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

Question 1: A mechanic discovers that a repair was incorrectly performed by a previous technician. Under professional and regulatory standards, the mechanic should:

Perform a risk assessment and decide independently
Notify the owner only if the aircraft is about to fly
Sign off the work since it is not their error
Document the discrepancy and refuse to approve the aircraft until it is corrected (Correct answer)

Correct answer: Document the discrepancy and refuse to approve the aircraft until it is corrected

A mechanic has a professional and regulatory obligation to document discrepancies and withhold approval for return to service until all known airworthiness issues are resolved.

Question 2: An EGT gauge shows all cylinders rise normally during leaning except one which rises sharply then drops off. What does this indicate?

That cylinder has a leaking exhaust valve
That cylinder has a partially clogged fuel injector (Correct answer)
That cylinder has high compression
That cylinder is misfiring

Correct answer: That cylinder has a partially clogged fuel injector

A clogged injector delivers less fuel, so that cylinder reaches peak EGT much earlier in the leaning process and then goes excessively lean before the others.

Question 3: What is the correct procedure if a hydraulic system fluid sample indicates particle contamination above allowable limits?

Add a chemical dispersant to the fluid to dissolve the particles
Filter the system fluid through progressively finer portable filters
Continue operation but reduce system pressure by 10% to compensate
Replace the hydraulic fluid and clean or replace contaminated components per maintenance manual (Correct answer)

Correct answer: Replace the hydraulic fluid and clean or replace contaminated components per maintenance manual

Contamination above allowable limits requires fluid replacement and inspection/cleaning of components because dispersants are not approved and portable filtering may not address the contamination source.

Question 4: Which inspection method is best for detecting surface cracks on aircraft structures?

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

Correct answer: Dye penetrant inspection

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

Question 5: What is the primary purpose of performing a cold cylinder check during engine diagnostics?

To verify compression ratio
To check valve spring tension
To measure cylinder wall wear
To identify cylinders not firing or producing power (Correct answer)

Correct answer: To identify cylinders not firing or producing power

A cold cylinder check identifies cylinders that are not contributing power, indicating ignition failure, fuel starvation, or mechanical issues.

Question 6: Which human factors concept describes a mechanic's tendency to complete a task as originally planned despite new information suggesting a change is needed?

Complacency
Normalization of deviance
Plan continuation error (Correct answer)
Confirmation bias

Correct answer: Plan continuation error

Plan continuation error (get-there-itis equivalent for maintenance) occurs when a technician proceeds with an original plan even after cues indicate it should change.

Question 7: Aircraft fuel quantity gauges are required by FAR to be accurate to within what tolerance?

±5% of total capacity
No tolerance is specified — they are advisory only
They must only be accurate when reading empty (zero fuel) (Correct answer)
±10% of indicated reading at all fuel levels

Correct answer: They must only be accurate when reading empty (zero fuel)

FAR 23.1337 requires fuel quantity gauges to be accurate only at the empty (zero) position; at all other quantities, accuracy is advisory and may vary.

Question 8: During a preflight fuel check, a pilot/mechanic finds a small amount of water in the fuel sample. The correct action is:

Drain only the affected sump and continue
Continue sampling and draining until no water is found, verifying the sample is clear (Correct answer)
Add fuel system icing inhibitor and return to service
Ground the aircraft indefinitely until the tank is removed

Correct answer: Continue sampling and draining until no water is found, verifying the sample is clear

When water is found in a fuel sample, continue draining and sampling from all sumps until all samples are consistently clear and free of water, then verify the quantity before flight.

Question 9: When inspecting a hydraulic actuator for internal leakage, what is the most reliable method?

Visually inspect the cylinder bore for scoring using a borescope
Check the fluid level drop in the reservoir over a 24-hour period
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)

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 10: What is the minimum bend radius for aluminum alloy sheet when forming a repair part?

As specified in the aircraft SRM or manufacturer's structural repair data (Correct answer)
Determined solely by the forming tool diameter
At least 10 times the material thickness for all alloys
Equal to the material thickness

Correct answer: As specified in the aircraft SRM or manufacturer's structural repair data

Minimum bend radius depends on alloy type, temper, and thickness, and must be obtained from the aircraft SRM or manufacturer's structural repair data, not a universal rule.

Question 11: When is it mandatory to bond and ground an aircraft during fueling?

Only when fueling in dry climates with low humidity
Grounding is optional if fueling from a bonded fuel truck
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 12: During a borescope inspection of a turbine engine combustion section, you observe hot spots and discoloration on the combustion liner. The next step should be:

Continue operating with increased monitoring intervals
Apply a protective coating to the discolored area
Compare findings to engine manufacturer's limits and serviceable criteria (Correct answer)
Immediately replace the combustion liner without further analysis

Correct answer: Compare findings to engine manufacturer's limits and serviceable criteria

Borescope findings must be compared against the manufacturer's inspection criteria to determine if the component is serviceable, requires repair, or replacement.

Question 13: What is the significance of a 'return to service' signature by a certificated mechanic?

It authorizes the next scheduled maintenance
It certifies that the work was performed per approved data and the aircraft is airworthy (Correct answer)
It satisfies all AD requirements automatically
It transfers liability to the aircraft owner

Correct answer: It certifies that the work was performed per approved data and the aircraft is airworthy

The return to service signature is the mechanic's professional certification that work was accomplished per approved standards and the aircraft is airworthy.

Question 14: During a magneto timing check, the engine is rotated to find the firing position. What tool is commonly used to locate top dead center (TDC)?

Piston stop tool (Correct answer)
Feeler gauge
Compression tester
Timing light

Correct answer: Piston stop tool

A piston stop tool is threaded into the spark plug hole to precisely locate TDC by stopping piston travel at a known point.

Question 15: What is the maximum period after which a mechanic certificate expires if the holder fails to meet recency-of-experience requirements?

The certificate expires after 12 months of inactivity
The certificate is revoked automatically after 36 months
The certificate expires on the holder's birthday every two years
Mechanic certificates never expire but privileges lapse after 24 months of inactivity (Correct answer)

Correct answer: Mechanic certificates never expire but privileges lapse after 24 months of inactivity

FAA mechanic certificates do not have expiration dates, but privileges cannot be exercised unless recency-of-experience requirements under 14 CFR 65.83 are met.

Question 16: What component cools the cylinders of an air-cooled engine?

Compressor
Radiator
Turbocharger
Cooling fins (Correct answer)

Correct answer: Cooling fins

Cooling fins attached to the cylinders dissipate heat.

Question 17: 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 18: How do ACS professionals contribute to organizational success?

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

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 19: An aircraft GPS receiver shows a valid position fix but the CDI needle of the integrated course deviation indicator remains deflected. What is the most likely cause?

An incorrectly entered flight plan or destination waypoint in the GPS (Correct answer)
Insufficient GPS satellite signal strength
A faulty CDI display unit
The aircraft is outside of GPS coverage area

Correct answer: An incorrectly entered flight plan or destination waypoint in the GPS

If the GPS has a valid fix but the CDI is deflected, the most common cause is an incorrect or incomplete flight plan entry causing the unit to navigate to an unintended waypoint.

Question 20: A mechanic finds a component listed on the aircraft's Minimum Equipment List (MEL) to be inoperative. According to the MEL provisions, the mechanic should:

Placard the component inoperative and defer maintenance per the MEL conditions and limitations (Correct answer)
Remove the component before the next flight to restore airworthiness
Ground the aircraft immediately regardless of the MEL category
Perform a test flight to verify the inoperative condition before any action

Correct answer: Placard the component inoperative and defer maintenance per the MEL conditions and limitations

The MEL allows certain inoperative equipment to be deferred; the mechanic must placard the item and comply with the MEL's applicable conditions and maintenance procedures.

Question 21: What is the regulatory requirement for retaining maintenance records after the work is performed?

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

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 22: Under the ACS standards, a mechanic must demonstrate knowledge of quality assurance by understanding that an Inspection Authorization (IA) is required to:

Sign off on 100-hour inspection records
Install PMA parts
Perform routine oil changes on turbine engines
Approve an aircraft for return to service after an annual inspection (Correct answer)

Correct answer: Approve an aircraft for return to service after an annual inspection

Annual inspections can only be approved for return to service by a mechanic holding an IA, per 14 CFR 65.95.

Question 23: An aircraft fuel-injected engine that runs rough at cruise power but smoothly at full throttle most likely has:

A partially blocked fuel injector nozzle causing a lean condition at cruise (Correct answer)
A malfunctioning magneto
Incorrect ignition timing
An air leak in the intake manifold

Correct answer: A partially blocked fuel injector nozzle causing a lean condition at cruise

A partially blocked injector creates a lean mixture in one cylinder that is more pronounced at cruise power settings where fuel flow is lower, causing rough running.

Question 24: Which NDT method is most appropriate for detecting delaminations in a carbon fiber reinforced polymer (CFRP) aircraft panel?

Eddy current surface probe testing
Ultrasonic testing (pulse-echo or through-transmission) (Correct answer)
Dye penetrant inspection
Magnetic particle inspection

Correct answer: Ultrasonic testing (pulse-echo or through-transmission)

Ultrasonic testing is the preferred method for detecting delaminations in CFRP composites because delaminations create internal interfaces that reflect ultrasonic energy, and the method works on non-conductive materials.

Question 25: What condition causes a hydraulic pump to cavitate?

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

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 26: What is the scope of practice for ACS certification in electrical systems & avionics?

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

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 27: Which document establishes the approved data a mechanic must use when performing a major repair?

The parts manual
FAA-approved data such as AMM, SRM, or FAA-accepted engineering order (Correct answer)
The manufacturer's service letter
The aircraft logbook

Correct answer: FAA-approved data such as AMM, SRM, or FAA-accepted engineering order

Major repairs must be performed per FAA-approved data; unapproved data (e.g., service letters alone) is insufficient without FAA acceptance.

Question 28: When checking ignition timing using a timing light on a running engine, the light should flash at what point relative to the crankshaft?

At TDC on the compression stroke
At BDC on the power stroke
At the intake valve opening point
At the specified degrees before TDC (Correct answer)

Correct answer: At the specified degrees before TDC

Ignition timing is set to fire the spark plug at a specified number of degrees before TDC to allow the fuel-air mixture to reach peak pressure at the optimal piston position.

Question 29: What is the function of a boost pump in an aircraft fuel system?

It provides positive fuel pressure for starting, backup fuel pressure, and transfer between tanks (Correct answer)
It controls the fuel-air mixture ratio
It replaces the engine-driven fuel pump as the primary pump
It filters fuel before delivery to the engine

Correct answer: It provides positive fuel pressure for starting, backup fuel pressure, and transfer between tanks

Electric boost pumps provide fuel pressure for engine starting, serve as backup if the engine-driven pump fails, and assist in fuel transfer between tanks.

Question 30: What qualifications are needed for advanced aviation mechanics practice?

Advanced certifications, specialized training, demonstrated experience, and ongoing professional development (Correct answer)
Only a college degree in any subject
No additional qualifications beyond initial certification
Advanced practice requires no formal credentials

Correct answer: Advanced certifications, specialized training, demonstrated experience, and ongoing professional development

Advanced practice requires building upon foundational knowledge through specialized certifications, targeted training, and demonstrated competence in specific areas.

Question 31: A mechanic with only an Airframe rating discovers a malfunctioning magneto during an inspection. What action may the mechanic legally take?

Perform any repair on the magneto because it directly affects flight safety
Replace the magneto with an approved unit and approve the aircraft for return to service
Remove the magneto and return it to the owner with a written discrepancy notice (Correct answer)
Repair and test the magneto since it is attached to the airframe

Correct answer: Remove the magneto and return it to the owner with a written discrepancy notice

A mechanic with only an Airframe rating cannot perform powerplant maintenance; they must note the discrepancy and inform the owner.

Question 32: 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?

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

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

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

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 34: What is the primary purpose of Advisory Circular AC 43.13-1B?

To establish Part 145 repair station requirements
To provide acceptable methods and techniques for aircraft inspection and repair (Correct answer)
To define ACS testing standards for mechanics
To outline pilot operating procedures

Correct answer: To provide acceptable methods and techniques for aircraft inspection and repair

AC 43.13-1B provides FAA-accepted methods, techniques, and practices for aircraft inspection and repair.

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

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

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: What does a hydraulic system pressure relief valve protect against?

Pump cavitation during low-fluid conditions
Fluid contamination entering the actuator
Thermal expansion causing pressure spikes that exceed system design limits (Correct answer)
Filter bypass due to clogging

Correct answer: Thermal expansion causing pressure spikes that exceed system design limits

The pressure relief valve opens to bypass fluid back to the reservoir when system pressure exceeds the maximum design limit, protecting components from overpressure damage.

Question 37: What is the primary radiation safety concern for technicians performing X-ray radiographic inspection?

Cumulative exposure to ionizing radiation increasing the risk of biological harm (Correct answer)
Hearing damage from high-frequency radiation noise
Ultraviolet skin burns from the X-ray tube housing
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 38: What is used to check crankshaft runout?

Micrometer
Dial indicator (Correct answer)
Torque wrench
Feeler gauge

Correct answer: Dial indicator

A dial indicator measures crankshaft runout during overhaul.

Question 39: Which type of visual inspection tool is used to inspect the interior of an engine cylinder without disassembly?

Borescope (Correct answer)
Dial indicator
Feeler gauge
Micrometer

Correct answer: Borescope

A borescope is an optical instrument with a rigid or flexible tube used to inspect the interior of inaccessible areas such as engine cylinders without requiring disassembly.

Question 40: A reciprocating engine's tachometer shows 50 RPM higher than normal at a fixed throttle setting after maintenance. What adjustment was most likely made incorrectly?

Oil viscosity changed to a lighter grade
Primer system reconnected
Magneto timing advanced beyond specification (Correct answer)
Fuel injector nozzles cleaned

Correct answer: Magneto timing advanced beyond specification

Advancing magneto timing beyond specification causes the engine to produce more power at a given throttle setting, resulting in higher RPM.

Question 41: When making a flared tube fitting for an aircraft fuel line, the correct flare angle for AN (Army-Navy) fittings is:

37 degrees (double flare equivalent per AN standard) (Correct answer)
60 degrees
45 degrees
90 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 42: Which tool is essential for checking the torque of aircraft fasteners?

Rivet gun
Caliper
Torque wrench (Correct answer)
Micrometer

Correct answer: Torque wrench

A torque wrench ensures that fasteners are tightened to the correct specifications.

Question 43: What is the purpose of the Minimum Equipment List (MEL) in aviation maintenance?

To define the minimum qualifications for mechanics working on turbine aircraft
To list all tools required for a 100-hour inspection
To identify equipment that may be inoperative while still allowing safe flight under specific conditions (Correct answer)
To outline required spare parts inventory for Part 145 stations

Correct answer: To identify equipment that may be inoperative while still allowing safe flight under specific conditions

An MEL specifies which systems or instruments may be inoperative with conditions and limitations, allowing dispatch of an aircraft that is not fully operational.

Question 44: When wet layup repair fabric must be stored before use, the recommended method is:

Store refrigerated in a sealed container and use before the manufacturer's out-life limit (Correct answer)
Store in a heated cabinet to keep the fabric pliable
Seal in a vacuum bag at room temperature indefinitely
Leave on the workbench covered with a dry cloth up to one week

Correct answer: Store refrigerated in a sealed container and use before the manufacturer's out-life limit

Even dry fabric should be kept clean and dry, but pre-wetted or pre-mixed materials must be refrigerated and tracked for out-life to prevent premature resin advancement.

Question 45: What is the purpose of a pneumatic system bootstrap reservoir?

Act as an expansion chamber for thermal growth of pneumatic tubing
Cool pneumatic fluid before it enters actuators
Pressurize the reservoir above atmospheric pressure to prevent pump cavitation at altitude (Correct answer)
Store excess bleed air for use during engine failure

Correct answer: Pressurize the reservoir above atmospheric pressure to prevent pump cavitation at altitude

A bootstrap reservoir is pressurized above the fluid inlet pressure so the hydraulic or pneumatic pump receives adequate inlet pressure, preventing cavitation at high altitudes.

Question 46: Which component in a pneumatic system performs the same function as a hydraulic system relief valve?

Filter/separator
Pressure relief valve (Correct answer)
Check valve
Pressure regulator

Correct answer: Pressure relief valve

A pneumatic pressure relief valve protects the system from overpressure just as a hydraulic relief valve does, opening to vent excess pressure to atmosphere.

Question 47: When inspecting a riveted skin joint, you find a rivet with a shop head that is too small. What is the correct corrective action?

Drill out and replace with the same diameter rivet driven correctly (Correct answer)
Leave in place if the shop head diameter is at least 1.2 times the rivet diameter
Drill out and replace the rivet with the next larger diameter
Apply epoxy adhesive to fill the gap around the rivet

Correct answer: Drill out and replace with the same diameter rivet driven correctly

An undersized shop head indicates improper driving; the rivet must be drilled out and replaced using correct driving technique with the same specification rivet.

Question 48: 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
A rich mixture condition, possibly caused by a malfunctioning fuel control unit (Correct answer)
Magneto timing retarded beyond limits

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 49: What type of fitting is typically used on high-pressure aircraft hydraulic lines (3,000 psi and above) where vibration is a concern?

Flared AN fitting with double flare
NPT pipe thread fitting with Teflon tape
Flareless MS fitting with bite-type ferrule (Correct answer)
Compression fitting with soft copper ferrule

Correct answer: Flareless MS fitting with bite-type ferrule

MS flareless (bite-type) fittings are preferred for high-pressure, high-vibration applications because the ferrule bites into the tube and provides excellent resistance to loosening.

Question 50: The concept of 'normalization of deviance' in aviation maintenance describes:

Using unapproved parts in low-risk applications
Accepting small deviations from standards as normal over time until a serious failure occurs (Correct answer)
Applying engineering judgment instead of published data
Documenting non-standard repairs with FAA approval

Correct answer: Accepting small deviations from standards as normal over time until a serious failure occurs

Normalization of deviance occurs when repeated minor violations of standards go uncorrected and become accepted as normal, increasing risk of catastrophic failure.

Question 51: In a turbine engine, what does the term 'compressor stall' refer to?

A condition where compressor inlet temperature exceeds limits during hot-day operations
Complete mechanical seizure of the compressor section due to bearing failure
Excessive RPM that causes compressor blades to exceed their design tip speed
A disruption in the smooth airflow through the compressor, causing momentary flow reversal and loss of compression (Correct answer)

Correct answer: A disruption in the smooth airflow through the compressor, causing momentary flow reversal and loss of compression

A compressor stall is an aerodynamic disruption where the angle of attack on compressor blades exceeds the stall angle, causing local flow separation and potentially violent pressure oscillations.

Question 52: When a maintenance technician completes a required inspection entry, the record must include all of the following EXCEPT:

Description of the work performed
Signature and certificate number of the approving person
Date of completion
Owner's written authorization to perform the work (Correct answer)

Correct answer: Owner's written authorization to perform the work

14 CFR 43.9 requires the work description, date, and approving technician's signature/certificate number—owner authorization is not a required element of the maintenance entry itself.

Question 53: What is the correct torque technique when installing AN/MS flareless tube fittings?

Use the 'finger-tight plus turns' method specified in the applicable maintenance manual (Correct answer)
Thread until metal-to-metal contact, then add 1/4 turn
Tighten until resistance is felt, then tighten 1/16 turn more
Torque to the manufacturer's value using only a calibrated torque wrench

Correct answer: Use the 'finger-tight plus turns' method specified in the applicable maintenance manual

Flareless fitting installation requires presetting the ferrule on the tube first, then during final assembly using the turns method specified in the maintenance manual.

Question 54: The FAA's Aviation Safety Hotline (1-800-255-1111) is used to report:

Alleged violations of aviation regulations or safety concerns (Correct answer)
Lost or stolen airman certificates
Weather hazards to ATC
Near-midair collisions only

Correct answer: Alleged violations of aviation regulations or safety concerns

The FAA Safety Hotline allows anyone to anonymously report suspected regulatory violations or safety hazards to the FAA.

Question 55: 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
Training is only needed in the first year of certification
No continuing education is ever required

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 56: An aircraft certificated under FAR Part 23 must have weight and balance data that includes:

Gross weight and fuel capacity only
Only the basic empty weight
Empty weight, empty weight CG, and useful load (Correct answer)
Maximum ramp weight only

Correct answer: Empty weight, empty weight CG, and useful load

FAR Part 23 requires the aircraft flight manual to include empty weight, empty weight CG location, and useful load information.

Question 57: What type of radiation is used in radiographic inspection of aircraft structural components?

Infrared (IR) radiation
Radio frequency (RF) radiation
X-rays or gamma rays (Correct answer)
Ultraviolet (UV) radiation

Correct answer: X-rays or gamma rays

Radiographic inspection uses X-rays (from an X-ray tube) or gamma rays (from radioactive isotopes such as Iridium-192) to penetrate materials and expose a detector or film.

Question 58: What documentation best practices should ACS professionals follow?

Brief notes are always sufficient
Documentation can be completed months after the work
Documentation is only needed for billing purposes
Maintain thorough, accurate, timely records that support findings, decisions, and compliance requirements (Correct answer)

Correct answer: Maintain thorough, accurate, timely records that support findings, decisions, and compliance requirements

Comprehensive documentation provides an audit trail, supports decision-making, facilitates knowledge transfer, and demonstrates compliance with professional standards.

Question 59: Which nondestructive inspection (NDI) method is BEST suited for detecting delamination in thick composite laminates?

Dye penetrant inspection
Eddy current inspection
Magnetic particle inspection
Ultrasonic inspection (A-scan or C-scan) (Correct answer)

Correct answer: Ultrasonic inspection (A-scan or C-scan)

Ultrasonic inspection can penetrate through multiple plies and detect internal delaminations, voids, and disbonds that are invisible to surface methods.

Question 60: When troubleshooting an aircraft hydraulic system that loses pressure only during high-demand operations, what is the most likely cause?

Incorrect hydraulic fluid viscosity
A leaking brake line
Worn hydraulic pump with insufficient flow capacity (Correct answer)
Contaminated hydraulic fluid

Correct answer: Worn hydraulic pump with insufficient flow capacity

A worn pump may maintain static pressure but fail to deliver sufficient flow under high demand, causing pressure drop during multiple simultaneous actuations.

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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