R **ON A/C 301-399,
R The clack valves 214QM(215QM), 216QM(217QM) are at the bottom of RIB22 and
R connect the vent surge tank to the related wing tank. During flight, fuel
R can collect in the vent surge tank. If this occurs, gravity causes it to
R move through the clack valves and back into the related wing tank.
R
R Each wing tank and the center tank has a vent system. The vent pipes in the
R LH wing tank and the center tank connect to the LH vent surge tank through
R the LH stringer vent duct. The vent pipes in the RH wing tank connect to the
R RH vent surge tank through the RH stringer vent duct.
R
R The vent for the LH(RH) wing tank between RIB2 and RIB3 is a 63.5 mm
R (2.5in.) dia. pipe. One end of the pipe is open and turned to face the upper
R wing at the highest point adjacent to RIB2/front spar. The other end of the
R vent pipe is connected to the stringer vent duct outboard of RIB2.
R
R A vent float valve is installed at RIB22. This valve will let air flow
R between the wing tank and the related surge tank to maintain an equal
R pressure. The valve willl close when the wing tank is full to prevent fuel
R spills into the surge tank.
R
R The stringer vent duct is an integral pipe that starts inboard of RIB2 and
R ends in the surge tank at RIB22.
R
R Check valves are installed at the lowest points of the vent pipes and the
R stringer vent ducts. The check valves let the fuel that has entered the wing
R tank vent system return to the related wing tank.
R
R **ON A/C ALL
The vent for the center tank is a 38.3 mm (1.5 in.) dia. pipe which is open
at each end. The pipe has an up-turned end fitting in the center tank to
make sure the fuel does not enter the vent pipe. The pipe connects the
middle of the center tank to the LH vent surge tank at RIB22. A check valve
is installed on the pipe at its lowest point. The check valve lets the fuel
that has entered the vent pipe return to the center tank.
The center tank has an overpressure protector 96QM installed on the inner
face of the LH RIB1. The overpressure protector makes sure that the pressure
in the center tank is not more than the specified limit. If the pressure in
the center tank increases to a specified value, the overpressure protector
breaks to release the pressure (into the LH wing tank).
4.
Power Supplies
______________ Not applicable
5.
Interfaces
__________ Not applicable
6.
Component Description
_____________________
A. Overpressure Protector 46QM(47QM) (Ref. Fig. 003)
The primary components of the overpressure protector are:
-
a body
-
a carbon disc (burst disc)
-
a collecting grid with a retaining ring.
One end of the body has a mounting flange which attaches it to the access panel 550CB(650CB). The burst disc is located at the other end of the body and is held in place with a flange. The collecting grid is held next to the burst disc with the retaining ring.
If a difference between external pressure and internal pressure occurs (which is more than the permitted tolerance), the burst disc breaks. If the burst disc breaks (because of low internal pressure), then the collecting grid does not let the pieces of the disc go into the vent surge tank.
The burst disc has a white cross painted on its lower side. When you can see this, the burst disc is not broken. The burst disc pressures are given in Table 001.
-------------------------------------------------------| Burst Disc | Pressure | | Function | (BAR) (PSI) | |----------------------|--------------------------------|
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