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Page Title:
Dual mode inertia reels demonstration |
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|  MIL-R-8236F
axis with the direction alternated in each series of tests. The webbing shall not lock with an acceleration of less
than 4.0 G and shall lock when the acceleration exceeds 6.0 G. Once the inertia reel locks, the webbing shall not
extend more than 1 inch when a load of 25 pounds is placed on the webbing. The inertia reel shall be unlocked
when the manual control handle is cycled to the "manual-lock" position and back to the "auto-lock" position.
4.5.1.5 Dual mode inertia reels demonstration. When a dual mode inertia reel is being qualified the tests
shall be conducted with one of the modes disabled to demonstrate that each mode of the dual mode type inertia reel
functions independently. These tests shall then be repeeated with the other mode disabled to demonstrate that the
second mode also functions independently.
4.5.2 Flight Performance simulation tests. Flight simulation tests are required for all types of inertia reels.
The tests shall consist of subjecting inertia reels, while in the automatic locking mode, to simulated flight
operational environments including the concurrent application of steady state acceleration from a centrifuge,
vibratory acceleration using an excitation device, and cyclic cable/webbing motion. In addition, the Government
Qualifying Activity may perform flight testing to confirm, or in lieu of any or all of the flight simulation
conditions.
4.5.2.1 Flight simulation conditions. Two inertia reels, 1 environentally conditioned, shall be subjected to
the flight simulation conditions. Nine tests are required to evaluate inertia reel performance in the 3 mounting
orientations of Figure 20. For each of the 3 mounting orientations, the steady state acceleration vector shall have a
resultant rnagnitude of 3.5 G. applied to the inertia reel in the vertical axis (Z) of the aircraft coordinate system as
shown in Figure 16. The vibratory acceleration shall be applied in each of the 3 orthogonal directions with a
sinusoidal sweep over a frequency range of 4 to 60 HZ. The vibration amplitude shall be 0.20 G from 4 to 10 HZ,
and 0.50 G from 10 to 60 HZ. Each vibration sweep shall be applied over a time period of not less than 7 minutes.
Each MA-1, MA-2, MA-6, and MA-8 type inertia reel shall include a standard 18 inch length of cable/webbing
attached to and wound on the drum/spool. as applicable. The MA-14 and MA-16 type inertia reels shall include a
standard 24 inch length of webbing attached 10 and wound on the spool. For each test, the exposed end of the
inertia reel cable/webbing shall be attached to a device which continuously cycles the Cable/webbing in and out of
the inertia reel. The cycling shall simulate occupant motion and permit detection of inertia reel locking. The
cycling rate shall be 30 cycles per minute with a displacement amplitude of 3.O inches. The inertia reel shall
remain unlocked throughout the duration of all 9 tests.
4.5.3 Stowage/take-up mechanism force demonstration.
4.5.3.1 Cable drum (MA-l and MA-2 type inertia reels) extension/retraction test. The force required to
extend the cable of a MA-1 and MA-2 type inertia reel shall be measured during the first 17 inches of cable
extension. The force shall be measured again as the cable is extended from 17 inches to full extension. The
retracting force shall be measured during retraction of the fully extended cable to 17 inches of cable extension and
again measured as the cable is retracted from 17 inches to full retraction. This extension/retraction test shall be
conducted 3 times for reproducibility. The inertia reel shall be activated to lock at 5 random extensions to
demonstrate that the drum is capable of locking the cable in increments of 0.50 inch or less. The extension and
retraction forces shall be as specified (see 3.5.3.1).
4.5.3.2 Rotating spool (MA-6, MA-8, MA-14, and MA-16 type inertia reels) extension/retraction test. The
force required to extend the webbing of MA-6, MA-8, MA-14, and MA-16 type inertia reels shall be measured
during the first 17 inches of webbing extension. The force shall be measured again as the webbing is extended
from 17 inches to full extension. The retracting force shall be measured during retraction from the full extension
to 17 inches of webbing extension and again measured as the webbing is retracted from 17 inches to full retraction
The inertia reel shall be activated to lock at 5 random extension to demontstrate that the rotating spool is capable
of locking the webbing in increments of 0.50 inch or less. The extension and retraction forces shall be as specified
(see 3.5.3.2).
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