FAA Advisory Circular 43.13-1B
Acceptable Methods, Techniques, and Practices
Aircraft Inspection and Repair
AC 43.13-1B | 5. Nondestructive Inspection (NDI) | 6. Radiography (X-Ray) Inspection | 5-75. Film or Paper Radiography
9/8/98
SECTION 6. RADIOGRAPHY (X-RAY) INSPECTION
AC 43.13-1B
5-73. GENERAL. Radiography (x-ray) is
an NDI method used to inspect material and
components, using the concept of differential
adsorption of penetrating radiation. Each
specimen under evaluation will have differ-
ences in density, thickness, shapes, sizes, or
absorption characteristics, thus absorbing dif-
ferent amounts of radiation. The unabsorbed
radiation that passes through the part is re-
corded on film, fluorescent screens, or other
radiation monitors. Indications of internal and
external conditions will appear as variants of
black/white/gray contrasts on exposed film, or
variants of color on fluorescent screens. (See
figure 5-14.)
5-74. LIMITATIONS. Compared to other
nondestructive methods of inspection, radiog-
raphy is expensive. Relatively large costs and
space allocations are required for a radio-
graphic laboratory. Costs can be reduced con-
siderably when portable x-ray or gamma-ray
sources are used in film radiography and space
is required only for film processing and inter-
pretation. Operating costs can be high because
sometimes as much as 60 percent of the total
inspection time is spent in setting up for radi-
ography. With real-time radiography, operat-
ing costs are usually much lower, because
setup times are shorter and there are no extra
costs for processing or interpretation of film.
5-75. FILM OR PAPER RADIOGRA-
PHY. In film or paper radiography, a two-
dimensional latent image from the projected
radiation is produced on a sheet of film or pa-
per that has been exposed to the unabsorbed
radiation passing through the test piece. This
technique requires subsequent development of
the exposed film or paper so that the latent im-
age becomes visible for viewing.
5-76. REAL-TIME RADIOGRAPHY.
A two-dimensional image that can be immedi-
ately displayed on a viewing screen or televi-
sion monitor. This technique converts unab-
sorbed radiation into an optical or electronic
signal which can be viewed immediately or
can be processed with electronic or video
equipment.
5-77. ADVANTAGE OF REAL-TIME
RADIOGRAPHY OVER FILM RADIOG-
RAPHY. The principal advantage of real-time
radiography over film radiography is the op-
portunity to manipulate the test piece during
radiographic inspection. This capability al-
lows the inspection of internal mechanisms
and enhances the detection of cracks and pla-
nar defects by allowing manipulation of the
part to achieve the best orientation for flaw
detection. Part manipulation during inspection
also simplifies three-dimensional dynamic im-
aging for the determination of flaw location
and size. In film radiography, depth parallel to
the radiation beam is not recorded. Conse-
quently, the position of a flaw within the vol-
ume of a test piece cannot be determined ex-
actly with a single radiograph. To determine
flaw location and size more exactly with film
radiography, other film techniques; such as ste-
reo-radiography, triangulation, or simply
making two or more film exposures with the
radiation beam being directed at the test piece
from a different angle for each exposure, must
be used.
5-78. COMPUTED TOMOGRAPHY
(CT). CT is another important radiological
technique with enhanced flaw detection and
location capabilities. Unlike film and real-
time radiography, CT involves the generation
of cross-sectional views instead of a planar
Par 5-73
Page 5-37