CH](https://openairdocs.org/stc/SE01524CH): Replace Slick 6000, 6100, 6200, 6300, 4000, 4100, 4200, and 4300 series magnetos and TCM/Bendix S6-20, S6-200, S6-1200, S-20, S-200, and S-1200 series magnetos with Champion Limited Authority Spark Advance Regulator (LASAR ) Model 4755 and 6755 bush kit ignition systems. Champion Aerospace LLC
- [STC SE524CH](https://openairdocs.org/stc/SE524CH): Replace Slick 4000, 4100, 4200, and 4300 series magnetos and TCM/Bendix S-20, S-200, and S-1200 series magnetos with the Champion Limited Authority Spark Advance Regulator (LASAR ). Champion Aerospace LLC
- [STC SE859GL](https://openairdocs.org/stc/SE859GL): Replacement of Bendix S4LN-20, -21, -1209, or -1227 model magnetos with Slick Model 4250 or 4251 magnetos. Champion Aerospace LLC
- [STC SA4005NM](https://openairdocs.org/stc/SA4005NM): Precise Flight Inc. Pulselite Control System. Precise Flight Inc
- [STC SE01930NY](https://openairdocs.org/stc/SE01930NY): Installation of Casper Labs 90 degree oil filter housing adapter. Casper Labs Inc
- [STC SE1779NM](https://openairdocs.org/stc/SE1779NM): Installation of Precise Flight, Inc. Standby Vacuum System SVS III. Precise Flight Inc
- [STC SE5743NM](https://openairdocs.org/stc/SE5743NM): Intallation of adapter for externally mounted oil filter. Aviation Development Corporation
- [STC SE09492SC](https://openairdocs.org/stc/SE09492SC): Installation and usage of Exxon 20W50 multigrade aircraft engine oil conforming to Exxon Oil formulation WS-3013. Exxon Company USA. Lists IO-320 Series
- [STC SE00590LA](https://openairdocs.org/stc/SE00590LA): Installation of Nickson's cylinder barrels on Lycoming reciprocating engine models. Nickson's Machine Shop Inc. Lists IO-320-C Series
- [STC SE00350SE](https://openairdocs.org/stc/SE00350SE): Installation of sump mounted chip detector. Aviation Development Corporation
- [STC SE8023SW](https://openairdocs.org/stc/SE8023SW): Installation and usage of AEROSHELL. Shell Development Co. Lists IO-320 Series
- [STC SE452NE](https://openairdocs.org/stc/SE452NE): Installation and usage of 'Mobil AV 1' aviation oil. Mobil Research & Development Corp. Lists IO-320 Series
- [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 IO-320 Series
- [STC SE5924SW](https://openairdocs.org/stc/SE5924SW): Installation of stainless steel replacement exhaust studs on AVCO engines. Perrigo & Steele Aircraft Engr Company. Lists IO-320 Series
- [STC SE244NE](https://openairdocs.org/stc/SE244NE): Installation of Mattituck plasma flame sprayed cylinder barrels in Teledyne reciprocating engines. Mattituck Airbase, Inc. Lists IO-320 Series
- [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. Lists IO-320 Series
- [STC SE1445SO](https://openairdocs.org/stc/SE1445SO): Use of Aero-blend oil additive in Teledyne (non turbocharged) aircraft engines. ProTec. Lists IO-320 Series
- [STC SE128NE](https://openairdocs.org/stc/SE128NE): Use of AMS/OIL 15W 50 synthetic piston aircraft oil in Avco engines. AMS/OIL. Lists IO-320 Series

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