R-Abbreviation for radius.

RATE OF DESCENT-The speed that a parachute descends through the air. The rate varies according to atmospheric pressure, weight of load, movement of air (updraft and downdraft), and size, design, and condition of canopy.

RAVEL (UNRAVEL)-TO separate, untwist or unwind, leaving a frayed or ragged edge. Ravel is the preferred word to describe such a condition.

RECEIVER ASSEMBLY, AUTOMATIC PARACHUTE RIPCORD RELEASE-That part of the cartridge-actuated automatic ripcord release that houses the aneroid, sear, and hammer.

REF-Abbreviation for reference.

REFILL (In reference to oxygen cylinders)- To refill is to recharge a cylinder, regardless of the residual pressure remaining within the cylinder.

REINFORCEMENT-Any strengthening measure that enhances the basic integrity of a structure, joint or assembly; for example, the tape or webbing used to strengthen parts of a canopy, container, harness, etc., in a parachute assembly. See also WEBBING and REINFORCEMENT.

RELEASE ASSEMBLY, RIPCORD HOUS-ING, MANUAL-An assembly that releases the ripcord housing at the top end flap when the parachute is at full suspension line stretch.

REPAIRS, MAJOR-Repairs requiring special equipment, personnel, or materials normally not available at intermediate or local levels of maintenance.

REPAIRS, MINOR-Repairs that can be effected at intermediate or local levels of maintenance.

RETAINING SLEEVE-A series of stowage tunnels.

RFI-Ready for issue.

RIG-To assemble and adjust; to equip. For example, the act of rigging a parachute assembly consists of assembling all component parts in preparation for packing.

RING, VENT-A molded rubber ring in the vent collar. It stretches when the air rushes into the canopy as the parachute begins to inflate.

RIPCORD-A locking device that secures the folded parachute within the container and that effects the release of the parachute. The ripcord consists basically of locking pins, a flexible cable and a handle. See also AUTOMATIC PARACHUTE RIPCORD RELEASE; BALL, CABLE RETAINING; CABLE, RIPCORD; CLAMP, RIPCORD HOUSING; HANDLE, RIPCORD; HOUSING, EXTENSIBLE RIP-CORD; HOUSING, RIPCORD; IN, RIP-CORD LOCKING; POCKET, and RIPCORD HANDLE.

RIPCORD PIN RETENTION TIE-A thread of a predetermined value that is usually secured to a lead ripcord pin of a packed parachute. Its function is to retain a ripcord pin in its cone and prevent premature disengagement of the pin from the cone. USE ONLY AS AUTHORIZED.

RISER-The webbing that connects an integrated torso suit or harness to the canopy assembly on parachutes. The riser is composed of two lift webs, and there are two risers on each parachute assembly.

RUNOFF-Sewing not on a seam or cloth.

RUPTURE-One or more yarns of suspension line casing being cut or severed, sometimes exposing the inner core. Occasionally, tears, cuts, or other forms of damage to the canopy are defined as a rupture when caused by dynamic load conditions.

SADDLE-That part of the main lift web of the harness that provides a seat or sling for the wearer.

SAFETY TIE-A low strength thread that serves to indicate that an assembly has not been damaged, tampered with, or opened since the last regular inspection.

SCRAP-To discard, with proper authorization, items, parts or materials that are obsolete or no longer usable.

SDLM-Standard depot-level maintenance. Provides for a comprehensive inspection of selected aircraft structures and materials, critical defect correction, preventive maintenance as required, modification and technical directive compliance to ensure reliability and operational availability of the aircraft at minimum cost for the established operating service period, and to provide intermediate support during the total service life.

SDLM/CONVERSION-Standard depotlevel rework concurrent with special rework, the accomplishment of which alters the basic characteristics of the aircraft to such an extent as to effect a change in any part of the model _{designation (i.e.,} F-4B to F-4D). NAVAIR approval required.

SDLM/CRASH DAMAGE-In addition to accomplishing SDLM (standard depot-level maintenance), repair and restoration to a serviceable condition that part of the aircraft that has sustained damage resulting from an accident or an incident.

SDLM/MODIFICATION-Accomplishment of standard depot-level rework concurrent with a modification that causes major work effort resulting from the installation of these technical directives. NAVAIR approval required.

SEAM-A series of stitches joining two or more pieces of cloth. For government work, the type of seam is indicated by a symbol that gives the class of seam, the number of stitching, and the number of rows of stitching. (Reference Fed. Std. 751.)

SEAM, DIAGONAL-A French-fell seam of the canopy that joins two sections of a gore. Diagonal seams meet the centerline of the gore at angles of 450 and 135.

SEAM, ENGLISH-FELL-A seam in which one piece of cloth is folded back upon itself, and the other piece is a plain overlap.

SEAM, FOUR-NEEDLE FOUR-STITCH- A method of stitching that can be performed in one operation by a four-needle sewing machine.

It is used in sewing the vent hem, skirt hem, and radial seams of a canopy.

SEAM, FRENCH-FELL-A seam in which the cloth is folded back upon itself and stitched.

SEAM, OVERLAP-A seam in which the two pieces of cloth are joined by overlapping enough to accommodate one or more rows of stitching.

SEAM, RADIAL-A seam, joining two gores, that extends radially from the vent to the skirt hem.

SEAM, TWO-NEEDLE TWO-STITCH-A seam in one operation by a two-needle sewing machine; for example, a diagonal seam.

SEAR-To melt or seal with heat; for example, to sear the end of nylon webbing, one heats the end until the nylon melts and fuses. This prevents raveling. Also, the catch that holds the hammer of a firing mechanism cocked. The sear in an automatic parachute ripcord release is attached to the aneroid in the receiver assembly.

SEAT PAN-A sponge-rubber-covered metal seat that is contoured for comfort to the user. A seat pan is used with seat-type parachutes and back-type parachutes when a packaged life raft assembly is used. A high-speed seat pan has sections for support under the pilot's thighs during ejection. This reduces leg strain caused by high acceleration loads.

SECTION-Each major part of a gore. Sections are bordered by radial seams, diagonal seams, or vent or skirt hems. In the 28-foot, flat canopy, four sections are used in each gore (previously known as panel).

SECURITY-An item firmly, positively, and safely attached in the authorized manner.

SELVAGE-An edge of a woven fabric so formed as to prevent raveling, as compared to a cut edge, which will ravel.

SELVAGE, BROKEN-Cut, broken, or tom selvage edge.

SELVAGE, STRINGY OR LOOPY-Irregular stringy or loopy selvage edge.

SEPARATOR, SUSPENSION LINE-A tool used to aid in keeping suspension lines and canopy skirt in order while packing a parachute.

SERVICE LIFE-The time period during which the item can be maintained in service without replacement.

SERVICING PARACHUTES-Inspecting, cleaning, repairing, and repacking parachutes at periodic (calendar) intervals. Periodic intervals for parachutes should correspond either to the aircraft calendar inspection or to the phased maintenance inspection cycle program, as directed by applicable MRC or Special Inspection Card Deck.

SERVING-A method of wrapping or binding the ends of a cord or a line so it will not ravel. Sometimes referred to as "whipping."

SEWING MACHINE-A machine with a power-driven needle, used for sewing and stitching.

SHEARS, PINKING-Shears with a sawtoothed inner edge on the blades for making zigzag cut.

SHROUD LINE-Slang for suspension line.

SKIPPED STITCHES-Threads that are not interlocked.

SKIRT, CANOPY-The lower edge of a canopy.

SLMIP-Suspension line mandatory inspection point.

SLUB-An abruptly thickened place in cloth caused by manufacturer's defect.

SM&R CODES-Abbreviation for source, maintenance, and recoverability codes. Comprised of three parts; a two-position source code, a two- position maintenance code, and a one-position recoverability code.

SMASH-Abrasion damage that causes broken warp and filling threads and weave separation.

SNAP, QUICK-CONNECTOR-A large, hook-shaped, spring-loaded snap used to attach the chest-type parachute to the two D-rings on the harness.

SNAP, QUICK-EJECTOR-A harness snap that attaches to the V-ring to secure two parts of the harness together. The ejector arm releases the V-ring when the finger-grip lever is pulled out ward.

SOCKET, AUTOMATIC PARACHUTE RIPCORD RELEASE-The part of the automatic parachute ripcord release that engages the ball on the power cable. This socket is attached to the piston by a rivet.

SPECIFIC GRAVITY-Density of fluid compared to density of water.

SPEED LINK-Slang for connector link.

SPLICE-The joining of two strands for core ends by interweaving or mechanical joint.

SPREADER BAR-A type of tension hook, used to hold connector links in position during parts of the packing procedure.

SPREADING GUN, BALLISTIC-A device attached to suspension lines just below the skirt hem on the parachute assembly. Just before full suspension line stretch, the gun discharges and, by explosive force, spreads the skirt of the canopy.

SPRING, CONTAINER OPENING BANDS-Stretchable bands composed of a series of springs installed in a cloth case with a hook at each end. They are installed under tension on the pack, to pull apart the end and side flaps after the ripcord is pulled. Also called pack opening band or bungee.

SQUIDDING-A state of incomplete canopy inflation in which the canopy has a squid- or pearlike shape.

STAND, CONTAINER-A rigid stand used to hold some parachute containers, such as the Martin-Baker horseshoe container, during part of the packing procedure.

STATIC LINE CUTTER-A device used to cut the static line to free the parachutist and prevent entanglement.

STIFFENER, CONTAINER-A piece of metal or fiber glass or phenolic fiber placed in the container to stiffen the flaps. These strips are also used for stiffening and shaping the bottoms of several back-type containers.

STITCH, BASEBALL-A stitch used in repair and patching of fabrics. Refer to "Repair/Fabrication," Chapter 4, of NAVAIR 13-1-6.2

STITCH, BASTING-A long, loose stitch made with single or double thread. Used to temporarily hold two or more pieces of material.

STITCH, BOX-Rectangular stitch used to attach and reinforce.

STITCH, BUTTONHOLE-A reinforced stitch made on the edge of a slit or hole. Each individual stitch forms a half-hitch. The distance from the edge, and the spacing of the stitches, is determined by the type of material used.

STITCH, OVERTHROW-A stitch used to repair weakened seams, to reinforce slide fasteners, and to join two pieces of material together.

STITCH, ZIGZAG-A stitch made by a sewing machine that stitches alternately on two or more parallel lines; for example, it is used to reinforce and anchor the suspension lines to the canopy. The number of stitches per inch is determined by counting the number of points on one side per linear inch.

STITCHES PER INCH-The number of needle penetrations where threads are interlaced, per linear inch.

STRIP BACK-Broken thread filament(s) wrapped around the remaining thread forming an enlarged area on cloth.

STRAP, CHEST-The harness webbing that is secured across the chest with a snap and a V-ring to prevent the wearer from falling out of the harness.

STRAP, CROSS CONNECTOR-A short length of webbing sewn across the lift web assembly or attached between suspension line connector links. It prevents streaming of a canopy in the event one riser was not properly attached to the harness.

STRAP, HORIZONTAL BACK-An adjustable part of harness webbing extending across the small of the wearer's back.

STRAP, LAP RESTRAINT-A strap attached to the integrated torso harness suit to retain the rigid seat survival kit to the wearer. Prior to ejection it serves as safety restraint for the aircrewman.

STRAP, LEG-That part of the harness webbing that encircles the wearer's leg. The leg straps are adjustable.

STRAP, PILOT PARACHUTE CONNEC-TOR-Tubular nylon webbing that joins the main parachute and the pilot parachute.

STRAP, SHOULDER-The part of the harness webbing that crosses the wearer's back at the shoulder blades.

STRAP, TENSION-A strap that attaches to the peak of a canopy to keep the canopy and suspension lines taut during parts of the packing procedures.

STOWING-The act of putting away in a neat, orderly way. Stowing of suspension lines involves inserting the lines into the hesitater loops or stowage channels in such a way as to ensure proper paying out of lines when the parachute is opened. Stowing of the canopy involves folding and inserting the canopy into the container in such a way as to ensure proper opening of the canopy when the parachute is used.

SUPPORT FIXTURE-A rectangular piece of metal used to aid in closing the LW-3B personnel parachute assembly. The fixture is bolted to the container base and clamped to the packing table.

SURVEY-A formal process by which a parachute or other accountable equipment is withdrawn from service or removed from records.

SWAGE-To attach a device to a cable by means of pressure. A swaging machine compresses a fitting, causing it to grip tightly to the cable to which it is being attached.