A&P Powerplant (AMP) practice questions with answers

Answer: D) Reduce blow-by

• AIncorrect. That would raise consumption.
• BIncorrect. Staggering is about sealing.
• CIncorrect. Rings don't change displacement geometry.
• DCorrect. Aligned gaps would leak more gas.

Answer: B) Horizontally opposed

• AIncorrect. Radials are mostly found on older aircraft.
• BCorrect. Opposed engines are compact, smooth and easy to cowl.
• CIncorrect. These are uncommon today.
• DIncorrect. These are rare in light aircraft.

Answer: A) Mixing with the fuel to support combustion

Primary air is the smaller share of combustor airflow and mixes with fuel to support combustion. Secondary air cools the liner and dilutes the gases, and compressor bleed air cools the turbine blades.

• ACorrect. Primary air enters near the fuel nozzles and mixes with the fuel to form a burnable mixture and sustain the flame.
• BIncorrect. Secondary air does this job, cooling the liner and insulating it from the flame.
• CIncorrect. Dilution (quenching) of the combustion gases is done by secondary air, not primary air.
• DIncorrect. Turbine blades and vanes are cooled by air bled from the compressor and routed through them, not by the combustor's primary air.

Answer: A) Rebuilt by the manufacturer or by an agency approved by the manufacturer

14 CFR 91.421 allows a zero-time record only for an engine rebuilt to new-engine standards by the manufacturer or by an agency approved by the manufacturer. Overhauled engines keep their previous operating history.

• ACorrect. 91.421(a) allows a new record without previous operating history for an engine rebuilt by the manufacturer or by an agency approved by the manufacturer. Under 91.421(c), a rebuilt engine meets the same tolerances and limits as a new engine.
• BIncorrect. An engine overhauled to service limits is not rebuilt to new-engine standards. It keeps its total time, and only the time since overhaul is reset.
• CIncorrect. 91.421 does not cover overhauls by individual mechanics, even ones with an inspection authorization. Only the manufacturer or a manufacturer-approved agency can rebuild an engine to zero time.
• DIncorrect. A top overhaul is not a rebuild. 91.421(c) requires complete disassembly, inspection, repair, reassembly, testing and approval to the same standards as a new engine.

Answer: C) Resistance is calibrated

• AIncorrect. Color is not the reason.
• BIncorrect. They carry a small voltage.
• CCorrect. Lead resistance is part of the calibration; changing length gives errors.
• DIncorrect. This is not the reason.

Answer: D) The bottle was fired normally

• AIncorrect. This is not shown by the disc.
• BIncorrect. That is the red disc.
• CIncorrect. A missing disc means discharge.
• DCorrect. The yellow disc blows out when the bottle is discharged by the crew.

Answer: A) 1,680 watts

Electrical power in watts is voltage multiplied by current (P = E × I). For a 28 V, 60 A generator, that is 1,680 W.

• ACorrect. Power equals voltage times current: P = E × I = 28 V × 60 A = 1,680 W.
• BIncorrect. This adds the voltage and current (28 + 60). Power is the product of the two, not the sum.
• CIncorrect. This is half the correct value. A DC generator's power is the full product of voltage and current, with no halving.
• DIncorrect. This is ten times too large, a decimal error. 28 × 60 = 1,680.

Answer: D) To build up voltage

• AIncorrect. DC has no frequency.
• BIncorrect. A reverse current relay does that.
• CIncorrect. This is unrelated.
• DCorrect. Residual field magnetism starts the voltage build-up.

Answer: B) Identify the material and continue inspecting to determine serviceability

A small amount of fine, filing-like particles calls for identifying the material and continuing the inspection against manufacturer limits. Heavy or unusual metal residue, such as flakes or chips, calls for removing the engine to find the source.

• AIncorrect. Removal and teardown are called for when an unusual or heavy amount of metal, such as flakes or chips, is found. A small amount of fine filings calls for further evaluation first.
• BCorrect. A small amount of fine particles isn't necessarily abnormal. Identify the material (for example, check whether it's ferrous with a magnet), compare it with the manufacturer's limits, and continue inspecting to decide whether the engine is serviceable.
• CIncorrect. Carbon can look like metal, but the material has to be identified, not assumed. Calling it carbon without checking skips the evaluation.
• DIncorrect. Fine particles can come from many wearing parts. Replacing a component on assumption, before identifying the material and evaluating the amount, is not proper practice.

Answer: A) More sparks per revolution

• ACorrect. The flux reverses more often.
• BIncorrect. More poles add reversals.
• CIncorrect. It still produces sparks.
• DIncorrect. Pole count sets spark rate.

Answer: A) To let the control meter the correct fuel mass when a fuel of different density is used

Hydromechanical fuel controls meter fuel by volume, but the engine needs a set fuel mass. The specific gravity adjustment corrects the metering when a fuel of a different density is used.

• ACorrect. The control meters fuel by volume, but the engine needs a set fuel weight (mass). When a fuel of a different specific gravity is used, this adjustment corrects the metering so the engine still gets the right mass flow.
• BIncorrect. The control compensates for temperature automatically through its compressor inlet temperature sensing. This is not a manual adjustment for fuel density.
• CIncorrect. The acceleration schedule is set inside the control from engine parameters. The specific gravity adjustment does not set it.
• DIncorrect. Idle speed and maximum speed (trim) have their own adjustments. The specific gravity adjustment only corrects for fuel density.

Answer: B) Partly closed, because the throttle valve restriction adds cooling

Throttle ice is most likely with the throttle partly closed. The added restriction at the throttle valve increases cooling on top of venturi and fuel-vaporization cooling.

• AIncorrect. At wide-open throttle the throttle valve causes little restriction, so its extra cooling is smallest. Throttle ice is less likely there.
• BCorrect. Throttle ice usually forms at or near a partly closed throttle, as at off-idle or cruise power. The restriction at the throttle valve adds to the venturi and fuel-vaporization cooling.
• CIncorrect. Fuel vaporization does cool the air, but the partly closed throttle valve is what makes ice most likely. Full throttle is not the worst case.
• DIncorrect. Temperature and humidity matter, but throttle position also affects icing. A partly closed throttle makes ice more likely.

Answer: C) Sprays cool fan air onto the engine case at high power so the blade tip gap gets smaller

Active clearance control uses cool fan air, controlled by the FADEC, to shrink the engine case. This reduces blade tip clearance and improves efficiency when the engine needs it most.

• AIncorrect. This describes the compressor bleed or surge valve system. It manages stall margin, not blade tip clearance.
• BIncorrect. This describes variable stator vanes. They set the angle at which air enters the rotor blades, not the gap between the blade tips and the case.
• CCorrect. When tight clearance is needed, the FADEC sends cool fan discharge air over the case. The case shrinks and the tip clearance goes down. When the air is shut off, the case expands back to its normal size.
• DIncorrect. Abradable shrouds are a passive way to control clearance. ACC is an active system that changes case size with cooling air during operation.

Answer: A) The translating sleeve moves aft, blocker doors close off the fan duct, and the exposed cascade vanes turn fan air forward

In a cascade reverser, the translating sleeve moves aft and blocker doors divert fan air through cascade vanes that turn it forward. Clamshell and bucket/target reversers block the exhaust stream mechanically instead.

• ACorrect. In a cascade reverser, blocker doors divert the fan stream outward through the cascade vanes. The vanes turn the flow forward and produce reverse thrust.
• BIncorrect. This describes a mechanical-blockage (clamshell) reverser, which works on the hot exhaust stream. It does not use cascade vanes in the fan duct.
• CIncorrect. The cascade vanes actually turn the fan flow forward to make reverse thrust. They do not just spoil the core exhaust.
• DIncorrect. This describes a target (bucket) reverser, which is a different mechanical-blockage design used mostly on older turbojets and low-bypass engines.

Answer: D) The flat side

• AIncorrect. That isn't the face.
• BIncorrect. That's the blade back.
• CIncorrect. The face is a surface.
• DCorrect. The cambered side is the blade back.