Aviation Electronics Technician 1 - Historic Naval Ships Association

ottle and the ECU are mounted on top of thelauncher assembly. A servicing valve is provided, onthe left-hand side of the helicopter, for servicing theair bottle. The air bottle should be serviced to1200-1250 psi. This ensures that the system will beable to launch all 25 sonobuoys.The distributor valve assembly uses a steppingmotor to route air pressure to the selected launch tube.A manual selection knob, distribution lock, andtube-selected indicator window are located on thevalve. The manual selection knob can be hand rotatedto move the rotary valve to vent or to any desiredlauncher tube position. The valve lock allows therotary valve to be manually secured to any desiredlauncher tube position or vent. The tube-selectedindicator window displays the position of the rotaryvalve at any one of 25 tubes or vent.The ECU front panel contains three controlsand one indicator. The controls are aAUTO/MANUAL switch, a SELF TEST switch,and a SAFE switch. The indicator is a STATUSdisplay. When the AUTO/MANUAL switch is inthe AUTO position, the ECU controls the rotaryvalve. In the MANUAL position, the rotary valve iscontrolled by manually turning the manual selectionknob. Depressing the SELF TEST switch initiatesthe BITE testing for the ECU and the launcher. TheSTATUS indicator displays any faults found duringself-test. If more than one fault is found, the failurecodes will cycle at 3-second intervals. The SAFEswitch causes the rotary valve to move to the ventposition.FIXED-WING KILL STORE SYSTEMSThe kill store system consists of all equipmentnecessary to select, arm, and release weapons fromthe bomb bay(s) and wing stations of the aircraft. Thesystem is divided into two subsystems—the bomb bayand the wing store systems.Bomb Bay SystemThe bomb bay system consists of the units andcomponents necessary for the carrying, arming, andreleasing of stores. On the P-3C, these stores areinstalled on bomb racks suspended from removablepylon assemblies, which are mounted across thecenter of the bomb bay. On the S-3A, the racks areattached to brackets mounted to the aircraft in acruciform pattern. Each of these basic installations isassigned a station number. Numbers followed byletters (such as A or B) designate these stations forspecial capacities or types of stores. In addition, thesestations are arranged in pairs: stations 1 and 2,stations 3 and 4, etc. As a further identificationfeature on the P-3C, the stations are grouped into twolayers. Odd numbered stations in the upper layer andeven numbered stations in the lower layer. When thebomb bay is loaded with mixed stores, each pair ofstations must be loaded with the same type of store toensure proper clearance between the stores. The S-3Ahas only one layer of stations because of its muchsmaller bomb bays.The bomb bay doors are electrically controlledand hydraulically operated. For ground maintenancewithout power, the doors may be opened or closedinternally on the P-3C by a manual control valve andhand pump. On the S-3A, the doors can be operatedexternally with a 3/8-inch drive crank. Both aircrafthave a ground safety pin that is used to disable thedoor mechanism in the open position. The door safetypin must be inserted when personnel are working inthe bays.The release of bomb bay stores is normallyaccomplished by the computer. In the P-3C, theTACCO performs programming, and the pilot orTACCO controls the release. In the S-3A, theTACCO does both, with the copilot acting as backup.The pilots in both aircraft have final control becausethey must activate the master arm switch.Wing Store SystemThe wing store system consists of the unitsand components necessary for carrying, arming,and releasing external stores. On the P-3C, thesestores are suspended from 10 wing stations,numbered 9 through 18. On the S-3A, the storesare suspended from two wing stations, W5 (left)and W6 (right).7-17