AVM 125 - Airframe Structure and Repair

Credits: 5
Lecture Hours: 3
Lab Hours: 4
Practicum Hours: 0
Work Experience: 0
Course Type: Voc/Tech

A course for students in aviation that covers materials associated with the structure of the aircraft. Utilization of proper materials, repair, replacement, testing, and the finishing of metal and nonmetal materials will be included in this course.
Competencies

Wood structures, aircraft coverings, and aircraft finishes
1. Identify wood defects
2. Select wood for structural members based on “aircraft quality” wood, species and standards
3. Identify and describe the working and strength characteristics of two kinds of wood which may be used as substitutes for spruce
4. Interpret the acceptable limits for wood defects, measure a pitch pocket, grain slope or grain divergence
5. Explain why pitch pockets would be considered more critical if they were located in the edge or spar cap of a wood spar
6. Interpret the limitations as imposed by FAA AC 43.13-1A to the acceptance of mineral streaks in a piece of aircraft spruce
7. Identify a compression failure in a piece of aircraft spruce
8. Describe what is meant by the term “brash” and describe physical characteristics that may indicate “dry rot” in a piece of spruce
9. Explain why a single knot in a piece of spruce is not sufficient cause for rejection of that piece of material
10. Describe the terms spiral/diagonal/interlocked/wavy/curly grain.
Inspect Wood Structures
1. Explain some of the advantages of laminated and plywood members over solid wood members.
2. Know types of wood most susceptible to warping, to be able to classify a laminated section or plywood member
3. Describe the splintering characteristics between spruce and douglas fir
4. Interpret information pertaining to the effect of moisture on the size and strength of wood structural members knowing the greatest dimensional change and direction due to moisture, the effect on alignment of a structure due to shrinkage
5. Explain the methods used to minimize the loosening of fittings due to shrinkage
Service and Repair Wood Structures
1. Judge the suitability of substitute materials, use of references to determine species substitution, determine authorization for material substitution.
2. Describe the kinds of glues and gluing techniques
3. Know the terms “open assembly” and ?closed assembly? as applied to the glued joint
4. Determine the proper clamping procedures to a spar slice. Explain clamping technique and pressure most generally applied to the gussets of ribs.
5. Describe the procedure used to extend the working life of a synthetic resin glue
6. Determine spar repair procedure at wing fittings.
7. Determine repair procedure for longitudinal cracks in a spar.
8. Describe the procedure and methods of elongated bolt holes in wood spars.
9. Describe rib repair procedures at a rib joint, between rib joint, and at the trailing edge
10. Determine procedure in making plywood skin repair, determine the limiting radius to bends, the types of skin repair and dimensional limits.
11. Identify protective finishes, use FAA AC 43.13-1A or equivalent reference information to determine protective finishes in particular to the end grain of a spar, and the importance of dope-proof paint.
12. Describe the procedure that should be followed to seal the interior surface of a wood structure that will be assembled
Select and apply fabric and fiberglass covering materials.
1. Name four factors that are considered when selecting the kind and quality of fabric that will be used in recovering an airplane
2. Compare the relative durability of the various kinds of fabric and its strength characteristics
3. Compare the relative strength of a plain overlap, French fell, and a folded fell seam; also, give the manner in which the seam must be located.
4. Give the limitation or disadvantage to the use of a plain sewed seam.
5. Explain the requirements for overlapping doped seams at the wing leading edge.
6. Explain the purpose of inter-rib bracing; also determining correct rib stitch spacing
7. Describe the difference between an envelope and a blanket method of covering
Inspect, test and repair fabric and fiberglass
1. Explain the results of poor ventilation and inadequate drainage, how it contributes to corrosion and deterioration when moisture is present, also the deterioration effect caused by sunlight
2. Describe the protective finishes used to minimize deterioration to the fabric covering. Explain damaging effect of a structure when infested with insects, birds and varmints. Describe factors in determining whether a fabric covered structure is airworth
3. Explain why fabric is strength tested, and at what intervals, also two common methods testing fabric strength and compare reliability. Explain which areas of the aircraft are the sample “strips” taken and the areas where “punch” tests are made
4. Explain some of the precautions in using and interpreting the readings of a “punch” tester. Explain the factor of aircraft performance which limits the repair of fabric by doped-on patches, also the kind of tests used to determine the kind of dope that h
5. Explain what publication classifies the repairs as major or minor repairs. Give recommended procedure when sewing an “L” shaped tear, give circumstances when necessary to ribstitch a patch; describe method to remove original dope-as a prelude to doping o
6. Explain precautions involved when patching fabric on movable control surfaces
Apply trim, letters and touch-up paint
1. Explain the positioning on fixed wing and rotary wing aircraft, and how registration numbers are assigned and issued to a specific airplane.
2. Give the procedure for changing a registration number that has been assigned to an airplane
3. Quote regulation as to the height and width, also explain the term “stroke” of the letter.
4. Explain requirement for contrasting color, a review of FAR 45 of registration markings as to forms referred to as “block slant or inclined letters.”
5. Explain marking of foreign registry of an airplane while it is operating within the airspace of the United States and what other regulations apply.
6. Explain the precautions to be observed when masking registration numbers on trim design prior to the application of paints. When using masking paper, give the importance of selecting a paper that will not “bleed through.”
7. Explain uses and advantages of decals, instructions for applying decals, and how decals are coated after they have applied to the aircraft surface.
Apply finishing materials
1. List why dope is usually brushed at a ?full-bodied? or unthinned consistency, advantages and disadvantages to the use of butyrate dope
2. Describe a procedure that will ensure penetration of the dope and saturation of the fabric without the detrimental effect of runs and sags. Also describe sanding technique
3. Apply surface tapes, drain grommets, inspections rings, and reinforceing patches
4. Explain the proper placing of grommets, inspection rings, and reinforcing patches. Describe a practice that will minimize the entrapment of air beneath tapes and patches
5. Describe why the surface of an aluminum alloy must be cleaned and etched before priming, also information as to the correct thinner to be used with a primer and how it can be found
6. Give the advantage to “wet sanding” a finish.
7. Explain the difference between a suction type and pressure type of spray gun. Describe the adjustments of a spray gun which permits control of the fluid quantity and spray pattern
8. Explain faulty operator techniques that will probably result in:
9. Inspect finishes and identify defects
10. Explain test procedure that may be made to determine whether a finishing material may be sprayed over an original finish. Advise what reference information should be used as a guide to the mixing and application of finishes
11. Explain some of the factors that contribute to the following:
Identify and select aircraft finishing materials
1. Describe the results of mixing nitrate and butyrate dope.
2. Perform test that could be made to determine whether the original finish was nitrate or butyrate
3. Describe some of the advantages and limitations of nitrate dope, and butyrate dope
4. Explain the purpose of a rejuvenator and how does rejuvenator differ from dope
5. Describe the difference between lacquer and enamel, and the results of mixing lacquers and enamels
6. Explain why there is such a wide variety of primers and special purpose paints; also, what special precautions apply to the mixing and application of special finishes that require a catalyst
7. Explain why some thinners may also be called “reduces.” Retarders, it’s functioning the thinning of dope.
8. Describe precautions that should be observed to ensure that thinners are correctly identified before pouring them into a finishing material
Select, install and remove special fasteners for metallic, bonded, and composite structures
1. Identify kinds of special rivets used in aircraft repair.
2. Remove and install hi-shear rivets
3. Remove and replace special rivets and fasteners
4. Select acceptable holes and install hi-shear rivets, and blind rivets.
Form, lay out, and bend sheet metal
1. Make a joggle in aluminum sheet
2. Describe theory of bend allowance and flat pattern development.
3. Layout and make bends in sheet metal
4. Form aluminum parts by bumping
Inspect and repair sheet metal structures
1. Select and use twist drills and countersinks.
2. Select and use hand files for soft metals
3. Repair shallow scratches in sheet metal
4. Repair a slightly oversize hole by reaming for next larger size rivet
5. Prepare dissimilar metals for assembly
6. Describe loads in fuselage and wing structures and types of overload failures.
7. Repair stressed-skin airplane wing
8. Repair aircraft structural units built from sheet metal.
9. Determine condition of stressed skin structure which has been critically loaded.
10. Construct a watertight joint
Inspect bonded structures
1. Inspect and repair metal sandwich structures
2. Evaluate damage to bonded structure and determine type of repair needed.
Inspect, test and repair fiberglass, plastics, honeycomb, composite, and laminated primary and secondary structures
1. Identify and repair plastic composite and fiberglass aircraft materials.
2. Repair damaged areas in fiberglass aircraft structures.
Inspect, check, service and repair windows, doors and interior furnishings.
1. Recognize distinguishing characteristics of transparent plastic and plate glass enclosures
2. Clean, protect, repair, and secure transparent plastic aircraft enclosures