TM 9-2320-387-24-2
1 33-8. ALUMINUM REPAIR (Cont’d) 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
cracks.
2. Negligible holes are repaired by rounding and smoothing edges of hole to alleviate stress risers
caused by sharp notches.
CAUTION
Heat will never be used to re-form parts because it greatly reduces
part strength.
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)
MINIMUM
STOP DRILL SIZE NO.
O-0.032
40
0.033 and thicker
30
33-13
