Why is a propeller dangerous even with the ignition switch OFF?

Because the switch stops the magneto by grounding its primary circuit through the P-lead rather than by cutting power to it. A magneto makes its own current whenever it turns, so if the P-lead is broken, chafed, or disconnected, the switch cannot ground it and the magneto still fires. Treat every propeller as live and confirm the grounding circuit before turning one by hand.

What is the function of the capacitor in a magneto?

It is connected across the breaker points in the primary circuit. When the points open, the capacitor absorbs the surge of current that would otherwise jump the gap as an arc, which prevents burning and pitting of the point faces. Suppressing that arc also makes the primary magnetic field collapse much faster, and a faster collapse induces a higher voltage in the secondary winding.

What does an impulse coupling do?

It solves the low-speed starting problem. During cranking, a spring in the coupling winds up while the magnet is held, then releases it so the rotating magnet snaps through its neutral position much faster than the engine is turning. That produces a spark hot enough to fire the mixture, and the delay also retards the spark timing so the engine does not kick back.

What does an excessive rpm drop on one magneto indicate?

A fault somewhere in that magneto's ignition circuit, since the engine is running on that side alone during the check. Common causes are fouled or worn spark plugs, a defective ignition lead or distributor, incorrect internal timing, or a magneto that is out of time to the engine. Troubleshooting works from the cheapest and most likely cause outward before removing the magneto.

How is turbine engine ignition different from a magneto system?

A turbine only needs ignition for starting and for relight, not continuously, so it uses an electrically powered ignition exciter that steps input power up to the high voltage the igniter plugs need. Igniter plugs have a much wider gap and produce a far more energetic spark than a reciprocating engine spark plug, and they are replaced on their own schedule.

What is the function of the capacitor (condenser) connected across the breaker points in a magneto?

Reduce arcing at the points and speed collapse of the primary field

Step up the secondary voltage delivered to the plug

Increase the primary current available to the coil

When an aircraft magneto switch is placed in the OFF position, the primary circuit is:

grounded so the magneto cannot produce a spark

connected directly to the battery for shutdown

opened so no current can flow in the primary

The purpose of an impulse coupling on a magneto is to:

provide a stronger, retarded spark for starting

advance ignition timing at high engine speed

distribute the spark to each cylinder in firing order

During a magneto ignition system check, an excessive rpm drop when operating on a single magneto most likely indicates:

a fouled spark plug or faulty ignition lead

an over-rich idle mixture setting

a clogged main fuel injector nozzle

In a turbine engine, the high voltage required to fire the igniter plugs is produced by the:

exciter unit of the ignition system

constant-speed drive in the gearbox

fuel control unit on the accessory case

What is the main advantage of a turbine engine starter-generator compared with separate starter and generator units?

One unit serves both functions, saving weight and space

It produces AC for the main aircraft bus directly

It removes the need for a battery during engine start

On a turbine engine, the electronic engine control (EEC) receives its primary electrical power from

a separate engine-driven permanent-magnet alternator.

the airplane 115-volt AC emergency bus.

the airplane 115-volt AC main bus.

In aircraft electrical terminology, feeders are

heavy-duty cables carrying generator output to the busbars.

protective conduits used to route electrical cable.

flexible hoses used to supply system fluids.

An electronic engine control (EEC/FADEC) typically exchanges digital data with aircraft systems using

Neither ARINC 429 nor ARINC 629 formatted data

What supplies the primary electrical power for a turbine engine's electronic engine control (EEC) once the engine is running?

A dedicated permanent magnet alternator driven by the engine

The 115V AC essential bus supplied from the aircraft generators

The 28V DC battery bus through a step-down transformer

What is the primary purpose of a bonding jumper in an aircraft engine electrical system?

To provide a low-resistance path between metallic parts to prevent static buildup and ensure a common ground

To boost system voltage between metallic parts for better conductivity

To increase the resistance between metallic parts and limit current flow

What is the function of the commutator in a DC generator?

It mechanically rectifies the AC generated in the armature into DC for the external circuit

It regulates the field current to maintain constant voltage

It increases the frequency of the AC output before it leaves the generator

Why is a DC alternator (alternator with a rectifier) generally preferred over a DC generator in modern aircraft?

It provides more constant output over a wide RPM range, including at low engine speeds

It eliminates the need for any voltage regulation in the system

It does not require any cooling during continuous operation

In a paralleled generator system, what is the function of the equalizing (paralleling) circuit?

It causes each generator to carry an equal share of the total electrical load

It synchronizes the rotational speed of all paralleled generators

It increases the total system voltage above each generator's individual output

What condition is indicated by a commutator that shows a smooth, polished, copper-colored or chocolate-brown surface?

A normal, desirable condition indicating proper brush seating and good commutation

Open armature windings requiring rewinding of the generator

Excessive arcing that requires immediate commutator turning

In a starter-generator system used on many turbine engines, how is the single unit used during engine start versus normal operation?

It acts as a motor to crank the engine during start, then operates as a generator once running

It functions only as a starter and a separate generator handles power generation

It acts as a generator during start and as a motor during normal operation

What is the purpose of flashing the field of a DC generator?

To restore residual magnetism in the field so the generator can build up voltage

To reverse the polarity of the generator output

To demagnetize the field and stop the generator from producing voltage

Which type of generator field circuit is most commonly used in aircraft DC generators because it allows the voltage regulator to control output?

Shunt-wound, with the field connected in parallel with the armature

Series-wound only, with the field in series with the load

Compound-wound with the regulator in the armature circuit

What is the primary function of slip rings in an aircraft alternator?

To carry field excitation current to the rotating field winding

To carry the full main output current from the stator to the load

To rectify the AC output into DC

In a three-phase aircraft alternator with a built-in rectifier, what type of device converts the AC to DC?

A bank of semiconductor diodes (rectifier assembly)

A mechanical commutator with carbon brushes

What is the recommended method for cleaning a slightly dirty or oily commutator on an aircraft generator?

Use fine (No. 000) sandpaper, never emery cloth

Use a steel file to dress the surface

Use emery cloth to remove the film quickly

What type of switch is typically used to control the application of power to an engine starter, and why?

A solenoid/contactor, so a small control current can switch the heavy starter current

A simple toggle switch rated to carry the full starter current directly

A circuit breaker used as the primary on-off control

When measuring brush spring tension on a generator, an excessively weak spring is likely to cause what problem?

Brush bouncing and poor contact, causing arcing and commutator pitting

Excessive brush and commutator wear from too much friction

An increase in generator output voltage above limits

Why is stranded wire, rather than solid wire, generally used for aircraft engine electrical wiring?

It is more flexible and more resistant to fatigue failure from vibration

It carries significantly more current than solid wire of the same size

It has much higher resistance, which limits current

When selecting the proper size (gauge) of electrical wire for an engine circuit, which two primary factors must be considered?

The current-carrying capacity and the allowable voltage drop over the wire length

The ambient light level and the wire's flexibility only

The frequency of the AC and the number of strands only

Engine Electrical ACS AM.III.F — Powerplant Test Prep

What ACS AM.III.F covers

This area covers ignition and engine-driven electrical generation on reciprocating and turbine powerplants, following the treatment in the Powerplant Handbook, FAA-H-8083-32. Magneto theory carries most of the questions. In a high-tension magneto, rotating magnetism induces current in the primary winding, the breaker points interrupt that primary current at the correct instant, and the sudden collapse of the primary magnetic field induces the high voltage in the secondary winding that fires the plug. The capacitor, or condenser, is wired across the points in the primary circuit; it absorbs the surge that would otherwise arc across the opening points, which both protects the point faces and makes the field collapse fast enough to produce a hot spark. The ignition switch works by grounding, not by opening: the P-lead shorts the primary to ground in the OFF position, so a broken or disconnected P-lead leaves that magneto live and the propeller dangerous regardless of switch position. Starting hardware appears through the impulse coupling, a spring device that holds the rotating magnet and then releases it to spin rapidly, delivering both a hot spark and a retarded spark at cranking speed. Troubleshooting questions read the magneto check: an excessive rpm drop on one magneto points to a fault on that side, such as fouled plugs, a failed lead, or incorrect timing, while no drop at all points to a grounding problem in the switch circuit. Turbine ignition is treated separately, with the exciter unit producing the high voltage that fires the igniter plugs. Generation questions close the area with voltage regulators controlling alternator output and brushes riding on the commutator of a DC generator or starter-generator.

Where this sits on the test

ACS AM.III.F is tested on the FAA Powerplant written test, one of 1,353 ACS-tagged questions in the Powerplant bank. Every question tagged to this area carries a worked rationale and its FAA handbook reference, so you can drill the code itself rather than the whole test.

FAA handbook references

FAA-H-8083-32

Three traps candidates fall into

Candidates believe the ignition switch opens the magneto circuit. It grounds the primary instead, so a broken, chafed, or disconnected P-lead leaves the magneto hot with the switch OFF. That is why the propeller of a piston aircraft is treated as live whenever the mag check or P-lead continuity has not been verified.
The condenser is described as storing charge for the spark plug. It sits in the primary circuit across the breaker points, where its job is to prevent arcing at the points and force the primary field to collapse quickly. The high voltage that reaches the plug is induced in the secondary winding, not stored.
A magneto check with no rpm drop gets called a good result. Zero drop usually means that magneto is not being grounded when it should be, so the switch or P-lead is faulty, and the aircraft is unairworthy for the same reason an excessive drop is. Both extremes are findings.

28 free sample questions from ACS AM.III.F

AM.III.FTap an answer
In a high-tension magneto ignition system, the primary winding circuit current is interrupted by the action of the:
Show the answer and explanation
Answer: breaker points opening
Why: In a high-tension magneto, primary current flows while the breaker (contact) points are closed, building a magnetic field. When the points open, the primary circuit is interrupted, the field collapses rapidly, and the changing flux induces the high voltage in the secondary winding that fires the plug. The distributor only routes the high voltage to the correct cylinder; the secondary does not interrupt primary current.· FAA-H-8083-32 — Ignition Systems (high-tension magneto, breaker points)
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What is the function of the capacitor (condenser) connected across the breaker points in a magneto?
Show the answer and explanation
Answer: Reduce arcing at the points and speed collapse of the primary field
Why: The capacitor is connected in parallel with the breaker points. As the points open, the capacitor momentarily absorbs the primary current, which minimizes arcing and pitting of the points and causes the primary magnetic field to collapse more rapidly. A faster field collapse produces a higher induced secondary voltage. It does not increase primary current or directly step up secondary voltage by transformer action.· FAA-H-8083-32 — Ignition Systems (magneto capacitor/condenser)
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When an aircraft magneto switch is placed in the OFF position, the primary circuit is:
Show the answer and explanation
Answer: grounded so the magneto cannot produce a spark
Why: The ignition switch is wired through the P-lead to ground the magneto primary circuit. With the switch OFF, the primary is grounded, so the field cannot collapse to induce high voltage and the magneto cannot fire. This is why a broken or disconnected P-lead leaves a magneto 'hot,' and a propeller must always be treated as if the ignition is on. The switch does not open the primary or connect it to the battery.· FAA-H-8083-32 — Ignition Systems (ignition switch, P-lead grounding)
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The purpose of an impulse coupling on a magneto is to:
Show the answer and explanation
Answer: provide a stronger, retarded spark for starting
Why: An impulse coupling is a spring-and-flyweight device that momentarily holds the magneto rotating magnet, then releases it so it snaps through the neutral position rapidly. This produces a hotter spark at low cranking speed and retards the timing for starting, reducing kickback. Once the engine starts and rpm rises, the flyweights disengage and the magneto runs at normal timing. It does not advance timing or distribute spark.· FAA-H-8083-32 — Ignition Systems (impulse coupling)
AM.III.FTap an answer
During a magneto ignition system check, an excessive rpm drop when operating on a single magneto most likely indicates:
Show the answer and explanation
Answer: a fouled spark plug or faulty ignition lead
Why: A normal mag check shows a small rpm drop on each single magneto because only one plug per cylinder is firing. An excessive drop on one magneto points to a problem in that ignition circuit, such as a fouled or defective spark plug, a faulty ignition lead, or a magneto-related fault, which causes a misfire. Mixture and fuel-nozzle issues affect both magnetos and overall power rather than producing a drop on only one magneto.· FAA-H-8083-32 — Ignition Systems (magneto/ignition system check)
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In a turbine engine, the high voltage required to fire the igniter plugs is produced by the:
Show the answer and explanation
Answer: exciter unit of the ignition system
Why: A turbine (capacitor-discharge) ignition system uses an exciter unit that stores electrical energy in a capacitor and then discharges it at high voltage through the ignition lead to the igniter plug, producing a high-energy spark for starting. The fuel control meters fuel, and the constant-speed drive governs generator speed; neither generates igniter voltage.· FAA-H-8083-32 — Turbine Engine Ignition Systems (exciter)
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Which device limits and controls the output of an aircraft engine-driven alternator to protect the electrical system?
Show the answer and explanation
Answer: Voltage regulator
Why: The voltage regulator controls alternator output by varying the field current, holding system voltage within limits as electrical load and engine speed change. This prevents overcharging the battery and protects connected equipment. A circuit breaker is an overcurrent protective device, and a bus tie relay connects buses; neither regulates alternator output voltage.· FAA-H-8083-32 — Engine Electrical Systems (alternator/voltage regulator)
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The brushes in a typical DC starter-generator or generator make electrical contact with the:
Show the answer and explanation
Answer: commutator
Why: In a DC machine, carbon brushes ride on the rotating commutator to carry current to and from the armature windings; the commutator also provides the switching action that produces or uses DC. The stator core and field frame house the field windings and magnetic structure and are not where the brushes ride. Worn or sticking brushes and a dirty commutator are common causes of poor generator output.· FAA-H-8083-32 — Engine Electrical Systems (DC generator/starter-generator)
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What is the main advantage of a turbine engine starter-generator compared with separate starter and generator units?
Show the answer and explanation
Answer: One unit serves both functions, saving weight and space
Why: A starter-generator is a single machine that acts as a motor to start the engine and, after start, is reconnected to operate as a generator. Combining both functions in one unit reduces weight, complexity, and the number of accessory drive pads, which is valuable on turbine engines. It still needs a power source such as the battery or external power to start, and it is a DC machine, not a main AC source.· FAA-H-8083-32 — Engine Electrical Systems (starter-generator)
AM.III.FTap an answer
On a turbine engine, the electronic engine control (EEC) receives its primary electrical power from
Show the answer and explanation
Answer: a separate engine-driven permanent-magnet alternator.
Why: Per FAA-H-8083-32, the EEC/FADEC is powered by its own dedicated permanent-magnet alternator driven by the engine so that the control remains operational independent of the aircraft electrical buses. As long as the engine is rotating, this alternator supplies the EEC, which is why a main or emergency AC bus is not relied upon for primary power.· FAA-H-8083-32 — Engine Electrical Systems
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In aircraft electrical terminology, feeders are
Show the answer and explanation
Answer: heavy-duty cables carrying generator output to the busbars.
Why: Feeders are the heavy-duty cables that carry the main generator output to the distribution busbars. They are not conduits or fluid hoses; their large cross-section reflects the high currents they must carry.· FAA-H-8083-32 — Engine Electrical Systems
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An electronic engine control (EEC/FADEC) typically exchanges digital data with aircraft systems using
Show the answer and explanation
Answer: ARINC 429 formatted data
Why: The EEC commonly exchanges digital information using ARINC 429, the standard one-way data-bus format for this generation of engine controls. ARINC 629 is a different, less common bus used on specific airframes, so the typical format is ARINC 429 (FAA-H-8083-32, Engine Electrical Systems).· FAA-H-8083-32 — Engine Electrical Systems
AM.III.FTap an answer
What supplies the primary electrical power for a turbine engine's electronic engine control (EEC) once the engine is running?
Show the answer and explanation
Answer: A dedicated permanent magnet alternator driven by the engine
Why: An electronic engine control receives its primary power from a dedicated permanent magnet alternator (PMA) driven by the engine gearbox. This makes the control self-powering once the engine is turning and independent of the aircraft electrical buses, so the EEC keeps operating even if the normal 115V AC supply is lost.· FAA-H-8083-32 — Engine Electrical Systems
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What is the primary purpose of a bonding jumper in an aircraft engine electrical system?
Show the answer and explanation
Answer: To provide a low-resistance path between metallic parts to prevent static buildup and ensure a common ground
Why: Per FAA-H-8083-32, bonding jumpers provide a low-resistance electrical path between metallic components to prevent the buildup of static charge and to ensure a continuous ground path, which reduces radio interference and the hazard of arcing.· FAA-H-8083-32 — Engine Electrical Systems
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What is the function of the commutator in a DC generator?
Show the answer and explanation
Answer: It mechanically rectifies the AC generated in the armature into DC for the external circuit
Why: Per FAA-H-8083-32, the commutator acts as a mechanical rectifier, reversing the armature connections to the external circuit at the proper instant so that the alternating EMF generated in the armature is delivered to the external circuit as direct current.· FAA-H-8083-32 — Engine Electrical Systems
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Why is a DC alternator (alternator with a rectifier) generally preferred over a DC generator in modern aircraft?
Show the answer and explanation
Answer: It provides more constant output over a wide RPM range, including at low engine speeds
Why: Per FAA-H-8083-32, alternators produce a more constant output over a wide RPM range and can provide rated output at lower engine speeds (such as idle), and they are generally lighter and require less maintenance than DC generators because field current is carried through slip rings rather than a heavily loaded commutator.· FAA-H-8083-32 — Engine Electrical Systems
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In a paralleled generator system, what is the function of the equalizing (paralleling) circuit?
Show the answer and explanation
Answer: It causes each generator to carry an equal share of the total electrical load
Why: Per FAA-H-8083-32, when two or more generators are operated in parallel, the equalizing circuit (equalizer) compares the voltages and causes the regulators to adjust field strength so that each generator carries an equal share of the total electrical load.· FAA-H-8083-32 — Engine Electrical Systems
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What condition is indicated by a commutator that shows a smooth, polished, copper-colored or chocolate-brown surface?
Show the answer and explanation
Answer: A normal, desirable condition indicating proper brush seating and good commutation
Why: Per FAA-H-8083-32, a glossy chocolate-brown or polished film on a commutator is a normal and desirable condition that indicates proper brush seating and good commutation; it should not be removed during cleaning.· FAA-H-8083-32 — Engine Electrical Systems
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In a starter-generator system used on many turbine engines, how is the single unit used during engine start versus normal operation?
Show the answer and explanation
Answer: It acts as a motor to crank the engine during start, then operates as a generator once running
Why: Per FAA-H-8083-32, a starter-generator functions as a motor (starter) to crank the engine during start, then, once the engine is running, is switched to operate as a generator to supply electrical power, saving the weight and complexity of two separate units.· FAA-H-8083-32 — Engine Electrical Systems
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What is the purpose of flashing the field of a DC generator?
Show the answer and explanation
Answer: To restore residual magnetism in the field so the generator can build up voltage
Why: Per FAA-H-8083-32, flashing the field momentarily applies battery voltage to the generator field to restore or re-establish residual magnetism in the field poles, which is necessary for the generator to begin building up output voltage if residual magnetism has been lost.· FAA-H-8083-32 — Engine Electrical Systems
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Which type of generator field circuit is most commonly used in aircraft DC generators because it allows the voltage regulator to control output?
Show the answer and explanation
Answer: Shunt-wound, with the field connected in parallel with the armature
Why: Per FAA-H-8083-32, aircraft DC generators are commonly shunt-wound (the field is connected in parallel with the armature), which permits a voltage regulator to control output by varying the relatively small field current.· FAA-H-8083-32 — Engine Electrical Systems
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What is the primary function of slip rings in an aircraft alternator?
Show the answer and explanation
Answer: To carry field excitation current to the rotating field winding
Why: Per FAA-H-8083-32, slip rings, contacted by brushes, carry the relatively small DC field excitation current to the rotating field winding of an alternator; the AC output is taken from the stationary stator windings, so the slip rings do not carry the main output current.· FAA-H-8083-32 — Engine Electrical Systems
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In a three-phase aircraft alternator with a built-in rectifier, what type of device converts the AC to DC?
Show the answer and explanation
Answer: A bank of semiconductor diodes (rectifier assembly)
Why: Per FAA-H-8083-32, a three-phase alternator's AC output is converted to DC by a bank of semiconductor diodes (a rectifier assembly), which conduct current in only one direction to produce a relatively smooth DC output.· FAA-H-8083-32 — Engine Electrical Systems
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What is the recommended method for cleaning a slightly dirty or oily commutator on an aircraft generator?
Show the answer and explanation
Answer: Use fine (No. 000) sandpaper, never emery cloth
Why: Per FAA-H-8083-32, a dirty commutator can be cleaned by holding a strip of No. 000 (very fine) sandpaper against it while it rotates; emery cloth or other conductive abrasives must never be used because the metallic particles can short the segments.· FAA-H-8083-32 — Engine Electrical Systems
AM.III.FTap an answer
What type of switch is typically used to control the application of power to an engine starter, and why?
Show the answer and explanation
Answer: A solenoid/contactor, so a small control current can switch the heavy starter current
Why: Per FAA-H-8083-32, because starter motors draw very heavy current, a solenoid (or starter relay/contactor) is used so that a small control current from the cockpit switch can close heavy-duty contacts that carry the large starter current, keeping the high current off the cockpit switch and its wiring.· FAA-H-8083-32 — Engine Electrical Systems
AM.III.FTap an answer
When measuring brush spring tension on a generator, an excessively weak spring is likely to cause what problem?
Show the answer and explanation
Answer: Brush bouncing and poor contact, causing arcing and commutator pitting
Why: Per FAA-H-8083-32, insufficient brush spring tension allows the brush to bounce and make poor contact with the commutator, causing arcing, sparking, and pitting; excessive tension causes rapid brush and commutator wear. Proper tension must be maintained per specifications.· FAA-H-8083-32 — Engine Electrical Systems
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Why is stranded wire, rather than solid wire, generally used for aircraft engine electrical wiring?
Show the answer and explanation
Answer: It is more flexible and more resistant to fatigue failure from vibration
Why: Per FAA-H-8083-32, stranded wire is used in aircraft because it is far more flexible and far more resistant to fatigue failure from the vibration present in the engine and airframe environment than solid wire of the same gauge.· FAA-H-8083-32 — Engine Electrical Systems
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When selecting the proper size (gauge) of electrical wire for an engine circuit, which two primary factors must be considered?
Show the answer and explanation
Answer: The current-carrying capacity and the allowable voltage drop over the wire length
Why: Per FAA-H-8083-32, wire size selection is based on the amount of current the wire must carry without overheating and the allowable voltage drop over the length of the conductor; both current-carrying capacity and voltage drop must be within limits.· FAA-H-8083-32 — Engine Electrical Systems

Related subject areas

The areas that share the most ground with AM.III.F — study them alongside it.

Fundamentals of Electricity and Electronics (AM.I.A)
Aircraft Electrical Systems (AM.II.K)
Ignition and Starting Systems (AM.III.H)

Frequently asked questions

Why is a propeller dangerous even with the ignition switch OFF?: Because the switch stops the magneto by grounding its primary circuit through the P-lead rather than by cutting power to it. A magneto makes its own current whenever it turns, so if the P-lead is broken, chafed, or disconnected, the switch cannot ground it and the magneto still fires. Treat every propeller as live and confirm the grounding circuit before turning one by hand.
What is the function of the capacitor in a magneto?: It is connected across the breaker points in the primary circuit. When the points open, the capacitor absorbs the surge of current that would otherwise jump the gap as an arc, which prevents burning and pitting of the point faces. Suppressing that arc also makes the primary magnetic field collapse much faster, and a faster collapse induces a higher voltage in the secondary winding.
What does an impulse coupling do?: It solves the low-speed starting problem. During cranking, a spring in the coupling winds up while the magnet is held, then releases it so the rotating magnet snaps through its neutral position much faster than the engine is turning. That produces a spark hot enough to fire the mixture, and the delay also retards the spark timing so the engine does not kick back.
What does an excessive rpm drop on one magneto indicate?: A fault somewhere in that magneto's ignition circuit, since the engine is running on that side alone during the check. Common causes are fouled or worn spark plugs, a defective ignition lead or distributor, incorrect internal timing, or a magneto that is out of time to the engine. Troubleshooting works from the cheapest and most likely cause outward before removing the magneto.
How is turbine engine ignition different from a magneto system?: A turbine only needs ignition for starting and for relight, not continuously, so it uses an electrically powered ignition exciter that steps input power up to the high voltage the igniter plugs need. Igniter plugs have a much wider gap and produce a far more energetic spark than a reciprocating engine spark plug, and they are replaced on their own schedule.

Engine Electrical Systems — FAA A&P Test Questions (ACS AM.III.F)

What ACS AM.III.F covers

Where this sits on the test

FAA handbook references

Three traps candidates fall into

28 free sample questions from ACS AM.III.F

Failed AM.III.F on your AKTR?

Related subject areas

Frequently asked questions

All 40 ACS areas

General

Airframe

Powerplant

Primary sources

Drill ACS AM.III.F inside the full Powerplant bank