have moved sufficiently to seat the shutoff
valve and stop flow through the regulator.
The inflated seal then fills the gap between
the canopy frame and the mating aircraft
structure, preventing loss of cockpit pressure.
If pressure downstream of the regulator in-
creases to 6 to 8 psi above the regulated
pressure, additional bellows movement causes
the relief valve stem to unseat the ball in
the seat to vent the excess pressure through
the relief/vent port. The check valve prevents
loss of pressure from the inflatable seal
should the air supply to the system fail.
When the canopy is unlocked, the regulator
plunger is depressed. The plunger moves
the bellows seat toward the relief valve stem
to close the shutoff valve and unseat the
ball, venting downsteam pressure through
the relief/vent port. The components of the
canopy seal system are discussed in the
following paragraphs.
Canopy Inflatable Seal
The hoselike rubberized canopy inflatable seal
(fig. 2-9) is retained in a channel around the
circumference of the canopy assembly frame.
When inflated, the seal fills the gap between the
frame and aircraft structure.
Canopy Seal Pressure Regulator
The canopy seal pressure regulator is on the
turtle deck (fig. 2-10). It consists mainly of a check
valve, shutoff valve, bellows, spring-loaded ball,
and plunger. The regulator regulates its 80 psi
bleed air input to the 25±5 psi required by the
canopy seal system, and controls inflation and
deflation of the canopy inflatable seal. The
regulator also relieves pressure in excess of 6 to
8 psi above the regulated value.
Figure 2-10.—Canopy seal pressure regulator location.
2-13
