Turnlock fasteners are used to secure panels that require frequent removal. These fasteners are available in several different styles and are usually referred to by the manufacturers trade name.

CAMLOC FASTENERS. The 4002 series Camloc fastener consists of four principal parts: the receptacle, the grommet, the retaining ring, and the

Figure 2-8.Jo-bolt.

stud assembly. See figure 2-9. The receptacle is an aluminum alloy forging mounted in a stamped sheet metal base. The receptacle assembly is riveted to the access door frame, which is attached to the structure of the aircraft. The grommet is a sheet metal ring held in the access panel with the retaining ring. Grommets are furnished in two types: the flush type and the protruding type. Besides serving as a grommet for the hole in the access panel, it also holds the stud assembly. The stud assembly consists of a stud, a cross pin, a spring, and a spring cup. The assembly is designed so it can be quickly inserted into the grommet by compressing the spring. Once installed in the grommet, the stud assembly cannot be removed unless the spring is again compressed.

The Camloc high-stress panel fastener, shown in figure 2-10, is a high-strength, quick-release rotary fastener, and may be used on flat or curved inside or outside panels. The fastener may have either a flush or protruding stud. The studs are held in the panel with flat or cone-shaped washersthe latter being used with flush fasteners in dimpled holes. This fastener may be distinguished from screws by the deep No. 2 Phillips recess in the stud head and by the bushing in which the stud is installed. 

A threaded insert in the receptacle provides an adjustable locking device. As the stud is inserted and turned counterclockwise one-half turn or more, it screws out the insert to permit the stud key to engage the insert cam when turned clockwise. Rotating the

Figure 2-9.-Camloc 4002 series fastener.

Figure 2-10.-Camloc high-stress panel fastener.

stud clockwise one-fourth turn engages the insert. Continued rotation screws the insert in and tightens the fastener. Turning the stud one-fourth turn counterclockwise will release the stud, but will not screw the insert out far enough to permit re-engagement. The stud should be turned at least one-half turn counterclockwise to reset the insert.

AIRLOC FASTENERS. Figure 2-11 shows the parts that make up an Airloc fastener. The Airloc fastener also consists of a receptacle, a stud, and a cross pin. The stud is attached to the access panel and is held in place by the cross pin. The receptacle is riveted to the access panel frame.

Two types of Airloc receptacles are available: the fixed (view A) and the floating (view B). The floating receptacle makes for easier alignment of the stud in the receptacle. Several types of studs are also available, but in each instance the stud and cross pin come as separate units so the stud may be easily installed in the access panel.

The Airloc receptacle is fastened to the inner surface of the access panel frame by two rivets. The rivet heads must be flush with the outer surface of the panel frame. When you are replacing receptacles, drill out the two old rivets and attach the new receptacle by flush riveting. Be careful not to mar the sheet. When you are inserting the stud and cross pin, insert the stud through the access panel and, by using a special hand tool, insert the cross pin in the stud. Cross pins can be removed by means of special ejector pliers.