1 33-8. ALUMINUM REPAIR (Contd) 1
e. Repair Parts Preparation.
1. Repair parts or patches should be painted with epoxy primer before installation.
2. Apply sealing compound (appendix C, item 611 to mating surfaces to prevent corrosion.
3. Install insertion or patch as detailed in 33-8g and 33-8h.
4. Paint repaired area with epoxy primer.
5. Paint repaired area with polyurethane as required.
f. Repair of Negligible Damage.
1. Negligible cracks as defined in para. 33-613 are repaired by drilling a small hole at each end of crack
to stop crack propagation. This is called stop-drilling. Table 33-5 gives proper drill sizes for stop-drilling
2. Negligible holes are repaired by rounding and smoothing edges of hole to alleviate stress risers
caused by sharp notches.
Heat will never be used to re-form parts because it greatly reduces
3. Small dents and distorted areas may be repaired by bending or hammering, as long as the
operation does not cause materials to crack or tear. Sharp bends should not be attempted.
Table 33-5. Stop-Drill Sizes for Negligible Cracks.
SHEET THICKNESS (INCH)
STOP DRILL SIZE NO.
0.033 and thicker