Engine Electrical Systems
Engine Electrical Systems is a core knowledge area on the AMT — Powerplant FAA written exam. This hub collects our 16 in-depth, ACS-aligned engine electrical systems articles — each written in plain English and grounded in the official FAA handbooks. Work through them below, then drill the topic with practice questions.
Aircraft Engine Magneto Operating Principles
Aircraft magnetos generate high-voltage ignition sparks independently of the aircraft's main electrical system, ensuring reliable engine ignition through self-contained electromagnetic induction principles.
High-Tension vs Low-Tension Magneto Systems
High-tension magneto systems generate and distribute high-voltage spark directly to each cylinder, while low-tension systems generate low voltage and step it up at the cylinder; understanding both is essential for AMT Powerplant certification.
Magneto Inspection and Troubleshooting
Aircraft magneto systems require precise inspection and troubleshooting procedures to ensure reliable ignition; understanding timing, drop checks, and common failure modes is essential for any powerplant technician.
Ignition Harness and Shielding Requirements
The ignition harness delivers high-voltage pulses from magnetos to spark plugs while shielding prevents radio frequency interference; proper installation and testing are critical for engine reliability and avionics performance.
Spark Plug Types Selection and Servicing
Spark plugs ignite the fuel-air mixture in aircraft reciprocating engines; selecting the correct type and servicing them properly is critical for engine reliability, performance, and airworthiness.
Capacitor Discharge Ignition Systems for Turbine Engines
Capacitor discharge ignition systems store electrical energy in capacitors and release it as high-voltage, high-energy sparks to reliably ignite turbine engine fuel-air mixtures under demanding conditions.
Magneto Timing and Timing Procedures
Magneto timing synchronizes spark delivery to piston position for efficient combustion; correct internal and engine timing is critical for safe engine operation and FAA airworthiness.
Ignition Exciter Units and Glow Plugs in Turbine Engines
Turbine engine ignition exciters convert low-voltage aircraft power into high-energy sparks, while glow plugs provide sustained heat for combustion starts — both are critical for reliable engine ignition.
Engine-Driven Generator and Alternator Operation
Engine-driven generators and alternators convert mechanical energy into electrical power to supply aircraft systems and charge batteries; understanding their operation, regulation, and failure modes is essential for AMT powerplant certification.
Starter-Generator Systems on Turbine Engines
Starter-generator systems serve dual roles on turbine engines, cranking the engine to start and then switching to supply electrical power once the engine is self-sustaining — a compact, weight-saving solution common in turbine-powered aircraft.
Aircraft Engine Starter Types and Engagement Mechanisms
Aircraft engine starters convert stored energy into mechanical rotation to initiate engine starts; understanding starter types, engagement mechanisms, and failure modes is essential for AMT powerplant certification.
P-Lead Circuit Function and Grounding Safety
The P-lead (primary lead) connects the magneto breaker points to the ignition switch, allowing the pilot to ground—and safely disable—the magneto; a broken or disconnected P-lead leaves a magneto live even with the switch OFF.
Ignition Switch Wiring and Circuit Protection
Aircraft ignition switches control magneto grounding circuits rather than power circuits, meaning an open circuit—not a closed one—fires the engine; understanding this wiring logic and its circuit protection is critical for safe maintenance.
Impulse Coupling Operation and Inspection
Impulse couplings give magneto-driven ignition a powerful, retarded spark at engine start, then automatically advance timing for normal flight; understanding their operation and inspection is essential for AMT powerplant certification.
Engine Electrical Bus Connections and Grounding Techniques
Proper bus connections and grounding techniques are the foundation of reliable aircraft engine electrical systems — poor grounds cause more mysterious electrical faults than nearly any other single factor.
Magneto-to-Engine Timing Verification with Timing Light
Magneto-to-engine timing verification ensures ignition spark occurs at exactly the right crankshaft position; a timing light and timing marks are the primary tools for confirming correct setup on reciprocating aircraft engines.
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.