DVD Process for Laminate Structures
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Questions and Answers

Which step involves using the tap test or ultrasonic test to map out the damage?

  • Step 2: Damage Removal
  • Step 5: Curing the Repair
  • Step 1: Investigating & Mapping the Damage (correct)
  • Step 3: Layup of the Repair Plies

    • What should be done after trimming out the damage to a smooth round or oval shape?

  • Applying Top Coat
  • Curing the Repair
  • Clean the surface with an approved solvent and cheese cloth. (correct)
  • Layup of the Repair Plies

    • Which method can improve the properties of a wet layup repair?

  • Use of scotch or sand paper
  • Heater blanket cure
  • SRM determination
  • Double Vacuum Debulk Method (DVD) (correct)

    • What is the temperature range at which most prepregs and film adhesives cure?

    <p>250 °F or 350 °F</p> Signup and view all the answers

    Why must the repair ply material and orientation match that of the parent structure?

    <p>To ensure a proper bond</p> Signup and view all the answers

    When should the vacuum bag be removed from the repair?

    <p>After curing and inspection</p> Signup and view all the answers

    What is the purpose of vacuum bagging in the repair process?

    <p>To reduce peel stresses at the edges of the repair</p> Signup and view all the answers

    What are typical failures found during inspection of lightning protection strips?

    <p>Disbonding from the radome surface</p> Signup and view all the answers

    What is a disadvantage of using an external patch in repairs?

    <p>Eccentric loading causing peel stresses</p> Signup and view all the answers

    Why are external patches usually stepped in repairs?

    <p>To reduce stress concentration at the edge</p> Signup and view all the answers

    Which materials can be used for external bonded repair according to the text?

    <p>Carbon, fiberglass, and Kevlar®</p> Signup and view all the answers

    What is important to avoid in lightning protection strips for a radome?

    <p>Protrusion into the air stream</p> Signup and view all the answers

    What is the purpose of the DVD process in wet layup laminates?

    <p>To remove entrapped air causing porosity</p> Signup and view all the answers

    How does the double vacuum bag process differ from a standard wet layup process?

    <p>It involves a debulking assembly for air removal</p> Signup and view all the answers

    What is the purpose of evacuating the air between the rigid outer box and inner vacuum bag in the double vacuum debulk principle?

    <p>To prevent atmospheric pressure from pressing down on the inner vacuum bag</p> Signup and view all the answers

    Why is it important to reduce resin viscosity during the debulking process?

    <p>To improve air and volatile removal</p> Signup and view all the answers

    What is the role of the DVD tool in preparing wet layup patches?

    <p>To facilitate patch preparation</p> Signup and view all the answers

    How does the double vacuum debulk principle help in preventing air bubbles in the laminate?

    <p>By preventing atmospheric pressure from pressing down on the inner vacuum bag</p> Signup and view all the answers

    What type of surfaces are precured patches not suitable for?

    <p>Compound curved surfaces</p> Signup and view all the answers

    In the repair process using precured patches, what is done in Step 3?

    <p>Consult the SRM for correct patch size</p> Signup and view all the answers

    What is required in Step 4 of using a precured patch for repair?

    <p>Apply film adhesive or paste adhesive to the damaged area</p> Signup and view all the answers

    What is a key advantage of bonded repairs over bolted repairs?

    <p>Stronger than original part material</p> Signup and view all the answers

    At what temperature do most film adhesives cure during the repair process with precured patches?

    <p>250 °F</p> Signup and view all the answers

    What type of surfaces are bonded repairs applicable to?

    <p>Any type of surface</p> Signup and view all the answers

    What is used to control the heat in the process described?

    <p>Thermocouples</p> Signup and view all the answers

    How is the debulking cycle completed?

    <p>By venting the vacuum source</p> Signup and view all the answers

    What is used to consolidate the plies during the compaction cycle?

    <p>Vacuum bag</p> Signup and view all the answers

    How are DVD tools fabricated according to the text?

    <p>From wood two-by-fours and plywood</p> Signup and view all the answers

    What is applied on the aircraft skin before placing the patch?

    <p>Film adhesive</p> Signup and view all the answers

    What is used to cure the adhesive used for patch installation?

    <p>Vacuum bag and heater blanket</p> Signup and view all the answers

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