TM 1-2840-252-23-3
GLOSSARY (Continued)
Definition
P
Parent Metal ................................ .............. The basic metal of a part, sometimes referred to as a base
metal; the term is used particularly in connection with weld-
ing, where the parent metal is that being welded rather
than that used in welding rod.
Peening ................................ ..................... Surface deformation.
Phenolic ................................ .................... A thermosetting resin or plastic made especially for molding
and insulating, coatings and adhesives.
Pitting ................................ ........................ Very shallow depressions in a surface, usually caused by
chemical reaction (rusting chemical corrosion).
Popping ................................ .................... Sharp abrupt noise normally caused by erratic bleed band
operation.
Protrusion................................ .................. Projection sticking out from the rest of the surrounding ma-
terial or surface.
Puncture................................ .................... A hole that is pierced in a material.
R
Repair................................ ........................ To restore a defective part, component, subassembly or
assembly to a serviceable condition.
Rollover ................................ ..................... A curl usually on the leading edge of a blade, resulting from
deformation by the peening action of foreign objects.
Rub ................................ .......................... When one component contacts another and is moved in
relationship to it causing material to be removed from it.
Rust ................................ .......................... Oxidation of iron. A red, crusty product which forms on iron
or steel when it unites with oxygen.
S
Scoring ................................ ...................... Multiple scratches, usually parallel and resulting from the
same cause.
Scratch ................................ ..................... A long, narrow sharp-cornered impression caused by the
movement of a sharp object across the surface of parent
material.
Serviceable ................................ ............... Equipment or parts that are in condition which allows them
to be returned to operational status on an aircraft.
Step................................ ........................... Wearing away of material, caused by movement of contact-
ing surfaces, in such a manner as to cause sharp edged
ridges or depressions. Usually a severe form of grooving.
Subassembly................................ ............. A self-contained unit of an assembly that can be removed,
replaced, and repaired separately; turbine nozzles and
combustion liner are typical subassemblies.
Glossary-4
