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

Question 1: 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 2: What is the purpose of Safety Management Systems (SMS)?

To control air traffic
To reduce aircraft weight
To manage and mitigate safety risks (Correct answer)
To increase operational costs

Correct answer: To manage and mitigate safety risks

SMS programs are designed to proactively manage safety risks.

Question 3: A mechanic using AC 43.13-1B for a structural repair must verify that:

The AC applies regardless of aircraft type
The AC supersedes all manufacturer data
The repair is approved by the owner
The repair method is acceptable to the FAA for that specific repair and no approved manufacturer data exists (Correct answer)

Correct answer: The repair method is acceptable to the FAA for that specific repair and no approved manufacturer data exists

AC 43.13-1B provides acceptable methods only when no approved manufacturer data exists; manufacturer data takes precedence when available.

Question 4: What documentation is required when performing hydraulic & pneumatic systems work?

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

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 5: What is the purpose of a flow control valve in a hydraulic system?

Block fluid flow completely when a system is not in use
Reduce system pressure to a lower value for downstream components
Prevent reverse fluid flow through a hydraulic line
Control the rate of actuator movement by limiting fluid flow regardless of pressure differential (Correct answer)

Correct answer: Control the rate of actuator movement by limiting fluid flow regardless of pressure differential

A flow control valve meters fluid flow rate to an actuator, controlling movement speed independently of the pressure differential across the valve.

Question 6: Ethics in aviation maintenance requires that a mechanic who is pressured by a supervisor to approve an unairworthy aircraft should:

Follow supervisor instructions since they carry final authority
Refuse to sign off and escalate to higher authority or the FAA if necessary (Correct answer)
Complete the task but file an anonymous ASRS report after the flight
Approve with a written note limiting personal liability

Correct answer: Refuse to sign off and escalate to higher authority or the FAA if necessary

A mechanic's signature on a return-to-service constitutes a personal safety certification; no supervisor can legally override this, and escalation to the FAA is always available.

Question 7: 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 sensitivity to small defects but reduces penetration depth (Correct answer)
Increases both penetration depth and sensitivity equally

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 8: Which item is mandatory for safe evacuation?

Emergency exits (Correct answer)
Oxygen mask
Survival beacon
First aid kit

Correct answer: Emergency exits

Clearly marked and accessible emergency exits are critical for safe evacuation.

Question 9: What is the scope of practice for ACS certification in electrical systems & avionics?

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

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 10: What career advancement paths exist for ACS certified professionals?

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

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 11: 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
Add fuel system icing inhibitor and return to service
Ground the aircraft indefinitely until the tank is removed
Continue sampling and draining until no water is found, verifying the sample is clear (Correct answer)

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 12: Which document serves as the authoritative source for an aircraft's certificated weight, engine model, and fuel type?

The Type Certificate Data Sheet (TCDS) (Correct answer)
The aircraft flight manual (AFM)
The weight and balance report
The aircraft maintenance manual (AMM)

Correct answer: The Type Certificate Data Sheet (TCDS)

The TCDS is the FAA's official record of the design specifications and limitations for a certificated aircraft.

Question 13: 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
Maintain the compressive and shear strength the core provides to the sandwich panel (Correct answer)
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 14: What is the correct procedure when an engine fire occurs during start on a reciprocating aircraft engine?

Apply carburetor heat and reduce throttle to idle
Continue cranking to draw the fire into the engine while keeping the mixture rich
Immediately shut off fuel and use fire extinguisher on the engine
Continue cranking with mixture at idle cutoff and throttle full open to draw fire into engine (Correct answer)

Correct answer: Continue cranking with mixture at idle cutoff and throttle full open to draw fire into engine

Continuing to crank with mixture cut off and throttle full open creates airflow that can draw burning fuel back into the induction system and extinguish the fire.

Question 15: According to Pascal's Law, if 100 psi of pressure is applied to a closed hydraulic system, the pressure throughout the system is:

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

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 16: What is the most important ethical consideration for ACS professionals in electrical systems & avionics?

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

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 17: During an eddy current inspection of an aluminum wing spar, a large meter deflection is noted at a specific location. This most likely indicates:

A crack, corrosion, or other discontinuity at that location requiring further evaluation (Correct answer)
Normal variation in aluminum alloy composition
The spar material is heat-treated aluminum
Interference from nearby ferromagnetic hardware

Correct answer: A crack, corrosion, or other discontinuity at that location requiring further evaluation

Eddy current meter deflections indicate changes in conductivity or permeability caused by cracks, corrosion, or thickness variations requiring further investigation.

Question 18: During engine overhaul, what is the primary purpose of magnaflux inspection?

Measure dimensional tolerances of rotating components
Detect surface and subsurface cracks in ferrous metal parts (Correct answer)
Check for corrosion on aluminum cylinder heads
Verify oil passage alignment in the crankcase

Correct answer: Detect surface and subsurface cracks in ferrous metal parts

Magnaflux (magnetic particle inspection) detects surface and subsurface cracks in ferrous metal parts by revealing disruptions in magnetic flux lines.

Question 19: When must a mechanic update the aircraft weight and balance records after maintenance?

Every 100 hours of operation
Only when a major alteration or repair changes the aircraft's weight or CG (Correct answer)
After every inspection, regardless of work performed
Whenever new avionics are inspected but not replaced

Correct answer: Only when a major alteration or repair changes the aircraft's weight or CG

FAR 43.9 and related regulations require updating weight and balance data only when a repair or alteration changes the aircraft weight or CG location.

Question 20: How does continuing education benefit ACS professionals?

Continuing education is purely optional with no benefits
Continuing education is not needed after certification
It ensures practitioners stay current with evolving standards, technologies, and best practices (Correct answer)
Only beginners benefit from additional training

Correct answer: It ensures practitioners stay current with evolving standards, technologies, and best practices

Professional fields evolve constantly — continuing education ensures practitioners maintain competence and stay current with industry developments.

Question 21: Under 14 CFR Part 43, who is authorized to approve an aircraft for return to service after a major repair?

Any person holding a repairman certificate
Only the aircraft manufacturer's representative
Any certificated pilot with a private certificate
A certificated mechanic holding an Airframe and Powerplant rating (Correct answer)

Correct answer: A certificated mechanic holding an Airframe and Powerplant rating

14 CFR Part 43.7 specifies that a certificated mechanic holding the appropriate rating may approve an aircraft for return to service after a major repair.

Question 22: How does technology impact modern hydraulic & pneumatic systems practices?

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

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 23: In a Safety Management System (SMS), the 'safety assurance' component is primarily responsible for:

Establishing the organization's safety policy
Investigating all maintenance incidents
Training employees on hazard identification
Monitoring safety performance and verifying controls remain effective (Correct answer)

Correct answer: Monitoring safety performance and verifying controls remain effective

Safety assurance involves continuous monitoring of safety performance data to verify that implemented controls are working and that new hazards are identified.

Question 24: What is the primary purpose of Advisory Circular AC 43.13-1B?

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

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 25: What does a transponder's MODE C capability provide to ATC?

Aircraft position in latitude and longitude
Ground speed and heading data
Aircraft identification code only
Pressure altitude information encoded with the transponder reply (Correct answer)

Correct answer: Pressure altitude information encoded with the transponder reply

Mode C transponders encode pressure altitude data (from the aircraft's encoding altimeter) with each reply, allowing ATC to display altitude alongside the target.

Question 26: What is the primary reason aircraft reciprocating engines use sodium-filled exhaust valves?

Hollow sodium-filled valves weigh less than solid steel valves of the same strength
Sodium reacts with lead in aviation fuel to prevent valve seat recession
Liquid sodium inside the valve transfers heat from the valve head to the stem, cooling the valve (Correct answer)
Sodium expands when heated to maintain a tight seal against the valve seat at operating temperature

Correct answer: Liquid sodium inside the valve transfers heat from the valve head to the stem, cooling the valve

Liquid sodium moves back and forth inside the hollow valve stem as the engine runs, conducting heat from the hot valve head to the cooler stem and valve guide, preventing valve burning.

Question 27: 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?

Ground the aircraft immediately
Contact the FAA for an exemption
Comply with the AD at or before the next scheduled inspection (Correct answer)
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 28: When inspecting aircraft tires for continued airworthiness, what condition mandates immediate removal from service?

Fabric cord showing through the tread (Correct answer)
Minor weather checking on the sidewalls
Uneven tread wear of less than 1/16 inch
Tread depth at the wear indicators

Correct answer: Fabric cord showing through the tread

Exposed fabric cords in aircraft tires represent a critical safety hazard requiring immediate removal from service regardless of remaining tread depth.

Question 29: A 10-lb item is added at a station 50 inches aft of the CG. What is the moment change?

500 in-lb aft (Correct answer)
100 in-lb aft
500 in-lb forward
50 in-lb aft

Correct answer: 500 in-lb aft

Moment change = Weight × Arm from CG = 10 × 50 = 500 in-lb acting aft, tending to move the CG aft.

Question 30: How should an aircraft mechanic test a repaired fuel system for leaks before returning the aircraft to service?

Pressure test or operational test per the AMM with fuel system pressurized and all connections checked for leaks (Correct answer)
Run the engine to operating temperature and inspect
Visual inspection alone with the fuel caps open
Dye penetrant test on all fittings

Correct answer: Pressure test or operational test per the AMM with fuel system pressurized and all connections checked for leaks

After repair, the fuel system must be leak-tested per the AMM procedure, typically by pressurizing the system and inspecting all connections, fittings, and repaired areas for any leakage.

Question 31: How should ACS professionals approach client or stakeholder communication?

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)
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 32: An aircraft exhaust system inspection reveals blue discoloration on the exhaust stack. This is significant because it may indicate:

Normal oxidation from high heat cycles
Incomplete combustion from an over-rich mixture
Engine oil leaking into the exhaust or extreme overheating of the exhaust system (Correct answer)
A lean mixture causing excess cylinder head temperature

Correct answer: Engine oil leaking into the exhaust or extreme overheating of the exhaust system

Blue discoloration on exhaust components can indicate oil contamination in the exhaust stream or localized overheating, both of which require investigation for engine health.

Question 33: What condition does a 'hung start' describe in a turbine engine?

The engine lights off and runs but stabilizes at an RPM below idle due to insufficient power from the starter (Correct answer)
The engine achieves start but then surges repeatedly above and below idle
Fuel flow is interrupted during the start sequence before light-off occurs
The starter motor fails to disengage after the engine reaches self-sustaining speed

Correct answer: The engine lights off and runs but stabilizes at an RPM below idle due to insufficient power from the starter

A hung start occurs when the turbine engine lights and reaches a self-sustaining condition but RPM stabilizes below normal idle because the starter cannot supply enough energy to accelerate the engine further.

Question 34: What material are most aircraft hydraulic lines made of when routing through areas subject to vibration?

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

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 35: According to FAA regulations, who may perform NDT inspections on certificated aircraft?

Only FAA inspectors
Only FAA-certificated airframe and powerplant mechanics with appropriate training and authorization (Correct answer)
Any person supervised by a licensed mechanic
Any FAA-certificated pilot with instrument rating

Correct answer: Only FAA-certificated airframe and powerplant mechanics with appropriate training and authorization

NDT inspections on certificated aircraft must be performed by FAA-certificated A&P mechanics who have received specific training and authorization in the applicable NDT method per the manufacturer's approved data.

Question 36: How do ACS professionals contribute to organizational success?

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

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

Continue operation but reduce system pressure by 10% to compensate
Filter the system fluid through progressively finer portable filters
Add a chemical dispersant to the fluid to dissolve the particles
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 38: Which type of maintenance record entry is required after completion of a 100-hour inspection?

A field approval form
A signed logbook entry per 14 CFR 43.11 (Correct answer)
An FAA Form 8130-3
A Supplemental Type Certificate

Correct answer: A signed logbook entry per 14 CFR 43.11

14 CFR 43.11 requires a maintenance record entry including the date, aircraft total time, signature, and certificate number after each inspection.

Question 39: How should ACS professionals handle conflicts of interest?

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
Conflicts of interest are normal and need not be addressed

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 40: When using a borescope to inspect cylinder combustion chambers, what condition would require immediate removal from service?

Slightly uneven spark plug electrode wear
Minor carbon deposits on piston crown
Cracks radiating from the exhaust valve seat (Correct answer)
Light rust on cylinder walls after storage

Correct answer: Cracks radiating from the exhaust valve seat

Cracks radiating from the exhaust valve seat indicate serious structural damage that could lead to valve failure or cylinder head separation in flight.

Question 41: A flexible fuel hose assembly should be replaced if it shows:

Manufacturer's label becoming difficult to read
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

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

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

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 43: To exercise Inspection Authorization (IA) privileges, a mechanic must hold an IA for at least how long before it must be renewed?

12 months (Correct answer)
6 months
It never expires
24 months

Correct answer: 12 months

An Inspection Authorization must be renewed annually (every 12 calendar months) by meeting one of the renewal activity requirements in 14 CFR 65.93.

Question 44: 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 45: What is the scope of practice for ACS certification in hydraulic & pneumatic systems?

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

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 46: When bleeding an aircraft hydraulic system, why is it important to work from the component farthest from the reservoir first?

To ensure maximum fluid velocity through the lines
To allow gravity to pull fluid through the system naturally
To protect the reservoir from contamination during bleeding
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 47: What is the purpose of a pneumatic system bootstrap reservoir?

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

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 48: What is the advantage of a brake-by-wire (electro-hydraulic) braking system compared to a conventional hydraulic brake system?

Provides faster and more precise brake pressure modulation for anti-skid performance (Correct answer)
Eliminates the need for hydraulic fluid entirely by using electric motors
Allows the pilot to apply greater mechanical advantage to brake pedals
Reduces aircraft weight by using smaller diameter brake lines

Correct answer: Provides faster and more precise brake pressure modulation for anti-skid performance

Electro-hydraulic brake systems use electronic control to modulate hydraulic pressure with greater speed and precision than mechanical inputs alone, improving anti-skid performance.

Question 49: Which type of visual inspection tool is used to inspect the interior of an engine cylinder without disassembly?

Dial indicator
Borescope (Correct answer)
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 50: 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)
The part surface was over-cleaned, removing all penetrant
Background fluorescence from the developer material only

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 51: What is the function of a hydraulic power transfer unit (PTU)?

Maintain equal pressure in both main and backup hydraulic systems
Convert hydraulic energy to electrical energy for emergency power
Pump fluid when the engine-driven pump fails
Transfer fluid between two separate hydraulic systems without cross-contaminating the fluids (Correct answer)

Correct answer: Transfer fluid between two separate hydraulic systems without cross-contaminating the fluids

A PTU allows one hydraulic system to power another using a hydraulic motor/pump combination, transferring power but keeping the fluids isolated.

Question 52: 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)
Ultraviolet skin burns from the X-ray tube housing
Chemical burns from radiographic film developer solutions
Hearing damage from high-frequency radiation noise

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 53: An aircraft engine fails to develop full static RPM during a pre-takeoff run-up. The magneto check is normal. What should be checked next?

Magneto timing advance mechanism
Propeller pitch setting and governor operation (Correct answer)
Alternator load on the engine
Cockpit fuel selector position

Correct answer: Propeller pitch setting and governor operation

A constant-speed propeller set to too coarse a pitch or a malfunctioning governor will prevent the engine from reaching full static RPM despite normal ignition.

Question 54: Under 14 CFR Part 43, who is responsible for ensuring a maintenance record entry is made after completing an inspection?

The aircraft owner
The FAA inspector
The person who performed the work (Correct answer)
The repair station manager

Correct answer: The person who performed the work

14 CFR 43.9 requires the person who performed the maintenance to make the appropriate record entry.

Question 55: What is the primary purpose of a fuel strainer (gascolator) in a reciprocating aircraft engine fuel system?

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

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 56: What career advancement paths exist for ACS certified professionals?

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

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 57: An aircraft engine exhibits black smoke from the exhaust. This symptom most likely indicates:

Rich fuel-air mixture or excessive fuel flow (Correct answer)
Ignition timing advanced too far
Lean fuel-air mixture
Oil burning due to worn piston rings

Correct answer: Rich fuel-air mixture or excessive fuel flow

Black exhaust smoke is a classic indicator of a rich mixture or excessive fuel flow resulting in incomplete combustion.

Question 58: When a maintenance technician completes a required inspection entry, the record must include all of the following EXCEPT:

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

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

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

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

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

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.

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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