Page 4 2
nd
Edition – Rev 0
51-20
DAMAGE CLASSIFICATION AND REPAIRS - GENERAL
(a) For steel parts, with the exception of highly stressed components or
stainless steel, it is possible to use abrasives, power brushes, steel brushes if
operated manually and steel wool. Removing corrosion by products from
highly stressed steel components (main gear steel spring) requires particular
care.
(b) For aluminum parts, treatment consists in mechanically removing as
much as possible corrosion by products, applying corrosion inhibitor and
replacing original finish. Steel wool, emery or steel brushes (unless stainless
steel) along with other highly abrasive material should not be used since steel
or emery particles become embedded in the softer material causing corrosion.
After cleaning surface corrosion, parts must be treated with an anti-corrosion
finish prepared as follows: 4-liter solution containing 10% cromic acid with 20
drops of battery electrolyte. Accurate brushing with a sturdy fiber brush will
rid of most of the corrosion and insure that the anti-corrosion agent will
penetrate completely in the cracks.
Leave the cromic acid solution on the part for at least five minutes and then
remove excess with water or a damp cloth. Apply protective finish the same
day in which treatment begins.
Delamination: separation of the layers of material in a laminate, either local or
covering a wide area, that occurs in service. Composites may delaminate when impacted
and not exhibit visible damage.
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