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

Question 1: MRM (Maintenance Resource Management) training is analogous to CRM (Crew Resource Management) for pilots and focuses on:

Improving tool inventory and parts tracking systems
Certifying mechanics in advanced avionics troubleshooting
Optimizing human performance and team communication to reduce maintenance errors (Correct answer)
Standardizing shift schedules to reduce fatigue

Correct answer: Optimizing human performance and team communication to reduce maintenance errors

MRM applies CRM principles—communication, situational awareness, decision-making, and teamwork—to the maintenance environment to reduce human-error-caused accidents.

Question 2: What continuing education is typically required in weight & balance?

Only education obtained before certification matters
Training is only needed in the first year of certification
Regular training to stay current with industry standards, regulations, and best practices (Correct answer)
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 3: What is the most important ethical consideration for ACS professionals in hydraulic & pneumatic systems?

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 4: The ASRS (Aviation Safety Reporting System) offers reporters immunity from FAA certificate action primarily to:

Encourage candid, voluntary disclosure of safety hazards (Correct answer)
Reward mechanics financially for reporting
Provide legal immunity in civil lawsuits
Replace mandatory accident reporting requirements

Correct answer: Encourage candid, voluntary disclosure of safety hazards

ASRS immunity protects reporters so they will voluntarily disclose safety-relevant incidents without fear of certificate action, improving overall system safety.

Question 5: Which type of hydraulic seal is most commonly used between two parts that have relative motion (dynamic application)?

O-ring or lip seal in a dynamic groove (Correct answer)
Metal crush washer
Anaerobic sealant
O-ring used as a static seal

Correct answer: O-ring or lip seal in a dynamic groove

Dynamic seals such as O-rings installed in dynamic grooves or lip seals are designed to prevent leakage between moving components.

Question 6: Which 14 CFR Part governs the certification of aviation mechanics?

Part 91
Part 43
Part 147
Part 65 (Correct answer)

Correct answer: Part 65

14 CFR Part 65 covers airmen other than flight crewmembers, including the certification requirements and privileges of aviation mechanics.

Question 7: What is the most important ethical consideration for ACS professionals in composite materials & repair?

Maintaining objectivity, integrity, and confidentiality in all professional work (Correct answer)
Maximizing personal profit from each engagement
Sharing all client information publicly
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 8: In reciprocating engine ignition timing, what does 'BTDC' mean and why is it used?

Below Top Dead Center; the piston fires at its lowest point to maximize power stroke length
Behind Top Dead Center; alternate term for retarded ignition timing
Between Two Dead Centers; timing between compression and power strokes
Before Top Dead Center; spark is fired early so combustion pressure peaks as the piston passes TDC (Correct answer)

Correct answer: Before Top Dead Center; spark is fired early so combustion pressure peaks as the piston passes TDC

BTDC means Before Top Dead Center; the spark fires early because combustion takes time, allowing peak pressure to build just after TDC for maximum mechanical advantage on the piston.

Question 9: Which risk assessment model used in aviation maintenance identifies likelihood and severity to prioritize hazards?

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

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 10: 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
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)
Add fuel system icing inhibitor and return to service

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

Chemical burns from radiographic film developer solutions
Cumulative exposure to ionizing radiation increasing the risk of biological harm (Correct answer)
Ultraviolet skin burns from the X-ray tube housing
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 12: During an overhaul, how are engine cylinders typically cleaned?

Sandpaper
High-pressure water jet
Bead blasting (Correct answer)
Chemical wash

Correct answer: Bead blasting

Cylinders are usually cleaned by bead blasting to remove carbon and debris.

Question 13: An aircraft landing gear extends normally but the green 'gear down and locked' light does not illuminate. The FIRST troubleshooting step should be:

Check the position switch and wiring circuit associated with the indicator light
Assume the gear is down and locked since it extended normally
Manually verify gear position via the viewing port and check the indicator light bulb (Correct answer)
Perform an emergency landing immediately

Correct answer: Manually verify gear position via the viewing port and check the indicator light bulb

The safest first step is to visually verify gear position via mirror or viewing port, then check if the indicator bulb is burned out before assuming a more serious fault.

Question 14: When must an FAA Form 337 be submitted after a major repair or alteration?

Only if the aircraft is registered under Part 121
Within 90 days of the aircraft's next annual inspection
Within 48 hours of completion
Within 30 days after approval for return to service (Correct answer)

Correct answer: Within 30 days after approval for return to service

14 CFR 43.9 requires Form 337 to be submitted to the FAA Aircraft Registration Branch within 48 hours, while one copy is kept with the aircraft records.

Question 15: 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 16: 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 with mixture at idle cutoff and throttle full open to draw fire into engine (Correct answer)
Immediately shut off fuel and use fire extinguisher on the engine
Continue cranking to draw the fire into the engine while keeping the mixture rich

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

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

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 18: Which method is primarily used to detect corrosion on aircraft structures?

X-ray imaging
Visual inspection (Correct answer)
Magnetic field mapping
Ultrasonic inspection

Correct answer: Visual inspection

Visual inspection is the first method to identify corrosion before using specialized tests.

Question 19: A mechanic is troubleshooting an aircraft electrical system where the ammeter shows a continuous discharge. The most likely cause is:

Excessive electrical load from avionics
The battery is fully charged and not accepting a charge
A failed alternator or generator not supplying charging current (Correct answer)
An open circuit in the landing light circuit

Correct answer: A failed alternator or generator not supplying charging current

A continuous ammeter discharge reading indicates the alternator or generator is not producing current and the battery is supplying all electrical loads.

Question 20: What is the purpose of an Airworthiness Directive (AD)?

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

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 21: An aircraft engine exhibits low oil pressure during ground run-up but normal pressure in flight. What is the most likely cause?

Diluted oil from fuel contamination
Worn main bearings
Clogged oil suction screen
Faulty oil pressure relief valve (Correct answer)

Correct answer: Faulty oil pressure relief valve

A stuck-open oil pressure relief valve can allow excess oil to bypass at low RPM, causing low pressure at idle that normalizes at higher power settings.

Question 22: What is the purpose of a pneumatic system bootstrap reservoir?

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

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

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

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

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)
Control the flow rate of bleed air to maintain boot inflation time
Filter moisture from bleed air before it reaches the de-ice boots

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 25: A pitot-static system check reveals the altimeter reads 200 feet higher than field elevation with the static port open on a standard day. This indicates:

A leak in the static system that must be repaired
The aircraft is at a higher elevation than the airport reference point
The altimeter is functioning correctly within tolerance
The altimeter has an excessive scale error requiring calibration or replacement (Correct answer)

Correct answer: The altimeter has an excessive scale error requiring calibration or replacement

An altimeter error of 200 feet at field elevation exceeds the FAA allowable tolerance of ±75 feet and requires calibration or replacement.

Question 26: What does the term 'floating ground' indicate in aircraft wiring troubleshooting?

A grounded circuit with proper continuity
A wire that is not connected to any circuit
A shielded coaxial cable ground
A ground wire with excessive resistance or an open circuit (Correct answer)

Correct answer: A ground wire with excessive resistance or an open circuit

A floating ground refers to a ground connection that has high resistance or is completely open, preventing proper circuit completion.

Question 27: A mechanic who makes a maintenance error that goes undetected and results in an accident may face all of the following EXCEPT:

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

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

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

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 29: Under 14 CFR 65.81, a certificated mechanic may exercise the privileges of their certificate only if they have:

Performed work in their certificate's category within the preceding 24 months (Correct answer)
Served as a pilot-in-command within the preceding 6 months
Attended an FAA safety seminar within the preceding 12 months
Passed a practical test within the last 24 months

Correct answer: Performed work in their certificate's category within the preceding 24 months

14 CFR 65.81 requires that a mechanic have performed work in the applicable category or subcategory within the preceding 24 months to exercise certificate privileges.

Question 30: What type of seal is most commonly used in aircraft landing gear actuating cylinders?

Teflon tape-wrapped pipe thread seals
Mechanical carbon face seals
Labyrinth seals
Lip-type dynamic seals (O-rings with backup rings) (Correct answer)

Correct answer: Lip-type dynamic seals (O-rings with backup rings)

O-ring seals with backup rings are the standard dynamic seals in hydraulic actuating cylinders, preventing fluid bypass past the piston and rod.

Question 31: 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)
Ethics only apply when clients are watching
Ethical standards are suggestions, not requirements

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 32: Aircraft brake assemblies with multiple discs (stacked rotors and stators) are typically used on:

Helicopters exclusively
Light general aviation aircraft under 6,000 lbs
Agricultural aircraft only
High-performance and large transport category aircraft requiring high heat capacity (Correct answer)

Correct answer: High-performance and large transport category aircraft requiring high heat capacity

Multiple-disc brakes are used on high-performance and large aircraft because the stacked rotor/stator design provides greater heat capacity and stopping force than single-disc systems.

Question 33: An aircraft has a moment of 186,000 in-lb and a weight of 2,400 lb. What is the CG location?

78.5 inches
77.5 inches (Correct answer)
75.0 inches
80.0 inches

Correct answer: 77.5 inches

CG = Moment ÷ Weight = 186,000 ÷ 2,400 = 77.5 inches.

Question 34: What is the purpose of a fuel crossfeed system on a multi-engine aircraft?

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

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

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

Question 35: What is the purpose of a current limiter (fuse link) installed in series with an aircraft alternator?

To disconnect the alternator during engine start
To protect the main bus wire from excessive current if the alternator fails internally (Correct answer)
To protect the alternator from reverse current flow
To regulate alternator output voltage

Correct answer: To protect the main bus wire from excessive current if the alternator fails internally

A current limiter protects the heavy alternator output cable from damage in the event of an alternator internal short circuit.

Question 36: During a pre-takeoff run-up, the engine idles smoothly but surges at mid-throttle. What is the most likely cause?

Magneto P-lead grounding intermittently
Accelerator pump defect in the carburetor (Correct answer)
Idle mixture set too lean
Oil pressure relief valve sticking

Correct answer: Accelerator pump defect in the carburetor

The accelerator pump provides an extra fuel shot during throttle advancement; a defective pump causes a lean surge at mid-throttle as the main jets take over.

Question 37: Which safety precaution is MOST critical when sanding or grinding carbon fiber composites?

Wetting the surface with water before any mechanical work
Wearing eye protection only, as carbon dust is non-toxic
Working only in outdoor environments to dilute carbon dust
Using respiratory protection (P100 respirator) and skin coverage to prevent inhalation and irritation (Correct answer)

Correct answer: Using respiratory protection (P100 respirator) and skin coverage to prevent inhalation and irritation

Carbon fiber dust is a respirable particulate and a skin irritant; NIOSH-approved P100 respirators and protective clothing are required during any dry sanding or grinding.

Question 38: What career advancement paths exist for ACS certified professionals?

Only changing careers provides advancement
Leadership roles, specialized consulting, education and training, and executive management positions (Correct answer)
Advancement requires leaving the field entirely
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 39: What type of hydraulic pump is most commonly used in high-performance aircraft as an engine-driven pump due to its variable output capability?

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

Correct answer: Variable displacement piston pump

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

Question 40: An aircraft with an expired annual inspection is considered:

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

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 41: Which wire gauge would be correct for a 20-ampere circuit run 15 feet in a non-bundle, non-conduit installation?

22 AWG
18 AWG
20 AWG
14 AWG (Correct answer)

Correct answer: 14 AWG

Per FAA AC 43.13-1B wire sizing charts, a 20-ampere circuit at 15 feet requires 14 AWG wire to limit voltage drop to 1 volt.

Question 42: 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 purge all air systematically toward the reservoir and prevent air pockets (Correct answer)
To protect the reservoir from contamination during bleeding

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

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

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

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 45: Which NDT method is most effective for detecting surface and near-surface cracks in ferromagnetic aircraft components?

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

Correct answer: Magnetic particle inspection

Magnetic particle inspection (MPI) is specifically designed for ferromagnetic materials and can reveal both surface and subsurface discontinuities by applying a magnetic field and iron particles.

Question 46: How should an aircraft mechanic test a repaired fuel system for leaks before returning the aircraft to service?

Visual inspection alone with the fuel caps open
Dye penetrant test on all fittings
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

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 47: 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 175 RPM drop has an ignition problem requiring investigation (Correct answer)
The magneto showing 50 RPM drop indicates a timing issue
The engine should be run longer to warm up before re-checking
Both magnetos are functioning normally

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 48: When an Airworthiness Directive is issued as an 'Emergency AD,' what is the typical compliance time frame?

Within the next scheduled inspection interval
90 days from the issue date
Immediately or within a very short specified period such as 24 hours (Correct answer)
At the next annual inspection

Correct answer: Immediately or within a very short specified period such as 24 hours

Emergency ADs require immediate action or compliance within a very short window because the unsafe condition poses an immediate threat to safety.

Question 49: What is the advantage of a brake-by-wire (electro-hydraulic) braking system compared to a conventional hydraulic brake system?

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

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 50: Under 14 CFR Part 65.92, a mechanic with both Airframe and Powerplant ratings may supervise and approve the return to service of aircraft maintained by:

Only certificated repair stations
Student pilots performing owner-authorized maintenance
Certificated mechanics holding the appropriate ratings under their supervision
Any person performing maintenance under their direct supervision per applicable regulations (Correct answer)

Correct answer: Any person performing maintenance under their direct supervision per applicable regulations

An A&P mechanic may supervise and approve work performed by others when the mechanic directly supervises the work and it is performed within applicable regulatory authority.

Question 51: An aircraft maintenance record entry for a 100-hour inspection must include all of the following EXCEPT:

Date of inspection
Total time in service
Fuel quantity at time of inspection (Correct answer)
Signature and certificate number of the person approving return to service

Correct answer: Fuel quantity at time of inspection

14 CFR 43.11 specifies required logbook entries for inspections; fuel quantity is not among the required items.

Question 52: The term 'useful load' is defined as the difference between:

Maximum gross weight and basic empty weight (Correct answer)
Maximum takeoff weight and maximum landing weight
Ramp weight and takeoff weight
Zero fuel weight and landing weight

Correct answer: Maximum gross weight and basic empty weight

Useful load = Maximum Gross Weight – Basic Empty Weight, and represents the total payload the aircraft can carry.

Question 53: When inspecting flexible hydraulic hose for serviceability, which condition requires immediate replacement?

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

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 54: What is the correct fiber orientation for a quasi-isotropic composite layup?

Plies at 0°, +45°, -45°, and 90° (Correct answer)
All plies at 0°
Plies at 0°, 45°, and 90° with no -45°
Alternating plies at 0° and 90° only

Correct answer: Plies at 0°, +45°, -45°, and 90°

A quasi-isotropic layup uses plies at 0°, +45°, -45°, and 90° to provide approximately equal stiffness and strength in all in-plane directions.

Question 55: What is the primary purpose of a hydraulic accumulator in an aircraft system?

Regulate fluid temperature during high-load operations
Filter contaminants from the hydraulic fluid
Store hydraulic fluid under pressure to supplement the pump during peak demands (Correct answer)
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 56: Which organization publishes Service Bulletins (SBs) for type-certificated aircraft, and what is their regulatory status?

The NTSB publishes SBs after accident investigations
The FAA publishes SBs, and compliance is always mandatory
ICAO publishes SBs, and compliance is mandatory for international operations
The aircraft manufacturer publishes SBs, and compliance is generally recommended but not mandatory unless referenced by an AD (Correct answer)

Correct answer: The aircraft manufacturer publishes SBs, and compliance is generally recommended but not mandatory unless referenced by an AD

Manufacturers publish Service Bulletins as recommended actions; they become mandatory only when incorporated into an FAA Airworthiness Directive.

Question 57: A mechanic notices an aircraft's compass reads 10 degrees off during a compass swing. What is the appropriate corrective action?

Adjust the compensation screws and update the compass correction card (Correct answer)
Declare the compass unserviceable if error exceeds 5 degrees
Replace the compass immediately
File a maintenance discrepancy and allow the pilot to compensate mentally

Correct answer: Adjust the compensation screws and update the compass correction card

Compass deviation within allowable limits can be corrected by adjusting the compensating magnets and must be documented on an updated compass correction card.

Question 58: What is the function of a boost pump in an aircraft fuel system?

It controls the fuel-air mixture ratio
It replaces the engine-driven fuel pump as the primary pump
It provides positive fuel pressure for starting, backup fuel pressure, and transfer between tanks (Correct answer)
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 59: What is the scope of practice for ACS certification in hydraulic & pneumatic systems?

The scope is determined individually by each professional
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)
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 60: 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.

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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