PLATE, LOCKING PINS—A temporary
locking pin attached to a thin, flat, rectangular
metal plate. The pin-plate arrangement is used to
temporarily lock the pilot parachute while the side
flaps are being closed.
PLEAT—A fold sewn in cloth.
POCKET, DATA CARD—Small patch
pocket sewn to specified parachute containers for
record data card. (Record card used for drogue
parachute assemblies only.)
P O C K E T , E L A S T I C S T O W A G E —A
pocket, formed of elastic cloth, that encloses the
external pilot parachute on the NB-11 parachute
assembly.
POCKET, RIB—A pocket made by sewing
lengths of tape to a type of pilot parachute canopy
to contain the four frame ribs.
POCKET, RIPCORD HANDLE—A small
pocket of cloth or elastic webbing sewn to the
harness (or container assembly). It holds the
ripcord handle in position.
POCKETS, DEFLATION—Pockets sewn to
the canopy at the skirt hem. After landing in
water, they serve to anchor the canopy, causing
the canopy to deflate. This prevents the canopy
from dragging the parachutist through water.
POROSITY OF A FABRIC—The measured
amount, in cubic feet, of the flow of air through
a square foot of fabric in 1 minute under specified
pressure. Also known as PERMEABILITY.
PREMATURE OPENING—Any accidental
opening of a parachute that occurs prior to
intended deployment.
PRESSURE—The force exerted by liquid or
gas per unit of area on the walls of a container.
See also PSIG, PSIA, and ATMOSPHERIC
PRESSURE.
PRESSURE DROP—Loss in pressure, as
from one end of a distribution line to the other,
due to friction and other factors.
PRESSURE EXPLOSION—Explosion
caused by rapid conversion of liquid oxygen to
gaseous oxygen in a confined space due to
evaporation and warming.
PROTRUDING YARN (Core Casing or
Tread)—A condition in which either the inner core
yarns extend through the casing or where the yarns
or threads of the casing extend beyond the surface
of the casing itself.
PSI—Abbreviation for pounds per square
inch. See also PSIA and PSIG.
PSIA—Abbreviation for pounds per square
inch, absolute. Absolute pressure is measured
from absolute zero (100-percent vacuum) rather
than from normal, or atmospheric pressure. It
equals gauge pressure plus 14,696 pounds per
square inch.
See also PSI, PSIG, and
ATMOSPHERIC PRESSURE.
PSIG—Abbreviation for pounds per square
inch, gauge. Indicates pressure above ambient
pressure, as indicated on a pressure gauge vented
to the atmosphere. See also PSI and PSIA.
PULL UP CORDS—Nylon cords of varying
lengths used to pull up the sides and ends of the
container flaps over the container cover and to
pull the cones through the grommets. They are
also used to pull the suspension lines into place
in some types of containers.
P U S H P I N — A s t r a i g h t p i n u s e d to
temporarily secure material while sewing.
PYRO BOX—The container used to store
pyrotechnic devices such as flares and cartridges
while they are removed from the ammunition
storage area.
PYROTECHNIC DEVICE—Any device that
either bums or explodes or uses burning or
exploding to operate a system. Examples of
pyrotechnic devices are static line cutters, ballistic
spreading guns, and automatic actuators.
QA—Abbreviation for quality assurance.
QUALIFIED PERSONNEL—Qualified
personnel are defined as personnel who have
satisfactorily completed a prescribed course at a
Navy training school, Fleet Readiness Aviation
Maintenance Personnel Training Program
(FRAMP), Interservice/factory training, or
formal or informal in-service training [refer to
OPNAVINST 4790.2 (series)]. In addition, a
practical demonstration of the skills acquired in
any of the foregoing training situations, to the
AI-11
