Before beginning any rework:
l. Position airplane in a wash rack or provide some type of washing apparatus for rapid rinsing of all
surfaces.
2. Connect static ground line to airplane.
3. Remove airplane battery if required.
4. Protect pitot-static ports, engine openings, airscoops, louvers, wheels, tires, and other portions of
airplane from moisture and chemical brightening agents.
5. Protect surfaces next to rework areas from chemical paint strippers, corrosion removal agents and
surface treatment materials. Evaluate corrosion damage to determine type and extent of repairs
required.
Proceed as follows:
l. Light Corrosion: discoloration or pitting. Remove by light hand sanding or a small amount of
chemical treatment.
2. Moderate Corrosion: similar to light corrosion except there could be some blistering or evidence
of scaling and flaking. Remove by extensive hand or mechanical sanding.
3. Severe Corrosion: similar to moderate corrosion with severe blistering, exfoliation, scaling or
flaking. Remove by extensive mechanical sanding or grinding.
—CAUTION—
The depth of material removed must not exceed safe limits.
—CAUTION—
Removal of severe corrosion may be considered a major repair.
This type repair must be FAA approved before returning airplane
to service.
CHART 2003. TYPES OF METAL CORROSION
TYPE OF MATERIAL TYPE OF CORROSION REMEDY~
Steel Rust* Complete removal of corrosion
by mechanical means
Aluminum White to grey powdery material Mechanical polishing or
brushing with material softer
than aluminum
Magnesium (highly susceptible White powdery snow-like Mechanical polishing or
to corrosion) mounds and white spots. brushing for a smooth
finish
Cadmium (plating) White to brown to black mott- Mechanical removal of
ling of surface (plating is corrosion should be limited to
still protecting until iron metal surfaces from which the
appears) cadmium has been depleted
Chromium (plating) May pit in chloride environment Polishing and buffing
20 - 24 - 00
Page - 20 - 12
Reissued: August 1, 1986
1E15
PIPER AIRCRAFT
PA-28-236
MAINTENANCE MANUAL
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