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

Question 1: Which method is best for locating hydraulic leaks?

Thermal imaging
Ultrasonic testing
X-ray scanning
Visual and tactile inspection (Correct answer)

Correct answer: Visual and tactile inspection

Visual inspection and tactile checks are standard for detecting leaks in hydraulic systems.

Question 2: Which type of maintenance record entry is required after completion of a 100-hour inspection?

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

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 3: 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 altimeter has an excessive scale error requiring calibration or replacement (Correct answer)
The aircraft is at a higher elevation than the airport reference point
The altimeter is functioning correctly within tolerance

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

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

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

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

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

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

Question 6: What material are most aircraft hydraulic lines made of when routing through areas subject to vibration?

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

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 7: What is the correct procedure when stop-drilling a crack in aluminum aircraft skin?

Drill two holes, one at each end, through the crack tips
Drill the hole through the center of the crack tip
Drill the hole 1/2 inch behind the crack tip
Drill the hole just ahead of the visible crack tip (Correct answer)

Correct answer: Drill the hole just ahead of the visible crack tip

The stop-drill hole must be placed just ahead of (beyond) the visible crack tip to eliminate the stress concentration at the crack tip and arrest crack propagation.

Question 8: A mechanic using AC 43.13-1B for a structural repair must verify that:

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

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 9: Nose wheel shimmy on an aircraft is most commonly caused by:

High-speed crosswind landings only
Incorrect toe-in alignment
Worn or defective shimmy damper, loose torque links, or improper tire balance (Correct answer)
Overinflated nose gear tires

Correct answer: Worn or defective shimmy damper, loose torque links, or improper tire balance

Nose wheel shimmy is most commonly caused by a defective or depleted shimmy damper, loose torque link bearings, or an out-of-balance tire/wheel assembly.

Question 10: During a landing gear retraction test, the gear takes longer than the published time to retract. What is the FIRST area to check?

Actuator cylinder for internal leakage
Hydraulic system fluid level and accumulator pressure (Correct answer)
Gear door rigging and interference
Uplock hook spring tension

Correct answer: Hydraulic system fluid level and accumulator pressure

Low hydraulic fluid level or insufficient accumulator pressure is the most common and easily checked cause of slow gear retraction before investigating actuators or rigging.

Question 11: Which component in a pneumatic system performs the same function as a hydraulic system relief valve?

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

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 12: Which document is the primary reference for an aircraft's approved weight and balance limits?

The FAA-approved Airplane Flight Manual (AFM) or Pilot's Operating Handbook (POH) (Correct answer)
The repair station's work order
The aircraft maintenance logbook
The type certificate data sheet only

Correct answer: The FAA-approved Airplane Flight Manual (AFM) or Pilot's Operating Handbook (POH)

The FAA-approved AFM or POH contains the official CG envelope, weight limits, and loading instructions for the aircraft.

Question 13: What is the correct procedure when a hydraulic system component is found to have a minor external seepage (not a drip) at a fitting?

Tighten the fitting incrementally until seepage stops, regardless of torque limits
Clean the area and monitor for progression; replace if seepage becomes a drip or increases (Correct answer)
Immediately ground the aircraft and replace all seals in the affected component
Apply an external sealant compound to stop the seepage temporarily

Correct answer: Clean the area and monitor for progression; replace if seepage becomes a drip or increases

Minor seepage that forms no drips is typically acceptable per maintenance manuals — it should be cleaned, identified, monitored, and addressed if it worsens to an active leak.

Question 14: What documentation is required when performing weight & balance work?

Documentation is only needed if problems are found
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

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 15: What type of inspection uses sound waves to detect material flaws?

Dye penetrant inspection
Ultrasonic inspection (Correct answer)
Visual inspection
Magnetic particle inspection

Correct answer: Ultrasonic inspection

Ultrasonic inspection uses high-frequency sound waves to detect flaws inside materials.

Question 16: After engine overhaul, a break-in run is performed. What oil type should NOT be used during engine break-in?

Synthetic oil (Correct answer)
Straight mineral oil
Ashless dispersant oil
Multi-viscosity mineral oil

Correct answer: Synthetic oil

Synthetic oil is too slippery during break-in and prevents cylinder walls from seating properly; mineral oil is required for new or overhauled engines.

Question 17: When removing paint before a composite repair, the preferred method over mechanical sanding is:

High-pressure water blasting
Chemical paint stripper rated for composites (Correct answer)
Open-flame heat gun softening
Solvent stripping with MEK

Correct answer: Chemical paint stripper rated for composites

Chemical strippers formulated for composites remove paint without abrading fibers or introducing heat that could damage the matrix resin.

Question 18: What standard must aircraft inspections comply with?

Local weather reports
Pilot's opinion
FAA and manufacturer standards (Correct answer)
Mechanic's experience

Correct answer: FAA and manufacturer standards

Inspections must comply with the manufacturer's instructions and FAA regulations.

Question 19: Aircraft fuel quantity gauges are required by FAR to be accurate to within what tolerance?

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

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

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

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

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

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 22: What is the purpose of a hydraulic system case drain line on a variable displacement piston pump?

Supply lubrication fluid to the pump shaft bearing from an external source
Return low-pressure fluid that bypasses the internal piston seals back to the reservoir (Correct answer)
Carry pump output to a secondary system during low-demand periods
Vent pressure from the pump housing if the outlet check valve fails

Correct answer: Return low-pressure fluid that bypasses the internal piston seals back to the reservoir

Case drain lines return internal leakage fluid that bypasses piston seals back to the reservoir, preventing case pressure buildup that could damage pump shaft seals.

Question 23: When drilling holes in a carbon fiber composite for fasteners, which drill bit type is preferred?

Diamond core drill for all composite thicknesses
Carbide-tipped or solid carbide drill bit (Correct answer)
Standard high-speed steel (HSS) twist drill
Cobalt drill bit designed for stainless steel

Correct answer: Carbide-tipped or solid carbide drill bit

Carbon fiber is highly abrasive and rapidly dulls HSS bits; carbide tooling maintains a sharp edge long enough to produce clean, delamination-free holes.

Question 24: During a preflight fuel check, a pilot/mechanic finds a small amount of water in the fuel sample. The correct action is:

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)
Drain only the affected sump and continue
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 25: 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 26: Which of the following actions requires FAA Form 337 to be submitted to the FAA Aircraft Registration Branch?

Engine oil change with filter replacement
Major repair or major alteration (Correct answer)
Annual inspection approval
100-hour inspection on a Part 91 aircraft

Correct answer: Major repair or major alteration

FAA Form 337 for major repairs and alterations must be submitted to the Aircraft Registration Branch in Oklahoma City within 48 hours of return to service.

Question 27: What is the importance of professional networking in aviation maintenance?

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

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

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

Question 28: During engine run-up, a pilot reports intermittent engine roughness that disappears when carburetor heat is applied. What does this indicate?

Fouled spark plugs
Ice formation in the carburetor venturi (Correct answer)
Lean fuel-air mixture
Cracked intake manifold

Correct answer: Ice formation in the carburetor venturi

Carburetor ice causes rough running and partial power loss; applying carb heat melts the ice and restores smooth operation.

Question 29: What is the advantage of a brake-by-wire (electro-hydraulic) braking system compared to a conventional hydraulic brake system?

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

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

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

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

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

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

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

Question 32: What type of radiation is used in radiographic inspection of aircraft structural components?

Radio frequency (RF) radiation
Ultraviolet (UV) radiation
X-rays or gamma rays (Correct answer)
Infrared (IR) 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 33: What does a hydraulic system pressure relief valve protect against?

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

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 34: What is the maximum allowable bend radius violation that can occur when bending aluminum aircraft tubing?

Kinks up to 1/16 inch depth are acceptable if within 6 inches of a fitting
No kinking is acceptable — kinked tubing must be replaced (Correct answer)
Minor kinks can be straightened with a tube repair tool
The tube may be kinked if the kink is less than 10% of the tube diameter

Correct answer: No kinking is acceptable — kinked tubing must be replaced

Any kink in aluminum aircraft tubing significantly weakens it and creates stress concentration points — kinked tubing must always be replaced, never repaired or reused.

Question 35: If an aircraft hydraulic system uses MIL-PRF-5606 fluid and is inadvertently serviced with MIL-PRF-83282 fluid, what action is required?

Simply add the correct fluid to dilute the contamination
Replace only the hydraulic pump since it is most susceptible to damage
No action; the fluids are completely interchangeable
Flush the system and replace all seals, as the fluids have different seal compatibility (Correct answer)

Correct answer: Flush the system and replace all seals, as the fluids have different seal compatibility

MIL-PRF-5606 and MIL-PRF-83282 have different base oils and different seal material requirements, requiring a full system flush and seal replacement if mixed.

Question 36: What career advancement paths exist for ACS certified professionals?

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

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 37: What parameter is monitored to detect early signs of internal engine bearing failure using oil analysis?

Iron and aluminum levels
Silicon and chromium levels
Lead and tin levels
Copper and silver levels (Correct answer)

Correct answer: Copper and silver levels

Copper and silver are typical bearing overlay and plating materials; elevated levels in oil analysis indicate bearing wear before catastrophic failure occurs.

Question 38: A turbine engine's N1 speed is normal but N2 speed is lower than expected at a given power setting. What is the most likely cause?

Turbine inlet temperature sensor failure
Slippage in the reduction gearbox (Correct answer)
Compressor stall in the low-pressure section
Fuel control unit malfunction limiting N1

Correct answer: Slippage in the reduction gearbox

If N1 (low-pressure compressor/fan) is normal but N2 (high-pressure spool) is low, a slipping or damaged reduction gearbox is the likely cause.

Question 39: When may a certificated mechanic return an aircraft to service after performing a major alteration?

Only after FAA Form 337 is approved by the local FSDO
After completing the work and making proper maintenance record entries with approved data
After completing a test flight
Only if the mechanic holds an Inspection Authorization (Correct answer)

Correct answer: Only if the mechanic holds an Inspection Authorization

Returning an aircraft to service after a major alteration requires an IA or DAR, not just a basic A&P certificate.

Question 40: What is the primary purpose of a fuel strainer (gascolator) in a reciprocating aircraft engine fuel system?

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

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

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

Question 41: An aircraft engine shows a high oil consumption but normal oil pressure. Which condition is MOST likely?

Clogged oil filter bypassing dirty oil to the bearings
Cracked engine case leaking oil externally
Failed oil pressure relief valve stuck open
Worn or broken piston rings allowing oil to enter the combustion chamber (Correct answer)

Correct answer: Worn or broken piston rings allowing oil to enter the combustion chamber

Worn or broken piston rings are the most common cause of high oil consumption with normal pressure, as oil bypasses the rings and burns in the combustion chamber.

Question 42: What are composite materials in aircraft construction?

Recycled materials from decommissioned aircraft
Paint and coating materials for aircraft exteriors
Engineered materials combining two or more constituents (like carbon fiber and resin) for superior strength-to-weight ratio (Correct answer)
Standard aluminum alloys used in all aircraft

Correct answer: Engineered materials combining two or more constituents (like carbon fiber and resin) for superior strength-to-weight ratio

Aircraft composites typically combine reinforcing fibers (carbon, glass, aramid) with a resin matrix, creating materials that are lighter and stronger than traditional metals for many applications.

Question 43: What is the role of the FAA's Safety Management System (SMS) concept as it relates to maintenance operations?

To replace individual mechanic judgment with automated checklists
To eliminate the need for AD compliance tracking
To certify avionics technicians separately from airframe mechanics
To provide a systematic approach for managing safety risks in an organization (Correct answer)

Correct answer: To provide a systematic approach for managing safety risks in an organization

SMS provides a structured, organization-wide framework to proactively identify and control safety risks in aviation maintenance.

Question 44: An aircraft engine exhibits low oil pressure during ground run-up but normal pressure in flight. What is the most likely cause?

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

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 45: How should ACS professionals approach client or stakeholder communication?

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

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 46: Which tool is commonly used to measure structural alignment in aircraft?

Torque wrench
Micrometer
Caliper
Plumb bob (Correct answer)

Correct answer: Plumb bob

A plumb bob is traditionally used to ensure vertical and horizontal alignment.

Question 47: Under 14 CFR Part 65, an A&P mechanic certificate with both Airframe and Powerplant ratings allows the holder to:

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

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

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

Question 48: Fuel flow is within normal limits but EGT is abnormally high on one cylinder. What is the most likely cause?

Intake valve sticking open
Incorrect spark plug gap
Cracked exhaust valve
Clogged fuel injector on that cylinder (Correct answer)

Correct answer: Clogged fuel injector on that cylinder

A clogged fuel injector delivers insufficient fuel to one cylinder, creating a lean mixture that raises EGT on that cylinder.

Question 49: What is the impact of regulatory changes on ACS professionals?

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

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

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

Question 50: 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 transfers liability to the aircraft owner
It satisfies all AD requirements automatically

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

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

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

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

Question 52: Which FAR part primarily governs the maintenance, preventive maintenance, rebuilding, and alteration of aircraft?

14 CFR Part 39
14 CFR Part 21
14 CFR Part 43 (Correct answer)
14 CFR Part 65

Correct answer: 14 CFR Part 43

14 CFR Part 43 specifically regulates the performance of maintenance, preventive maintenance, rebuilding, and alteration of aircraft.

Question 53: What is the primary purpose of a peel ply in composite layup?

To provide a sacrificial surface layer that creates a bondable texture when removed (Correct answer)
To reinforce the outer skin of the composite panel
To seal the vacuum bag against air leaks
To distribute resin evenly across the laminate

Correct answer: To provide a sacrificial surface layer that creates a bondable texture when removed

Peel ply is a woven fabric applied as the last layer during layup; when peeled off after cure it leaves a clean, textured surface ready for secondary bonding.

Question 54: After completing a composite skin repair, what is the FIRST post-cure inspection step before returning the aircraft to service?

Apply primer and topcoat paint immediately to seal the repair
Install all removed panels and fasteners and conduct a functional flight test
Perform a tap test and visual inspection of the repair area to verify consolidation and surface quality (Correct answer)
Measure the total repair weight to update the aircraft weight and balance record

Correct answer: Perform a tap test and visual inspection of the repair area to verify consolidation and surface quality

A post-cure tap test and visual inspection verify that the repair is void-free, properly consolidated, and bonded before any finish work or return-to-service is authorized.

Question 55: Quality escape prevention in aviation maintenance requires mechanics to prioritize:

Minimizing downtime regardless of procedure compliance
Verification that every step was completed using approved data before signing off (Correct answer)
Cost-effective parts substitutions
Speed of repair over documentation

Correct answer: Verification that every step was completed using approved data before signing off

Aviation quality systems require procedural compliance verification at each step; documentation confirms that approved data was followed before return to service.

Question 56: 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
Variable, depending on the cross-sectional area of the tubing
100 psi everywhere in the system simultaneously (Correct answer)

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

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

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 58: What causes brake fade on aircraft disc brakes during repeated hard stops?

Excessive heat buildup reducing friction between pads and disc (Correct answer)
Low hydraulic fluid viscosity
Air in the brake lines
Worn brake pressure seals

Correct answer: Excessive heat buildup reducing friction between pads and disc

Brake fade occurs when excessive heat reduces the coefficient of friction between the brake pads and disc, decreasing stopping effectiveness.

Question 59: When performing a dye penetrant inspection, what is the correct sequence of steps?

Apply penetrant, clean, inspect, apply developer
Clean surface, apply developer, apply penetrant, inspect
Apply developer, apply penetrant, clean, inspect
Clean surface, apply penetrant, remove excess, apply developer, inspect (Correct answer)

Correct answer: Clean surface, apply penetrant, remove excess, apply developer, inspect

The correct dye penetrant sequence is: clean the surface, apply penetrant and allow dwell time, remove excess penetrant, apply developer, then inspect under appropriate lighting.

Question 60: A suspected unapproved part (SUP) is discovered during maintenance. The correct action is to:

Tag it, remove it from service, and report it to the FAA (Correct answer)
Install it if it fits correctly
Test it and install if it passes
Return it to the supplier for a refund

Correct answer: Tag it, remove it from service, and report it to the FAA

FAA Order 8120.10 directs mechanics to remove SUPs from service, quarantine them, and report to the FAA's Suspected Unapproved Parts Program.

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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