MIL-DTL-26521L
j. Then split hose lengthwise and inspect for cracks, breaks and layers separation, see 3.6.5.
Failure of this test shall be cause for rejection of the production lot.
FIGURE 4. Test fixture for cold flexibility evaluation.
4.6.3.8 Adhesion test (see 3.6.4). A sample of the friction layers shall be tested for adhesion and
meet the requirements of 3.6.4; the following details shall apply:
a. Sample preparation and testing shall be in accordance with ASTM D380 and ASTM D413
using the "Ring" or "Strip 90 degrees" method.
b. At a rate of 2 in/min (51mm/min), using a tension tester (stress strain machine), at 72°F ±2°F
(22°C ±1.1°C).
c. The test specimen shall be pulled completely around the circumference of the hose, with the
average value around the circumference being 17 lb/in width, and 10 lb/in width after bore
aging the hose with JP-4 in accordance with MIL-DTL-5624, JP-8 in accordance with
MIL-DTL-83133 or commercial jet A and A1 fuel for 168 ±2 hours at 72°F ±2°F (22°C ±1.1°C).
4.6.3.9 Collapsibility test (see 3.6.10). Uncoupled hoses assemblies shall be collapsibility tested and
meet the requirements of 3.6.10; the following details shall apply:
a. Hoses uncoupled having a length of 50 ft ±6 inch (15240 mm) shall be tested by winding
cylindrically (not spirally) around a reel having a diameter as specified below:
(1) 2 inch ID (50.8 mm) hose shall use a reel diameter of 9 ± .125 inch (229 ±3.18 mm).
(2) 2.5, 3, and 4 inch (63.5, 76.2, and 101.6 mm) ID hose shall use a reel diameter of 13 ±
.125 inch (330 ±3.18 mm).
b. The second coil and each succeeding coil shall be centered directly over the previous coil.
c. After winding the diameter of the coils of hose shall be measured at the point of greatest
diameter and meet the requirements of 3.6.10.
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