Union Connection - Bell OH-58A Technical Manual

9-9. O-RING, PACKING, AND GASKET
APPLICATIONS.
a. O-rings are used in static and
dynamic applications.
(1) In static applications, the o-
ring serves as a gasket when it is
compressed within a recess.
not normally acceptable.
(2) In dynamic applications, the
sealing action is dependent primarily on
the resilience of the o-rings. When
moving parts are involved, minor seepage
may be normal and acceptable. A moist
surface found on moving parts of a
hydraulic unit (piston shaft) is an
indication that the seal is being pro-
perly lubricated.
Figure 9-14.
Section III. SEALS, PACKINGS, AND GASKETS
Leakage is

Union Connection

(3) Seal replacement is required
when:
(a) The amount of fluid being
lost will cause system failure.
(b) The leak creates a hazard.
(c) The leak will not permit
the system to function safely for one
more flight.
NOTE
Packings and gaskets are identi-
fied by part number on packages.
Do not remove from package until
ready for use.
TM 55-1520-228-BD
HYDRAULIC
9-13