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Jeppesen Airframe Oral Chapter 4-6

Terms in this set (60)

Name the principle types of welding.
Gas welding, electric arc welding, and electric resistance welding.
What are some advantages of gas shielded arc welding?
The weld is stronger, more ductile, and corrosion resistant.
Which method of welding is less likely to cause buckling or warping of thin metal sheets?
Electric arc (or tig) welding
What is the purpose of shielding an arc weld with an inert gas?
The gas prevents atmospheric oxygen and/or nitrogen from contaminating the weld.
What is a common method of controlling expansion when welding a joint?
Place tack welds along the length of the joint.
What is the effect of inadequate penetration on a weld?
The weld will be weak.
What is the purpose of the flux used with brazing and silver soldering?
The flux cleans the base metal by removing any oxide film.
What type of flame is used when torch brazing or silver soldering?
A neutral flame.
What must be done to a soldering iron tip to increase the amount of heat transferred from the tip to the work?
The tip must be cleaned of all contaminates and properly tinned.
What is the preferred method for welding aluminum?
Tungsten Inert Gas (TIG) welding.
What is the preferred method for welding magnesium?
Tungsten Inert Gas (TIG) welding.
What precautions must be observed in order to weld titanium?
All traces of oxygen and nitrogen must be kept away from the weld area.
Describe one type of repair that could be made to a dented steel tube cluster joint.
A formed steel patch plate could be welding over the damaged area.
How can a soft flame be obtained without reducing the heat output of the torch?
Use a larger tip and adjust the gas pressure accordingly.
What factors determine the amount of heat delivered by a gas welding torch?
The size of the torch tip and the gas pressure.
When a oxyacetylene torch is extinguished, which valve is turned off first?
Turn off the acetylene gas valve first.
When a gas welding project is completed, what safety precautions should be accomplished?
All valves are turned off and the gas pressures are relieved.
What should be done to a heat treated aluminum part after welding repairs are completed?
The part must be re-heat treated.
Welding magnesium can create a serious safety hazard. What is the nature of this hazard?
Magnesium burns with a very hot flame that is very hard to extinguish.
What technique might be used to enable a tight-fitting inner sleeve to be inserted into a tubular repair?
The inner tube could be chilled with dry ice or in a freeze while the outer tube could be heated slightly with a torch.
Aircraft covering fabrics are made of materials from what two sources?
Organic materials and synthetic materials.
How would you determine the strength requirements for fabric used to re-cover an aircraft?
The fabric must be of at least the quality and strength of the fabric used by the original manufacturer.
What two types of organic fibers are used to covering aircraft?
Cotton and Linen.
What is meant by warp, weft, and bias.
Warp is the direction along the length of the fabric, weft is the direction across the the fabric at right angles to the warp, and bias is a direction at a 45 degree angle to the warp and weft.
What is the purpose of the selvage edge on a roll of fabric?
It prevents the fabric from unraveling.
What identification marking is found on the selvage edge, and in which direction is the warp applied?
The FAA-PMA stamp is found on the selvage edge, and the warp is applied parallel to the line of flight.
How are the fabric type and strength requirements determined for fabric-covered aircraft?
The original manufacturer determines the fabric type, and the strength requirements are a function of the never-exceed speed and wing loading.
What types of synthetic fibers are used for covering aircraft?
Fiberglass and heat shrinkable polyester fibers.
Which of the several types of fabric is unaffected by moisture and mildew?
fiberglass.
What is the function or purpose of reinforcing tape?
Reinforcing tape is used between the fabric and the rib stitching to prevent the lacing cord from cutting through the fabric.
Where would you use surface tape?
Over rib stitching and sewed seams, over lapped edges, around corners, and along leading and trailing edges.
How should the edges of drainage, inspection, and ventilation holes be reinforced?
With plastic, aluminum, or brass grommets.
What are the principle methods used to test the condition of fabric?
Punch testers such as Maule or Seybolt test, and laboratory pull testing.
Fabric is considered unairworthy when it has deteriorated to what percentage of its original strength?
Less than 70%
How should a structure that will be covered with doped fabric be prepared following inspection and prior to covering?
Treat it with a protective coating of paint or varnish as appropriate.
What is the principle advantage of the envelop method for covering wings?
Almost all the seams are machine sewn by the envelope supplier.
What is a tie off knot?
A standard, modified seine knot used on all stitches except the starting stitch.
Name three common types of machine-sewed seams.
Plain overlap, folded-fell, and French-fell.
Where are anti-tear strips used?
Under wing rib stitching when the never-exceed speed is greater than 250 mph.
How would you determine the correct spacing for rib stitching if the original spacing was unknown.
Consult chart in AC 43.13-1B
Why is butyrate dope safer to use than nitrate dope?
It is much less flammable.
What are the two types of dope used for fabric finishes?
Cellulose Nitrate and Cellulose Acetate Butyrate.
What is the appearance of a blushing paint finish?
Chalky or cloudy.
What finishing defect is the result of a paint room temperature that is too warm?
Pinholes or blisters.
What causes dope to blush?
High humidity, moisture in the spray system, or application over a damp surface.
What factors cause spray paint sags and runs.
Inadequate surface preparation or paint sprayed on too thickly.
What components or parts of the airframe must be protected from damage when using paint stripper?
Windshields and windows, plastics, composites, synthetic rubber, and fabrics.
What is the function of zinc chromate or wash primers?
Primers serve to inhibit corrosion and provide a good bond between the metal and the topcoats.
Name several common types of paint used on aircraft.
Zinc chromate and wash primers, synthetic enamels, acrylic lacquer, and polyurethane.
What is the proper thinner to use with zinc chromate primer?
Toluene.
What health and safety precautions must be observed when using the toxic solvents and thinners that are part of modern finishing systems?
Respirators and/or mask must be worn when spraying finishes.
If spray painting dust causes a surface to appear dry and rough, what are the most likely causes?
Too much air pressure or the spray gun is too far from the surface being painted.
What causes "orange-peel"?
Spray pressure too high, use of a thinner that dries too fast, cold temperatures, or a damp draft over the surface.
What regulation governs the application of the registration numbers to aircraft registered in the United States.
FAR Part 45
Other than appearance, what is another reason for touching up painted surfaces?
Reduction or elimination of general corrosion problems.
What references should be used to determine if a control surface must be checked and/or rebalanced after painting?
The manufacturer's service manual.
What would be the effect if dope was used over paint or enamel?
The dope tends to dissolve these materials.
What are the three most commonly used methods of applying paint?
Dipping, brushing, and spraying.
What is the effect on paint finishes if too much drier is added to the paint?
The paint film will be brittle and tend to crack and peel.
What paints systems may be used with epoxy topcoats?
Any paint system in good condition.
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