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Page Title:
Stowage/take-up mechanism life cycle test |
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|  MIL-R-8236F
4.5.6.1 Stowage/take-up mechanism life cycle test. The inertia reel stowage/take-up mechanism shall be
cycled 60,000 times by pulling the take-up cable/webbing to the required extension and allowing it to return to the
fully-retracted position. The cycle distribution shal1 be as follows for the full 60.000 cycles:
0 to 0.25 full extension.
a. 36,000 cycles
0 to 0.50 full extension.
b. 12,000 cycles
0 to 0.75 full extension.
c. 6,000 cycles
0 to full extension.
d. 6,000 cycles
At least 10,000 cycles shal1 be completed with the axis of the cable or webbing extended at an angle of 30 lateral
or vertical from the axis of the cable or webbing at the point where they enter the inertia reel housing. The cycles
shall be completed in sets of 120 cycles composed of 72 cycles of O to 0.25 full extension, 24 cycles of 0 to 0.50 full
extension, 12 cycles of 0 to 0.75 full extension and 12 cycles of 0 to full extension. After every 120 cycles, the
cable or webbing shall be fully extended, the control handle placed in the "manual-lock" position, and the cable
allowed to retract with a resisting tension of at least 2 pounds. Before the extension and retraction test is begun, at
24.000 and 48,000 cycles. and after completion of the test, the cable or webbing shall be totally extended, the control
handle placed in the "manual-lock" position, and the maximum cable or webbing movement measured at 4
different positions of extension to determine that the movement does not exceed 0.50 inch. After completing the
tests, the inertia reel shall demonstrate compliance (see 4.5.1, 4.5.3.1, or 4.5.3.2 as applicable, and 4.4.3.3
excluding 4.4.3.3 subparagraphs). There shall be no evidence of excessive wear on the external or internal
surfaces of the inertia reel mechanism. The inertia reel shall then be subjected to the proof strength test specified
(see 4.5.4) and meet the operating conditions described within the paragraph.
4.5.6.2 Shoulder harness attachment cable terminal fitting life cycle test. For MA-1 and MA-2 type inertia
reels, the inertia reel cable shall be fully retracted and bent until the axis of the cable terminaI is inclined at an
angle of 30 with the axis of the cable at the point where the cable enters the inertia reel housing. Maintaining this
angle, the cable terminal fitting shall be rotated, generating a conical surface, about the axis of the cable at the
0
point where the cable enters the inertia reel housing. Each 360 of rotation shall constitute 1 cycle. The fitting
shall be subjected to 5,000 cycles with the control handle in the "auto-lock" position, and to 5,000 cycles with the
control handle in the "manual-lock" position. After each 100 cycles. the cable shall be fully extended and
permitted to return to the retracted position. Upon completion of this 10,000 cycle test, the inertia reel shall be
subjected to the proof strength test specified (see 4.5.4). The cable and terminal fitting shall then be visually
inspected, and there shall be no evidence of breakage or excessive wear on either the cable or the terminal fitting.
4.5.6.3 Manual control cable and handle subassembly life cycle test. With the inertia reel and manual control
cable and handle subassemblies on a simulated mounting, the manual control mechanism shall be subjected to
25,000 cycles of locking and unlocking. Each cycle shall contsist of moving the manual control handle from the
"manual-lock" position to the "auto-lock" position and back. Upon completion of this test, the inertia reel shall be
tested as specified (see 4.5.1,4.5.3.1, or 4.5.3.2 as applicable, and 4.4.3.3 excluding 4.4.3.3 subparagraphs).
4.5.7 Design static strength test.
4.5.7.1 Design static strength of inertia reels. The design static strength test shall be conducted on 6 inertia
reels, including 2 that were previously subjected to the environmental tests. as identified in Table I. The inertia
reels shall be at full retraction and lockcd by placing the control handle into the "manual-lock" position. The
inertia reel shall not fail structurally. For inertia reels having 2 separate locking mechanisms for the
"manual-lock" and "auto-lock", this test shall be conducted for each locking mechanism.
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