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

Question 1: A mechanic who makes a maintenance error that goes undetected and results in an accident may face all of the following EXCEPT:

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

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 2: What information is required to be included in a maintenance record entry per 14 CFR 43.9?

Only the date and the technician's name
The aircraft registration number, work description, and owner's signature
A description of the work, date, aircraft total time, and the certificating person's signature and certificate number (Correct answer)
A description of the work and the repair station's name

Correct answer: A description of the work, date, aircraft total time, and the certificating person's signature and certificate number

14 CFR 43.9 requires the maintenance entry to include a description of the work, the date, total time in service, the approving person's signature, certificate number, and certificate type.

Question 3: Which type of hydraulic seal is most commonly used between two parts that have relative motion (dynamic application)?

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

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 4: What is the purpose of a firewall shutoff valve (fuel selector/firewall valve) in an aircraft fuel system?

To regulate fuel pressure to the engine
To filter fuel before it enters the engine
To balance fuel between left and right tanks
To allow the crew to stop fuel flow to the engine compartment in the event of an engine fire or fuel leak (Correct answer)

Correct answer: To allow the crew to stop fuel flow to the engine compartment in the event of an engine fire or fuel leak

The firewall shutoff valve allows the flight crew to cut fuel flow to the engine compartment to starve a fire or stop a fuel leak from reaching the engine bay.

Question 5: What does a sudden drop in fuel flow during an engine operational test with no corresponding change in throttle position indicate?

Fuel pump pressure exceeding regulator limits
Mixture control moved inadvertently
Idle cutoff valve partially engaging
Fuel vapor lock or cavitation in the fuel system (Correct answer)

Correct answer: Fuel vapor lock or cavitation in the fuel system

Vapor lock causes intermittent fuel starvation as fuel vaporizes in the fuel lines, creating a pocket that temporarily reduces liquid fuel flow.

Question 6: In ultrasonic testing, what is 'back-wall echo loss' an indication of?

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

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

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

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

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

Question 8: Which statement about aircraft control cable tension is correct?

Tension must be set at the temperature specified, with correction applied for ambient temperature using a rigging chart (Correct answer)
Cable tension should remain constant regardless of ambient temperature
Cable tension must be set at the highest expected temperature and checked cold
Cables should always be tensioned to the maximum allowable to prevent flutter

Correct answer: Tension must be set at the temperature specified, with correction applied for ambient temperature using a rigging chart

Control cable tension varies with temperature; a rigging chart must be used to apply temperature corrections so final tension is correct across the operating temperature range.

Question 9: In a wet layup repair, the pot life of a two-part epoxy refers to:

The time required to reach full cure at room temperature
The time needed before the part can be demolded
The time after mixing during which the resin remains usable for application (Correct answer)
The total shelf life of the unmixed components

Correct answer: The time after mixing during which the resin remains usable for application

Pot life is the working time after mixing during which viscosity remains low enough to wet out fabric and achieve consolidation before the resin gels.

Question 10: Which method is primarily used to detect corrosion on aircraft structures?

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

Correct answer: Visual inspection

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

Question 11: Which type of brake system uses a single-disc design with one puck-style actuating cylinder on each side?

Multiple-disc brake
Single-disc floating caliper brake (Correct answer)
Segmented rotor brake
Expander tube brake

Correct answer: Single-disc floating caliper brake

A single-disc floating caliper brake uses one rotor disc and a caliper that floats to apply equal pressure from both sides with pistons.

Question 12: What is the purpose of a hydraulic system case drain line on a variable displacement piston pump?

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

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

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

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

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

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

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

Question 15: What does a Special Airworthiness Certificate in the Experimental category allow an aircraft owner to do?

Conduct research, development, and flight testing outside standard category limitations (Correct answer)
Operate the aircraft in commercial air carrier service
Operate with unlimited passengers for hire
Bypass all Airworthiness Directives applicable to standard category aircraft

Correct answer: Conduct research, development, and flight testing outside standard category limitations

An Experimental certificate is issued for specific purposes such as research, development, and amateur-building, with operating limitations imposed by the FAA.

Question 16: What qualifications are needed for advanced aviation mechanics practice?

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

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

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

Question 17: Which rivet is used when access is available to only one side of the structure?

AN426 countersunk rivet
Blind rivet (such as a Cherry or Bulb-Tite) (Correct answer)
AN470 universal head rivet
Hi-Lok fastener installed from both sides

Correct answer: Blind rivet (such as a Cherry or Bulb-Tite)

Blind rivets are specifically designed to be installed from one side only, making them necessary when the back side of the structure is inaccessible.

Question 18: During a magneto timing check, the engine is rotated to find the firing position. What tool is commonly used to locate top dead center (TDC)?

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

Correct answer: Piston stop tool

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

Question 19: 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?

Fuel injector flow rate for that cylinder
Spark plug gap on that cylinder
Cylinder baffling and cooling fins for that cylinder (Correct answer)
Valve timing 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 20: During a structural inspection, a mechanic finds a corrosion pit in an aluminum structural member. Which measurement determines if the component remains airworthy?

The distance of the pit from the nearest fastener
The color and type of corrosion products present
The surface area of the corroded region
The depth of the pit compared to the material thickness and manufacturer's allowable limits (Correct answer)

Correct answer: The depth of the pit compared to the material thickness and manufacturer's allowable limits

Corrosion pit depth relative to material thickness is the critical measurement because excessive pitting reduces structural cross-section below allowable limits.

Question 21: 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
Drain only the affected sump and continue
Add fuel system icing inhibitor and return to service
Continue sampling and draining until no water is found, verifying the sample is clear (Correct answer)

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

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

Question 22: Which FAA publication is the primary source of guidance on human factors in aviation maintenance?

AC 65-31A
FAR Part 43
AC 43.13-1B
AC 120-72 (Correct answer)

Correct answer: AC 120-72

AC 120-72, Maintenance Resource Management Training, provides guidance on human factors principles applied to aviation maintenance.

Question 23: What is the purpose of a pneumatic system bootstrap reservoir?

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

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

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

Question 24: 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)
Continue operation but reduce system pressure by 10% to compensate
Add a chemical dispersant to the fluid to dissolve the particles

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 25: 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
Return it to the supplier for a refund
Test it and install if it passes

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.

Question 26: During a landing gear retraction test, the gear takes longer than the published time to retract. What is the FIRST area to check?

Gear door rigging and interference
Hydraulic system fluid level and accumulator pressure (Correct answer)
Actuator cylinder for internal leakage
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 27: What ethical standards guide ACS professionals in their work?

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

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 28: Under an SMS framework, a 'just culture' policy primarily aims to:

Standardize disciplinary procedures across all maintenance stations
Transfer liability for errors to the operator rather than the mechanic
Eliminate punishment for all maintenance errors
Differentiate between honest mistakes and reckless behavior to encourage reporting (Correct answer)

Correct answer: Differentiate between honest mistakes and reckless behavior to encourage reporting

Just culture distinguishes between unintentional errors and willful violations so that honest mistakes are treated with support and coaching, encouraging open reporting of safety concerns.

Question 29: 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)
Continue cranking to draw the fire into the engine while keeping the mixture rich
Immediately shut off fuel and use fire extinguisher on the engine

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 30: Before applying a chemical film treatment (Alodine/Iridite) to an aluminum repair part, the surface must be:

Primed with zinc chromate and allowed to dry completely
Roughened with 120-grit sandpaper to improve adhesion
Heated to 250°F to remove all moisture
Thoroughly cleaned and deoxidized to bare, active metal (Correct answer)

Correct answer: Thoroughly cleaned and deoxidized to bare, active metal

Chemical film treatments react with bare aluminum oxide; the surface must be completely clean and freshly deoxidized so the conversion coating bonds directly with the base metal.

Question 31: What color is 100LL aviation gasoline (AVGAS) dyed, and why?

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

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 32: 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 33: A fuselage frame made of 4130 steel tubing has a crack in a non-primary member. Which welding rod is most appropriate for repair?

E308L
ER70S-2 (Correct answer)
E6013
ER4043

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

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

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

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

Question 35: What documentation is required when performing hydraulic & pneumatic systems work?

Documentation is only needed if problems are found
Only a verbal summary to the supervisor
Detailed records of methods used, findings, conclusions, and supporting evidence (Correct answer)
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 36: During a ground run, manifold pressure is 2 inches Hg higher than standard atmosphere with the throttle closed. What does this indicate?

Manifold pressure gauge is miscalibrated
Supercharger is engaged
Throttle plate is not fully closing (Correct answer)
Intake air filter is clogged

Correct answer: Throttle plate is not fully closing

A throttle plate that does not fully close allows high-pressure air to leak into the intake manifold, raising manifold pressure above atmospheric.

Question 37: What is the purpose of a magnetic particle inspection on steel aircraft components?

To identify corrosion beneath paint coatings
To check material hardness and tensile strength
To detect surface and near-surface cracks in ferromagnetic materials (Correct answer)
To verify material composition and alloy type

Correct answer: To detect surface and near-surface cracks in ferromagnetic materials

Magnetic particle inspection reveals surface and near-surface discontinuities in ferromagnetic materials by attracting iron particles to areas where magnetic flux leaks at defects.

Question 38: A TSO authorization granted to a manufacturer signifies that the article:

Has been approved for installation on any aircraft
Is exempt from AD compliance
Meets the minimum performance standards of the TSO (Correct answer)
Has been certified for 10,000 flight hours

Correct answer: Meets the minimum performance standards of the TSO

A TSO authorization means the article was produced to meet FAA minimum performance standards, but installation approval is still required.

Question 39: What is the scope of practice for ACS certification in hydraulic & pneumatic systems?

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
The scope is determined individually by each professional

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

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

Correct answer: Monitoring safety performance and verifying controls remain effective

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

Question 41: A mechanic finds exfoliation corrosion on an aluminum alloy wing spar cap. What action is required?

Treat with Alodine and apply primer immediately
Clean, treat, and determine if remaining material meets minimum thickness per SRM (Correct answer)
Remove the spar cap and replace it
Polish smooth, apply zinc chromate, and return to service

Correct answer: Clean, treat, and determine if remaining material meets minimum thickness per SRM

Exfoliation corrosion causes layer-by-layer material loss; the mechanic must clean, treat, measure the remaining material, and compare it to the SRM minimum thickness allowable to determine airworthiness.

Question 42: An engine is returned to service after overhaul. During the test run, EGT is higher than normal but RPM and manifold pressure are normal. What is the MOST likely cause?

A clogged exhaust stack is restricting outflow and backing heat into the cylinder
Mixture is running too rich, causing incomplete combustion and elevated exhaust temperatures (Correct answer)
The EGT probe calibration was not checked after overhaul and reads erroneously high
Timing is advanced too far, causing the flame front to arrive too early in the cycle

Correct answer: Mixture is running too rich, causing incomplete combustion and elevated exhaust temperatures

An over-rich mixture results in incomplete combustion with excess unburned fuel entering the exhaust, elevating EGT; with normal power output (RPM/MP), the fuel/air ratio is the most likely variable.

Question 43: According to 14 CFR Part 39, an Airworthiness Directive (AD) that requires compliance within a specific number of hours time-in-service must be complied with:

At the next scheduled maintenance interval after the hours are accumulated
At the owner's discretion within one year of the effective date
Within 30 days of the AD's effective date regardless of hours
Before exceeding the specified hours time-in-service (Correct answer)

Correct answer: Before exceeding the specified hours time-in-service

ADs with hour-based compliance requirements must be accomplished before the aircraft exceeds the specified time-in-service threshold.

Question 44: 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 remove water and sediment from fuel before it reaches the carburetor or fuel injector (Correct answer)
To regulate fuel pressure to the engine

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

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

Question 45: Which formula correctly expresses the relationship used to find CG from weight and moment data?

CG = Total Moment ÷ Total Weight (Correct answer)
CG = Total Moment × Total Weight
CG = Total Weight ÷ Total Moment
CG = Weight × Moment

Correct answer: CG = Total Moment ÷ Total Weight

CG arm = Total Moment divided by Total Weight, giving the CG location in inches from the datum.

Question 46: Which document outlines the maintenance requirements for U.S. aircraft?

Title 14 CFR Part 145
Title 14 CFR Part 91
Title 14 CFR Part 65
Title 14 CFR Part 43 (Correct answer)

Correct answer: Title 14 CFR Part 43

Title 14 CFR Part 43 details maintenance, preventive maintenance, rebuilding, and alteration regulations.

Question 47: MRM (Maintenance Resource Management) training is analogous to CRM (Crew Resource Management) for pilots and focuses on:

Optimizing human performance and team communication to reduce maintenance errors (Correct answer)
Improving tool inventory and parts tracking systems
Certifying mechanics in advanced avionics troubleshooting
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 48: A Designated Engineering Representative (DER) has authority to:

Grant IA certificates to mechanics
Approve technical data for major repairs and alterations on behalf of the FAA (Correct answer)
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 49: When bleeding an aircraft hydraulic system, why is it important to work from the component farthest from the reservoir first?

To allow gravity to pull fluid through the system naturally
To protect the reservoir from contamination during bleeding
To purge all air systematically toward the reservoir and prevent air pockets (Correct answer)
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 50: What is the purpose of an aircraft's essential (emergency) bus?

To start the engine in case of battery failure
To supply power to cabin entertainment systems
To power all avionics during normal operations
To provide power to critical flight instruments and navigation equipment when the main bus fails (Correct answer)

Correct answer: To provide power to critical flight instruments and navigation equipment when the main bus fails

The essential bus maintains power to flight-critical instruments and navigation equipment even if the main electrical bus fails.

Question 51: What is the purpose of a fuel heat exchanger on a turbine aircraft?

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

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

Regulations never change once established
Regulatory changes require updating practices, procedures, and documentation to maintain compliance (Correct answer)
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 53: What does a hydraulic snubber do in a pressure gauge line?

Filters contamination out of the fluid sample going to the gauge
Amplifies small pressure changes to improve gauge sensitivity
Dampens pressure surges to protect the gauge and provide a steady reading (Correct answer)
Prevents fluid from flowing backward through the gauge during pressure drops

Correct answer: Dampens pressure surges to protect the gauge and provide a steady reading

A snubber is a small orifice or restriction that dampens rapid pressure pulsations, protecting the gauge bourdon tube from fatigue damage and providing a readable steady indication.

Question 54: After engine overhaul, a break-in run is performed. What oil type should NOT be used during engine break-in?

Multi-viscosity mineral oil
Synthetic oil (Correct answer)
Straight mineral oil
Ashless dispersant 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 55: According to 14 CFR Part 91.417, how long must an aircraft owner retain records of the current status of applicable Airworthiness Directives?

Until the next annual inspection
For one year from the date of AD compliance
Indefinitely for the life of the aircraft
Until the AD is superseded or the aircraft is sold (Correct answer)

Correct answer: Until the AD is superseded or the aircraft is sold

Records showing compliance with ADs, including recurring ADs, must be retained until the work is superseded by work of equal or greater scope or the aircraft is sold.

Question 56: When may a certificated mechanic return an aircraft to service after performing a major alteration?

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

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 57: Which part of the maintenance manual specifies troubleshooting steps?

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

Correct answer: Troubleshooting section

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

Question 58: To exercise Inspection Authorization (IA) privileges, a mechanic must hold an IA for at least how long before it must be renewed?

It never expires
24 months
6 months
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 59: Which NDT method is LEAST effective for detecting defects in non-metallic composite materials?

Magnetic particle inspection (Correct answer)
Radiographic inspection
Ultrasonic testing
Thermographic inspection

Correct answer: Magnetic particle inspection

Magnetic particle inspection requires the material to be ferromagnetic; composite materials are non-metallic and non-ferromagnetic, making MPI completely ineffective for composites.

Question 60: When removing paint before a composite repair, the preferred method over mechanical sanding is:

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

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.

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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