8083 General Aviation

Define a negative number and how it is expressed.

A negative number is a number less than zero, and is expressed by placing a negative sign in front of the number.

Define a proportion.

A proportion is a statement of equality between two or more rations.

What form of corrosion is exfoliation and how would you describe its appearance?

Exfoliation is a very severe form of intergranular corrosion and can cause lifting or flaking of the metal at the surface due to delamination of the grain boundaries caused by the pressure of corrosion residual product buildup.

List the three methods of cleaning an aircraft exterior.

Wet wash, dry wash, and polishing.

7-11(O). How much slack must flexible lines have when installed?

When installing flexible hose, provide slack or bend in the hose line from 5 to 8 percent of its length.

Explain the special characteristics of Alclad 2024-T4.

"Alclad and Pureclad" are used to designate sheets that consist of an aluminum alloy core coated with a layer of pure aluminum to a depth of approximately 5 1⁄2 percent on each side.

Explain the term "ice box rivets".

"Ice box rivets," are 2017-T and 2024-T rivets that have been annealed, and must be kept refrigerated until they are to be driven. This refrigeration delays the hardening of the rivets.

Name the preventive maintenance steps that can be taken to reduce the effects caused by corrosion.

1. Adequate cleaning 2. Thorough periodic lubrication 3. Detailed inspection for corrosion and failure of protective systems 4. Prompt treatment of corrosion and touchup of damaged paint areas 5. Keeping drain holes free of obstructions 6. Daily draining of fuel cell sumps 7. Daily wipe down of exposed critical areas 8. Sealing of aircraft against water during foul weather and proper ventilation on warm, sunny days 9. Maximum use of protective covers on parked aircraft.

Name the various components for a complete corrosion treatment (removal) program.

1. Cleaning and stripping of the corroded area, 2. Removing as much of the corrosion products as practicable, 3. Neutralizing any residual materials remaining in pits and crevices, 4. Restoring protective surface films, and 5. Applying temporary or permanent coatings or paint finishes.

Why are cork gaskets the best choice for mating rough surfaces?

A cork gasket best conforms to the uneven or varying space.

7-10(O). What is an advantage of a double flare on aluminum tubing?

A double flare is smoother and more concentric than a single flare and therefore seals better. It is also more resistant to the shearing effect of torque.

11-11(O). Explain the term "hot start".

A hot start occurs when the engine starts, but the exhaust gas temperature exceeds specified limits. This is usually caused by an excessively rich fuel/air mixture entering the combustion chamber. This condition can be caused by either too much fuel or not enough airflow. The fuel to the engine should be shut off immediately.

12-3(O). What information is required to be entered into the maintenance record upon completion of maintenance or alteration and approving for return to service?

A maintenance record must include the following information: a description (or reference to acceptable data) of work performed, date of completion, the name of the person performing the work (if someone else), signature, certificate number, and kind of certificate held.

Define ratio and describe how it is expressed.

A ratio is the comparison of two numbers or quantities. It can be expressed in three ways: as a fraction, with a colon, or with the word "to".

What is ferrous oxide?

A type of surface corrosion, commonly referred to as rust, which is the result of atmospheric oxidation on the surface of steel.

11-28(O). Name the four main classifications of fires.

A, B, C, and D

State the formula to calculate the volume of a cylinder.

Volume = ∏ × radius2 × Height of the cylinder or V = ∏ × r2 × H

11-17(O). Can AVGAS be used in a turbine engine and explain why or why not.

Adding AVGAS to jet fuel, although allowed, can cause lead deposits in the turbine engine and can lead to reduced service life.

11-21(O). How can the various AVGAS grades be identified?

AVGAS can be identified by its color. The color of the fuel should match the color band on piping and fueling equipment.

Name the three methods of case hardening.

carburizing, cyaniding, and nitriding.

11-26(O). What benefits are achieved when tetraethyl lead (TEL) is added to aviation fuel?

Adding TEL to aviation fuel increases the critical pressure and temperature of a fuel. It also lubricates the engine valves.

11-16(O). Explain the possible results of mixing jet fuel with AVGAS in a reciprocating engine.

Adding jet fuel to AVGAS will cause a decrease in the power developed by the engine and could cause damage to the engine (through detonation) and [engine failure leading to] loss of life.

7-9(O). What is the color of an AN steel flared-tube fitting?

All AN steel fittings are colored black.

7-2(O). Which metal is used for low to medium pressure hydraulic and pneumatic systems?

Aluminum alloy tubing.

7-1(O). What are the three most common types of metals used for rigid fluid line fabrication in aviation?

Aluminum alloy, steel, and titanium.

State the formula to calculate the area of a triangle.

Area = 1/2 × (Base × Height) or A = 1/2 × (B × H)

State the formula to calculate the area of a rectangle.

Area = Length × Width or A=L × W

State the formula to calculate the area of a circle.

Area = ∏ × radius2 or A = ∏ × r2

11-8(O). Who is authorized to taxi aircraft?

As a general rule, only rated pilots and qualified airframe and powerplant technicians are authorized to start, run up, and taxi aircraft.

11-19(O). Describe the general safety practices and precautions that should be observed when servicing aircraft oxygen systems.

Before servicing any aircraft, consult the specific aircraft maintenance manual to determine the proper type of servicing equipment to be used. Two personnel are required to service an aircraft with gaseous oxygen. One person should be stationed at the control valves of the servicing equipment and one person stationed where he or she can observe the pressure in the aircraft system. Communication between the two people is required in case of an emergency. Aircraft should not be serviced with oxygen during fueling, defueling, or other maintenance work, which could provide a source of ignition. Oxygen servicing of aircraft should be accomplished outside hangars.

11-4(O). Describe the brake usage rules when towing aircraft.

Before the aircraft to be towed is moved, a qualified person must be in the cockpit to operate the brakes in case the tow bar should fail or become unhooked. The aircraft can then be stopped, preventing possible damage. When moving aircraft, do not start and stop suddenly. For added safety, aircraft brakes must never be applied during towing except in emergencies, and then only upon command by one of the tow team members.

7-5(O). Name at least three synthetic materials commonly used in the manufacture of flexible hose.

Buna-N, neoprene, butyl, ethylene propylene diene rubber (EPDM) and Teflon™. While Teflon™ is in a category of its own, the others are synthetic rubber.

7-6(O). Which synthetic rubber hosing is best for use with fuel?

Buna-N.

7-7(O). Which synthetic rubber hosing is best for use with phosphate ester base hydraulic fluid (Skydrol)?

Butyl

7-8(O). How do you determine the correct sizing for flexible hose?

By a dash number, stenciled on the side of the hose, indicating the size of tubing with which it is compatible. When the dash number of the hose corresponds with the dash number of the tubing, the proper size hose is being used.

What specialty fastener is best suited to secure an aircraft cowling?

Camloc fasteners are used to secure aircraft cowlings and fairings.

11-29(O). Give an example of a combustible material associated with each of the four main classifications of fire.

Class A fires occur in ordinary combustible materials, such as wood, cloth, paper, upholstery materials, etc. Class B fires occur in flammable petroleum products of other flammable or combustible liquids, greases, solvents, paints, and so forth. Class C fires occur involve energized electrical wiring and equipment. Class D fires involve magnesium.

Compare the tensile strength of composite aircraft structures and those made of steel or aluminum.

Composite aircraft structures have a tensile strength 4 to 6 times that of steel or aluminum.

Wet washing can remove accumulated dirt, oil, grease, and carbon deposits. What does it not remove?

Corrosion and oxide films.

Why is keeping the interior of an aircraft just as important as maintaining a clean exterior?

Corrosion can establish itself on the inside structure to a greater degree because it is difficult to reach some areas for cleaning. Nuts, bolts, bits of wire, or other metal objects carelessly dropped and neglected, combined with moisture and dissimilar metal contact, can cause electrolytic corrosion.

7-3(O). Which metals are best suited for high-pressure hydraulic systems?

Corrosion resistant steel and titanium.

Define intergranular corrosion.

Corrosion that attacks along the grain boundaries of an alloy and is commonly the results of a lack of uniformity caused by changes that occur in the alloy during heating and cooling during the material's manufacturing process.

Define stress corrosion.

Corrosion that occurs by combined effect of sustained tensile stresses and a corrosive environment.

Define fretting corrosion.

Corrosion that occurs when two mating surfaces, normally at rest with respect to one another, are subject to slight relative motion.

What are the two general classifications of corrosion?

Direct chemical attack and electrochemical attack.

11-25(O). How can the presence of water be determined in a fuel sample?

Entrained water is suspended water droplets. These droplets may not be visible to the eye, but will give the fuel a cloudy look. The entrained water will settle out in time.

Name the areas of an aircraft that are prone to corrosion.

Exhaust trail areas, battery compartments and vent openings, bilge areas on float aircraft, wheel well and landing gear, water entrapment areas, engine frontal areas and cooling air vents, wing flap and spoiler recesses, external skin areas, helicopter rotor heads and gear boxes, and control cables.

12-2(O). Where can a mechanic find a listing of items considered to be a major airframe repair?

FAR 43 Appendix A provides a list of items that are considered major repairs.

11-10(O). Explain the term "hung start".

False or hung starts occur when the engine starts normally, but the rpm remains at some low value rather than increasing to the normal starting rpm. This is often the result of insufficient power to the starter, or the starter cutting off before the engine starts self-accelerating. In this case, the engine should be shut down.

11-31(O). Describe how to identify the correct fire extinguisher for each fire classification.

Fire extinguisher are marked using the same classification system as fires. Use the corresponding class fire extinguisher with the fire classification. A for A, B for B, C for C, and D for D. There are some fire extinguishers that can be used on multiple fire classifications and these are marked accordingly.

11-15(O). List at least three possible hazards associated with the ground operations of aircraft.

Fire, during engine starting. Turning propellers and rotor blades. Jet exhaust or propeller blast. Jet inlets while engines are operating. Foreign object debris. Other aircraft, vehicles, personnel, and other obstacles. Additional hazards include high noise levels, slips, trips, and falls.

7-13(O). Why should you never overtighten a flareless tube fitting?

Flareless tube fittings should never be overtightened as this may cause permanent damage to the sleeve and nut.

7-12(O). Why must a pressurized flexible hose be installed with slack?

Flexible hose contracts in length and expands in diameter when pressurized.

Define grip length or range.

Grip length is the length of the unthreaded portion of the bolt shank.

Explain the use of helicoils.

Helicoils can be used to restore damaged threads.

Explain the construction of a honeycomb composite material.

Honeycomb's core is made from paper, Nomex, carbon, fiberglass or metal. The core is sandwiched together between a high-density laminate or solid face and back and held together with an adhesive.

11-14(O). Describe the procedures for extinguishing an engine induction fire on a reciprocating engine.

If an engine fire develops during the starting procedure, continue cranking to start the engine and blow out the fire. If the engine does not start and the fire continues to burn, discontinue the start attempt. The fireguard should extinguish the fire using the available equipment. The fireguard must observe all safety practices at all times while standing by during the starting procedure.

11-7(O). Describe the safety precautions to be followed when hand cranking an engine.

If the aircraft has no self-starter, the engine must be started by turning the propeller by hand (hand propping the propeller). The person who is turning the propeller calls: "Fuel on, switch off, throttle closed, brakes on." The person operating the engine will check these items and repeat the phrase. The switch and throttle must not be touched again until the person swinging the prop calls "contact." The operator will repeat "contact" and then turn on the switch. Never turn on the switch and then call "contact." A few simple precautions will help to avoid accidents when hand propping the engine. While touching a propeller, always assume that the ignition is on. The switches which control the magnetos operate on the principle of short- circuiting the current to turn the ignition off. If the switch is faulty, it can be in the "off" position and still permit current to flow in the magneto primary circuit. This condition could allow the engine to start when the switch is off. Be sure the ground is firm. Slippery grass, mud, grease, or loose gravel can lead to a fall into or under the propeller. Never allow any portion of your body to get in the way of the propeller. This applies even though the engine is not being cranked. Stand close enough to the propeller to be able to step away as it is pulled down. Stepping away after cranking is a safeguard in case the brakes fail. Do not stand in a position that requires leaning toward the propeller to reach it. This throws the body off balance and could cause you to fall into the blades when the engine starts. In swinging the prop, always move the blade downward by pushing with the palms of the hands. Do not grip the blade with the fingers curled over the edge, since "kickback" may break them or draw your body in the blade path.

Explain the correct way to line up a hole for use with a cotter pin.

If the cotter pin hole does not align within the recommended torque range, the acceptable practice is to change washers and try realigning the holes again.

Explain how to determine the correct grip length or range when selecting a bolt.

In general, bolt grip lengths should equal the material thickness. To determine grip length or grip range measure the thickness of the material with a hook scale inserted through the hole. Once this measurement is determined, select the correct grip range by referring to the charts provided by the manufacturer.

Explain the industry standard for securing fasteners with safety wire.

In safetying, arrange the wire so that if the bolt or screw begins to loosen, the force applied to the wire is in the tightening direction.

Explain case hardening.

It is a heat-treating operation where the surface of the metal is changed chemically by introducing a high carbide or nitride content producing a hard wear-resistant surface or case over a strong, tough core.

11-22(O). What is JET A fuel made of?

Kerosene

11-12(O). Explain why an AMT should be familiar with standard light signals.

Light signals are used if radio communications are unavailable to control and expedite the taxing of aircraft.

12-1(O). How is a major structural repair documented?

Major repairs are documented on FAA Form 337. Upon completion of the repair and Form 337, an entry is made in the maintenance records referencing the Form 337 by its date.

11-6(O). Describe the safety precautions that should be observed while starting and running an engine.

Make sure no property damage or personal injury will occur from the propeller blast or jet exhaust. During any and all starting procedures, a "fireguard" equipped with a suitable fire extinguisher shall be stationed in an appropriate place. If the aircraft is turbine engine powered, the area in front of the jet inlet must be kept clear of personnel, property, and/or debris (FOD). Follow manufacturer's checklists for start procedures and shutdown procedures.

12-4(O). Upon completion of a 100 hour inspection, what is required of the mechanic holding an airframe and powerplant rating?

Make the proper entries in the aircraft's maintenance record.

7-4(O). How is metal tubing fluid line sized?

Metal tubing is sized by outside diameter(OD, which is measure fractionally in sixteenths of an inch.

11-30(O). Describe how to use a fire extinguisher.

Most extinguishers have a pin to pull that will allow the handle to activate the agent. Stand back 8 feet and aim at the base of the fire or flames. Squeeze the lever and sweep side to side until the fire is extinguished. A great way to remember this is use the acronym PASS - PULL the pin, AIM the hose/nozzle at the base of the fire, SQUEEZE the lever, and SWEEP the hose side to side.

11-18(O). List at least three precautions that should be observed when fueling an aircraft.

NOTE: Choose from the any of the following precautions. Prior to fueling, the person fueling should check the following: 1. Ensure all aircraft electrical systems and electronic devices, including radar, are turned off. 2. Do not carry anything in the shirt pocket. These items could fall into the fuel tanks. 3. Ensure no flame-producing devices are carried by anyone engaged in the fueling operation. A moment of carelessness could cause an accident. 4. Ensure the proper type and grade of fuel is used. Do not mix AVGAS and JET fuel. 5. Ensure all the sumps have been drained. 6. Wear eye protection. Although generally not as critical as eye protection, other forms of protection, such as rubber gloves and aprons, can protect the skin from the effects of spilled or splashed fuel. 7. Do not fuel aircraft if there is danger of other aircraft in the vicinity blowing dirt in the direction of the aircraft being fueled. Blown dirt, dust, or other contaminants can enter an open fuel tank, contaminating the entire contents of the tank. 8. Do not fuel an aircraft when there is lightning within 5 miles. 9. Do not fuel an aircraft within 500 feet of operating ground radar. 10. When using mobile fueling equipment: a. Approach the aircraft with caution, positioning the fuel truck so that if it is necessary to depart quickly, no backing will be needed. b. Set the hand brake of the fuel truck and chock the wheels to prevent rolling. c. Ground the aircraft and then ground the truck. Next, ground or bond them together by running a connecting wire between the aircraft and the fuel truck. This may be done by three separate ground wires or by a "Y" cable from the fuel truck. d. Ensure the ground cables are in contact with bare metal or are in the proper grounding points on the aircraft. Do not use the engine exhaust or propeller as grounding points. Damage to the propeller can result, and there is no way of quickly ensuring a positive bond between the engine and the airframe. e. Ground the nozzle to the aircraft, then open the fuel tank. f. Protect the wing and any other item on the aircraft from damage caused by spilled fuel or careless handling of the nozzle, hose, or grounding wires. g. Check the fuel cap for proper installation and security before leaving the aircraft. h. Remove the grounding wires in the reverse order. If the aircraft is not going to be flown or moved soon, the aircraft ground wire can be left attached. When fueling from pits or cabinets, follow the same procedures as when using a truck. Pits or cabinets are usually designed with permanent grounding, eliminating the need to ground the equipment. However, the aircraft still must be grounded, and then the equipment must be grounded to the aircraft as it was with mobile equipment.

11-27(O). Is it acceptable to use automotive fuel in aircraft engines?

No. The lower grades of automobile fuel are not held within the tolerances required for aviation gasoline and usually contain a conservable amount of cracked gasoline, which may form excessive gum deposits. For these reasons, automobile fuels should not be used in aircraft engines, especially air-cooled engines operating at cylinder temperatures. NOTE: Some engines have been issued Supplemental Type Certificates that allow the engine to be modified to use automotive gasoline. This modification will be noted in the aircraft documentation.

11-1(O). For aircraft with a steerable nose gear, what should be done before towing the aircraft?

On aircraft with a steerable nose wheel, the locking scissors are set to full swivel for towing. The locking device must be reset after the tow bar has been removed from the aircraft. Persons stationed in the aircraft should not attempt to steer or turn the nose wheel when the tow bar is attached to the aircraft.

Name the two types of heat treatments applicable to aluminum alloys.

One is called solution heat treatment, and the other is known as precipitation heat treatment.

Define percentage.

Percentage means "parts out of one hundred."

What is the numerical value for the mathematical constant ∏?

Pi (∏) = 3.1416

What are AN960 and AN970 washers used for?

Plain washers, such as the AN960 and AN970, are used to form a smooth bearing surface and act as a shim in obtaining correct grip length for a bolt and nut assembly, prevent damage to the surface material and provide protection of structures where corrosion caused by dissimilar metals is a factor.

When would you polish an aircraft and what are the benefits.

Polishing is usually performed after surfaces have been cleaned. It restores luster to painted and unpainted surfaces of the aircraft. It is also used to remove oxidation and corrosion.

Artificial aging is another term for what type of heat treatment?

Precipitation heat treatment.

11-5(O). What should be done prior to towing an aircraft on or across an active runway?

Prior to any movement of aircraft across runways or taxiways, contact the airport control tower on the appropriate frequency for clearance to proceed.

11-3(O). How fast can an aircraft be towed?

The towing speed of the aircraft should not exceed that of the walking team members.

When are self-locking nuts used on aircraft?

Self-locking nuts are used on aircraft to provide tight connections, which will not shake loose under severe vibration.

11-13(O). Where can you find a listing of standard aircraft taxiing signals?

Standard aircraft taxiing signals published in the FAA Aeronautical Information Manual (AIM).

Name the five forms of corrosion.

Surface, dissimilar metal, intergranular, stress, and fretting.

11-20(O). What do the numbers represent in AVGAS grade classifications?

The two numbers indicate the lean mixture and rich mixture octane rating numbers of the specific fuel. In other words, with 80/87 aviation gasoline, the 80 is the lean mixture rating and 87 is the rich mixture rating number.

11-23(O). Name three types of contamination that can be found in aviation fuel.

The types of contamination found in aviation fuel include water, solids, and microbial growths.

When are "ice box rivets" used?

The 2017-T and 2024-T rivets are used in aluminum alloy structures where more strength is needed than is obtainable with the same size 2217-T rivet.

Name the classes of bolt threads and explain what the differences are between them.

The Class of a thread indicates the tolerance allowed in manufacturing. Class 1 is a loose fit, Class 2 is a free fit, Class 3 is a medium fit, and Class 4 is a close fit.

Explain the primary benefit of an MS33737 instrument nut.

The MS33737 instrument nut reduces magnetic influences in the cockpit.

What does the code "1100" tell us about aluminum?

The code 1100 is given to aluminum that is 99% pure aluminum.

Explain the corrosion process.

The corrosion process involves two simultaneous changes: The metal that is attacked or oxidized suffers what may be called anodic change, and the corrosive agent undergoes cathodic change.

Define metal corrosion.

The deterioration of the metal by chemical or electrochemical attack that can occur internally as well as on the surface of the metal changing the smooth surface, weakening the interior, or damaging or loosening adjacent parts.

11-24(O). Describe how each of the three types of contamination can affect the fuel system.

The dissolved water is not a major problem until, as the temperature lowers, it becomes free water. This then poses a problem if ice crystals form, clogging filters and other small orifices. Solid contaminants are insoluble in fuel. The more common types are rust, dirt, sand, gasket material, lint, and fragments of shop towels. The close tolerances of fuel controls and other fuel-related mechanisms can be damaged or blocked by particles as small as one twentieth the diameter of a human hair. The effects of microorganisms are: 1) Formation of slime or sludge that can foul filters, separators, or fuel controls, 2) Emulsification of the fuel and 3) Corrosive compounds that can attack the fuel tank's structure. In the case of a wet wing tank, the tank is made from the aircraft's structure. They can also have offensive odors.

12-5(O). Who is responsible for making the entry in the maintenance records after an annual, 100 hour, or progressive inspection?

The person approving or disapproving the item for return to service must document the completion of the inspection and note any discrepancies in the maintenance record.

11-2(O). Where should team members be stationed when towing an aircraft?

The person in charge should assign team personnel as wing walkers. A wing walker should be stationed at each wingtip in such a position that he or she can ensure adequate clearance of any obstruction in the path of the aircraft. A tail walker should be assigned when sharp turns are to be made, or when the aircraft is to be backed into position. A qualified person should occupy the pilot's seat of the towed aircraft to observe and operate the brakes as required. When necessary, another qualified person is stationed to watch and maintain aircraft hydraulic system pressure.

How can the accumulation of dirt and grease affect an air-cooled engine?

They provide an effective insulation against the cooling effect of air flowing over it. Such an accumulation can also cover up cracks or other defects.

If given an unknown piece of metal, how can you tell if it is titanium or stainless steel?

Two methods can be used. One is the spark test; titanium will give off a brilliant white trace ending in a brilliant white burst. The other is by moistening the titanium and using it to draw a line on a piece of glass. This will leave a dark line similar in appearance to a pencil mark.

Explain the standard positioning for aircraft bolts when installed on an aircraft and why.

Unless otherwise specified or required, aircraft bolts should be installed so the bolt head is facing upward or in a forward direction. This positioning tends to prevent the bolt from slipping out if the nut is accidentally lost.

11-9(O). If radio communication is unavailable, how does the AMT communicate with ATC when taxiing an aircraft?

Using standard taxi light signals.

State the formula to calculate the volume of a rectangle.

Volume = Length × Width × Height or V = L × W × H

When would a dry wash be accomplished on an aircraft and what does it clean or remove?

When the use of liquids is neither desirable nor practical and removes film, dust, and small accumulations of dirt and soil.