A Lycoming aircraft engine is a horizontally opposed, air-cooled, four-, six-, or eight-cylinder internal combustion powerplant designed for general aviation aircraft. Renowned for operational reliability and standardized modular architecture, Lycoming engines power a wide range of certified and experimental platforms produced by OEMs such as Cessna, Piper, Beechcraft, and Mooney.
Key Technical Features of Lycoming Engines
Lycoming powerplants rely on a direct-drive, overhead-valve architecture utilizing individual air-cooled cylinder assemblies mounted to a two-piece aluminum crankcase. Ignition is provided by dual independent magnetos driving two spark plugs per cylinder for redundancy and optimal combustion efficiency. Ignition overhaul kits, such as the Slick Kit K4317-40 Gray RHM40E K4317-38 K4317-40 With URHM38E Plug or the Slick Kit K4520R-40 Red K4520R-40, are routinely specified during major engine inspections and magneto overhaul intervals.
Key architectural variations across the Lycoming product line include:
- Induction Systems: Naturally aspirated carburetors (MA-3, MA-4 series) or continuous-flow fuel injection systems (RSA series).
- Aspiration: Standard sea-level calibration versus turbocharging (T) and turbo-supercharging (TO) for high-altitude power maintenance.
- Cylinder Configuration: Parallel-valve cylinders offering light weight and mechanical simplicity versus angle-valve cylinders optimized for enhanced airflow and higher horsepower output.
- Mounting Styles: Conical mounts or dynafocal mounts (Type 1 and Type 2) designed to attenuate engine vibration transferred into the airframe.
Model Sizing and Specifications
Lycoming uses a standardized prefix and displacement naming convention. Prefixes designate major design features: O (Opposed), I (Fuel Injected), T (Turbocharged), L (Left-Hand Rotation / Counter-rotating), and AE (Aerobatic). Numeric values indicate engine cubic-inch displacement.
| Engine Series | Cylinder Count | Horsepower Range | Typical Induction | Common Applications |
|---|---|---|---|---|
| O-235 | 4 Cylinder | 108 – 125 hp | Carbureted | Cessna 152, Piper Tomahawk |
| O-320 / IO-320 | 4 Cylinder | 150 – 160 hp | Carbureted / Injected | Cessna 172, Piper Warrior |
| O-360 / IO-360 | 4 Cylinder | 180 – 200 hp | Carbureted / Injected | Piper Archer, Mooney M20, Husky |
| IO-390 | 4 Cylinder | 210 – 215 hp | Fuel Injected | Cirrus SR20, Experimental Aircraft |
| O-540 / IO-540 | 6 Cylinder | 235 – 300 hp | Carbureted / Injected | Cessna 182, Piper Saratoga, Robinson R44 |
Engine Price Ranges and Overhaul Options
When sourcing a replacement engine or planning a overhaul, operators evaluate four major condition categories depending on budget and airworthiness requirements:
- Factory New Engine ($35,000 – $95,000+): Direct from the OEM with zero total time on airframe components, original factory warranty, and zero-time logbooks.
- Factory Rebuilt ($30,000 – $80,000+): Rebuilt by Lycoming to factory-new tolerances, issued a zero-time logbook, and classified as zero-hour under FAA regulations.
- Overhauled / Zero-Time Field Overhaul ($22,000 – $60,000+): Disassembled, inspected, repaired, and reassembled by certified repair stations or an AMT/A&P mechanic in accordance with current Lycoming Overhaul Manual limits. Total time carries forward from the original engine logbook.
- Serviceable / As-Removed Core ($8,000 – $25,000): Mid-time or high-time engines removed for upgrade or tear-down. Requires thorough logbook audit and physical inspection before return to service.
PMA Alternatives and Supporting Components
In addition to OEM parts, FAA Parts Manufacturer Approval (PMA) components offer high-quality options for maintaining Lycoming powerplants. Replacement seal kits, such as the Lycoming Superior Gasket Set SL75439-1 75439-1, provide technicians with reliable sealing solutions during top or major overhauls. Operators evaluating non-OEM parts can consult the guide on FAA PMA Parts Explained - American Aviation Parts to ensure conformity and compliance with airworthiness regulations.
Key engine-driven accessories—including belt-driven or gear-driven Alternators, starters, and fuel pumps—must be specified by engine model and airframe interface to match drive ratios and mounting clearances.
Common Selection and Installation Pitfalls
Evaluating Lycoming powerplants requires exact precision. Subtle variations between sub-models (dash numbers) can affect airworthiness certification and physical installation:
- Dash Number Incompatibility: Assuming an IO-360-A1A is identical to an IO-360-B1E is a frequent mistake. Differences in sump design, mounting angles, fuel injection servos, and counterweight configurations can prevent installation.
- Intermixing Airframe and Engine Components: Engine mounts, exhaust risers, and baffle interfaces connect directly to adjacent Airframe Parts. Always verify cowl clearance and mounting pad geometries before purchasing replacement powerplants.
- Propeller Governor and Drive Ratios: Front-mounted vs. rear-mounted propeller governor pads utilize different drive gear ratios and oil transfer passages.
- Incomplete Maintenance Documentation: Purchasing used cores without total time since overhaul (TTSN/TSOH), compliance records for Airworthiness Directives (ADs), or 8130-3 airworthiness tags risks unexpected airworthiness non-compliance.
Expert Recommendations for Engine Sourcing
When preparing to source a engine or overhaul components through American Aviation Parts, follow these steps to confirm fitment:
- Record Full Engine Data Plate Details: Capture the exact model number, complete dash suffix, and serial number directly from the engine data plate.
- Consult Approved Technical Data: Reference current Lycoming Illustrated Parts Catalogs (IPC), Service Bulletins, and the applicable Aircraft Maintenance Manual prior to purchase.
- Verify Form 8130-3 Traceability: Ensure major components carry valid airworthiness documentation and logbook entries indicating accurate operating hours and maintenance history.
At American Aviation Parts, our technical specialists help you verify exact part numbers, model applicability, and component cross-references to keep your aircraft fully airworthy and operational.