demand. The higher the altitude, the shorter the
duration, because oxygen is delivered by the mask
regulator under pressure upon demand.
NOTE: Automatic actuation of the emergency
oxygen supply also provides automatic actuation
of the emergency locator beacon.
COMPONENT MAINTENANCE
Since the seat assembly is designed for one-
shot operation, it cannot be operationally
checked as a unit. However, various components
that contribute to the successful functioning of
the seat assembly must be operationally checked
and tested.
It is your responsibility to check, test, and
adjust ejection seat components as well as remove
and replace cartridges. By using the applicable
MIMs that contain the procedures for testing,
adjusting, and checking components, along with
diagrams, drawings, and trouble-shooting charts,
you will be able to maintain the ejection seat
properly and safely.
NOTE: The following material contains only
typical maintenance practices and must not be
used during actual component repair and tests.
Use only the information contained in the
applicable MIM.
There are several procedural checks that may
be performed on the Stencel ejection seat. For
each of these checks, you should ensure that the
safe/arm control is in the SAFE (up and locked)
position and that all three maintenance safety
streamer safety pins are installed prior to
beginning the tests. Most of the checks require
that you remove the survival kit and wedge
assemblies prior to starting the test and reinstall
them at the completion of the test. This is not
required for the height adjustment actuator check-
out. When you are performing several checks in
succession, you do not need to remove and
reinstall the survival kit and wedge assemblies
between each test.
Safe/Arm Control Assembly
Check-out
The individual actions required to check-out
the safe/arm control assembly may be grouped
into 11 major steps.
1. Install the initiator pull test tool set, as
shown in figure 6-44.
6-62
2. Manually release the safe/arm control
assembly release. You should ensure that spring
tension is evident in the release knob. Then, you
should lower the safe/arm control to the full
DOWN position.
3. Attach a push-pull gauge to the safe/arm
control assembly and then pull upward. The
handle should move upward and lock in the
SAFE (full up) position with a maximum force
of 10 pounds with no evidence of binding.
You should observe the outboard bell crank rotate
downward, disengaging the upper and lower
connect and disconnect sears. Also observe that
the inboard bell crank rotates upward to fully
engage, the safety plunger between the initiator
rotors.
4. Raise the emergency release handle to
the UP and LOCKED position. You should
not see movement of the upper connect and
disconnect sear; however, the lower connect and
disconnect sear should move down. You should
check to see that the T-bar blocks the initiation
rotors.
5. Lower the emergency release handle to the
full DOWN position: You should see the bell
crank connected to the lower sear rotating up-
ward, the initiation subsystem rotors not moving,
and the T-bar moving, down.
6. Observe that the initiation rotors do not
move when you pull on the ejection control
handle.
7. Lower the safe/arm control assembly to
the full DOWN position. You should ensure
the safe/arm control moves to the DOWN
position with no evidence of binding, and the
inboard bell crank moves downward and
completely disengages the safety plunger from the
rotors.
8. Raise the safe/arm control assembly
to the full UP position. You should ensure
that the safe/arm control is locked into
position.
9. Lower the safe/arm control assembly to the
full DOWN position. The emergency release
handle is raised to the UP and LOCKED position.
You should observe that the upper sear moves
down and the pull-test tool extends to the
RELAXED position.