Reciprocating Engines
Reciprocating Engines is a core knowledge area on the AMT — Powerplant FAA written exam. This hub collects our 16 in-depth, ACS-aligned reciprocating engines articles — each written in plain English and grounded in the official FAA handbooks. Work through them below, then drill the topic with practice questions.
Compression Ratio and Its Effect on Engine Performance
Compression ratio defines how much an engine compresses the air-fuel mixture before ignition, directly governing power output, efficiency, and fuel requirements in reciprocating aircraft engines.
Volumetric Efficiency in Reciprocating Aircraft Engines
Volumetric efficiency measures how completely a reciprocating engine fills its cylinders with a fresh charge, directly governing power output, fuel economy, and engine health for every piston-powered aircraft.
Valve Timing and Valve Overlap in Aircraft Engines
Valve timing and valve overlap govern when intake and exhaust valves open and close in a reciprocating engine, directly impacting power output, efficiency, and engine health at all operating speeds.
Horizontally Opposed Engine Configuration and Design
Horizontally opposed engines dominate light aircraft powerplants, offering a low-profile, balanced design with excellent power-to-weight ratios — a foundational topic for the FAA AMT Powerplant exam.
Magneto Ignition System Operation and Timing
Magneto ignition systems provide self-contained, high-voltage spark to aircraft reciprocating engines; precise timing of that spark relative to piston position is critical for safe, efficient engine operation.
Carburetor Icing and Alternate Air Systems
Carburetor ice can form even on warm days, silently robbing engine power; understanding how it forms and how alternate air systems prevent it is essential knowledge for any powerplant technician.
Detonation and Pre-Ignition Causes and Prevention
Detonation and pre-ignition are two distinct but dangerous abnormal combustion events in reciprocating aircraft engines that can destroy pistons and cylinders within seconds if not corrected.
Fuel-Air Mixture Ratio and Mixture Control Operations
Fuel-air mixture ratio determines combustion efficiency and engine health in reciprocating engines; proper mixture control prevents detonation, fouling, and power loss across varying altitudes and power settings.
Spark Plug Types, Heat Range Selection, and Inspection
Spark plugs must match the engine's heat range requirements for reliable ignition—choosing wrong causes fouling or pre-ignition, both of which can destroy an engine. This article covers types, heat range selection, inspection, and servicing for AMT Powerplant.
Engine Cooling Systems: Cylinder Baffling and Cowl Flaps
Cylinder baffling and cowl flaps direct airflow around engine cylinders to prevent overheating; understanding their design, inspection, and operation is essential for AMT Powerplant certification.
Engine Lubrication System Types and Oil Flow Paths
Aircraft engine lubrication systems — wet-sump, dry-sump, and pressure-spray designs — circulate oil to reduce friction, cool components, and carry contaminants away from critical engine parts.
Dry-Sump vs Wet-Sump Lubrication Systems in Aircraft Engines
Dry-sump and wet-sump lubrication systems both deliver pressurized oil to an aircraft reciprocating engine, but differ fundamentally in oil storage location, component count, and suitability for aerobatic or high-performance use.
Supercharging and Turbocharging in Reciprocating Aircraft Engines
Supercharging and turbocharging compress induction air to maintain or boost engine power at altitude, overcoming the density loss that otherwise reduces reciprocating engine performance as altitude increases.
TBO, Engine Run-Out Inspection, and Airworthiness Limits
Time Between Overhaul (TBO), engine run-out inspections, and airworthiness limits define when and how a reciprocating aircraft engine must be overhauled or retired to remain legally airworthy.
Engine Power Output: BHP, BMEP, and Manifold Pressure Relationships
Brake horsepower, brake mean effective pressure, and manifold pressure are tightly linked indicators of reciprocating engine power that every powerplant technician must understand for accurate diagnosis, performance testing, and airworthiness decisions.
Four-Stroke Otto Cycle in Aircraft Reciprocating Engines
The four-stroke Otto cycle—intake, compression, power, and exhaust—forms the thermodynamic foundation of every aircraft reciprocating engine, converting fuel energy into shaft work through precisely timed mechanical events.
More AMT — Powerplant subjects
Articles are original summaries grounded in the public-domain FAA handbooks and cite their source. ACS-aligned study aids — not a substitute for the official handbooks or regulations.