By Ohm's law, what voltage drives 2 amperes through a 6-ohm resistance?
ACS code: AM.G.EL.K1
Correct answer: 12 volts
Rationale: E = I × R = 2 A × 6 Ω = 12 V.
FAA General Written Test Prep
The Aviation Mechanic General test (FAA test code AMG) is the first of the three knowledge tests on the way to an A&P certificate, and the one every applicant sits regardless of which rating they are after. It is 60 multiple-choice questions in two hours, and you need 70 percent to pass. This page covers what the test actually asks, the twelve ACS subject areas it draws from, where candidates lose points, and free practice questions with worked rationales.
Written by the AMTprep editorial team · Published · Last reviewed
Written against the FAA primary sources cited at the foot of this page.
- FAA test code
- AMG
- Questions
- 60
- Time limit
- 2 hours
- Pass mark
- 70%
- Results valid
- 24 months
What is on the General written test
The General test covers the knowledge every certificated mechanic needs before the airframe/powerplant split matters, and it maps to the twelve subject areas in Section I of the FAA Aviation Mechanic Airman Certification Standards (FAA-S-ACS-1). Those areas are electricity and electronics, aircraft drawings, weight and balance, fluid lines and fittings, materials and hardware and processes, ground operations and servicing, cleaning and corrosion control, mathematics, regulations and maintenance forms and records and publications, physics for aviation, inspection concepts and techniques, and human factors.
The reference text is the Aviation Maintenance Technician Handbook — General, FAA-H-8083-30B. It is public-domain and free from the FAA, and the question bank tracks it closely enough that a chapter of the handbook and an ACS subject area are effectively the same body of material. Two of the twelve areas — electricity and mathematics — produce a disproportionate share of the questions, and both are computational, which is why they are also where most of the recoverable marks sit.
The questions themselves are recall or single-step application. You will be asked to compute a current from a voltage and a resistance, find a center of gravity from a weight and a moment, name a line type on a drawing, identify a bolt from its head markings, say which record a maintenance entry belongs in, or recognise a form of corrosion from its description. Nothing on the General test is a multi-stage design problem, and no formula sheet is provided.
How the test is administered and scored
The three mechanic knowledge tests are computer-based and delivered at FAA-authorized testing centers operated by PSI. You register with PSI, pick a center and a slot, and sit the test on their equipment. Check the current fee with PSI directly — it has moved more than once and any figure quoted on a prep site goes stale.
The General test gives you 60 questions and two hours. That is two minutes per question, which is generous for this material: most candidates who fail run out of knowledge, not clock. Scoring is a straight percentage of questions answered correctly, and 70 percent is the pass mark — so on a 60-question test you can miss 18 and still pass. There is no separate per-subject pass requirement; a bad run in one area can be carried by the rest.
You get your result immediately, printed as an Airman Knowledge Test Report (AKTR). Keep it: the AKTR is the document your Designated Mechanic Examiner will want at the oral and practical, and it is valid for 24 calendar months. If you pass the General in January and let two years elapse without completing the oral and practical, that pass expires and you sit it again.
The AKTR also lists an ACS code for every question you got wrong. Those codes are not decoration — the DME is required to re-examine you on each subject area they name during the oral and practical, so the report is simultaneously your score, your study list, and a preview of the examiner's opening questions.
Where candidates lose points on the General
Three patterns account for most General failures, and none of them is about intelligence.
The first is arithmetic done under time pressure with a formula recalled backwards. Ohm's law and the weight-and-balance relationships are simple, but the test writes stems that invert them: you are given a moment and a weight and asked for an arm, or given a total resistance and asked for one branch. Candidates who memorised one arrangement of E = I × R rather than all three lose points they already knew the physics for.
The second is vocabulary treated as approximate. The General test is unusually strict about definitions. Tare weight, datum, useful load, and empty weight all have exact meanings on a weighing sheet; hidden lines and centerlines are both broken lines with different meanings; a blueprint in the test's usage is a specific reproduction process, not any drawing. The distractors are written by people who know precisely which pairs of terms candidates blur.
The third is regulatory material studied as trivia instead of as structure. Part 43 and Part 65 questions are not asking you to quote section numbers. They are asking who may perform a task, who may approve it for return to service, what has to be recorded, and where. Learn the shape of the privilege — mechanic, repairman, IA, pilot-owner — and the individual questions resolve themselves.
How to study for it
Work the ACS, not a book cover to cover. The subject areas are the unit the FAA writes questions against and the unit your fail report will name, so studying by area lets you measure progress in the same currency the test uses.
A workable sequence: take a diagnostic run across all twelve areas to find your real weak points rather than your assumed ones, then drill the weakest three or four until you are consistently above 85 percent on them, then rotate the rest to keep them warm. Leave the two computational areas — electricity and mathematics — until you can do them without hesitation, because they are the ones that reward repetition most and the only ones where speed matters.
Read the rationale on every question you get wrong and on every question you got right by guessing. The rationale is where the transferable knowledge is; the individual question is disposable. If a rationale cites a handbook section you do not recognise, go read that section of FAA-H-8083-30B before moving on. This is the single habit that separates candidates who pass on the first attempt from candidates who plateau in the low 60s.
Aim to be scoring 85 percent or better in practice before you book. The 70 percent pass mark has no margin in it for a bad night, an unfamiliar phrasing, or the two or three questions on every form that are simply harder than the rest.
What to bring on test day
Bring a government-issued photo identification that shows your name, date of birth, signature, and a physical residential address. PSI will not seat you without it, and a passport without an address on it has turned candidates away — bring a second document if your primary ID lacks any of those four items.
You do not need to bring a calculator. The testing center supplies an on-screen calculator and permits certain basic models, but the rules on what you may carry in change, so confirm with PSI when you book rather than arriving with a device that has to go in a locker. Scratch paper and something to write with are provided; you may not bring your own.
Nothing else comes into the room — no phone, no watch, no notes, no handbook. Plan for the check-in process to take longer than you expect and arrive early enough that you are not still catching your breath when the clock starts.
When you finish, you will be handed the AKTR before you leave the building. Read it in the car park while it is fresh: the ACS codes on it are the study plan for whichever test you take next, and if you failed, they are the specific subject areas you have to fix before you can book again.
The ACS subject areas this test draws from
Every question on the General test is tagged to one of these subject areas, and so is every code that appears on your Airman Knowledge Test Report. Each page below explains what that area covers, its FAA handbook reference, the traps candidates fall into, and free practice questions drawn from the same bank.
- Fundamentals of Electricity and Electronics (AM.I.A)
- Aircraft Drawings (AM.I.B)
- Weight and Balance (AM.I.C)
- Fluid Lines and Fittings (AM.I.D)
- Aircraft Materials, Hardware, and Processes (AM.I.E)
- Ground Operations and Servicing (AM.I.F)
- Cleaning and Corrosion Control (AM.I.G)
- Mathematics (AM.I.H)
- Regulations, Maintenance Forms, Records, and Publications (AM.I.I)
- Physics for Aviation (AM.I.J)
- Inspection Concepts and Techniques (AM.I.K)
- Human Factors (AM.I.L)
40 free General practice questions
Tap an answer to reveal the correct choice and its worked rationale. Every question carries its ACS code and FAA handbook reference, so a miss tells you exactly which subject area to go and read.
- AM.G.EL.K1Tap an answer
By Ohm's law, what voltage drives 2 amperes through a 6-ohm resistance?
- AM.G.PH.K1Tap an answer
What is the standard atmospheric pressure at sea level, in inches of mercury?
- AM.G.WB.K1Tap an answer
An aircraft's center of gravity is the point at which the aircraft would:
- AM.I.ATap an answer
According to Ohm's law, what current flows in a circuit having a 12-volt source connected across a 6-ohm resistance?
- AM.I.BTap an answer
On an aircraft drawing, what is the purpose of the title block?
- AM.I.CTap an answer
The center of gravity (CG) of an aircraft is best described as the point where the aircraft would
- AM.I.DTap an answer
What color marking on aircraft tubing identifies it as fabricated from aluminum alloy that should be used for that application?
- AM.I.ETap an answer
When installing a standard AN bolt with a self-locking nut in a joint subject to tension loads, what is the proper thread engagement requirement?
- AM.I.FTap an answer
When approaching a turbine-powered aircraft for ground servicing, the area that presents the greatest hazard to personnel is the
- AM.I.GTap an answer
What two conditions must be present for galvanic corrosion to occur between two pieces of metal?
- AM.I.HTap an answer
A rectangular fuel tank measures 30 inches long, 20 inches wide, and 12 inches deep. What is its volume in cubic inches?
- AM.I.ITap an answer
An aircraft maintenance record entry for a completed repair must include which of the following?
- AM.I.JTap an answer
What is the relationship between absolute pressure, gauge pressure, and atmospheric pressure?
- AM.I.KTap an answer
When performing nondestructive inspection, which method is best suited for detecting surface and slightly subsurface cracks in ferromagnetic steel parts?
- AM.I.LTap an answer
In aviation maintenance human factors, what is the meaning of the term "Dirty Dozen"?
- AM.I.ATap an answer
In a series circuit containing three resistors, how does the current compare at different points in the circuit?
- AM.I.BTap an answer
A drawing prepared by passing light through a tracing onto sensitized paper, producing white lines on a blue background, is called a:
- AM.I.CTap an answer
The moment of an item in a weight and balance computation is found by
- AM.I.DTap an answer
When fabricating a replacement rigid fluid line, the bend radius should be kept as large as practical primarily to prevent which condition?
- AM.I.ETap an answer
Why should the threaded portion of a bolt, rather than the grip, never bear the shear load in a joint?
- AM.I.FTap an answer
When a fuel truck is used to refuel an aircraft, the bonding cable is connected primarily to
- AM.I.GTap an answer
When two dissimilar metals form a galvanic couple in the presence of an electrolyte, which metal corrodes?
- AM.I.HTap an answer
A gear ratio is given as 3 to 1. If the driving gear turns 1,500 rpm, how fast does the driven gear turn when the ratio reduces speed?
- AM.I.ITap an answer
How long must a record of maintenance performed on an aircraft be retained under 14 CFR Part 91?
- AM.I.JTap an answer
According to Boyle's law, if the volume of a confined gas is decreased while temperature is held constant, the pressure of the gas will
- AM.I.KTap an answer
Liquid penetrant inspection is capable of detecting defects only when those defects are:
- AM.I.LTap an answer
Which of the following is a recognized item in the Dirty Dozen list of human-factors error precursors?
- AM.I.ATap an answer
What is the total resistance of two 10-ohm resistors connected in parallel?
- AM.I.BTap an answer
On an aircraft drawing, a hidden line (a line that is out of view) is represented by a:
- AM.I.CTap an answer
An aircraft has a total weight of 4,000 pounds and a total moment of 600,000 inch-pounds. The center of gravity is located at
- AM.I.DTap an answer
A flared tube fitting forms its fluid-tight seal at which location?
- AM.I.ETap an answer
What is the primary purpose of using a cotter pin with a castellated (castle) nut on a bolt?
- AM.I.FTap an answer
Which color marking on a fire extinguisher background identifies it as suitable for use on a Class B (flammable liquid) fire?
- AM.I.GTap an answer
Corrosion that attacks along the grain boundaries of an alloy, often from improper heat treatment, is called
- AM.I.HTap an answer
Convert the fraction 5/8 to a decimal.
- AM.I.ITap an answer
Compliance with an Airworthiness Directive (AD) is the responsibility of the
- AM.I.JTap an answer
Which statement correctly describes the heat transfer method known as convection?
- AM.I.KTap an answer
Which inspection method uses high-frequency sound waves to locate internal flaws and measure the thickness of a part?
- AM.I.LTap an answer
A technician fails to pass along information about an unfinished task to the next shift, and a step is left incomplete. Which Dirty Dozen factor most directly applies?
- AM.I.ATap an answer
How should a voltmeter be connected to measure the voltage drop across a resistor?
What is the standard atmospheric pressure at sea level, in inches of mercury?
ACS code: AM.G.PH.K1
Correct answer: 29.92 inHg
Rationale: ICAO standard sea-level pressure is 29.92 inHg (1013.25 hPa).
An aircraft's center of gravity is the point at which the aircraft would:
ACS code: AM.G.WB.K1
Correct answer: balance if suspended
Rationale: The CG is the point about which the aircraft would balance if suspended.
According to Ohm's law, what current flows in a circuit having a 12-volt source connected across a 6-ohm resistance?
ACS code: AM.I.A
Correct answer: 2 amperes.
Rationale: Ohm's law states I = E/R. Dividing the 12-volt source by the 6-ohm resistance gives 12 / 6 = 2 amperes. The 18-ampere choice incorrectly adds voltage and resistance, and 72 amperes incorrectly multiplies them.
On an aircraft drawing, what is the purpose of the title block?
ACS code: AM.I.B
Correct answer: To identify the drawing by number, name, scale, and date
Rationale: The title block is normally located in the lower right corner of a drawing and contains the drawing number, the name of the part or assembly, the scale, the drafting date, and the name of the firm. It identifies the drawing so it can be filed and retrieved. The list of changes belongs in the revision block, and parts are listed in the bill of materials, not the title block.
The center of gravity (CG) of an aircraft is best described as the point where the aircraft would
ACS code: AM.I.C
Correct answer: balance if it were suspended
Rationale: The center of gravity is the point about which the nose-heavy and tail-heavy moments are exactly equal; it is the point at which the aircraft would balance if suspended. It is found by dividing total moment by total weight. The other options describe stall behavior and ground contact, which are unrelated to the definition of CG.
What color marking on aircraft tubing identifies it as fabricated from aluminum alloy that should be used for that application?
ACS code: AM.I.D
Correct answer: A stamped code and color band identifying the alloy
Rationale: Aircraft metal tubing is identified by markings stamped or coded on the tube indicating the material and, for aluminum alloy tubing, color bands or codes that identify the specific alloy (such as 1100, 3003, 5052, or 6061). A mechanic must verify the correct material before installation because each alloy has different strength and corrosion characteristics. There is no convention of a single full-length red stripe or a generic yellow end band serving as the material identifier.
When installing a standard AN bolt with a self-locking nut in a joint subject to tension loads, what is the proper thread engagement requirement?
ACS code: AM.I.E
Correct answer: At least one thread of the bolt must extend beyond the nut.
Rationale: FAA guidance requires that a bolt of correct length show at least one thread (including the chamfer) extending past the nut after tightening. A bolt threaded flush or short of the nut may not be fully engaged, and stating 'three threads inside the nut' does not address the visible-thread inspection standard used to verify correct grip length.
When approaching a turbine-powered aircraft for ground servicing, the area that presents the greatest hazard to personnel is the
ACS code: AM.I.F
Correct answer: intake suction zone at the front of the engine
Rationale: An operating turbine engine creates a powerful intake suction zone in front of the inlet capable of pulling personnel and loose objects into the engine. This intake hazard area (along with the rear exhaust blast) is the primary danger when working around running turbine engines. Static ports and pitot tubes are sensing instruments, not personnel ingestion hazards.
What two conditions must be present for galvanic corrosion to occur between two pieces of metal?
ACS code: AM.I.G
Correct answer: Dissimilar metals in contact and the presence of an electrolyte
Rationale: Galvanic corrosion is an electrochemical action that requires two dissimilar metals in electrical contact and an electrolyte (such as moisture) to complete the circuit. The greater the difference in electrical potential between the two metals on the galvanic series, the faster the more active (anodic) metal corrodes. Identical metals have no potential difference, and without an electrolyte the corrosion cell cannot form.
A rectangular fuel tank measures 30 inches long, 20 inches wide, and 12 inches deep. What is its volume in cubic inches?
ACS code: AM.I.H
Correct answer: 7,200 cubic inches
Rationale: The volume of a rectangular solid equals length times width times height. Here 30 x 20 x 12 = 7,200 cubic inches. The 3,600 value comes from omitting one dimension, and 600 is only length times width, which gives surface area of one face, not volume.
An aircraft maintenance record entry for a completed repair must include which of the following?
ACS code: AM.I.I
Correct answer: A description of the work, the date, and the signature and certificate number of the person approving return to service
Rationale: Under 14 CFR 43.9, a maintenance record entry for maintenance, preventive maintenance, or alteration must contain a description of the work performed, the date of completion, and the name plus signature and certificate number of the person approving the aircraft for return to service. The owner does not sign off the work, and removed-part serial numbers are not a required element of the basic record entry.
What is the relationship between absolute pressure, gauge pressure, and atmospheric pressure?
ACS code: AM.I.J
Correct answer: Absolute pressure equals gauge pressure plus atmospheric pressure
Rationale: Gauge pressure is measured relative to ambient atmospheric pressure (a gauge reads zero when open to the atmosphere). To obtain absolute pressure, which is measured from a perfect vacuum, you add the atmospheric pressure to the gauge reading. The handbook's physics chapter defines absolute pressure as gauge pressure plus atmospheric pressure.
When performing nondestructive inspection, which method is best suited for detecting surface and slightly subsurface cracks in ferromagnetic steel parts?
ACS code: AM.I.K
Correct answer: magnetic particle inspection
Rationale: Magnetic particle inspection relies on magnetizing a ferromagnetic part so that a crack distorts the magnetic field and creates leakage fields that attract iron particles, revealing the flaw. Because it works only on materials that can be magnetized, it is the preferred method for steel parts and can show surface and slightly subsurface defects. Liquid penetrant detects only flaws open to the surface, and ultrasonic gauging is primarily used to measure thickness rather than reveal small cracks visually.
In aviation maintenance human factors, what is the meaning of the term "Dirty Dozen"?
ACS code: AM.I.L
Correct answer: Twelve common human-factors conditions that contribute to maintenance errors
Rationale: The "Dirty Dozen" is a well-known list of twelve human-factors conditions (such as lack of communication, complacency, fatigue, and distraction) that can act as precursors to maintenance errors. The handbook discusses these as the most common contributors to mistakes in the maintenance environment, so recognizing and guarding against them is central to error prevention.
In a series circuit containing three resistors, how does the current compare at different points in the circuit?
ACS code: AM.I.A
Correct answer: It is the same through every resistor.
Rationale: A series circuit provides only one path for current flow, so the same current passes through every component. Voltage divides across the resistors in proportion to their values, but the current is identical at all points, as described for series circuits in the handbook.
A drawing prepared by passing light through a tracing onto sensitized paper, producing white lines on a blue background, is called a:
ACS code: AM.I.B
Correct answer: Blueprint
Rationale: The term blueprint comes from the original reproduction process that produced white lines on a blue background. The handbook notes that although modern copies are often black-on-white, the term blueprint is still used for working drawings. A schematic shows function rather than physical form, and a pictorial gives a three-dimensional view, so neither describes the reproduction process.
The moment of an item in a weight and balance computation is found by
ACS code: AM.I.C
Correct answer: multiplying the weight by its arm
Rationale: Moment equals weight multiplied by arm, expressed in inch-pounds. This is the basic relationship used to build a weight and balance computation, where the total moment is divided by total weight to find the CG. Dividing or subtracting the values does not yield a valid moment and would produce incorrect balance results.
When fabricating a replacement rigid fluid line, the bend radius should be kept as large as practical primarily to prevent which condition?
ACS code: AM.I.D
Correct answer: Flattening or wrinkling of the tube wall
Rationale: Bends in metal tubing must be made with as large a radius as practical, and tube benders are used so the tube is not flattened, wrinkled, or kinked. A flattened or wrinkled bend restricts flow and creates a stress concentration that can lead to cracking. Bend radius does not control fitting-nut tension, and the weight difference between a tight and generous bend is negligible.
Why should the threaded portion of a bolt, rather than the grip, never bear the shear load in a joint?
ACS code: AM.I.E
Correct answer: Threads concentrate stress and reduce the effective cross-sectional area in shear.
Rationale: A bolt's grip is the smooth, full-diameter shank designed to carry shear. The threaded section has a smaller root diameter and the thread roots act as stress risers, so loading threads in shear weakens the joint. Threads are not specially case-hardened to brittleness, and the nut does not carry the joint's shear load.
When a fuel truck is used to refuel an aircraft, the bonding cable is connected primarily to
ACS code: AM.I.F
Correct answer: equalize the static charge between the truck and aircraft
Rationale: Bonding connects the fueling equipment and the aircraft so they are at the same electrical potential, preventing a static spark from igniting fuel vapors as fuel flows. The cable does not transfer operating power or ground the battery; its sole purpose is static charge equalization during fueling.
When two dissimilar metals form a galvanic couple in the presence of an electrolyte, which metal corrodes?
ACS code: AM.I.G
Correct answer: The more anodic (more active) metal
Rationale: In a galvanic couple the more active metal becomes the anode and corrodes, while the less active metal becomes the cathode and is protected. This is why coupling a small area of anodic metal to a large cathodic area produces rapid, severe attack on the anode. Identifying the anodic member of the pair on the galvanic series predicts which part will deteriorate.
A gear ratio is given as 3 to 1. If the driving gear turns 1,500 rpm, how fast does the driven gear turn when the ratio reduces speed?
ACS code: AM.I.H
Correct answer: 500 rpm
Rationale: A 3-to-1 reduction means the output turns one-third as fast as the input. Dividing 1,500 by 3 gives 500 rpm. Multiplying by 3 (4,500) would be a speed increase, and 1,500 would mean no ratio change at all.
How long must a record of maintenance performed on an aircraft be retained under 14 CFR Part 91?
ACS code: AM.I.I
Correct answer: Until the work is repeated, superseded, or for one year after the work is performed
Rationale: Per 14 CFR 91.417, records of maintenance, preventive maintenance, and alterations must be retained until the work is repeated, superseded by other work, or for one year after the work is performed. The total-time and inspection-status records are kept permanently and transferred with the aircraft, but the individual maintenance record itself follows the one-year rule.
According to Boyle's law, if the volume of a confined gas is decreased while temperature is held constant, the pressure of the gas will
ACS code: AM.I.J
Correct answer: increase
Rationale: Boyle's law states that, at constant temperature, the pressure of a confined gas is inversely proportional to its volume (P x V = constant). Reducing the volume forces the same number of gas molecules into a smaller space, so they strike the container walls more often, raising the pressure.
Liquid penetrant inspection is capable of detecting defects only when those defects are:
ACS code: AM.I.K
Correct answer: open to the surface of the part
Rationale: Liquid penetrant inspection works by drawing dye into a discontinuity by capillary action, then drawing it back out with a developer to form a visible indication. The dye can only enter a flaw that breaks the surface, so the method finds only surface-connected defects. Subsurface flaws and any defect hidden under paint or primer cannot trap or release penetrant and so go undetected.
Which of the following is a recognized item in the Dirty Dozen list of human-factors error precursors?
ACS code: AM.I.L
Correct answer: Complacency
Rationale: Complacency is one of the twelve human-factors conditions in the Dirty Dozen. It describes a state of self-satisfaction and reduced alertness, often caused by repetition of familiar tasks, that can lead a technician to overlook a problem. Calibration and certification are technical or administrative concepts, not human-factors precursors.
What is the total resistance of two 10-ohm resistors connected in parallel?
ACS code: AM.I.A
Correct answer: 5 ohms.
Rationale: For two equal resistors in parallel, total resistance equals the value of one resistor divided by the number of resistors: 10 / 2 = 5 ohms. Parallel resistance is always less than the smallest individual resistor, so 10 ohms or 20 ohms cannot be correct.
On an aircraft drawing, a hidden line (a line that is out of view) is represented by a:
ACS code: AM.I.B
Correct answer: Series of short dashes
Rationale: Hidden lines represent edges and surfaces that are not visible from the viewing direction and are drawn as a series of short evenly spaced dashes. A heavy solid line is a visible (object) line, and a line of alternating long dashes and dots is a centerline. Recognizing line conventions is essential to reading a drawing correctly.
An aircraft has a total weight of 4,000 pounds and a total moment of 600,000 inch-pounds. The center of gravity is located at
ACS code: AM.I.C
Correct answer: 150 inches from the datum
Rationale: The CG is found by dividing total moment by total weight: 600,000 ÷ 4,000 = 150 inches from the datum. The other answers result from incorrect arithmetic, such as using the wrong divisor, and do not satisfy the moment-divided-by-weight relationship.
A flared tube fitting forms its fluid-tight seal at which location?
ACS code: AM.I.D
Correct answer: Between the flare cone and the fitting seat
Rationale: In an AN/MS flared fitting, the tube end is flared to a cone, and the seal is made where that flared cone is compressed against the mating cone-shaped seat of the fitting by the sleeve and coupling nut. The coupling-nut threads only provide the clamping force; they do not seal. The sleeve backs up the flare but does not itself form the fluid-tight joint.
What is the primary purpose of using a cotter pin with a castellated (castle) nut on a bolt?
ACS code: AM.I.E
Correct answer: To prevent the nut from rotating off the bolt.
Rationale: A cotter pin passes through the slots of a castellated nut and a hole in the bolt to positively lock the nut against rotation. It is a mechanical safety device, not a means of adding clamping force or sealing threads; the torque on the nut establishes clamp load.
Which color marking on a fire extinguisher background identifies it as suitable for use on a Class B (flammable liquid) fire?
ACS code: AM.I.F
Correct answer: A red square containing the letter B
Rationale: The fire-class symbol system marks Class B (flammable liquids, such as fuel and oil) with a red square. Class A uses a green triangle and Class C uses a blue circle. Knowing these markings lets the technician select the correct extinguisher for a fuel or oil fire during ground operations.
Corrosion that attacks along the grain boundaries of an alloy, often from improper heat treatment, is called
ACS code: AM.I.G
Correct answer: intergranular corrosion
Rationale: Intergranular corrosion is an attack along the grain boundaries of an alloy, frequently the result of a lack of uniformity in the alloy structure caused by improper or interrupted heat treatment. Because it follows the boundaries between grains, it can progress deep into the metal with little visible surface evidence, making it especially dangerous.
Convert the fraction 5/8 to a decimal.
ACS code: AM.I.H
Correct answer: 0.625
Rationale: A fraction is converted to a decimal by dividing the numerator by the denominator: 5 divided by 8 equals 0.625. The 0.580 value simply re-reads the digits as a decimal, and 1.600 is the result of dividing 8 by 5, which inverts the fraction.
Compliance with an Airworthiness Directive (AD) is the responsibility of the
ACS code: AM.I.I
Correct answer: aircraft owner or operator
Rationale: Under 14 CFR 39 and 91.403, the owner or operator is primarily responsible for maintaining the aircraft in an airworthy condition, which includes ensuring compliance with all applicable Airworthiness Directives. The manufacturer issues service information and the FSDO provides oversight, but neither is responsible for AD compliance on a specific aircraft.
Which statement correctly describes the heat transfer method known as convection?
ACS code: AM.I.J
Correct answer: Heat transfer by the circulation of a heated fluid or gas
Rationale: Convection is the transfer of heat by the movement of a heated fluid or gas; warmer, less dense fluid rises and cooler fluid moves in to replace it, creating circulation. Conduction is transfer through direct contact, and radiation is transfer by electromagnetic waves, so those describe the other two heat-transfer methods.
Which inspection method uses high-frequency sound waves to locate internal flaws and measure the thickness of a part?
ACS code: AM.I.K
Correct answer: ultrasonic inspection
Rationale: Ultrasonic inspection introduces high-frequency sound waves into a part and analyzes the energy that reflects from the back surface or from an internal discontinuity, allowing both flaw detection and thickness measurement. Eddy current uses induced electrical currents rather than sound, and radiographic inspection uses X-rays or gamma rays passing through the part to expose film.
A technician fails to pass along information about an unfinished task to the next shift, and a step is left incomplete. Which Dirty Dozen factor most directly applies?
ACS code: AM.I.L
Correct answer: Lack of communication
Rationale: Lack of communication is the Dirty Dozen factor involving failure to transmit or receive information, and it is a frequent problem during shift turnover. The handbook emphasizes verbal and written turnover, including proper documentation, so that the next technician knows exactly what was and was not completed. The missing handoff, not a shortage of parts or training, caused the omission.
How should a voltmeter be connected to measure the voltage drop across a resistor?
ACS code: AM.I.A
Correct answer: In parallel with the resistor.
Rationale: A voltmeter has very high internal resistance and is connected in parallel (across) the component being measured so it reads the potential difference without disturbing circuit current. An ammeter, by contrast, is connected in series. Connecting a voltmeter in series would not read the drop correctly.
Frequently asked questions
- How many questions are on the FAA General written test?
- Sixty multiple-choice questions, with a two-hour time limit. You need 70 percent to pass, so 42 correct answers out of 60. Every question has three answer choices, and there is no penalty for a wrong answer over a blank one — answer everything.
- What score do I need to pass the FAA mechanic knowledge tests?
- Seventy percent on each of the three tests, scored independently. There is no combined score and no per-subject minimum: passing is a straight 70 percent of the questions on that test. Practise to 85 percent or better before booking, because 70 leaves no room for an unfamiliar phrasing on the day.
- How long are my written test results valid?
- Twenty-four calendar months from the date on the Airman Knowledge Test Report. You must complete the oral and practical exam with a Designated Mechanic Examiner within that window or the written passes expire and have to be retaken. Plan the whole sequence — three writtens, then the O&P — inside two years.
- What happens if I fail the General test?
- Under 14 CFR §65.19 you may reapply 30 days after a failed test. You can retest sooner only by presenting a signed statement from an airman who holds the certificate and rating you are seeking, certifying that they have given you additional instruction in each subject you failed and consider you ready to retest.
- Do I have to take the General test first?
- There is no required order for the three knowledge tests, and you may sit them in any sequence or on the same day. Most candidates take General first because its material underpins the other two — electrical theory, hardware, corrosion and regulations all reappear in the Airframe and Powerplant banks — so passing it makes the next two easier rather than the other way round.
- Which FAA handbook covers the General test?
- The Aviation Maintenance Technician Handbook — General, FAA-H-8083-30B. It is public domain and downloadable free from faa.gov. The Mechanic ACS (FAA-S-ACS-1) lists the subject areas and knowledge codes; the handbook is where the underlying content actually lives. Between those two documents you have the entire official basis of the test.
Keep reading
- FAA A&P Written Tests Explained — General, Airframe & Powerplant
- FAA Mechanic ACS Explained — What Is the Airman Certification Standards?
- Retaking the FAA A&P Written Test — AKTR, ACS Codes, and Remediation
- FAA AMT Handbooks — Free Public-Domain Study Guides for A&P Mechanics
- How to Become an FAA Aircraft Mechanic (A&P Certificate Guide)
Primary sources
Practice with the full question bank
Adaptive engine, timed exam simulator, ACS-code remediation, and oral prep — everything you need to pass.