Ignition & Starting Systems
Ignition & Starting Systems is a core knowledge area on the AMT — Powerplant FAA written exam. This hub collects our 16 in-depth, ACS-aligned ignition & starting 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.
Magneto Operating Principles and Construction
Aircraft magnetos generate high-voltage ignition sparks independently of the aircraft electrical system using rotating permanent magnets, coils, breaker points, and distributors — a self-contained, safety-critical system every AMT must master.
Shower of Sparks Ignition System
A shower-of-sparks ignition system fires multiple rapid sparks during engine start to reliably ignite the fuel-air mixture in aircraft piston engines, especially when the mixture is rich or the engine is cold.
Impulse Coupling Function and Inspection
Impulse couplings give reciprocating engine magnetos the high-voltage spark needed for starting by briefly retarding and then snapping the rotor, and they require careful periodic inspection to remain airworthy.
High-Tension vs. Low-Tension Ignition Systems
High-tension ignition systems deliver high-voltage current directly to spark plugs, while low-tension systems step up voltage near each plug — each design has distinct maintenance implications for aviation powerplants.
Magneto-to-Engine Timing and Timing Marks
Magneto-to-engine timing precisely aligns spark delivery to piston position for maximum combustion efficiency and safety; understanding timing marks is essential for any powerplant technician.
Magneto Timing: Internal and External Timing Procedures
Magneto timing ensures spark delivery at precisely the right crankshaft position for safe, efficient combustion; mastering both internal and external timing procedures is essential for any powerplant technician.
Ignition Harness: Inspection, Testing, and Replacement
The ignition harness carries high-voltage pulses from magnetos to spark plugs; proper inspection, testing, and timely replacement are critical for reliable engine ignition and airworthiness.
Capacitor Discharge Ignition (CDI) Systems for Turbine Engines
Capacitor Discharge Ignition (CDI) systems store electrical energy in capacitors and release it in high-voltage bursts to fire turbine engine igniters, providing the reliable, intense sparks needed to ignite jet fuel across a wide range of operating conditions.
Spark Plug Servicing, Gap Inspection, and Fouling Analysis
Proper spark plug servicing—covering gap inspection, cleaning, and fouling diagnosis—is critical for reliable engine ignition and is a foundational AMT powerplant skill tested on the FAA knowledge exam.
Ignition Switch and P-Lead Circuit Operation
The ignition switch and P-lead circuit control and ground magneto output; understanding how they interact is essential for safe engine operation and correct maintenance practice.
Spark Plug Types, Construction, and Heat Range Selection
Spark plugs ignite the fuel-air charge in aircraft engines and must match the engine's heat range, thread reach, and electrode design to ensure safe, efficient operation.
Turbine Engine Igniter Plugs and Exciter Units
Turbine engine igniter plugs and exciter units generate the high-energy electrical discharges needed to initiate and sustain combustion in jet and turboprop engines, differing fundamentally from piston-engine spark plugs in design, energy level, and duty cycle.
Direct-Cranking Electric Starter Operation and Troubleshooting
Direct-cranking electric starters convert electrical energy into mechanical torque to spin an aircraft engine to start, and understanding their operation and failure modes is essential for safe, airworthy maintenance.
Starting System Components: Starters, Solenoids, and Relays
Aircraft starting systems rely on starters, solenoids, and relays working together to crank the engine; understanding each component's role is essential for safe maintenance and troubleshooting.
Magneto Safety and Grounding Circuit Testing
A magneto's grounding circuit is the primary safety mechanism that stops the engine; understanding how to test it correctly prevents both accidental starts and undetected failures that leave a magneto live when it should be dead.
Hot, Hung, and False Start Identification in Turbine Engines
Hot starts, hung starts, and false starts are distinct turbine engine start anomalies that every AMT must recognize instantly — misidentifying them can destroy an engine or risk lives on the ramp.
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.