B. NDI Procedure. Once visual detection of corrosion has been made, an assess-ment of the extent of corrosion damage must be made before repairs can be
started. Where visual means cannot determine the extent of damage the appli-cable NDI technique can be used for the assessment. Microcracks must neces-sarily be checked by one of the NDI techniques.
Volume 1
20-20-00
Page 3 OCT 01/01
CORROSION PREVENTION MANUAL
GENERAL INFORMATION
INSPECTION AND DETECTION
C. Special. In some cases, operators will be transporting cargo that will
require special detection attention or techniques due to the nature of the
cargo. Examples of these cargoes are listed below:
(1)Mercury. During the transporting of mercury, containers have been known
to break, spilling into cargo hold areas and seeking its way to airplane
structure between frames, stringers, skins and under repair patches.
Mercury is highly corrosive when in contact with aluminum and its alloy
and will compromise the structural integrity of structural member
affected. The presence of mercury in an area, after a known spill has
been reported, can be identified by a white powder on the surface
resulting from the chemical combination of mercury and aluminum parti-cles. Detailed inspection, detection and treatment of mercury corrosion
is explained in 20-41-00.
(2)Livestock. Special provisions are made for the transporting of live-stock. There are several factors such as humidity, expulsion of salt
from the body, waste spillage, etc., that require special corrosion
detection techniques. Detailed inspection, detection and treatment for
transportation of livestock is given in 20-61-00.
D. Marking. Areas requiring cleaning and stripping for inspection should be
clearly marked after detection. The extent of the corroded area should also
be clearly identified and reported for repair or treatment.
Volume 1
20-20-00
Page 4
OCT 01/01
1. General
A. The probability of encountering corrosion damage to an airplane is dependent
on a number of factors such as the degree of protection afforded during man-ufacture, the maintenance of the protection during service life, and the
environment in which the airplane is operated.
B. Some environmental factors are within the control of the manufacturer or the
operator such as the Location of battery compartments or the prevention of
spillage from galleys and lavatories. In these instances, recommended
inspection frequencies or requirements for preventive maintenance can be
established which are not dependent on the operator's route structure.
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