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

Question 1: During an annual inspection, you find a crack in an aircraft's aluminum skin near a rivet hole. What is the correct procedure?

Report it in the maintenance log and defer repair
Immediately ground the aircraft and replace the entire panel
Apply a patch and return to service without documentation
Measure the crack, determine if it exceeds limits, and consult manufacturer's structural repair manual (Correct answer)

Correct answer: Measure the crack, determine if it exceeds limits, and consult manufacturer's structural repair manual

The mechanic must measure the defect, compare it against the manufacturer's allowable limits in the SRM, and follow approved repair procedures.

Question 2: How should ACS professionals approach client or stakeholder communication?

Only communicate in writing, never verbally
Use technical jargon regardless of the audience
Communication skills are unimportant for technical professionals
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 3: During maintenance, a mechanic finds corrosion on a primary structural member exceeding limits in the SRM. This is classified as a:

Cosmetic issue requiring no documentation
Preventive maintenance item
Minor repair
Major repair (Correct answer)

Correct answer: Major repair

Damage to primary structure exceeding manufacturer limits is a major repair requiring FAA-approved data and Form 337.

Question 4: What is the regulatory requirement for retaining maintenance records after the work is performed?

Records must be kept for 2 years after the work
Records are the owner's property and may be discarded at any time
Records must be kept for 1 year or until the work is repeated (Correct answer)
Records must be kept until the aircraft is scrapped

Correct answer: Records must be kept for 1 year or until the work is repeated

14 CFR 43.9 and 91.417 generally require maintenance records to be retained for 1 year or until superseded by equivalent work.

Question 5: An aircraft with a Continental fuel-injected engine experiences engine roughness after takeoff that smooths out as power is reduced. This symptom most closely suggests:

A cracked cylinder head affecting compression
A lean condition caused by a blocked injector nozzle
Magneto timing retarded beyond limits
A rich mixture condition, possibly caused by a malfunctioning fuel control unit (Correct answer)

Correct answer: A rich mixture condition, possibly caused by a malfunctioning fuel control unit

Roughness at high power that smooths at reduced power suggests an over-rich condition, as excess fuel is more problematic at higher power where flow is greatest.

Question 6: After replacing a cylinder on a reciprocating engine, the cylinder head temperature on the new cylinder is abnormally low compared to adjacent cylinders at the same power setting. What does this most likely indicate?

The cylinder baffling is too effective
The new cylinder is not receiving ignition on both plugs (Correct answer)
The fuel injector nozzle flow is too high for that cylinder
The new cylinder has excessive compression

Correct answer: The new cylinder is not receiving ignition on both plugs

A cylinder with no ignition (both plugs misfiring) will not combust fuel normally, resulting in low CHT because little or no combustion heat is being generated.

Question 7: What is the most critical compliance requirement in aviation maintenance?

Only following regulations when audited
Compliance is optional for certified professionals
Ignoring regulations to save time
Following all applicable federal and state regulations while maintaining detailed documentation (Correct answer)

Correct answer: Following all applicable federal and state regulations while maintaining detailed documentation

Compliance with applicable regulations is fundamental to professional practice, requiring knowledge of current requirements and meticulous documentation.

Question 8: What is the impact of regulatory changes on ACS professionals?

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

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.

Question 9: What does a negative differential compression reading between cylinder top and side ports indicate?

Exhaust valve leakage (Correct answer)
Intake valve leakage
Piston ring leakage
Head gasket failure

Correct answer: Exhaust valve leakage

Air escaping into the exhaust stack during a differential compression test indicates a leaking exhaust valve.

Question 10: Which statement about dissimilar metal corrosion is correct?

It can occur between any two metals regardless of their galvanic difference
Painting only the less noble metal prevents galvanic corrosion
It occurs only when metals are in direct contact in the presence of an electrolyte (Correct answer)
Aluminum and stainless steel can be in direct contact without risk of corrosion

Correct answer: It occurs only when metals are in direct contact in the presence of an electrolyte

Galvanic (dissimilar metal) corrosion requires both direct metallic contact between dissimilar metals and the presence of an electrolyte to complete the circuit for current flow.

Question 11: Which NDT method is most appropriate for detecting internal voids and delaminations in composite aircraft structures?

Magnetic particle inspection
Ultrasonic inspection or tap testing (Correct answer)
Eddy current inspection
Dye penetrant inspection

Correct answer: Ultrasonic inspection or tap testing

Ultrasonic testing and tap testing are the primary methods for detecting internal defects such as voids and delaminations in composite structures.

Question 12: What material are most aircraft hydraulic lines made of when routing through areas subject to vibration?

Rigid aluminum tubing with compression fittings
Copper tubing with soldered joints
Flexible rubber hose reinforced with braided wire (Correct answer)
PVC plastic tubing with barb fittings

Correct answer: Flexible rubber hose reinforced with braided wire

Flexible braided hose is used in areas subject to vibration or relative movement because it can absorb movement without cracking or failing.

Question 13: 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 14: A reciprocating engine exhibits detonation during high-power operation. Which of the following will most effectively reduce detonation?

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

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

FAA certificate action
Automatic loss of all future FAA employment eligibility (Correct answer)
Civil lawsuit from affected parties
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 16: When inspecting a hydraulic actuator for internal leakage, what is the most reliable method?

Visually inspect the cylinder bore for scoring using a borescope
Pressurize the extend port and check for fluid weeping at the retract port with both ports open
Measure the time it takes the actuator rod to drift under a known load with ports blocked (Correct answer)
Check the fluid level drop in the reservoir over a 24-hour period

Correct answer: Measure the time it takes the actuator rod to drift under a known load with ports blocked

Applying a load and timing rod drift with ports blocked reveals internal seal bypass, which is the definitive test for internal actuator leakage.

Question 17: What is the purpose of a firewall shutoff valve (fuel selector/firewall valve) in an aircraft fuel system?

To allow the crew to stop fuel flow to the engine compartment in the event of an engine fire or fuel leak (Correct answer)
To regulate fuel pressure to the engine
To balance fuel between left and right tanks
To filter fuel before it enters the engine

Correct answer: To allow the crew to stop fuel flow to the engine compartment in the event of an engine fire or fuel leak

The firewall shutoff valve allows the flight crew to cut fuel flow to the engine compartment to starve a fire or stop a fuel leak from reaching the engine bay.

Question 18: During turbine engine inspection, 'creep' damage on turbine blades is characterized by:

Micro-cracking from rapid thermal cycling between starts and shutdowns
Permanent elongation of the blade caused by sustained high temperature and centrifugal stress (Correct answer)
Erosion of blade tip material from contact with abrasive particles in the airstream
Surface oxidation forming a scale layer on the leading edge of the blade

Correct answer: Permanent elongation of the blade caused by sustained high temperature and centrifugal stress

Turbine blade creep is the slow, permanent plastic deformation (elongation) that occurs when blades are subjected to high centrifugal loads at elevated temperatures over many operating hours.

Question 19: When troubleshooting an intermittent avionics failure, what is the recommended first approach?

Monitor the system over several flights before taking action
Send the unit for bench testing even if the fault cannot be duplicated
Duplicate the failure condition, inspect connectors and wiring for corrosion or loose connections (Correct answer)
Replace the suspected unit immediately

Correct answer: Duplicate the failure condition, inspect connectors and wiring for corrosion or loose connections

Intermittent avionics faults are most commonly caused by poor connections; inspecting connectors and wiring while attempting to duplicate the failure is the systematic first step.

Question 20: What condition is indicated when aircraft skin shows 'oil canning' between stringers?

The skin is too thick for the structural loads
Excessive tension is stretching the skin beyond its elastic limit
The skin has buckled due to compression stress exceeding its stability limit (Correct answer)
Normal behavior that requires no attention during inspection

Correct answer: The skin has buckled due to compression stress exceeding its stability limit

Oil canning is a visible buckling of thin metal skin between stringers caused by compression loads exceeding the skin's local buckling stability, and it must be evaluated per the SRM.

Question 21: How should ACS professionals approach client or stakeholder communication?

Only communicate in writing, never verbally
Use technical jargon regardless of the audience
Communication skills are unimportant for technical professionals
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 22: What is the most important ethical consideration for ACS professionals in weight & balance?

Maximizing personal profit from each engagement
Sharing all client information publicly
Maintaining objectivity, integrity, and confidentiality in all professional work (Correct answer)
Avoiding all challenging work assignments

Correct answer: Maintaining objectivity, integrity, and confidentiality in all professional work

ACS professionals must maintain the highest ethical standards including objectivity, integrity, and confidentiality to protect clients and uphold professional credibility.

Question 23: What is the purpose of an Airworthiness Directive (AD)?

To mandate corrective action for unsafe conditions (Correct answer)
To document scheduled maintenance intervals
To recommend optional upgrades
To approve new parts for installation

Correct answer: To mandate corrective action for unsafe conditions

ADs are legally enforceable regulations issued by the FAA to correct unsafe conditions found in aircraft, engines, propellers, or appliances.

Question 24: What is the function of a hydraulic system priority valve?

Ensure flight-critical systems receive hydraulic pressure before non-critical systems during low-pressure conditions (Correct answer)
Switch automatically from one hydraulic system to another if pressure drops
Prevent two hydraulic systems from operating at the same time
Regulate pump output pressure to a constant predetermined value

Correct answer: Ensure flight-critical systems receive hydraulic pressure before non-critical systems during low-pressure conditions

A priority valve ensures that flight-critical hydraulic consumers (such as flight controls) are served first, with non-essential systems receiving flow only when adequate pressure exists.

Question 25: What is the function of the torque links (scissors) on a nose gear oleo strut?

To limit strut extension travel
To prevent strut rotation while allowing vertical movement (Correct answer)
To connect the steering actuator to the wheel
To provide shimmy dampening

Correct answer: To prevent strut rotation while allowing vertical movement

Torque links (scissors links) connect the upper and lower strut cylinders to prevent rotation while allowing the strut to extend and compress freely.

Question 26: When performing a repair to aircraft fabric covering using the brush method, the fabric patches should overlap the damaged area by a minimum of:

1 inch on all sides
1/2 inch on all sides
3 inches on all sides
2 inches on all sides (Correct answer)

Correct answer: 2 inches on all sides

FAA AC 43.13-1B specifies that fabric patches must overlap the undamaged fabric by at least 2 inches on all sides to ensure adequate adhesion and strength.

Question 27: What is the MAIN reason that cure pressure is applied during composite repair?

To increase the cure temperature uniformly across the repair
To hold the repair patch in position until the adhesive sets
To prevent thermal expansion of the honeycomb core during cure
To consolidate plies, remove voids, and ensure intimate fiber-to-matrix contact (Correct answer)

Correct answer: To consolidate plies, remove voids, and ensure intimate fiber-to-matrix contact

Applied pressure (via vacuum bag or autoclave) compacts the fiber layers, expels entrapped air and excess resin, and ensures full consolidation for maximum structural properties.

Question 28: A TSO authorization granted to a manufacturer signifies that the article:

Is exempt from AD compliance
Has been approved for installation on any aircraft
Meets the minimum performance standards of the TSO (Correct answer)
Has been certified for 10,000 flight hours

Correct answer: Meets the minimum performance standards of the TSO

A TSO authorization means the article was produced to meet FAA minimum performance standards, but installation approval is still required.

Question 29: When inspecting flexible hydraulic hose for serviceability, which condition requires immediate replacement?

A small area of faded color on the outer jacket from UV exposure
Slight surface scuffing on the outer protective jacket without wire braid exposure
Wire braid visible through the outer cover at any point (Correct answer)
Minor routing deviation of less than 10% from the installed bend radius

Correct answer: Wire braid visible through the outer cover at any point

Exposed wire braid indicates the outer protective cover is compromised, meaning the hose is susceptible to further damage and must be replaced immediately.

Question 30: In a pneumatic de-icing system, what is the function of a distributor valve?

Filter moisture from bleed air before it reaches the de-ice boots
Control the flow rate of bleed air to maintain boot inflation time
Regulate bleed air pressure to the de-ice boots to a safe working pressure
Sequence the inflation and deflation of individual de-ice boot sections (Correct answer)

Correct answer: Sequence the inflation and deflation of individual de-ice boot sections

The distributor valve sequences inflation of leading-edge boot sections in the correct order to most effectively shed ice while minimizing bleed air consumption.

Question 31: What is the purpose of a desiccant in an aircraft pneumatic system?

Regulate downstream pressure to a constant value
Filter particulate contamination larger than 10 microns
Lubricate moving components within the pneumatic valves
Remove moisture from compressed air before it enters system components (Correct answer)

Correct answer: Remove moisture from compressed air before it enters system components

A desiccant absorbs moisture from compressed air, preventing ice formation at altitude and corrosion within system components.

Question 32: An aircraft with an expired annual inspection is considered:

Unairworthy and may not be operated (Correct answer)
Airworthy with a ferry permit
Airworthy for day VFR operations only
Airworthy if no new defects are found

Correct answer: Unairworthy and may not be operated

An aircraft whose annual inspection has expired is not in compliance with 14 CFR 91.409 and is therefore unairworthy and may not be legally operated.

Question 33: What is the primary purpose of the developer in dye penetrant inspection?

To draw the trapped penetrant back to the surface to form an indication (Correct answer)
To remove excess penetrant from the surface
To increase the viscosity of the penetrant
To clean the surface before penetrant application

Correct answer: To draw the trapped penetrant back to the surface to form an indication

The developer acts as a blotter, drawing the entrapped penetrant out of discontinuities to form a visible indication on the surface.

Question 34: Which part of the regulations pertains to airworthiness certification?

Part 21 (Correct answer)
Part 135
Part 147
Part 91

Correct answer: Part 21

Title 14 CFR Part 21 covers certification procedures for products and parts.

Question 35: Honeycomb core damage repair typically requires restoring core density primarily to:

Maintain the compressive and shear strength the core provides to the sandwich panel (Correct answer)
Provide an attachment point for skin repair plies
Prevent moisture ingress into the honeycomb cells
Restore the electrical conductivity of the panel

Correct answer: Maintain the compressive and shear strength the core provides to the sandwich panel

Honeycomb core transfers shear loads between face sheets and provides compressive stability; restoring equivalent density/cell size is essential for structural integrity.

Question 36: 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 everywhere in the system simultaneously (Correct answer)
100 psi minus friction losses through tubing and fittings
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 37: What is the primary purpose of a hydraulic accumulator in an aircraft system?

Store hydraulic fluid under pressure to supplement the pump during peak demands (Correct answer)
Regulate fluid temperature during high-load operations
Filter contaminants from the hydraulic fluid
Convert hydraulic pressure to pneumatic pressure

Correct answer: Store hydraulic fluid under pressure to supplement the pump during peak demands

A hydraulic accumulator stores pressurized fluid to assist the pump during peak demand periods, such as when multiple systems operate simultaneously.

Question 38: How should discrepancies be documented during inspection?

On personal notes
Only after repairs
By verbal communication only
In maintenance logbooks (Correct answer)

Correct answer: In maintenance logbooks

All discrepancies should be clearly recorded in the maintenance records/logbooks.

Question 39: When is it mandatory to bond and ground an aircraft during fueling?

Grounding is optional if fueling from a bonded fuel truck
Only when fueling in dry climates with low humidity
Only when fueling turbine aircraft
Always, before fueling begins, to prevent static discharge ignition of fuel vapors (Correct answer)

Correct answer: Always, before fueling begins, to prevent static discharge ignition of fuel vapors

Bonding and grounding are always required before fueling to equalize static electrical charges and prevent sparks that could ignite fuel vapors.

Question 40: 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 prevent vapor lock in the fuel lines
To measure fuel flow rate

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 41: When bonding a composite repair patch using a heat blanket cure, what is a critical parameter to monitor throughout the cure cycle?

Resin pot life at room temperature
Color change of the prepreg material
Ambient relative humidity only
Temperature uniformity across the repair area and pressure applied by vacuum bag (Correct answer)

Correct answer: Temperature uniformity across the repair area and pressure applied by vacuum bag

Uniform temperature distribution and adequate bag pressure (typically 25–30 inHg vacuum) are critical during heat-blanket cure to ensure proper resin flow, consolidation, and adhesion throughout the patch.

Question 42: When is a Form 337 (Major Repair and Alteration) required to be submitted to the FAA?

For every scheduled maintenance inspection
Only when the repair involves powerplant components
When performing any repair listed in AC 43.13
Upon completion of a major repair or major alteration (Correct answer)

Correct answer: Upon completion of a major repair or major alteration

FAA Form 337 must be completed and submitted to the FAA Flight Standards District Office within 48 hours after a major repair or major alteration is completed.

Question 43: Aramid (Kevlar) fiber composite panels present a unique machining challenge because:

Aramid fibers conduct electricity, requiring insulated tooling
Aramid fibers expand significantly when heated by cutting tools
Aramid fibers are tough and tend to fray or delaminate rather than cut cleanly (Correct answer)
Aramid fibers are brittle and shatter when drilled

Correct answer: Aramid fibers are tough and tend to fray or delaminate rather than cut cleanly

Aramid fibers are extremely tough and absorb energy rather than fracturing, causing fuzzing and delamination during drilling or trimming without special tooling.

Question 44: When performing a 100-hour inspection on a reciprocating engine, a mechanic finds the oil consumption has doubled since the last inspection. The most likely cause is:

Worn or stuck piston rings (Correct answer)
Using the wrong grade of oil
Incorrect oil pressure setting
A clogged oil filter

Correct answer: Worn or stuck piston rings

Worn or stuck piston rings allow oil to enter the combustion chamber and be burned, significantly increasing oil consumption.

Question 45: Under 14 CFR 65.81, a certificated mechanic may NOT supervise:

Students learning maintenance procedures
Uncertificated persons performing major alterations without direct supervision (Correct answer)
Other mechanics on tasks within his/her rating
Apprentice mechanics performing oil changes

Correct answer: Uncertificated persons performing major alterations without direct supervision

14 CFR 65.81 prohibits mechanics from supervising or allowing uncertificated persons to perform major repairs or major alterations.

Question 46: 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?

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
The gear is properly functioning within actual operational tolerances

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 47: A multiengine aircraft has an inoperative engine on the left side. How does this affect weight and balance considerations?

Only longitudinal CG must be recalculated
No effect; engines are always on the CG centerline
Lateral CG shifts toward the operating engine, which must remain within lateral limits (Correct answer)
Weight decreases by the engine mass automatically

Correct answer: Lateral CG shifts toward the operating engine, which must remain within lateral limits

If an engine fails or is removed, weight is lost asymmetrically, shifting lateral CG toward the remaining engine side, which must stay within lateral limits.

Question 48: Engine oil temperature rises above limits during taxi but returns to normal during climb. What is the most probable explanation?

Incorrect oil viscosity grade
Insufficient airflow at low taxi speeds with no forward motion cooling (Correct answer)
Defective oil cooler thermostat stuck closed
Oil pump cavitation at low RPM

Correct answer: Insufficient airflow at low taxi speeds with no forward motion cooling

Air-cooled engines rely heavily on forward airspeed for cooling; taxiing at low speed reduces airflow over cylinders and oil cooler significantly.

Question 49: What is the correct tube material for a high-pressure aircraft fuel line (above 1,500 PSI)?

Aluminum alloy 5052-O
Copper tubing
Rigid PVC tubing
Corrosion-resistant steel (CRES / stainless steel) or titanium (Correct answer)

Correct answer: Corrosion-resistant steel (CRES / stainless steel) or titanium

High-pressure fuel lines require CRES (stainless steel) or titanium tubing for the strength and corrosion resistance needed at pressures above 1,500 PSI.

Question 50: A mechanic discovers an Airworthiness Directive applies to a component already installed on an aircraft. The AD has a compliance time of 'next scheduled inspection.' What must the mechanic do?

Comply with the AD at or before the next scheduled inspection (Correct answer)
Contact the FAA for an exemption
Ground the aircraft immediately
Note it in the logbook and defer until owner requests it

Correct answer: Comply with the AD at or before the next scheduled inspection

The compliance time stated in the AD establishes the deadline; the mechanic must accomplish it no later than that time.

Question 51: What document governs the minimum bend radii and tube material specifications for aircraft fluid lines?

MIL-SPEC-5015 only
AC 43.13-1B Chapter 9 and the applicable aircraft maintenance manual (Correct answer)
FAR Part 21
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 52: When bleeding an aircraft hydraulic system, why is it important to work from the component farthest from the reservoir first?

To allow gravity to pull fluid through the system naturally
To protect the reservoir from contamination during bleeding
To ensure maximum fluid velocity through the lines
To purge all air systematically toward the reservoir and prevent air pockets (Correct answer)

Correct answer: To purge all air systematically toward the reservoir and prevent air pockets

Bleeding from the farthest point ensures air bubbles are progressively pushed back toward the reservoir rather than trapped in the system.

Question 53: Under 14 CFR Part 43.3(g), what maintenance may the holder of a sport pilot certificate perform on a light sport aircraft they own?

Any maintenance specified in the aircraft manufacturer's maintenance manual
Maintenance that does not require specialized tools or equipment
Only preventive maintenance as defined in Part 43, Appendix A (Correct answer)
Major repairs and alterations with supervision from a certified mechanic

Correct answer: Only preventive maintenance as defined in Part 43, Appendix A

Sport pilot certificate holders may perform only the preventive maintenance tasks specifically listed in Part 43, Appendix A on aircraft they own or operate.

Question 54: What ethical standards guide ACS professionals in their work?

Maximizing personal profit is the primary ethical obligation
Integrity, objectivity, confidentiality, and professional competence in all engagements (Correct answer)
Ethical standards are suggestions, not requirements
Ethics only apply when clients are watching

Correct answer: Integrity, objectivity, confidentiality, and professional competence in all engagements

Professional ethics require maintaining the highest standards of integrity, objectivity, and confidentiality while continuously developing competence.

Question 55: Why is proper weight and balance critical for aircraft safety?

Weight and balance calculations are optional for certified mechanics
An aircraft loaded outside its center of gravity limits may become uncontrollable, leading to a potential crash (Correct answer)
It only matters for cargo aircraft, not passenger aircraft
Weight and balance only affects fuel consumption, not safety

Correct answer: An aircraft loaded outside its center of gravity limits may become uncontrollable, leading to a potential crash

Proper weight and balance ensures the aircraft's center of gravity remains within approved limits, directly affecting controllability, stability, structural integrity, and performance.

Question 56: 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
Longitudinal seams on the bottom of the fuselage
Window and door cutouts, fastener holes, and areas of stress concentration (Correct answer)

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 57: A mechanic performing a required inspection on a pressurized aircraft must ensure that the aircraft's pressurization system inspection is accomplished:

Only by a repair station with a pressurization specialization rating
Only when the owner requests it as an added service
Every 500 hours regardless of other inspection intervals
As part of the required inspection items per Part 43, Appendix D (Correct answer)

Correct answer: As part of the required inspection items per Part 43, Appendix D

Pressurization system checks are included in the inspection requirements under Part 43 Appendix D for aircraft equipped with such systems.

Question 58: Which risk assessment model used in aviation maintenance identifies likelihood and severity to prioritize hazards?

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

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 59: An aircraft's nose gear shimmy damper is found to be completely non-functional. What is the most likely consequence if the aircraft is taxied without repair?

Increased nose gear tire wear only, with no structural risk
Rapid oscillation of the nose gear that can cause structural damage to the gear and airframe (Correct answer)
The steering system will lock in the straight-ahead position
The nose gear will not extend during the next flight

Correct answer: Rapid oscillation of the nose gear that can cause structural damage to the gear and airframe

A non-functional shimmy damper allows the nose gear to oscillate rapidly (shimmy) during taxi and roll-out, generating cyclic loads that can crack the gear structure and airframe attach points.

Question 60: What type of material condition can eddy current testing detect that magnetic particle inspection cannot?

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

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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