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

Question 1: What is the correct torque technique when installing AN/MS flareless tube fittings?

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

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

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

Question 2: What is a couplant used for in contact ultrasonic testing?

To magnetize the test piece
To develop the penetrant indication
To eliminate the air gap between the transducer and the test surface, enabling sound transmission (Correct answer)
To enhance fluorescent visibility under UV light

Correct answer: To eliminate the air gap between the transducer and the test surface, enabling sound transmission

A couplant (such as water, oil, or gel) fills the air gap between the transducer and test surface because ultrasonic sound waves cannot effectively transmit through air.

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:

The altimeter is functioning correctly within tolerance
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
A leak in the static system that must be repaired

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: What does 'spectrometric oil analysis' (SOAP) detect in aircraft engine maintenance?

Trace metal particles in engine oil that indicate wear of specific engine components (Correct answer)
Fuel contamination levels in the engine lubrication system
Viscosity changes indicating oil oxidation or thermal breakdown
Acid number increase showing oil additive depletion

Correct answer: Trace metal particles in engine oil that indicate wear of specific engine components

SOAP identifies and quantifies specific metallic elements in oil samples; elevated levels of iron, chromium, copper, or other metals indicate wear of the corresponding engine components.

Question 5: During a top overhaul, a technician finds chrome cylinder walls. What special consideration applies?

Chrome cylinders must use cast iron piston rings, not chrome rings (Correct answer)
Chrome cylinders cannot be re-honed and must be replaced
Chrome cylinders require a longer break-in period than steel cylinders
Chrome cylinders require higher-viscosity oil for break-in

Correct answer: Chrome cylinders must use cast iron piston rings, not chrome rings

Chrome-plated cylinders must be fitted with cast iron piston rings because two chrome surfaces together will not seat properly and will cause excessive wear.

Question 6: What is the result if an aircraft is loaded with the CG forward of the forward limit?

Reduced stall speed and better spin recovery
Excessive nose-down tendency requiring full aft elevator to maintain level flight (Correct answer)
Better fuel burn at altitude
Improved cruise efficiency

Correct answer: Excessive nose-down tendency requiring full aft elevator to maintain level flight

A CG forward of the forward limit may exhaust available elevator authority, preventing the pilot from raising the nose for landing or recovery.

Question 7: What material are most aircraft hydraulic lines made of when routing through areas subject to vibration?

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

Correct answer: Flexible rubber hose reinforced with braided wire

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

Question 8: What is the purpose of a desiccant in an aircraft pneumatic system?

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

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

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

Question 9: How does technology impact modern hydraulic & pneumatic systems practices?

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)
Only large organizations benefit from technology in this field

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 10: An aircraft with an expired annual inspection is considered:

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

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

Only online networking has value
Networking is a waste of time for established professionals
Building relationships with peers enables knowledge sharing, professional development, and career advancement (Correct answer)
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 12: A mechanic's certificate, once issued, is:

Valid as long as annual recurrency training is completed
Valid only while employed by a certificated repair station
Valid for two years and must be renewed
Valid for life unless surrendered, suspended, or revoked (Correct answer)

Correct answer: Valid for life unless surrendered, suspended, or revoked

An FAA mechanic certificate is issued for life and does not expire; however, privileges can only be exercised if the currency requirements of 14 CFR 65.83 are met.

Question 13: Which type of damage to a composite structure is MOST difficult to detect visually?

Surface scratches and paint chips
Impact craters that dent the outer ply
Delamination beneath an intact surface skin (Correct answer)
Frayed edges at fastener holes

Correct answer: Delamination beneath an intact surface skin

Delamination (separation of plies) can exist beneath an undamaged-looking outer skin and requires tap testing or NDI methods to detect.

Question 14: 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 AC supersedes all manufacturer data
The repair is approved by the owner

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 15: What color is 100LL aviation gasoline (AVGAS) dyed, and why?

Red, to distinguish it from Jet-A
Blue, to identify it as 100 octane low lead and prevent misfueling with other grades (Correct answer)
Green, per FAA standard
Clear/colorless, undyed for purity

Correct answer: Blue, to identify it as 100 octane low lead and prevent misfueling with other grades

100LL AVGAS is dyed blue to identify it as 100 octane low lead fuel and prevent misfueling with Jet-A or other grades.

Question 16: What is the purpose of a bus bar in an aircraft electrical system?

To regulate voltage output from the alternator
To convert AC power to DC power
To distribute electrical power to multiple circuits from a common point (Correct answer)
To protect individual circuits from overcurrent

Correct answer: To distribute electrical power to multiple circuits from a common point

A bus bar serves as a common distribution point that connects multiple electrical circuits to a power source.

Question 17: Under 14 CFR 65.83, a certificated mechanic must have performed or supervised work in the aviation maintenance field within the preceding how many months to exercise certificate privileges?

36 months
12 months
6 months
24 months (Correct answer)

Correct answer: 24 months

14 CFR 65.83 requires mechanics to have performed or supervised at least 6 months of work within the preceding 24 months to exercise certificate privileges.

Question 18: During an aircraft weighing procedure, the tare weight refers to:

The structural weight of the landing gear
The empty weight before oil is added
The weight of chocks, stands, or equipment placed on the scales that must be subtracted (Correct answer)
The weight of the fuel remaining in the tanks

Correct answer: The weight of chocks, stands, or equipment placed on the scales that must be subtracted

Tare is the combined weight of any equipment (jacks, chocks, dollies) resting on the scales during weighing, which must be deducted from the scale readings.

Question 19: When fuel is burned during flight, how does the CG typically shift in a high-wing aircraft with wing tanks?

CG does not shift
CG moves forward (Correct answer)
CG moves up
CG moves aft

Correct answer: CG moves forward

In most high-wing designs, wing fuel is located forward of the CG, so as fuel burns off, the CG moves forward.

Question 20: Which risk assessment model used in aviation maintenance identifies likelihood and severity to prioritize hazards?

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

Correct answer: Risk matrix (likelihood × severity)

A risk matrix that evaluates both the likelihood of an event and its potential severity is the standard tool for prioritizing hazards in SMS and maintenance risk management.

Question 21: Which NDT method is most appropriate for detecting internal voids and delaminations in composite aircraft structures?

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

Correct answer: Ultrasonic inspection or tap testing

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

Question 22: FAA Form 337 (Major Repair and Alteration) must be submitted to the FAA within:

90 days of work completion
24 hours of return to service
Immediately before the first flight after the work
30 days of work completion (Correct answer)

Correct answer: 30 days of work completion

14 CFR 43.9 and related regulations require Form 337 to be submitted to the FAA Aircraft Registration Branch within 30 days after the work is approved for return to service.

Question 23: 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)
No advancement is possible beyond initial certification
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 24: What is the purpose of a fuel heat exchanger on a turbine aircraft?

To chill fuel for increased density and greater range
To use fuel to cool engine oil while also preventing fuel system icing by warming the fuel (Correct answer)
To separate water from fuel using temperature differential
To increase fuel temperature for improved combustion efficiency

Correct answer: To use fuel to cool engine oil while also preventing fuel system icing by warming the fuel

The fuel-oil heat exchanger cools hot engine oil using cooler fuel as the heat sink, simultaneously warming the fuel to prevent ice crystal formation in the fuel system.

Question 25: Which component in a pneumatic system performs the same function as a hydraulic system relief valve?

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

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

Worn main bearings
Clogged oil suction screen
Diluted oil from fuel contamination
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 27: Which organization publishes Service Bulletins (SBs) for type-certificated aircraft, and what is their regulatory status?

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

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 28: Under FAR Part 65, a mechanic certificate with both Airframe and Powerplant ratings is commonly referred to as:

Repairman
Designated mechanic examiner
A&P mechanic (Correct answer)
IA holder

Correct answer: A&P mechanic

A mechanic holding both the Airframe and Powerplant ratings under 14 CFR Part 65 is commonly called an A&P mechanic.

Question 29: An A&P mechanic with an Inspection Authorization (IA) may perform which of the following that a basic A&P may not?

Sign off 100-hour inspections
Approve major repairs and alterations for return to service (Correct answer)
Perform sheet metal repairs
Replace aircraft engines

Correct answer: Approve major repairs and alterations for return to service

An IA holder can approve major repairs and major alterations for return to service on certificated aircraft.

Question 30: According to 14 CFR Part 43.13, maintenance must be performed using methods, techniques, and practices that are acceptable to the FAA and:

Documented in the mechanic's personal logbook
Listed only in AC 43.13-1B regardless of the manufacturer's data
Described in the current manufacturer's maintenance manual or an equivalent accepted by the FAA (Correct answer)
Approved by the aircraft owner in writing

Correct answer: Described in the current manufacturer's maintenance manual or an equivalent accepted by the FAA

14 CFR 43.13 requires maintenance to be performed per the current manufacturer's maintenance manual or other methods, techniques, and practices acceptable to the FAA.

Question 31: 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)
24 months
It never expires
6 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 32: Which instrument uses a Wheatstone bridge circuit to measure fuel quantity?

The float-type fuel quantity system
The resistor-type fuel quantity system
The pressure-differential fuel system
The capacitance-type fuel quantity system (Correct answer)

Correct answer: The capacitance-type fuel quantity system

Capacitance-type fuel quantity systems use a Wheatstone bridge to compare capacitance values and determine fuel quantity accurately.

Question 33: What ethical standards guide ACS professionals in their work?

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

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 34: How do ACS professionals contribute to organizational success?

They only perform routine tasks with no strategic impact
Only executives contribute to organizational success
By applying specialized knowledge to solve problems, reduce risks, improve processes, and drive strategic outcomes (Correct answer)
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 35: Which wire gauge would be correct for a 20-ampere circuit run 15 feet in a non-bundle, non-conduit installation?

18 AWG
22 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 36: When inspecting control cable tension, you find the elevator cable is at 40 lbs when the maintenance manual specifies 50-70 lbs. What is required?

Document the finding and re-check at the next 100-hour inspection
The cable tension is acceptable as long as it is above 30 lbs
Adjust cable tension to within the specified range using the cable turnbuckles (Correct answer)
Replace the cables as worn cables cause low tension

Correct answer: Adjust cable tension to within the specified range using the cable turnbuckles

Flight control cables must be adjusted to within the manufacturer's specified tension range using the turnbuckles before the aircraft is returned to service.

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

Ultraviolet skin burns from the X-ray tube housing
Cumulative exposure to ionizing radiation increasing the risk of biological harm (Correct answer)
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 38: What is the purpose of a hydraulic system case drain line on a variable displacement piston pump?

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
Supply lubrication fluid to the pump shaft bearing from an external source
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 39: Which part of the maintenance manual specifies troubleshooting steps?

General Information section
Troubleshooting section (Correct answer)
Schematics section
Parts Catalog section

Correct answer: Troubleshooting section

The Troubleshooting section of the manual provides step-by-step diagnostic guidance.

Question 40: What is the most important ethical consideration for ACS professionals in hydraulic & pneumatic systems?

Sharing all client information publicly
Maximizing personal profit from each engagement
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 41: What is the purpose of a propeller reduction gearbox in a turboprop engine?

Increase shaft torque while decreasing rotational speed to drive accessories
Redirect thrust from the gas generator to the propeller shaft
Provide a mechanical connection between the N1 and N2 spools
Reduce turbine shaft RPM to a speed appropriate for efficient propeller operation (Correct answer)

Correct answer: Reduce turbine shaft RPM to a speed appropriate for efficient propeller operation

A reduction gearbox steps down the high RPM of the turbine shaft to the much lower RPM range (typically 1,000–2,000 RPM) at which a propeller operates most efficiently.

Question 42: The FAA's Aviation Safety Hotline (1-800-255-1111) is used to report:

Alleged violations of aviation regulations or safety concerns (Correct answer)
Near-midair collisions only
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 43: A fuselage frame made of 4130 steel tubing has a crack in a non-primary member. Which welding rod is most appropriate for repair?

ER4043
E308L
E6013
ER70S-2 (Correct answer)

Correct answer: ER70S-2

ER70S-2 is the correct TIG welding rod for 4130 chromoly steel airframe tubing repairs, providing compatible strength and weld characteristics.

Question 44: In ultrasonic testing, what is 'back-wall echo loss' an indication of?

Surface roughness causing signal scatter at the entry point only
Insufficient couplant application
Calibration error in the time base
A large internal discontinuity or severe attenuation blocking the return of the back-wall reflection (Correct answer)

Correct answer: A large internal discontinuity or severe attenuation blocking the return of the back-wall reflection

Loss of the back-wall echo indicates that a large internal flaw or severe attenuation is preventing the ultrasonic pulse from reaching and reflecting off the far wall of the test piece.

Question 45: Which tool is essential for checking the torque of aircraft fasteners?

Micrometer
Rivet gun
Torque wrench (Correct answer)
Caliper

Correct answer: Torque wrench

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

Question 46: What documentation is required when performing hydraulic & pneumatic systems work?

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

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

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

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

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

Correct answer: Surface cracks in non-ferromagnetic alloys such as aluminum and titanium

Eddy current testing works on all electrically conductive materials, including non-ferromagnetic alloys like aluminum and titanium, whereas magnetic particle inspection is limited to ferromagnetic materials.

Question 49: An engine cylinder head temperature (CHT) gauge shows one cylinder consistently 50°F hotter than the others in level cruise. What should be inspected first?

Valve timing on that cylinder
Fuel injector flow rate for that cylinder
Cylinder baffling and cooling fins for that cylinder (Correct answer)
Spark plug gap on that cylinder

Correct answer: Cylinder baffling and cooling fins for that cylinder

Damaged or missing baffling disrupts cooling airflow to individual cylinders and is the most common cause of a single cylinder running consistently hotter.

Question 50: What condition causes a hydraulic pump to cavitate?

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

Correct answer: Inlet pressure is too low, causing vapor bubbles to form in the fluid

Cavitation occurs when fluid pressure at the pump inlet drops below the fluid's vapor pressure, causing vapor bubbles to form and then violently collapse, damaging pump internals.

Question 51: When performing a dye penetrant inspection, what is the correct sequence of steps?

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

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

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

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

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

Question 53: Which document is the primary reference for an aircraft's approved weight and balance limits?

The aircraft maintenance logbook
The repair station's work order
The FAA-approved Airplane Flight Manual (AFM) or Pilot's Operating Handbook (POH) (Correct answer)
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 54: A Designated Engineering Representative (DER) has authority to:

Approve technical data for major repairs and alterations on behalf of the FAA (Correct answer)
Grant IA certificates to mechanics
Perform annual inspections on all aircraft types
Issue Airworthiness Directives

Correct answer: Approve technical data for major repairs and alterations on behalf of the FAA

DERs are delegated by the FAA to approve engineering data, which can serve as the approved data basis for major repairs and alterations.

Question 55: How should discrepancies be documented during inspection?

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

Correct answer: In maintenance logbooks

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

Question 56: In a pneumatic de-icing system, what is the function of a distributor valve?

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

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

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

Question 57: What component prevents an aircraft's structure from buckling under compressive loads?

Bulkheads
Ribs
Spars
Stringers (Correct answer)

Correct answer: Stringers

Stringers are structural elements that prevent buckling by reinforcing aircraft skin.

Question 58: What type of material is prohibited for use in aircraft fuel system tubing due to incompatibility with aviation fuels?

titanium
Aluminum alloy 5052
Galvanized steel tubing (Correct answer)
Stainless steel

Correct answer: Galvanized steel tubing

Galvanized steel is prohibited in fuel systems because zinc from the galvanizing reacts with tetraethyl lead in AVGAS to form lead compounds that clog filters and damage fuel system components.

Question 59: After completing a composite skin repair, what is the FIRST post-cure inspection step before returning the aircraft to service?

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

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

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

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

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

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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