MK 7 MOD 0 JET BLAST DEFLECTOR

Figure 5-1.—General arrangement of jet blast deflectors. There are various modifications of JBDs in use. Each type of JBD is identified by a model number, such as Mk 6 Mod 1, Mk 6 Mod 2, and Mk 7 Mod 0. The most common types of JBDs in use are the Mk 6 Mod 2, Mk 7 Mod 0, and Mk 7 Mod 1. However, since Mk 6 Mod 1, Mk 6 Mod 3, and Mk 7 Mod 2 JBDs are also in use, you will need to consult the specific NAVAIR technical manual for the type of JBD installed on your ship. The Mk 7 Mod 0 JBD is discussed in this chapter to familiarize you with the general operation and maintenance of JBDs. MK 7 MOD 0 JET BLAST DEFLECTOR The Mk 7 Mod 0 JBD consists of six water-cooled panels and three operating gear assemblies. Each operating gear assembly is connected to a pair of panel assemblies. The panel assemblies operate in pairs and may be raised or lowered independently or simultaneously with others in the same installation. This allows for deck equipment mobility. The electrical, hydraulic, and mechanical equipment needed to operate the panels are located under the panel installation. When the panel is lowered, the JBDs serve as part of the deck over which an aircraft passes on its way to the catapult. When the panel is raised behind the aircraft, the panels deflect the heat and high-velocity exhaust gases generated by the aircraft’s engines upward and away from personnel and other aircraft. All Mk 7 JBD installations are electrically controlled by a deckedge control panel or a portable control box. Each control panel (fig. 5-2) has its own electrical installation and is independent of the other installations. Most JBD assembly installations are controlled by a portable electrical system consisting of portable control boxes and umbilical cables (fig. 5-3). Each portable control box operates independently and will only control the JBD installation identified on its faceplate. An auxiliary control panel and transfer switch are provided for emergency operations, and they are located in the retraction-engine machinery room. Operating Gear Assembly The JBD panel assemblies are raised and lowered by an operating gear linkage assembly and a hydraulic cylinder located just under each panel cutout in the deck. The operating gear linkage 5-2