FAA Aviation Mechanic – ACS Airman Certification Standards Knowledge Test — Questions and Answers

Question 1: A landing gear retraction test reveals the gear takes 12 seconds to retract, while the maintenance manual specifies 6-8 seconds maximum. What is the most likely cause?

The gear is properly functioning within actual operational tolerances
Excessive aerodynamic drag on the gear doors
Low hydraulic fluid level or reduced hydraulic pump output (Correct answer)
A faulty gear position indicator causing incorrect timing

Correct answer: Low hydraulic fluid level or reduced hydraulic pump output

Slow gear retraction is typically caused by low hydraulic fluid, a worn pump with insufficient flow, or a restriction in the hydraulic circuit.

Question 2: What does 'maximum landing weight' refer to?

The weight after a minimum fuel load is consumed
The maximum certificated weight at which the aircraft can land without exceeding structural limits (Correct answer)
The same value as maximum takeoff weight
The weight including all passengers but no cargo

Correct answer: The maximum certificated weight at which the aircraft can land without exceeding structural limits

Maximum landing weight is the highest weight at which the landing gear and structure can absorb landing loads without damage.

Question 3: How should ACS professionals approach client or stakeholder communication?

Only communicate in writing, never verbally
Use clear, professional language appropriate to the audience, confirm understanding, and document key communications (Correct answer)
Communication skills are unimportant for technical professionals
Use technical jargon regardless of the audience

Correct answer: Use clear, professional language appropriate to the audience, confirm understanding, and document key communications

Effective communication tailored to the audience's knowledge level is essential for building trust, ensuring understanding, and achieving professional objectives.

Question 4: A mechanic who makes a maintenance error that goes undetected and results in an accident may face all of the following EXCEPT:

Automatic loss of all future FAA employment eligibility (Correct answer)
Civil lawsuit from affected parties
FAA certificate action
Criminal prosecution

Correct answer: Automatic loss of all future FAA employment eligibility

While mechanics can face certificate action, criminal charges, and civil liability, there is no automatic statutory bar from all FAA employment eligibility following an accident.

Question 5: How should ACS professionals approach client or stakeholder communication?

Communication skills are unimportant for technical professionals
Use technical jargon regardless of the audience
Only communicate in writing, never verbally
Use clear, professional language appropriate to the audience, confirm understanding, and document key communications (Correct answer)

Correct answer: Use clear, professional language appropriate to the audience, confirm understanding, and document key communications

Effective communication tailored to the audience's knowledge level is essential for building trust, ensuring understanding, and achieving professional objectives.

Question 6: What is the scope of practice for ACS certification in hydraulic & pneumatic systems?

The scope is determined individually by each professional
Defined boundaries of competence and authority established by the certifying body and applicable regulations (Correct answer)
Only the employer defines the scope of practice
There are no limits on what certified professionals can do

Correct answer: Defined boundaries of competence and authority established by the certifying body and applicable regulations

Scope of practice defines the activities, procedures, and processes that a certified professional is authorized to perform based on their education, training, and certification level.

Question 7: What does a hydraulic snubber do in a pressure gauge line?

Filters contamination out of the fluid sample going to the gauge
Prevents fluid from flowing backward through the gauge during pressure drops
Dampens pressure surges to protect the gauge and provide a steady reading (Correct answer)
Amplifies small pressure changes to improve gauge sensitivity

Correct answer: Dampens pressure surges to protect the gauge and provide a steady reading

A snubber is a small orifice or restriction that dampens rapid pressure pulsations, protecting the gauge bourdon tube from fatigue damage and providing a readable steady indication.

Question 8: After replacing a magnetic compass on an aircraft, what procedure must be performed before returning the aircraft to service?

Calibration of the compass against the aircraft's GPS heading
An IFR certification flight check
A compass swing to determine and record deviation errors on a new compass correction card (Correct answer)
A functional test of the compass light only

Correct answer: A compass swing to determine and record deviation errors on a new compass correction card

After compass installation, a compass swing must be performed to check for and compensate deviation errors, with results recorded on a new deviation card placed at the compass.

Question 9: How do ACS professionals contribute to organizational success?

Professional expertise has minimal organizational value
They only perform routine tasks with no strategic impact
By applying specialized knowledge to solve problems, reduce risks, improve processes, and drive strategic outcomes (Correct answer)
Only executives contribute to organizational success

Correct answer: By applying specialized knowledge to solve problems, reduce risks, improve processes, and drive strategic outcomes

Certified professionals bring specialized expertise that directly contributes to organizational goals through problem-solving, risk reduction, process improvement, and strategic decision support.

Question 10: What is the importance of professional networking in aviation maintenance?

Building relationships with peers enables knowledge sharing, professional development, and career advancement (Correct answer)
Networking is a waste of time for established professionals
Networking only benefits entry-level professionals
Only online networking has value

Correct answer: Building relationships with peers enables knowledge sharing, professional development, and career advancement

Professional networks provide opportunities for knowledge exchange, mentorship, collaboration, and staying informed about industry trends and opportunities.

Question 11: How often should fire extinguishers be inspected on aircraft?

Only after discharge
Every 6 months
Every 12 months (Correct answer)
Every 24 months

Correct answer: Every 12 months

Fire extinguishers must be inspected at regular intervals, typically annually.

Question 12: AC 43.13-1B is best described as:

FAA-accepted methods, techniques, and practices for aircraft inspection and repair (Correct answer)
The type certificate data sheet reference manual
A mandatory training curriculum for A&P schools
A legally binding regulation for all aircraft maintenance

Correct answer: FAA-accepted methods, techniques, and practices for aircraft inspection and repair

AC 43.13-1B provides FAA-accepted (not mandatory) methods, techniques, and practices for aircraft inspection and repair, commonly used when no manufacturer data exists.

Question 13: What document governs the minimum bend radii and tube material specifications for aircraft fluid lines?

MIL-SPEC-5015 only
FAR Part 21
AC 43.13-1B Chapter 9 and the applicable aircraft maintenance manual (Correct answer)
NFPA 407

Correct answer: AC 43.13-1B Chapter 9 and the applicable aircraft maintenance manual

AC 43.13-1B Chapter 9 provides the FAA-accepted data for aircraft plumbing including bend radii, materials, flare types, and installation standards, supplemented by the AMM.

Question 14: A reciprocating engine exhibits detonation during high-power operation. Which of the following will most effectively reduce detonation?

Advancing ignition timing
Leaning the mixture further
Reducing cooling airflow
Enriching the fuel-air mixture (Correct answer)

Correct answer: Enriching the fuel-air mixture

Enriching the mixture reduces cylinder temperatures and lowers the tendency for detonation by decreasing peak combustion temperatures.

Question 15: Under 14 CFR Part 65, an A&P mechanic certificate with both Airframe and Powerplant ratings allows the holder to:

Perform annual inspections without an IA
Perform and approve return to service for maintenance within the scope of those ratings (Correct answer)
Approve major alterations on transport category aircraft
Approve any aircraft for return to service after any repair

Correct answer: Perform and approve return to service for maintenance within the scope of those ratings

An A&P certificate authorizes the holder to perform and approve return to service for maintenance within the scope of their ratings per 14 CFR 65.81.

Question 16: An aircraft engine has a magneto drop of 175 RPM on one magneto and 50 RPM on the other during run-up. The maximum allowable drop is 125 RPM. What does this indicate?

Both magnetos are functioning normally
The magneto showing 50 RPM drop indicates a timing issue
The engine should be run longer to warm up before re-checking
The magneto showing 175 RPM drop has an ignition problem requiring investigation (Correct answer)

Correct answer: The magneto showing 175 RPM drop has an ignition problem requiring investigation

A magneto drop exceeding the maximum allowable limit (175 RPM vs. 125 RPM limit) indicates a faulty ignition component such as spark plugs, ignition leads, or the magneto itself.

Question 17: What is the importance of peer review in aviation mechanics?

Peer review ensures quality, catches errors, provides learning opportunities, and maintains professional standards (Correct answer)
Peer review is unnecessary for experienced professionals
Only management should review professional work
Peer review undermines professional confidence

Correct answer: Peer review ensures quality, catches errors, provides learning opportunities, and maintains professional standards

Peer review is a cornerstone of professional quality assurance, providing independent verification, knowledge sharing, and continuous improvement opportunities.

Question 18: When using a Structural Repair Manual (SRM) for composite repairs, a mechanic must ensure the manual revision used is:

Any revision published after the aircraft was manufactured
The latest revision that is current and applicable to the specific aircraft serial number (Correct answer)
The original issue regardless of subsequent revisions
The revision the operator's maintenance director approves

Correct answer: The latest revision that is current and applicable to the specific aircraft serial number

Technicians must use the current, applicable revision of the SRM for the specific aircraft's serial number to ensure the repair meets the type design requirements.

Question 19: What is the primary purpose of a fuel strainer (gascolator) in a reciprocating aircraft engine fuel system?

To remove water and sediment from fuel before it reaches the carburetor or fuel injector (Correct answer)
To regulate fuel pressure to the engine
To measure fuel flow rate
To prevent vapor lock in the fuel lines

Correct answer: To remove water and sediment from fuel before it reaches the carburetor or fuel injector

A fuel strainer (gascolator) filters water and particulate contamination from the fuel before it enters the engine fuel metering system.

Question 20: How often should aircraft control cables be inspected?

Only during major overhaul
Every 100 hours (Correct answer)
Every 50 hours
Every 200 hours

Correct answer: Every 100 hours

Control cables should be inspected periodically as prescribed by the manufacturer and FAA regulations, often every 100 flight hours.

Question 21: When inspecting a pressurized fuselage, fatigue cracks most commonly originate at:

Painted exterior surfaces that have not been touched
Smooth, unpierced skin panels away from all fasteners
Window and door cutouts, fastener holes, and areas of stress concentration (Correct answer)
Longitudinal seams on the bottom of the fuselage

Correct answer: Window and door cutouts, fastener holes, and areas of stress concentration

Stress concentrations at fastener holes, window frames, and door cutouts create the highest cyclic stress levels during pressurization cycles, making them the most common fatigue crack initiation sites.

Question 22: How should ACS professionals handle conflicts of interest?

Conflicts of interest are normal and need not be addressed
Disclose potential conflicts, recuse when appropriate, and always prioritize the client's best interests (Correct answer)
Keep conflicts hidden to avoid complications
Only financial conflicts matter

Correct answer: Disclose potential conflicts, recuse when appropriate, and always prioritize the client's best interests

Conflicts of interest must be identified, disclosed, and managed transparently to maintain professional integrity and client trust.

Question 23: Which risk assessment model used in aviation maintenance identifies likelihood and severity to prioritize hazards?

Risk matrix (likelihood × severity) (Correct answer)
5M model
DECIDE model
PAVE checklist

Correct answer: Risk matrix (likelihood × severity)

A risk matrix that evaluates both the likelihood of an event and its potential severity is the standard tool for prioritizing hazards in SMS and maintenance risk management.

Question 24: On an A-scan ultrasonic display, what do the peaks (echoes) represent?

Magnetic field intensity at various depths
Electrical impedance changes caused by eddy currents
Reflections of sound energy from surfaces, boundaries, or discontinuities within the material (Correct answer)
Radiation intensity measured by the detector

Correct answer: Reflections of sound energy from surfaces, boundaries, or discontinuities within the material

On an A-scan display, peaks represent reflected ultrasonic echoes from surfaces or internal discontinuities; the horizontal axis shows time (depth) and the vertical axis shows signal amplitude.

Question 25: What hazard does 'hydraulic lock' present to a reciprocating engine during start?

Engine oil thickens at low temperatures and locks the crankshaft, preventing rotation
Hydraulic fluid contaminating the fuel system causes the mixture to run dangerously lean
Liquid accumulation in a lower cylinder can prevent the piston from reaching TDC, potentially bending a connecting rod (Correct answer)
Water ingested into the induction system creates ice that blocks airflow to cylinders

Correct answer: Liquid accumulation in a lower cylinder can prevent the piston from reaching TDC, potentially bending a connecting rod

Hydraulic lock occurs when oil or unburned fuel accumulates in a lower cylinder; liquids are incompressible, so if the piston tries to compress liquid it can bend or break the connecting rod.

Question 26: How should ACS professionals approach client or stakeholder communication?

Only communicate in writing, never verbally
Use technical jargon regardless of the audience
Use clear, professional language appropriate to the audience, confirm understanding, and document key communications (Correct answer)
Communication skills are unimportant for technical professionals

Correct answer: Use clear, professional language appropriate to the audience, confirm understanding, and document key communications

Effective communication tailored to the audience's knowledge level is essential for building trust, ensuring understanding, and achieving professional objectives.

Question 27: Which inspection method is best for detecting surface cracks on aircraft structures?

Ultrasonic testing
Radiographic inspection
Eddy current testing
Dye penetrant inspection (Correct answer)

Correct answer: Dye penetrant inspection

Dye penetrant inspection is a popular method for identifying surface-breaking defects.

Question 28: What type of hydraulic pump is most commonly used in high-performance aircraft as an engine-driven pump due to its variable output capability?

Vane pump
Variable displacement piston pump (Correct answer)
Centrifugal pump
Gear pump

Correct answer: Variable displacement piston pump

Variable displacement piston pumps can adjust their output flow based on system demand, maintaining constant pressure while reducing heat generation and power consumption when demand is low.

Question 29: What is a couplant used for in contact ultrasonic testing?

To magnetize the test piece
To develop the penetrant indication
To eliminate the air gap between the transducer and the test surface, enabling sound transmission (Correct answer)
To enhance fluorescent visibility under UV light

Correct answer: To eliminate the air gap between the transducer and the test surface, enabling sound transmission

A couplant (such as water, oil, or gel) fills the air gap between the transducer and test surface because ultrasonic sound waves cannot effectively transmit through air.

Question 30: A retractable landing gear strut that extends but will not lock down may be caused by:

A worn or misadjusted downlock mechanism, foreign object obstruction, or actuator rigging error (Correct answer)
Excessive squat switch tension
Low hydraulic pressure only
A blown hydraulic fuse in the retract line

Correct answer: A worn or misadjusted downlock mechanism, foreign object obstruction, or actuator rigging error

Failure to achieve downlock can result from a worn, broken, or misadjusted downlock hook, an obstruction in the gear bay, or an actuator that does not travel far enough to cam the lock over center.

Question 31: What is the purpose of a fuel crossfeed system on a multi-engine aircraft?

To transfer fuel only to the landing gear hydraulic reservoir
To feed both engines from either tank to manage fuel load or feed a live engine from any tank after an engine failure (Correct answer)
To preheat fuel in cold weather
To dump fuel overboard in an emergency

Correct answer: To feed both engines from either tank to manage fuel load or feed a live engine from any tank after an engine failure

A crossfeed system allows either engine to draw from any tank, balancing fuel loads and enabling a surviving engine to draw from the opposite side's tank after an engine failure.

Question 32: Which document outlines the maintenance requirements for U.S. aircraft?

Title 14 CFR Part 145
Title 14 CFR Part 43 (Correct answer)
Title 14 CFR Part 65
Title 14 CFR Part 91

Correct answer: Title 14 CFR Part 43

Title 14 CFR Part 43 details maintenance, preventive maintenance, rebuilding, and alteration regulations.

Question 33: What is the purpose of 'borescope inspection' of turbine engine components?

Measure internal clearances between turbine blades and the case
Check fuel nozzle spray patterns during engine operation
Visually inspect hot section components for cracks, erosion, and FOD damage without engine disassembly (Correct answer)
Verify compressor blade angle settings without removing the engine

Correct answer: Visually inspect hot section components for cracks, erosion, and FOD damage without engine disassembly

Borescope inspection allows visual examination of turbine blades, combustion liners, and other internal hot section parts through access ports without requiring engine removal or disassembly.

Question 34: What effect does increasing the frequency of an ultrasonic transducer have on inspection capability?

Has no effect on penetration or sensitivity
Increases penetration depth but reduces sensitivity to small defects
Increases both penetration depth and sensitivity equally
Increases sensitivity to small defects but reduces penetration depth (Correct answer)

Correct answer: Increases sensitivity to small defects but reduces penetration depth

Higher ultrasonic frequencies produce shorter wavelengths, improving resolution and sensitivity to small defects, but are attenuated more rapidly, reducing penetration depth in the material.

Question 35: What does a bright fluorescent indication under UV (black) light during fluorescent penetrant inspection (FPI) indicate?

The developer has not yet reacted with the penetrant
Penetrant has been drawn out of a surface-opening discontinuity, indicating a crack or porosity (Correct answer)
Background fluorescence from the developer material only
The part surface was over-cleaned, removing all penetrant

Correct answer: Penetrant has been drawn out of a surface-opening discontinuity, indicating a crack or porosity

A bright fluorescent indication means penetrant trapped in a surface discontinuity has been drawn out by the developer and is fluorescing under UV light, revealing the location and extent of the flaw.

Question 36: What is the purpose of a penetrameter (Image Quality Indicator, IQI) in radiographic testing?

To measure the total radiation dose received by the technician
To calibrate the X-ray machine voltage and current settings
To verify that the radiograph has sufficient sensitivity and quality to detect a defined minimum flaw size (Correct answer)
To remove scattered radiation artifacts from the film

Correct answer: To verify that the radiograph has sufficient sensitivity and quality to detect a defined minimum flaw size

An IQI/penetrameter is placed on the part during exposure; its visibility on the finished radiograph confirms that the technique has adequate sensitivity to detect the minimum required discontinuity size.

Question 37: A mechanic notices that an Airworthiness Directive (AD) note requires repetitive compliance. What does this mean?

The AD only applies when the aircraft is operated under IFR
Compliance is optional if an alternative method is available
The action must be performed at specified intervals throughout the aircraft's service life (Correct answer)
The AD must be complied with once and then documented

Correct answer: The action must be performed at specified intervals throughout the aircraft's service life

Repetitive ADs require recurring compliance at specified intervals (flight hours, cycles, or calendar time) and cannot be performed just once.

Question 38: What is used to check crankshaft runout?

Dial indicator (Correct answer)
Micrometer
Feeler gauge
Torque wrench

Correct answer: Dial indicator

A dial indicator measures crankshaft runout during overhaul.

Question 39: Under an SMS framework, a 'just culture' policy primarily aims to:

Standardize disciplinary procedures across all maintenance stations
Differentiate between honest mistakes and reckless behavior to encourage reporting (Correct answer)
Eliminate punishment for all maintenance errors
Transfer liability for errors to the operator rather than the mechanic

Correct answer: Differentiate between honest mistakes and reckless behavior to encourage reporting

Just culture distinguishes between unintentional errors and willful violations so that honest mistakes are treated with support and coaching, encouraging open reporting of safety concerns.

Question 40: What documentation is required when performing hydraulic & pneumatic systems work?

Documentation is only needed if problems are found
Only a verbal summary to the supervisor
Detailed records of methods used, findings, conclusions, and supporting evidence (Correct answer)
No documentation is required for professional work

Correct answer: Detailed records of methods used, findings, conclusions, and supporting evidence

Thorough documentation protects both the professional and the client, provides an audit trail, and ensures work can be reviewed, verified, or continued by others.

Question 41: What type of material condition can eddy current testing detect that magnetic particle inspection cannot?

Porosity in welds
Surface cracks in non-ferromagnetic alloys such as aluminum and titanium (Correct answer)
Subsurface cracks in ferromagnetic steel
Delaminations in composites

Correct answer: Surface cracks in non-ferromagnetic alloys such as aluminum and titanium

Eddy current testing works on all electrically conductive materials, including non-ferromagnetic alloys like aluminum and titanium, whereas magnetic particle inspection is limited to ferromagnetic materials.

Question 42: What type of material is prohibited for use in aircraft fuel system tubing due to incompatibility with aviation fuels?

titanium
Aluminum alloy 5052
Stainless steel
Galvanized steel tubing (Correct answer)

Correct answer: Galvanized steel tubing

Galvanized steel is prohibited in fuel systems because zinc from the galvanizing reacts with tetraethyl lead in AVGAS to form lead compounds that clog filters and damage fuel system components.

Question 43: What is the purpose of a fuel heat exchanger on a turbine aircraft?

To use fuel to cool engine oil while also preventing fuel system icing by warming the fuel (Correct answer)
To separate water from fuel using temperature differential
To chill fuel for increased density and greater range
To increase fuel temperature for improved combustion efficiency

Correct answer: To use fuel to cool engine oil while also preventing fuel system icing by warming the fuel

The fuel-oil heat exchanger cools hot engine oil using cooler fuel as the heat sink, simultaneously warming the fuel to prevent ice crystal formation in the fuel system.

Question 44: What is the primary radiation safety concern for technicians performing X-ray radiographic inspection?

Ultraviolet skin burns from the X-ray tube housing
Cumulative exposure to ionizing radiation increasing the risk of biological harm (Correct answer)
Hearing damage from high-frequency radiation noise
Chemical burns from radiographic film developer solutions

Correct answer: Cumulative exposure to ionizing radiation increasing the risk of biological harm

Ionizing radiation (X-rays and gamma rays) can damage living tissue and DNA; cumulative occupational exposure is regulated by the NRC/OSHA, and technicians must use dosimetry badges and stay within annual dose limits.

Question 45: According to Pascal's Law, if 100 psi of pressure is applied to a closed hydraulic system, the pressure throughout the system is:

Variable, depending on the cross-sectional area of the tubing
100 psi minus friction losses through tubing and fittings
100 psi everywhere in the system simultaneously (Correct answer)
100 psi only at the point of application, decreasing with distance

Correct answer: 100 psi everywhere in the system simultaneously

Pascal's Law states that pressure applied to a confined fluid is transmitted equally and undiminished in all directions throughout the fluid.

Question 46: What is the minimum dwell time typically specified for dye penetrant inspection of standard discontinuities in aluminum alloy parts?

5 to 30 minutes (Correct answer)
1 to 2 hours
1 minute
30 seconds

Correct answer: 5 to 30 minutes

For most aluminum alloy parts, penetrant dwell times typically range from 5 to 30 minutes to allow adequate capillary action into discontinuities, as specified by the applicable process specification.

Question 47: What type of fuel is used in most turbine-powered aircraft operated in the United States?

Jet-A (kerosene-based turbine fuel) (Correct answer)
Jet-B wide-cut turbine fuel
100LL AVGAS
MOGAS (automotive gasoline)

Correct answer: Jet-A (kerosene-based turbine fuel)

Jet-A is the standard turbine fuel used in most US turbine aircraft, with a flash point above 100°F and freeze point around -40°C.

Question 48: The 'Swiss Cheese Model' of accident causation, as applied to aviation maintenance, illustrates that accidents occur when:

An individual mechanic ignores established procedures
Multiple layers of defenses each have gaps that align to allow a hazard to reach an outcome (Correct answer)
Maintenance errors are not caught by quality assurance inspection
A single catastrophic component failure overwhelms all safety systems

Correct answer: Multiple layers of defenses each have gaps that align to allow a hazard to reach an outcome

James Reason's Swiss Cheese Model shows that accidents result from multiple aligned failures across defensive layers (procedures, inspections, design), not a single cause.

Question 49: What is the purpose of antiskid system on aircraft brakes?

To prevent wheel lockup during braking, optimizing stopping distance and directional control (Correct answer)
To automatically apply brakes on landing touchdown
To equalize brake pressure between left and right brakes
To reduce brake pedal effort for the pilot

Correct answer: To prevent wheel lockup during braking, optimizing stopping distance and directional control

The antiskid system monitors wheel speed and modulates hydraulic pressure to prevent lockup, maximizing braking efficiency and maintaining steering control.

Question 50: What information is required to be included in a maintenance record entry per 14 CFR 43.9?

The aircraft registration number, work description, and owner's signature
Only the date and the technician's name
A description of the work and the repair station's name
A description of the work, date, aircraft total time, and the certificating person's signature and certificate number (Correct answer)

Correct answer: A description of the work, date, aircraft total time, and the certificating person's signature and certificate number

14 CFR 43.9 requires the maintenance entry to include a description of the work, the date, total time in service, the approving person's signature, certificate number, and certificate type.

Question 51: After an alteration that changes aircraft weight or balance, the mechanic must:

Notify the FAA within 30 days
Only update the logbook entry
Ground the aircraft until a new type certificate is issued
Reweigh the aircraft and update the weight and balance record (Correct answer)

Correct answer: Reweigh the aircraft and update the weight and balance record

Any alteration affecting weight or CG requires reweighing and updating the official weight and balance data in the aircraft records.

Question 52: How does technology impact modern electrical systems & avionics practices?

Technology has no impact on this field
Technology has made professional expertise unnecessary
Technology improves accuracy, efficiency, and capabilities while requiring new skills and knowledge (Correct answer)
Only large organizations benefit from technology in this field

Correct answer: Technology improves accuracy, efficiency, and capabilities while requiring new skills and knowledge

Technological advances have transformed professional practice by improving diagnostic capabilities, data analysis, documentation, and efficiency while requiring practitioners to develop new competencies.

Question 53: What career advancement paths exist for ACS certified professionals?

No advancement is possible beyond initial certification
Only changing careers provides advancement
Leadership roles, specialized consulting, education and training, and executive management positions (Correct answer)
Advancement requires leaving the field entirely

Correct answer: Leadership roles, specialized consulting, education and training, and executive management positions

Certified professionals can advance through specialization, leadership roles, consulting, academic/training positions, and executive management within their field.

Question 54: What continuing education is typically required in hydraulic & pneumatic systems?

Regular training to stay current with industry standards, regulations, and best practices (Correct answer)
Only education obtained before certification matters
No continuing education is ever required
Training is only needed in the first year of certification

Correct answer: Regular training to stay current with industry standards, regulations, and best practices

Professional fields require ongoing education to ensure practitioners stay current with evolving standards, technologies, regulations, and best practices in their specialty.

Question 55: What condition causes a hydraulic pump to cavitate?

Fluid temperature drops below the pour point, increasing viscosity
System demand exceeds pump output, causing pressure fluctuations
Outlet pressure exceeds the system relief valve setting
Inlet pressure is too low, causing vapor bubbles to form in the fluid (Correct answer)

Correct answer: Inlet pressure is too low, causing vapor bubbles to form in the fluid

Cavitation occurs when fluid pressure at the pump inlet drops below the fluid's vapor pressure, causing vapor bubbles to form and then violently collapse, damaging pump internals.

Question 56: During a ground run, manifold pressure is 2 inches Hg higher than standard atmosphere with the throttle closed. What does this indicate?

Intake air filter is clogged
Throttle plate is not fully closing (Correct answer)
Supercharger is engaged
Manifold pressure gauge is miscalibrated

Correct answer: Throttle plate is not fully closing

A throttle plate that does not fully close allows high-pressure air to leak into the intake manifold, raising manifold pressure above atmospheric.

Question 57: What is a borescope used for?

Internal visual inspections (Correct answer)
Removing corrosion
Cleaning components
Measuring airspeed

Correct answer: Internal visual inspections

A borescope allows internal inspection of engines and airframes without disassembly.

Question 58: When making a flared tube fitting for an aircraft fuel line, the correct flare angle for AN (Army-Navy) fittings is:

90 degrees
60 degrees
37 degrees (double flare equivalent per AN standard) (Correct answer)
45 degrees

Correct answer: 37 degrees (double flare equivalent per AN standard)

AN (Army-Navy) standard fittings use a 37-degree flare angle, which is different from the 45-degree flare used in automotive applications.

Question 59: A flexible fuel hose assembly should be replaced if it shows:

Minor discoloration from fuel residue
Blistering, cracking, collapse under load, or has exceeded its calendar life limit (Correct answer)
Any slight surface scuffing on the outer cover
Manufacturer's label becoming difficult to read

Correct answer: Blistering, cracking, collapse under load, or has exceeded its calendar life limit

Flexible hoses must be replaced if they exhibit blistering, cracking, inner tube collapse, chafing through to reinforcement, or if the calendar service life has expired.

Question 60: What is the impact of regulatory changes on ACS professionals?

Regulatory changes only affect large organizations
Only government employees need to follow regulatory changes
Regulations never change once established
Regulatory changes require updating practices, procedures, and documentation to maintain compliance (Correct answer)

Correct answer: Regulatory changes require updating practices, procedures, and documentation to maintain compliance

Professionals must monitor and adapt to regulatory changes that affect their practice, ensuring continued compliance and effective service delivery.

FAA Aviation Mechanic – ACS Airman Certification Standards Knowledge Test

The FAA Aviation Mechanic knowledge test evaluates candidates on general aviation maintenance principles, airframe systems, fuel/hydraulic systems, and NDT inspection skills required to earn an FAA Mechanic Certificate under the Airman Certification Standards (ACS) framework.

Questions

150 min

Time Limit

70%

To Pass

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Exam Rules

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No feedback shown until you submit the entire exam
Unanswered questions count as wrong — answer everything
10 pretest questions are mixed in and don't affect your score
Timer auto-submits when time runs out
Your progress is auto-saved every 30 seconds

These practice questions were written with AI tools. They are not real exam questions. Exam facts are checked against the official sources listed below. Not reviewed by a subject-matter expert. Editorial policy

Sources & references

Exam facts on this page (fees, format, dates, passing scores) are checked against these official sources; the date is our last check. Editorial policy

faa.gov — Score release, score validity, eligibility, passing score, retake policy, time limit, exam format, exam information · verified Oct 2026
psiexams.com — Test delivery · verified Oct 2026