TM 9-2320-361-20 8-35. SHUTTLE (DOUBLE CHECK) VALVE REPLACEMENT (Contd) 6. Install air line (2) on elbow (1). 7. Install two connectors (8) on switch (9). FOLLOW-ON TASK: Start engine (TM 9-2320-361-10), build up air pressure, and check for leaks. 8-85