11. When servicing a liquid oxygen system, en-
sure that only oxygen conforming to specification
CAUTION
MIL-0-27210 is used. Oxygen procured under Federal
If lines are fabricated locally, ensure that only
Specification BB-0-925A is intended for technical use
clean, oil-free tubing and fittings are used. Also,
and should NOT be used in aircraft oxygen systems.
ensure that no hydraulic fluid is used in the
12. After the completion of repairs, always
fabrication procedure.
perform an operational check of the system and make
the required test to ensure that the oxygen is safe for use
2. Use only the type of fittings specified for the
by the pilot and crew.
particular oxygen system. Never use fittings with pitted
Q7-15.
When the temperature of gaseous oxygen is
or otherwise disfigured cones or imperfect threads.
lowered to 182F under 720 psi pressure,
what transformation will occur?
3. I t i s M A N D AT O RY t h a t E X T R E M E
CAUTION be exercised with regard to cleanliness of
Q7-16.
True or False. When working with LOX, the
hands, clothing, and tools. It must be emphasized that
wearing of trousers with cuffs is authorized.
all items that come into contact with the oxygen system
Q7-17.
A sealed container of LOX can generate up to
must be free of dirt, oil, or grease.
what amount of pressure?
4. Use thread anti-seize tape that is approved
Q7-18.
What component on a LOX converter pro-
under specification MIL-T-27730.
vides a margin of safety from explosion?
5. When installing tubing assemblies between
Q7-19.
In a 24-hour period, a normal LOX system
fixed units, the tube assembly should align without the
will lose what amount of pressure?
use of undue force.
Q7-20.
Where is the low-pressure switch for a LOX
6. The torque values specified for the particular
system located?
oxygen system should be strictly adhered to when
Q7-21.
What are the three sequences of operation for
tightening the fittings.
a LOX converter?
7. If a section of line is left open or disconnected
Q7-22.
An aircraft liquid oxygen system should have
during an installation, the open fittings must be covered
what type of maintenance performed after
with suitable caps or plugs. When making connections,
replacement of any component or tubing
be certain that no lint, dust, chips, or other foreign
assembly?
material is allowed to enter the oxygen system.
8. Upon completion of the installation of a tube
ONBOARD OXYGEN GENERATING
assembly or component, a pressure check of the system
SYSTEM
should be conducted. The system should be pressurized
LEARNING OBJECTIVE: Identify the sys-
and the connections checked with a leak-test solution
tem components and operation of the onboard
conforming to specification MIL-L-25567. After the
oxygen generating system.
connections have been checked, the leak-test solution
should be washed off with clean water.
The onboard oxygen generating system (OBOGS)
is an alternative to liquid oxygen. When compared to a
9. The aircraft liquid oxygen system should be
LOX system, the OBOGS has several advantages. First,
purged after the replacement of any component or
its availability may be as high as 99 percent. There are
tubing assembly.
no requirements for depot-level maintenance. The
OBOGS has no daily servicing requirements, and
10. The type of clothing and footwear that is worn
scheduled preventive maintenance occurs at 2,000
when maintaining and servicing a liquid oxygen system
hours. Incorporation of the OBOGS eliminates the need
is an extremely important factor. Do not wear anything
to store and transport LOX, and it eliminates the need
that will produce sparks or static electricity, such as
for LOX support equipment. The potential for
nylon clothing or shoes with steel taps or hobnails.
accidents related to LOX and high-pressure gases is
Oxygen-permeated clothing will burn vigorously--a
greatly reduced.
most painful way to die.
7-20
