Operating instructions

MARCH 1982 6-1
SECTION VI
INSPECTION
6-1. DEFINITIONS OF TERMS.
6-2. The following definitions apply to terms used to
describe kinds of damage for which parts should be
inspected.
A. ABRASION: Scratching of a surface, either by
motion while in contact with another part or by
mechanical cleaning or resurfacing with abrasive cloth
or lapping compound.
B. BURNING: As applied to valve heads, this term
indicates roughening or erosion due to high
temperature gases escaping past valve faces. In other
instances it indicates drawing of the temper of steel
parts to a soft (blue) condition as a result of
overheating in absence of lubrication on moving
surfaces, such as gear teeth, subject to high loading.
C. BURR: A sharp projection of metal from an edge,
usually the result of drilling, boring, countersinking,
etc., but may also be caused by excessive wear of one
or both surfaces adjacent to the burred edge.
D. CORROSION: Deterioration of a surface,
usually caused by oxidation of metal.
E. ELONGATION: Stretching or increase in length.
F. FRETTING: Scuffing or deterioration of a metal
surface caused by vibration or chattering of/or against
another part. A fretted steel surface may appear dull,
scuffed or corroded, depending on length of time
subject to the action, dissimilarity and link of
contacting metal and presence or absence of moisture.
G. GALLING: Excessive friction between two
metals resulting in particles of the softer metal being
torn away and "welded" to the harder metal.
H. INDENTATION: Dents or depressions in a
surface caused by severe blows.
I. OXIDATIONS: Chemical combining of a metal
with atmospheric oxygen. Aluminum oxide forms a
tough, hard film and protects the surface from further
decomposition; however, iron oxides do not form
continuous cover or protect underlying metal, thus
oxidation of steel parts is progressive and destructive.
J. PITTING (OR SPALLING): Small, deep
cavities with sharp edges. May be caused in hardened
steel surfaces by high impacts or in any smooth steel
part by oxidation.
K. RUNOUT: Eccentricity or wobble of a rotating
part. Eccentricity of two bored holes or two shaft
diameters. A hole or bushing out of square with a flat
surface. Usually measured with a dial indicator, and
limits stated indicate full deflection of indicator needle
in one revolution of part or indicator support.
L. SCORING: Deep grooves in a surface caused by
abrasion when fine, hard particles are forced between
moving surfaces, as in a bearing and journal, or by
galling when a moving part is not supplied with
lubricant.
6-3. PROTECTION FROM CORROSION. Bare
steel should be covered with oil or a corrosion
preventive oil mixture except during the actual
inspection operations. Since inspection involves
handling of dry steel parts it is advisable to apply a
fingerprint remover solution after such handling,
particularly since perspiration and skin oils often have
a high acid content. Application of lubricating oil or
corrosion-preventive mixture will not necessarily stop
corrosion from this cause.
6-4. VISUAL INSPECTION: Parts without critical
dimensions and small parts, as well as running parts
and others of major importance, should be inspected
visually under good light for surface damage such as
nicks, dents, deep scratches, visible cracks, distortion,
burned areas, pitting, pick-up of foreign metal and
removal of enamel coating. Visual inspection should
also determine the need for further cleaning of obscure