3-35. EXCITER-AUXILIARY GENERATOR ASSEMBLY (cont)
CLEANING, INSPECTION, AND REPAIR (cont)
If bands are loose, repair at depot level maintenance facility.
Check that bands are tight and secure and soldering is intact.
Use a dial indicator and check commutator for roughness or out-of-roundness. Commutator is out-of-round if
there is a 0.002-inch (0.05 mm) variance within a six bar span. Inspect surface for wear, burns, or pitting. If
these conditions exist perform the following:
(1) Use fine grinding stone and give commutator a smooth finish.
(2) Check that mica is undercut to a depth of 1/16 to 3/32 inch (1.6 to 2.4 mm). If mica depth is not within these
limits, use a mica undercutter saw and regroove mica.
Do not damage commutator bars during cleaning process.
(3) Clean slots between copper bars to remove burrs.
Compressed air used for cleaning purposes will not exceed 30 psi (207 kPa). Do not direct compressed
air against skin. Use goggles or full face shield.
(4) Use dry compressed air and remove loose mica and copper from commutator.
Do not coat commutator surfaces with insulating varnish.
Paint surfaces of coil insulation with red insulating varnish.