100+ Free ANAC GMP Theoretical Exam (Powerplant Group) Practice Questions

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Key Facts: ANAC GMP Theoretical Exam (Powerplant Group) Exam

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This bank provides 100 English-language practice questions adapted for the official ANAC Powerplant Group (GMP) theoretical exam in Brazil under RBAC 65.

Sample ANAC GMP Theoretical Exam (Powerplant Group) Practice Questions

Try these sample questions to test your ANAC GMP Theoretical Exam (Powerplant Group) exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1In a standard four-stroke four-cylinder aircraft piston engine operating on the Otto cycle, how many revolutions of the crankshaft occur during one complete four-stroke cycle in a single cylinder?

A.One revolution

B.Two revolutions

C.Four revolutions

D.Half a revolution

Explanation: A complete four-stroke Otto cycle consists of five events across four piston strokes (intake, compression, power, exhaust). Since each stroke corresponds to 180 degrees of crankshaft rotation, four strokes equal 720 degrees, which is exactly two full revolutions of the crankshaft.

2What is the primary function of piston rings installed on aircraft reciprocating engine pistons?

A.To seal combustion chamber pressure and control cylinder wall oil lubrication

B.To connect the piston directly to the crankshaft journal pin

C.To equalize gas pressure between adjacent cylinders during valve overlap

D.To reduce thermal expansion of the aluminum piston crown

Explanation: Piston rings perform three critical roles: compression rings seal high-pressure combustion gases above the piston, oil control rings distribute and scrape excess oil off cylinder walls, and the rings transfer heat from the piston crown to the cylinder wall.

3Which component in an horizontally opposed aircraft engine converts the reciprocating motion of the pistons into rotational motion to drive the propeller?

A.Camshaft

B.Crankshaft

C.Pushrod

D.Rocker arm

Explanation: The crankshaft converts the linear reciprocating motion of the pistons (transmitted via connecting rods) into smooth rotary motion to turn the aircraft propeller or reduction gearing.

4What is the purpose of valve overlap in a four-stroke reciprocating aircraft engine?

A.To allow both valves to remain closed during the entire compression stroke

B.To improve cylinder scavenging and volumetric efficiency using exhaust gas velocity

C.To prevent ignition spark from firing until the piston reaches top dead center

D.To lock the hydraulic lifter mechanism during high engine RPM operation

Explanation: Valve overlap is the angular period of crankshaft rotation during which both intake and exhaust valves are open simultaneously at top dead center between exhaust and intake strokes. The velocity of outgoing exhaust gases creates a low-pressure area that draws fresh fuel-air charge into the cylinder, improving scavenging and volumetric efficiency.

5Why are sodium-filled exhaust valves utilized in many high-performance aircraft reciprocating engines?

A.To increase valve spring tension at high crankshaft speeds

B.To dissipate intense heat from the valve head to the valve stem and guide

C.To prevent carbon buildup on the valve seat during engine idling

D.To eliminate the need for rocker arm lubrication

Explanation: Metallic sodium melts at approximately 208°F (98°C). As the valve moves up and down, the liquid sodium sloshes inside the hollow stem, transferring thermal energy away from the hot valve head toward the cooler stem and valve guide for dissipation into the cylinder head cooling fins.

6What type of piston pin (wrist pin) installation allows the pin to float freely in both the piston bosses and the connecting rod small-end bushing?

A.Fixed piston pin

B.Semi-floating piston pin

C.Full-floating piston pin

D.Interference-fit piston pin

Explanation: A full-floating wrist pin is free to turn in both the connecting rod bushing and the piston bosses. Aluminum or bronze end plugs (or retaining rings) are fitted at each end of the pin to prevent the steel pin from contacting and scoring the cylinder wall.

7What is meant by the term 'choke bore' (choke-ground) cylinder in aircraft piston engine design?

A.A cylinder manufactured with a smaller internal diameter at the top (head) than at the bottom when cold

B.A cylinder with an adjustable intake restriction to govern maximum airflow

C.A cylinder with a tapered exhaust port to restrict backpressure

D.A cylinder bore lined with rubber to absorb piston slap during cold starting

Explanation: Choke-bore cylinders are machined with a slight taper near the top (head end) so that when cold, the cylinder top diameter is smaller. When the engine reaches operating temperature, the greater expansion of the hot cylinder head causes the bore to expand into a uniform straight cylinder.

8Which condition describes uncontrolled, instant explosion of the fuel-air mixture in a cylinder prior to normal spark ignition?

A.Pre-ignition

B.Detonation

C.Backfiring

D.Afterburning

Explanation: Detonation occurs when fuel-air mixture remaining in the combustion chamber spontaneously ignites due to excessive heat and pressure, producing an instantaneous release of energy, severe pressure spikes, and knocking. Pre-ignition is ignition caused by a hot spot prior to the timed spark.

9An engine develops an Indicated Horsepower (IHP) of 240 HP and experiences a Friction Horsepower (FHP) loss of 36 HP. What is the Mechanical Efficiency of this engine?

A.70%

B.85%

C.88%

D.92%

Explanation: Brake Horsepower (BHP) = Indicated Horsepower (IHP) - Friction Horsepower (FHP) = 240 HP - 36 HP = 204 HP. Mechanical Efficiency = (BHP / IHP) x 100 = (204 / 240) x 100 = 85%.

10When performing a differential compression check on an aircraft engine cylinder with an 80 PSI regulated inlet supply, what is the minimum acceptable static pressure reading according to standard ANAC maintenance guidelines?

A.40 PSI

B.50 PSI

C.60 PSI

D.75 PSI

Explanation: Standard aircraft maintenance practices (such as AC 43.13-1B and engine manufacturer manuals) specify that a pressure drop exceeding 25% (reading below 60 PSI on an 80 PSI supply) indicates excessive cylinder leakage requiring investigation.

About the ANAC GMP Theoretical Exam (Powerplant Group) Exam

This practice question bank is an English-language MCQ study adaptation for the official ANAC / FGV Powerplant Group (GMP - Grupo Motopropulsor) maintenance mechanic theoretical examination in Brazil under RBAC 65. The exam tests essential technical competence across piston engines, gas turbine engines, engine fuel metering and control, ignition and starting systems, lubrication and cooling systems, propellers, engine troubleshooting, and Brazilian civil aviation safety regulations (RBAC 65, 43, 145).

Assessment

Official ANAC/FGV computerized theoretical exam: 3 papers × 20 MCQ (BAS, GMP1, GMP2) unless BAS previously passed. Pass standard: 70% per subject paper. Language: Portuguese only.

Time Limit

90 minutes (30 minutes per paper; shared across papers)

Passing Score

70% per subject paper

Exam Fee

TFAC R$ 200 (duration band 30 min–2h30) (FGV (Fundação Getulio Vargas) on behalf of ANAC (Agência Nacional de Aviação Civil))

ANAC GMP Theoretical Exam (Powerplant Group) Exam Content Outline

25%

Reciprocating Piston Engines & Overhaul

Four-stroke Otto cycle theory: intake, compression, power, and exhaust strokes, Engine construction: crankcase, crankshaft, connecting rods, pistons, cylinders & valves, Valve timing, overlap, clearance adjustment & hydraulic lifters, Engine power output: Indicated (IHP), Brake (BHP), Friction (FHP), and Manifold Pressure, Piston engine inspection, cylinder differential pressure check & top/major overhaul procedures

25%

Gas Turbine Engines & Auxiliary Power Units (APUs)

Brayton cycle operational principles, thrust equations & engine station identification, Compressor types: centrifugal, axial-flow, rotor blades, stator vanes & compressor stall/surge, Combustion chambers: multiple-can, can-annular, and annular combustors, Turbine section: impulse, reaction, guide vanes, blade creep & thermal barrier coatings, Turboprop, turboshaft, and turbofan engine configurations, reduction gearboxes & APU operation

20%

Engine Fuel Metering, Ignition & Electrical Systems

Float-type carburetors, mixture control, idle cutoff, main metering orifice & carburetor ice, Pressure carburetors & direct fuel injection systems (Bendix, RSA, Continental), FADEC (Full Authority Digital Engine Control) architecture, dual channels & sensor inputs, Aircraft high-tension magnetos, internal timing (E-gap), dual ignition & spark plug gapping, Gas turbine high-energy ignition igniters, pneumatic starters, electric starter-generators

15%

Engine Lubrication, Cooling & Propellers

Wet-sump vs dry-sump lubrication systems, pressure pumps, scavenge pumps & oil coolers, Aviation engine oil viscosity, SAE grades, mineral vs ashless dispersant (AD) oils, Propeller principles: fixed-pitch, constant-speed governors, counterweight & feathering systems, Propeller pitch control, blade angle, aerodynamic twist, reverse pitch & synchronization, Engine cooling systems: baffle plates, cowl flaps, intercoolers & turbine oil cooling

15%

RBAC Regulations, Maintenance Standards & Engine Troubleshooting

RBAC 65 mechanic privileges, ratings (GMP / Powerplant) & maintenance authorization limits, RBAC 43 maintenance records, major repairs, major alterations & Form ANAC 337 / SEGVOO, RBAC 145 Approved Maintenance Organizations (OM), quality assurance & release to service, Engine troubleshooting: backfiring, pre-ignition, detonation, power loss & vibration analysis, Airworthiness Directives (ADs), Service Bulletins (SBs) & engine logbook entries

How to Pass the ANAC GMP Theoretical Exam (Powerplant Group) Exam

What You Need to Know

Passing score: 70% per subject paper
Assessment: Official ANAC/FGV computerized theoretical exam: 3 papers × 20 MCQ (BAS, GMP1, GMP2) unless BAS previously passed. Pass standard: 70% per subject paper. Language: Portuguese only.
Time limit: 90 minutes (30 minutes per paper; shared across papers)
Exam fee: TFAC R$ 200 (duration band 30 min–2h30)

Keys to Passing

Complete 500+ practice questions
Score 80%+ consistently before scheduling
Focus on highest-weighted sections
Use our AI tutor for tough concepts

ANAC GMP Theoretical Exam (Powerplant Group) Study Tips from Top Performers

1Master four-stroke engine valve timing, valve overlap, and calculation of Indicated, Friction, and Brake Horsepower.

2Understand gas turbine compressor stall dynamics, guide vane adjustments, and turbine blade thermal creep inspection.

3Review float carburetor icing conditions, mixture ratio adjustments (stoichiometric 15:1 air-fuel ratio), and fuel injection systems.

4Learn magneto internal timing (E-gap position), breaker point opening, and dual-ignition system troubleshooting.

5Know constant-speed propeller governor mechanics (flyweights, speeder spring, pilot valve) and feathering/unfeathering procedures.

Frequently Asked Questions

What is the ANAC GMP examination under Brazilian regulations?

The ANAC GMP (Grupo Motopropulsor) examination is the theoretical certification test administered via FGV for aircraft maintenance technicians specializing in piston and gas turbine engines, propellers, engine fuel and ignition systems, and regulatory standards under RBAC 65.

What passing score is required for ANAC maintenance mechanic exams?

Candidates must achieve a minimum score of 70% on each subject paper to pass the theoretical examination requirement under RBAC 65.

How many questions are in the official ANAC examination battery?

The official examination is divided into 5 subject papers of 20 questions each (100 questions total), administered via computerized testing centers by FGV on behalf of ANAC.

Does this question bank include gas turbine engine and FADEC questions?

Yes. The bank covers gas turbine Brayton cycles, axial compressors, turbine blade maintenance, FADEC dual-channel controls, hydromechanical fuel control units, and turboprop reduction gearboxes.

Is this practice question bank available in English?

Yes. This question bank is an English-language study adaptation designed to help candidates prepare for the technical concepts, regulations, calculations, and troubleshooting tested on the official ANAC/FGV GMP examination.