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ANCHORS FOR TETHERS
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AIRPLANE RECOVERY DOCUMENT
Figure 3-8 THROUGH-FUSELAGE TETHERING
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AIRPLANE RECOVERY DOCUMENT
Figure 3-9 DOOR TETHER FIXTURE DETAILS
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AIRPLANE RECOVERY DOCUMENT
Figure 3-10 EXAMPLES OF ANCHOR INSTALLATIONS
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3-20-4 Materials and Attachments
1.
General
2.
You can use various materials to lift or pull the airplane. The paragraphs that follow discuss the usual materials that are available. Figure 3-11 and Figure 3-12 show the rated capacities or breaking strengths of these materials.
A. Straps
(1)
Straps made from Nylon (or Dacron) material are the usual straps used to lift the airplane structure. They prevent damage to the fuselage surface. These straps are very resistant to a tear and they absorb less water. They also dry quickly and are resistant to the other problems caused by water (rot and mold).
Nylon (and Dacron) straps can be damaged by a long (120 hours) time of high temperatures (125 degrees F or 52 degrees C) and dry air conditions. These straps will not hold their approved load with these conditions. You must then use straps made from a different (polyproplene) material.
(2)
Usually, you must make sure that the straps agree with the conditions at your incident. They must have sufficient devices for protection and a large factor (20 or more) of safety. Some straps have some wire in their material for a larger strength. See the manufacturer’s documents (catalogs) for more data on a strap and its approved load. These documents will also recommend the correct straps for the conditions at your incident.
(3)
We know from safety test data that sharp edges decrease the approved loads for Nylon slings. If the object that you lift has sharp edges (a radius less than 3/16 inch or 5 mm), you must decrease the load on the sling. Figure 3-11 shows these changes in the load capacity.
3. Manila Rope (Abaca)
A. You can use a rope (manila rope) for some conditions (tiedowns, power transmissions, etc). You can also use it for hoist (block and tackle) operations. Do not use it at a connection point for a load or in other positions that can cut it (load droppers).
B. A rope always absorbs water. If you have very cold temperatures, the water freezes and the rope has a lower load capacity. A rope can also decrease in its length (shrink). A change in the length can be a change in the load. Make sure that you know the loads you have when you use a rope.
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