Non Metallic Structures Flashcards
Name an aircraft structure that a honeycomb panel can be used for.
floor panel, bulkheads, and control surfaces, as well as wing skin panels
What is bonded honeycomb (sandwich) construction?
It is a laminar construction consisting of a combination of alternating dissimilar materials, assembled and fixed in relation to each other so that the properties of each can be used to attain specific structural
middle)
advantages for the whole assembly while reducing weight. (A laminar construction with honeycomb in the
What type of materials are used in honeycomb construction?
Honeycomb construction may employ stainless steel, titanium, magnesium, plywood, resin impregnated paper, E-glass, nylon in various combinations.
Where are sandwich construction assemblies used?
They are used for such areas as bulkheads, control surfaces, fuselage panels, wing panels, radoms, empennage skins, or shear webs.
What procedures should be used to prevent damage to the hole when drilling though Plexiglas?
The Plexiglas should be backed with wood and the feed slowed as the drill point breaks through the underside of the sheet. A drill bit that is to be used for this purpose should be modified to a 60° tip angle, the cutting edge to a zero-rake angle, and the back lip clearance angle increased to 12-15 degrees.
What is crazing and how does it occur?
Hairline cracks in the surface of plastic. A form of heat damage caused by uneven heating, one side expanding more than the other causing excessive stress. Subjecting plastic to large stresses and exposure to harmful solvents will cause crazing.
When inspecting Plexiglas, what should you look for?
Crazing and discoloration.
What causes honeycomb structure to delaminate?
Moisture.
What are the acceptable repair methods for bonded honeycomb structure that has been damaged?
There are two acceptable methods of repair currently being used on damaged skin and core of bonded honeycomb structures. 1. potted repair method. 2. laminated glass fabric cloth overlay which is applied to honeycomb damage which exceeds the repair limitations of the potted compound method.
What is used for hole filling in a bonded honeycomb repair?
Potting compound.
What special precautions should be observed when repairing a radome?
The repair must retain its strength and electrical transparency.
What is a warp line?
A highlighted strand in the fabric used for ply orientation.
What does “pot-life” mean?
The length of time a resin will remain workable after the catalyst has been added.
What is a Barcol hardness tester?
A device that pushes a spike into material such as composites. The depth of penetration can be measured to determine if resins in the composite have cured.
What is done to honeycomb before repairing?
Remove damaged honeycomb and either replace with potting compound or use
plug.
What is the difference between thermoplastics and thermosetting plastics?
Thermoplastics can be remelted and reformed, Thermo setting cannot.
What species of wood do you use for repairs?
Spruce.
What does a metal bushing do in a wood structure?
It protects the wood.
What type of wood should be used for structural repairs in aircraft?
Softwood.
What kind of wood is used in aircraft besides solid wood?
Plywood or Laminate.
How do you repair pin holes in doped fabric?
You brush on dope with retarder onto/in the pin holes.
The Silver Layer on dope and fabric protects from what?
Antimicrobial rot.
What knot is used in fabric between the first and last knot?
Modified Seine Knot.
What happens to composite when you spill skydrol on it?
Damage, Delamination.
Are pin knot clusters allowable in aircraft structural wood?
Yes, if they cause only a small effect on grain direction
What is the preferred seam used when machine sewing pieces of aircraft fabric together?
The french fell seam
What are two types of fabric used to cover aircraft?
Polyester and cotton
What type of hand sewing stitch is used when sewing in a panel of new fabric on an aircraft fabric covered wing?
A baseball stitch, Locked every eight to ten stitches.
What are two methods of attaching the fabric to the aircraft structure?
By sewing and with cement.
Why is the scarf joint angle and condition of a wood spar repair important?
Strength of the joint/repair
What is the term for a piece of wood that has deteriorated to the point where when you crush it, it will turn to a dry powder?
Dry rot
