FAA Advisory Circular 43.13-1B
Acceptable Methods, Techniques, and Practices
Aircraft Inspection and Repair
AC 43.13-1B | 5. Nondestructive Inspection (NDI) | 5. Penetrant Inspection | 5-63. Cleaners and Applications
9/27/01
AC 43.13-1B CHG 1
CAUTION: Improper cleaning meth-
ods can cause severe damage or deg-
radation of the item being cleaned.
Personnel must select and apply
cleaning processes in accordance with
aircraft, engine, propeller, or appli-
ance manufacturer’s recommenda-
tions.
5-63. CLEANERS AND APPLICATIONS.
Use a cleaner to remove contaminants from
parts prior to the application of penetrant in-
spection materials. After the inspection is
completed, penetrant inspection material resi-
dues are removed. The following cleaners are
commonly used during the penetrant inspec-
tion process.
a. Detergents. Detergent cleaners are
water-based chemicals called surfactants,
which surround and attach themselves to parti-
cles of contaminants allowing them to be
washed away.
b. Solvents. Solvents dissolve contami-
nants such as oils, greases, waxes, sealants,
paints, and general organic matter so they can
easily be wiped away or absorbed on a cloth.
They are also used to remove Method C pene-
trant material prior to developer application.
c. Alkalies. Alkaline cleaners are water
solutions of chemicals that remove contami-
nants by chemical action or displacement
rather than dissolving the contaminant.
d. Paint Removers. The general types of
removers used for conventional paint coatings
are solvent, bond release, and disintegrating.
f. Acids. Solutions of acids or their salts
are used to remove rust, scale, corrosion prod-
ucts, and dry shop contamination. The type of
acid used and its concentration depends on the
part material and contaminants to be removed.
g. Etching Chemicals. Etching chemicals
contain a mixture of acids or alkalies plus in-
hibitors. They are used to remove a thin layer
of surface material, usually caused by a me-
chanical process, that may seal or reduce the
opening of any discontinuities. The type of
etching solution used depends on the part ma-
terial and condition.
h. Penetrant Application. Apply the
penetrant by spraying, brushing, or by com-
pletely submerging the part in a container of
penetrant. Wait the recommended amount of
time after the penetrant has been applied to
allow it to enter any discontinuities
(1) Removal of Excess Penetrant. Ex-
cess penetrant must be removed from the
part’s surface to prevent a loss of contrast be-
tween indications of discontinuities and the
background during the inspection. Removal
may require actually washing or spraying the
part with a cleansing liquid, or may simply re-
quire wiping the part clean with a solvent-
moistened cloth. The removal method is de-
termined by the type of penetrant used.
(2) Drying. If removal of the excess
penetrant involves water or other cleaning liq-
uids, drying of the part may be required prior
to developer application. When drying is re-
quired, the time can be decreased by using ov-
ens or ventilation systems.
e. Salt Baths. Molten salt baths are used
in removing heavy, tightly-held scale and ox-
ide from low alloy steels, nickel, and cobalt-
base alloys, and some types of stainless steel.
They cannot be used on aluminum, magne-
sium, or titanium alloys.
i. Developer Application. Apply devel-
oper after excess penetrant is removed and,
where required, the surface is dried. Apply the
developer in a thin uniform layer over the sur-
face to be inspected. Developer acts like a
Par 5-62
Page 5-33