2-77. INSPECTION. Corrosion should be suspected at every inspection. In trouble areas, the inspection
frequency should be increased.
In addition to routine inspections:
a. Aircraft operating around a marine environment should be given special checks on a weekly basis.
b. Aircraft operating in semi-acid condition should be inspected monthly.
c. Inspections for corrosion should be performed by personnel familiar with corrosive problems and their
remedies as follows:
1. Daily and preflight inspections should include the engine frontal areas, all intake vents, engine
compartment, gaps, seams, and faying surfaces in the exterior skins, wheel and wheel well areas, battery
compartments, fuel cell and all other drains, and any bilge areas not requiring extensive removal of inspection
access covers.
2. Detailed inspection should include the above referenced areas along with areas requiring removal of
screw attached inspection plates and panels to thoroughly inspect the internal cavities of the aircraft.
d. During inspection, remember that paint tends to hide corrosion in its initial stages. However, the results of
corrosion can sometimes be seen as blisters, flakes, chips and other irregularities in the paint.
2-78. CORROSION REMOVAL AND CONTROL. Corrosion cannot be prevented or eliminated on aircraft; it
can only be reduced to an acceptable level by proper control methods.
All corrosion products must be removed prior to refinishing. If they are not removed, corrosion will begin
again, even though the affected area is refinished.
Before beginning any rework:
a. Position the airplane in a wash rack or provide some type of washing apparatus for rinsing of all surfaces.
b. Connect a static ground line to the airplane.
c. Remove the airplane battery if required.
d. Protect the pitot-static ports, engine openings, airscoops, louvers, wheels, tires and other portions of the
airplane from moisture and chemical brightening agents.
e. Protect the surfaces next to the rework areas from chemical paint strippers, corrosion removal agents and
surface treatment materials.
An evaluation of the corrosion damage is necessary to determine the type and extent of repairs required. The
following are general guidelines:
a. Light Corrosion: discoloration or pitting normally removed by light hand sanding or a small amount of
chemical treatment.
b. Moderate Corrosion: similar to light corrosion except there could be some blistering or evidence of
peeling and flaking; removed by extensive hand sanding or mechanical sanding.
c. Severe Corrosion: similar to moderate corrosion with severe blistering, exfoliation, sealing and/or flaking;
normally removed by extensive mechanical sanding or grinding.
— CAUTION —
Removal of severe corrosion may be deemed as a major repair. The repair must be approved by the FAA
upon completion.
PIPER AIRCRAFT
PA-28-161 CADET
AIRPLANE MAINTENANCE MANUAL
Issued: FEBRUARY 28, 1989
HANDLING AND SERV I C I N G
1C12
