satisfaction of the work center supervisor/division officer, is required before the designation “qualified” can be assigned. 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 down- draft), 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 suspen- sion 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. AI-12