Figure 1-30.--Airframe (tripod) jacks.
Center. It contains a list of approved prime and alternate
only two of five extension leg kits installed. Each leg
jacks for all Navy and Marine aircraft.
extension kit increases the effective height of the basic
jack by 18 inches. The airframe tripod jacks weight
PREOPERATIONAL INSPECTION
varies from 275 pounds to 837 pounds.
Several safety features are built into the tripod
The same basic safety precautions apply to all
jacks. A locknut (also called a ring or collar) on the ram
jacks. Conduct a good preoperational inspection before
mechanically locks the ram in position. The locknut
you use it. NAVAIR 19-600-135-6-1 is the general
prevents the ram from settling in the event of hydraulic
preop Maintenance Requirements Card (MRC) for all
failure or inadvertent lowering. A safety bypass valve
jacks. Make sure that the jack has been load tested
in the system bypasses fluid from the pump or ram
within the last 13 weeks. Next, if the jack is dirty, take
when excessive pressure is built up.
the time to wipe it down. You can't see cracks or broken
welds under dirt. If the jack is covered with hydraulic
Airframe (tripod) jacks are normally checked out
fluid, you can suspect it may be leaking. Inspect it more
from the SE division (AIMD) when needed. Since
closely.
transporting these heavy and cumbersome jacks is a
problem, they often remain in custody of an
Check the reservoir; it should be full with the jack
organization for a prolonged period of time. The
ram fully collapsed. If the reservoir is low, you can
organization must be responsible for their care and
suspect a leak somewhere. Fill the reservoir with clean,
cleanliness during periods when not in use. As with
fresh, hydraulic fluid. Check the filler plug vent valve to
axle jacks, these jacks need to be load tested prior to
make sure it is not clogged. If the plug is blocked, you
being placed in service and annually thereafter. Special
may get an air lock, and the jack may not operate
inspections are performed every 13 weeks at AIMD SE
correctly. You could also get a pressure buildup in the
and recorded on the OPNAV Form 4790/51.
reservoir and a possible rupture. Check the pump
handle for bends and the pump rocker arm and link for
The MIM will tell you what type of aircraft jack to
elongated or out-of-round holes. These are signs that
use at each position. When deployed, you may not be
the jack may have been overloaded, and that the safety
able to get the jacks that are called for in the MIM. You
bypass valve is malfunctioning.
will have to refer to the Index and Application Tables
for Aircraft Jacks, NAVAIR 19-70-46. It was prepared
With the filler plug air vent valve open and the
under the direction of the Commander, Naval Air
release valve closed, pump up the ram and check for
System Command, by the Naval Air Engineering
leaks and full extension. When the ram reaches full
1-31
