Figure 2-18. Straight Flow Ball / Valve-Type Coupling

TM 1-1500-204-23-3 Figure 2-17. Full Grip Push/Pull-Type Coupling Figure 2-18. Straight Flow Ball / Valve-Type Coupling Figure 2-19. Ball Lock-Type Coupling i. Closed-Circuit Refueling Receptacles. Closed- Circuit Refueling (CCR) is a system of equipment in which a special aircraft fill port (receiver) and a special nozzle mate to form a vapor-proof seal. This system prevents vapors from escaping at the aircraft fill port, and so reduces the danger of ignition from static electricity or engine heat. Use of closed-circuit equipment is especially ,desirable when aircraft are being serviced by the riot refueling method. Hot refueling is used to reduce the ground time needed to refuel aircraft, particularly helicopters used in support of combat operations. Closed -circuit refueling prevents spills, prevents fuel vapors from escaping at the aircraft fill port, and prevents dirt, water or, and other contaminants from entering the aircraft fuel supply during refueling. These factors contribute to safe ground operations by reducing fire hazards and contribute to safe flight operations by protecting the quality of the fuel used. (1) Types. Any closed system of aircraft refueling depends on two basic pieces of equipment: a receiver that is mounted in the aircraft, and a nozzle. These two pieces of equipment are designed for each other, to mate or lock together before fuel can flow through them. The Army has two such equipment systems, the CCR system that: is part of the Forward Area Refueling Equipment (FAIRE) system and the D-1 pressure system (also called the centerpoint system). (2) Inspection. The CC:R receiver as shown in figure 2-20 is inspected as follows: (a) Check receiver structural support assembly for damage, corrosion, and galling of flanges and webs. (b) Check retainer four condition, cracks, or scoring of grooved breakaway tabs. Replace a retainer if damaged. (c) Check receiver for condition and corrosion, floats for freedom, and fuel nozzle receptacle for scoring or damage. (3) Maintenance. Maintenance of the] CCR receiver consists of inspection (and replacement if necessary) in accordance with the applicable maintenance manuals. Scoring and nicks iin the cylindrical fuel nozzle opening may be repaired by polishing out damage. Refer to the applicable maintenance manual for polishing procedures. j. Fuel System Troubleshooting. Troubleshooting should be accomplished in accordance with applicable aircraft maintenance manuals. A typical troubleshooting chart and a schematic are shown in table 2-9 and figure 2- 21. 2-33