FAA AMT General Cheat Sheet

Electricity and Electronics

5-15% of exam
Ohm and Watt Formulas Series and Parallel Rules Resistor Color Code Batteries and Meters Series vs Parallel

Aircraft Drawings

5-10% of exam
Drawing Line Conventions Drawing Types and Blocks Title block Tolerances

Weight and Balance

5-10% of exam
Weight and Balance Formulas Weighing and Loading Checks Weight Shift Proportion Tare vs Ballast

Fluid Lines and Fittings

5-10% of exam
Tubing and Hose Sizing Hose and Fitting Rules AN vs MS Fittings 37-degree flare

Materials, Hardware, Processes

5-10% of exam
AN Bolt Part Numbers Torque and Safetying Materials and Hardness Tests Rivet alloys

Ground Operations and Servicing

5-15% of exam
Ground Operations and Servicing Avgas Color Codes Fire extinguisher classes Fueling and bonding

Cleaning and Corrosion Control

5-10% of exam
Corrosion Types Corrosion Control Products Corrosion Treatment Picker Filiform corrosion

Mathematics

5-10% of exam
Maintenance Math Area and volume Unit conversions Compression ratio

Regulations, Forms, Records

5-10% of exam
Regulation Quick Map Required Record Entries Part 65 Mechanic Rules Major vs Minor Work

Physics for Aviation

5-10% of exam
Physics Facts and Laws Standard atmosphere Gas laws Simple machines

Inspection Concepts and Techniques

5-10% of exam
Inspection Intervals Nondestructive Test Methods Precision Measuring Tools NDT Method Picker

Human Factors

5-10% of exam
Human Factors Essentials Dirty Dozen PEAR Model Shift turnover

Quick Facts

Test code AMG
Questions 60 multiple-choice
Time 2 hours
Pass 70 percent
Delivery PSI computer-based
Fee About $175, center varies
Subjects 12 subjects, 5-10% or 5-15%
All tests within 24 months, 65.71(a)(3)
Retest 30 days, or signed statement
Certificate age 18 years, 14 CFR 65.71
Blueprint ACS November 1, 2021

Ohm and Watt Wheel EL

E = I x R and P = I x E
E: volts I: amperes R: ohms P: watts Cover the unknown

Series vs Parallel EL

Series

One current path
Current same everywhere
Resistances add up

Parallel

Several current paths
Voltage same everywhere
Total below smallest branch
Current same versus voltage same

Ohm and Watt Formulas EL

E = I x R Volts from amps, ohms
I = E / R Amps from volts, ohms
R = E / I Ohms from volts, amps
P = I x E Watts from amps, volts
P = I^2 x R Watts from current squared
P = E^2 / R Watts from volts squared
Kirchhoff current law Current in equals out
Kirchhoff voltage law Drops equal applied voltage
Watt's law Power links volts, amps P = I x E

Lead-Acid vs Ni-Cad EL

Lead-acid

Sulfuric acid electrolyte
Gravity shows state of charge
About 2 volts per cell

Ni-Cad

Potassium hydroxide electrolyte
Gravity does not show charge
About 1.25 volts per cell
Hydrometer works only lead-acid

Series and Parallel Rules EL

Series total resistance Add every resistance
Series current Same at every point
Series voltage Drops add to source
Parallel total resistance Less than smallest branch
Two parallel resistors Product over sum
Equal parallel resistors One value over count
Parallel voltage Same across each branch
Parallel current Branch currents add up
Open in series Whole circuit stops
Open in parallel Other branches keep working

Resistor Color Code EL

Black Digit 0
Brown Digit 1
Red Digit 2
Orange Digit 3
Yellow Digit 4
Green Digit 5
Blue Digit 6
Violet Digit 7
Gray Digit 8
White Digit 9
Gold band Tolerance 5 percent
Silver band Tolerance 10 percent
No fourth band Tolerance 20 percent
Third band Number of zeros added

Batteries and Meters EL

Lead-acid electrolyte Sulfuric acid and water
Charged lead-acid gravity 1.275 to 1.300
Discharged lead-acid gravity About 1.150
Lead-acid cell About 2 volts
Ni-Cad electrolyte Potassium hydroxide, KOH
Ni-Cad cell About 1.25 volts
Ammeter Connect in series
Voltmeter Connect in parallel
Ohmmeter Circuit power off first
Hydrometer Reads electrolyte specific gravity
Cells in series Voltage adds, capacity same
Cells in parallel Capacity adds, voltage same

Drawing Line Conventions DR

Visible line Solid, edges you see
Hidden line Short dashes, unseen edges
Center line Long and short dashes
Dimension line Arrowheads carrying the size
Extension line Projects the measured edge
Leader line Arrow pointing to note
Phantom line Alternate position or motion
Cutting plane line Where the section cuts
Section lines Hatching on cut material
Break line Shortens a long part

Drawing Types and Blocks DR

Detail drawing One part, fully dimensioned
Assembly drawing Parts joined together
Installation drawing Part located on aircraft
Sectional view Interior after a cut
Schematic Function, not actual location
Block diagram System flow by blocks
Orthographic projection Front, top, side views
Title block Name, number, scale, date
Zone numbers Locate detail on print
Tolerance Allowable variation from dimension
Bill of material Parts list for drawing
Revision block Changes made to drawing

Weight Shift Proportion WE

Weight moved / total = CG change / distance
Solve for CG change Or solve weight moved Distance is load travel Total weight stays same

Tare vs Ballast WE

Tare

Chocks and blocks weighed
Subtract from scale reading
Not part of aircraft

Ballast

Weight added deliberately
Moves CG into limits
Recorded in the records
Subtract tare, add ballast

Which Formula to Use WE

Need moment from weight → Weight times arm
Need arm from moment → Moment divided by weight
Need aircraft CG → Total moment over total weight
Equipment added or removed → Adjust weight and moment ( Recompute the CG )
Moving an existing load → Weight shift proportion
CG forward of limit → Add ballast aft ( Solve required weight )
Need power from work → Work divided by time
Need current from volts → Volts divided by ohms

Weight and Balance Formulas WE

Moment = weight x arm Turning effect about datum
Arm = moment / weight Distance back from moment
CG = total moment / total weight Balance point of aircraft
Datum Reference for all arms
Station Inches from the datum
Positive arm Behind the datum
Negative arm Ahead of the datum
Useful load Max weight minus empty
Empty weight CG Empty moment over empty weight
Moment index Moment reduced by factor
MAC Mean aerodynamic chord

Weighing and Loading Checks WE

Empty weight includes Unusable fuel, full operating fluids
Before weighing Level, clean, drain fuel
Scales Check calibration first
Tare Chocks and blocks, subtract
Ballast Added weight correcting CG
Forward adverse check Load only forward stations
Aft adverse check Load only aft stations
Avgas 6 lb per gallon
Turbine fuel 6.7 lb per gallon
Lubricating oil 7.5 lb per gallon
Water 8.35 lb per gallon
Standard person 170 lb each

AN vs MS Fittings FL

AN flared

Cone on fitting end
Tube must be flared
Black steel, blue aluminum

MS flareless

Straight fitting end
Sleeve bites the tube
Body, sleeve and nut
Cone versus straight end

Tubing and Hose Sizing FL

Rigid tube size Outside diameter in sixteenths
Wall thickness Printed in thousandths inch
Tube inside diameter OD minus twice wall
Hose dash number Matching tube size only
AN fitting dash Tube OD in sixteenths
Aircraft flare angle 35 to 37 degrees
Automotive flare angle 45 degrees, never used
AN steel fitting Colored black
AN aluminum fitting Colored blue
Aluminum bronze fitting Cadmium plated, natural color
Aluminum tube marking Painted color code band

Hose and Fitting Rules FL

Lay line Printed stripe showing twist
Twisted hose Straighten before final torque
MS flareless fitting Body, sleeve and nut
Flareless use High pressure, 3,000 psi
AN flared fitting Cone on fitting end
MS flareless end Straight, no cone
Buna-N hose Petroleum fuel and oil
Butyl hose Phosphate ester Skydrol fluid
Teflon hose Wide temperature, chemical resistant
New hose test 1.5 times system pressure
Torque seal Witness mark after torquing
Titanium warning Never in oxygen systems

AN Bolt Decode MA

AN3DD5A: sixteenths, alloy, eighths, undrilled
3: 3/16 inch diameter DD: 2024 aluminum alloy C: corrosion-resistant steel 5: 5/8 inch long A: undrilled shank

AN Bolt Part Numbers MA

AN prefix Air Force-Navy standard bolt
First number Diameter in sixteenths inch
DD code 2024 aluminum alloy
C code Corrosion-resistant steel
No letter code Cadmium-plated steel
Second number Length in eighths inch
A suffix Undrilled shank
H before length Head drilled for safetying
AN310 Aircraft castle nut
AN320 Castellated shear nut
AN315 and AN335 Plain nuts
AN350 Wing nut
AN960 Plain washer

Torque and Safetying MA

Inch-pounds to foot-pounds Divide by twelve
Lubricating threads Only when manual says
Turn the nut Preferred over the bolt
Drive-end extension Recompute using the formula
Torque wrench check Test at least monthly
Cotter pin holes Never loosen to align
Double twist wire Most common safetying method
Single wire method Small closely spaced screws
Widely spaced bolts Three maximum per series
Closely spaced bolts 24-inch wire length limit
Wire pull direction Toward tightening the fastener
Fiber locknut limit Not above 250 F

Materials and Hardness Tests MA

Alclad Pure aluminum over alloy
Anodizing Electrolytic oxide film
1100 rivet As fabricated, low strength
2117 rivet Most used, drive anytime
2017 and 2024 rivets Icebox rivets, reheat-treat
5056 rivet For magnesium alloy sheet
Brinell tester 10 millimeter hardened ball
Brinell load 3,000 kg ferrous metals
Rockwell C Diamond penetrator, 150 kilograms
Rockwell B Ball penetrator, 100 kilograms
Barcol tester Portable hardness tester
Tension Pulls material apart
Compression Squeezes material together
Shear Slides layers sideways
Torsion Twisting force

Avgas Color Codes GR

Red 80, green 100, blue 100LL
Red: grade 80 Green: grade 100 Blue: grade 100LL Purple: grade 115

Ground Operations and Servicing GR

Grade 80 Colored red
Grade 100 Colored green
Grade 100LL Colored blue
Grade 115 Colored purple
Class A fire Wood, paper, cloth
Class B fire Fuel, oil, solvents
Class C fire Energized electrical equipment
Class D fire Flammable metal, never water
Bonding wire Truck to aircraft before fueling
Nozzle bond Bond before opening tank
Never ground to Exhaust stack or propeller
Lightning limit None within five miles
Ground radar limit None within 500 feet
Water slugs Free water drained after fueling
Entrained water Droplets making fuel cloudy
Oxygen servicing No oil, grease, fuel

Corrosion Severity Ladder CO

Surface, pitting, intergranular, exfoliation
Surface: uniform etch Pitting: small deep holes Intergranular: grain boundaries Exfoliation: lifted layers

Galvanic vs Intergranular CO

Galvanic

Two dissimilar metals touching
Needs an electrolyte
Worst right at joint

Intergranular

Along the grain boundaries
From improper heat treatment
Often no surface evidence
Metals touching versus grain structure

Corrosion Treatment Picker CO

Light corrosion on aluminum → Nonwoven pad, aluminum wool ( Never steel wool )
Corrosion on steel part → Steel wool or brush ( Ferrous tools only )
Superficial aluminum corrosion → Chromic acid inhibitor ( Dwell five minutes )
Bare aluminum after removal → Conversion coating, then primer ( Refinish promptly )
Filiform found under paint → Strip, treat, refinish ( Store below 70 percent )
Exfoliation on an extrusion → Ultrasonic or eddy current ( Assess depth first )
Dissimilar metal joint → Insulate with sealant, primer ( Break the circuit )
Pits in stressed area → Blend out completely ( Prevent stress risers )

Corrosion Types CO

Surface corrosion Uniform etch, powdery deposit
Pitting Small deep holes
Filiform Wormlike traces under paint
Intergranular Attack along grain boundaries
Exfoliation Lifted grains, advanced intergranular
Galvanic Dissimilar metals plus electrolyte
Concentration cell Crevice or faying surface
Stress corrosion Stress plus corrosive environment
Fretting Slight rubbing between parts
Filiform humidity 78 to 90 percent
Steel filiform traces Never cross each other
Aluminum filiform traces Cross under one another

Corrosion Control Products CO

Chemical conversion coating Alodine on bare aluminum
Chromic acid Inhibitor for aluminum alloys
Chromic acid dwell At least five minutes
Anodized film Do not abrade it
Alclad layer Sacrificial, avoid removing it
Corrosion preventive compound Waxy sealant or thin film
Never on aluminum Steel wool, steel brush
Abrasive pad rule Never reuse across metals
Caustic cleaners Attack aluminum, use neutral
Filiform prevention Store below 70 percent
Magnesium fire Water makes it worse

Maintenance Math MA

Circle area Pi times radius squared
Cylinder volume Base area times height
Rectangle area Length times width
Triangle area Half base times height
Compression ratio Total volume over clearance volume
Percent Part over whole, times 100
Ratio Compares two like quantities
1 inch 25.4 millimeters
1 gallon 231 cubic inches
1 cubic foot 1,728 cubic inches
Celsius to Fahrenheit Times 9/5, then add 32
Fahrenheit to Celsius Minus 32, times 5/9
Scientific notation Digits times power of ten

Major vs Minor Work RE

Major

May appreciably affect airworthiness
Not by elementary operations
Form 337 required

Minor

Anything not major
Elementary operations, accepted practices
Logbook entry only
Form 337 marks major

Who Approves Return to Service RE

Minor airframe maintenance → Mechanic, airframe rating ( 65.85 )
Minor powerplant maintenance → Mechanic, powerplant rating ( 65.87 )
100-hour inspection → Appropriately rated mechanic ( 65.85 and 65.87 )
Annual inspection → Mechanic holding IA ( 65.95 )
Major repair or alteration → IA or repair station ( Approved data required )
Progressive inspection → IA performs or supervises ( 91.409(d) )
Preventive maintenance, own aircraft → Private pilot or higher ( 43.3(g), 43.7(f) )
Work done under supervision → Supervising certificate holder ( 43.3(d) )

Regulation Quick Map RE

14 CFR 1.1 Maintenance and repair definitions
43.3 Who may perform maintenance
43.5 Conditions before return to service
43.7 Who may approve return
43.9 Maintenance record entry content
43.11 Inspection record entry content
43 Appendix A Major, minor, preventive maintenance
43 Appendix B Form 337 disposition rules
43 Appendix D Annual and 100-hour scope
43 Appendix E Altimeter and static tests
43 Appendix F Transponder tests and inspections
Part 39 Airworthiness directives are mandatory
39.7 Operating noncompliant is a violation
39.19 Alternative method of compliance
91.403 Owner keeps aircraft airworthy
91.409 Annual and 100-hour requirement
91.417 Owner maintenance record keeping

Preventive Maintenance vs Maintenance RE

Preventive maintenance

Listed in 43 Appendix A
No complex assembly operations
Pilot owner may perform

Maintenance

Inspection, overhaul, repair, replacement
Excludes preventive maintenance
Certificated mechanic required
Listed items are preventive

Which Form or Record RE

Routine maintenance completed → 43.9 record entry
Inspection completed → 43.11 record entry
Major repair or alteration → Form 337 plus 43.9 entry ( 43 Appendix B )
Aircraft found unairworthy → Dated discrepancy list ( 43.11(b) )
Service defect discovered → FAA Form 8010-4 ( Malfunction or Defect Report )
Part released for installation → FAA Form 8130-3 ( Authorized release )
AD action cannot work → Request an AMOC ( 39.17 and 39.19 )
Recurring AD complied with → Record method and next due ( 91.417(a)(2)(v) )

Required Record Entries RE

43.9 first item Description of work performed
43.9 second item Date the work completed
43.9 third item Name of person performing
43.9 fourth item Signature, certificate number, kind
43.11 first item Inspection type and extent
43.11 second item Date and total time
43.11 third item Signature, number, certificate kind
Airworthy wording Certify inspected, airworthy condition
Unairworthy wording Dated discrepancy list provided
Inoperative equipment Placard and list it
Work records kept One year or until superseded
Permanent records Transfer with the aircraft
AD record content Number, revision date, method, next due

Approved vs Acceptable Data RE

Approved data

FAA specifically approved
Major repair or alteration
STC, AD, approved 337

Acceptable data

Manufacturer manual, AC 43.13
Minor repair or alteration
Not FAA approved
Major needs approved data

Part 65 Mechanic Rules RE

65.17 Passing grade is 70 percent
65.19 Retest after 30 days
65.19 shortcut Signed statement of instruction
65.71 Age 18, English, 24 months
65.75 Written test from the ACS
65.77 one rating 18 months practical experience
65.77 both ratings 30 months concurrent experience
65.80 School students may test early
65.81 Never approve unfamiliar work
65.83 Six months within 24
65.85 Airframe 100-hour return privilege
65.87 Powerplant and propeller privileges
65.91 Inspection authorization eligibility
65.95 IA annual, major repairs

Physics Facts and Laws PH

Standard pressure 29.92 inHg, 14.7 psi
Standard temperature 15 C, or 59 F
One horsepower 33,000 ft-lb per minute
Horsepower per second 550 ft-lb per second
Work Force times distance
Power Work divided by time
Bernoulli Velocity up, pressure down
Pascal Pressure acts equally everywhere
Boyle Pressure up, volume down
Charles Temperature up, volume up
Newton third law Equal and opposite reaction
Specific gravity Density compared with water
Mechanical advantage Resistance divided by effort

100-Hour vs Annual IN

100-hour

Every 100 hours
Hire or provided-aircraft instruction
Rated mechanic signs

Annual

Every 12 calendar months
Unless 91.409(c) exempts
Mechanic needs IA
Same scope, different signer

Which Inspection Applies IN

Private aircraft, no hire → Annual only ( 12 calendar months )
Carrying persons for hire → Annual plus 100-hour ( 91.409(b) )
Flight instruction for hire → Annual plus 100-hour ( Provider supplies aircraft )
Owner wants split inspection → Progressive program ( FSDO approval needed )
En route to inspection → 10-hour extension ( Subtract from next )
IFR in controlled airspace → Altimeter and static test ( 24 calendar months )
Transponder installed → Transponder test ( 24 calendar months )
Part 135 operator → Approved inspection program ( Operations specifications )

Inspection Intervals IN

Annual inspection Every 12 calendar months
100-hour inspection Carrying persons for hire
Instruction for hire 100-hour also required
100-hour overfly 10 hours reaching inspection place
Overfly payback Excess counts toward next
Annual substitution Annual satisfies the 100-hour
Progressive inspection FSDO approved, IA supervised
Altimeter and static 24 calendar months, IFR
Transponder test 24 calendar months
ELT inspection Every 12 calendar months
ELT battery One cumulative hour, 50 percent
Same scope Appendix D covers both

Penetrant vs Magnetic Particle IN

Dye penetrant

Any nonporous material
Surface-open defects only
No electricity required

Magnetic particle

Ferromagnetic parts only
Surface and near subsurface
Demagnetize when finished
Material decides the method

NDT Method Picker IN

Crack open to surface → Dye penetrant
Steel part, surface cracks → Magnetic particle ( Demagnetize afterward )
Aluminum skin around fastener → Eddy current ( Immediate results )
Flaw deep inside metal → Ultrasonic
Internal assembly, no disassembly → Radiography ( Radiation hazard )
Composite skin suspected loose → Tap test
Inside an engine cylinder → Borescope
Porous or magnetic part → Not dye penetrant ( Penetrant needs nonporous )

Nondestructive Test Methods IN

Visual Fastest, surface defects only
Dye penetrant Surface-open, nonporous materials
Fluorescent penetrant Read under ultraviolet light
Magnetic particle Ferromagnetic parts only
Eddy current Conductive, surface and near-surface
Ultrasonic Internal flaws and thickness
Radiography Internal, radiation hazard
Tap test Composite delamination check
Borescope Inside view without disassembly
Demagnetize Required after magnetic particle
NDI personnel Qualified and certified required

Precision Measuring Tools IN

Steel rule 1/64 inch or 0.01
Micrometer Reads to 0.001 inch
Vernier micrometer Reads to 0.0001 inch
Micrometer fixed parts Frame, barrel, anvil
Micrometer moving parts Thimble and spindle
Dial indicator Runout, warpage, travel
Feeler gauge Measures small gaps
Telescoping gauge Bore size, read with micrometer
Small hole gauge Very small bore measurement
Thread pitch gauge Threads per inch
Calibration Track and mark due dates

Dirty Dozen HU

Twelve human factors behind maintenance error
Lack of communication Complacency Lack of knowledge Distraction Lack of teamwork Fatigue Lack of resources Pressure Lack of assertiveness Stress Lack of awareness Norms

Human Factors Essentials HU

PEAR People, Environment, Actions, Resources
Dirty Dozen source Transport Canada, twelve factors
Active error Immediate effect at task
Latent error Hidden until conditions expose
Unintentional slip Accidental deviation from accuracy
Intentional error Treated as a violation
Norms Unwritten habits, not procedures
Complacency Overconfidence from repeated tasks
Shift turnover Brief incomplete work clearly
Malfunction or Defect Report FAA Form 8010-4
Human error Manageable, not fully avoidable

PEAR Model HU

People, Environment, Actions, Resources
People do the job Environment they work in Actions they perform Resources to finish it

Common Traps

Test length confusion

General has 60 questions ≠ Airframe and powerplant have 100

Who signs the inspection

Annual: mechanic needs IA ≠ Rated mechanic signs 100-hour

The 10-hour overfly

Allowed only en route ≠ Excess subtracts from next

Data type for the job

Major work needs approved data ≠ Minor work takes acceptable data

Flare angle

Aircraft flare 35 to 37 ≠ Automotive 45 degrees prohibited

Hose dash number

Matches the tubing size ≠ Not the inside diameter

Battery hydrometer

Lead-acid gravity shows charge ≠ Ni-Cad gravity does not

Tube sizing

Rigid tube by outside diameter ≠ Hose by matching tube size

Recent experience

Six months within 24 ≠ Not six months yearly

Test report validity

All tests within 24 months ≠ Retake knowledge test if outside

Cleaning tool choice

Steel wool suits steel ≠ It ruins aluminum surfaces

Last Minute

1. AMG is 60 questions, 2 hours
2. Passing grade is 70 percent
3. Twelve ACS General subject areas
4. Subjects 5-10%; two reach 15%
5. Volts equal amps times ohms
6. Watts equal amps times volts
7. Moment equals weight times arm
8. CG equals total moment over weight
9. Annual 12 months, 100-hour for hire
10. IA signs annual, mechanic signs 100-hour
11. Major repair needs approved data, 337
12. 43.9 is maintenance, 43.11 is inspection
13. Recent experience 6 months in 24
14. Aircraft flare 37 degrees, not 45
15. Rigid tubing sized by outside diameter
16. Alodine is a conversion coating
17. Filiform corrosion hides under paint
18. Dye penetrant needs surface-open cracks
19. Dirty Dozen lists twelve error factors
20. Avgas 100LL is colored blue

FAA Aviation Mechanic — General (AMG)

Practice Questions 237 questions Study Guide 51 topics Cheat Sheet 307 facts Flashcards 50 cards Shorts 2 short s Free CE