•
All fittings, connections, and joints
8.
Replace leaking or damaged fuel lines. Repair or
replace leaking or damaged fittings.
47–06 CNG High-Pressure Fuel
Filter Element Replacing
CNG filter element replacement cycles are an impor-
tant factor in maintaining the CNG fuel system integ-
rity and ensuring maximum operating performance.
Actual frequency of the filter element replacement
could increase or decrease depending on the cleanli-
ness of the fill station fueling system.
1.
Shut down the engine and apply the parking
brake.
2.
Close the CNG fuel cylinder shutoff valves.
3.
Start the engine and let it idle until the fuel lines
are empty and the engine stops. The gauges on
the fuel panel should now read at or near 0 psi.
4.
Close the manual fuel shutoff valve on the fuel
panel.
5.
Remove the two capscrews that secure the ac-
cess cover to the fill panel, then remove the ac-
cess cover. See
. Save the capscrews for
reinstallation.
6.
Slowly open the bleed valve on the manifold to
relieve remaining fuel pressure within the sys-
tem. See
IMPORTANT: Some pressure may remain in the
fuel system between the solenoid valve and the
engine. Use caution when loosening fittings, as
a small amount of gas may leak out.
7.
Put a clean receptacle under the filter assembly.
Using a 1-1/4-inch wrench, unscrew the filter
bowl from the filter housing.
8.
Remove and discard the filter element.
9.
Install a new filter element in the filter housing.
10. Inspect the O-ring on the filter housing for dam-
age or cracks. If necessary, replace the O-ring.
05/04/2010
f470555
1
2
3
3
1.
Frame Rail
2.
CNG Fuel Cylinder Storage Box
3.
Mounting Bolts (qty 12 per side)
Fig. 7, Fuel Cylinder Storage Box Mounting Bracket
(passenger side shown)
H IG
H PRESSURE
PRESS
UR
E
LOW
CYLINDERS
INSPECT CYLINDERS
EVERY 36 MONTHS
OR 36000 MILES
WHICHEVER OCCURS FIRST
NATURAL
GAS
VEHICLE
110 PSIG
ON
M
A
N
U
A
L
S
H
U
T
O
FF
V
A
LV
E
OPEN VALVE
SLOWLY
3600 PSIG MAX.
SERVICE PRESSURE
REGULATOR
FILTER
INSPECT PRESSURE
RELIEF DEVICE
EVERY 2000 MILES
DRAIN HOUSING
EVERY 1500 MILES
REPLACE ELEMENT
EVERY 3000 MILES
1
2
3
4
04/30/2010
f470556
1.
High Pressure Gauge
2.
Low Pressure Gauge
3.
Manual Fuel Shutoff Valve
4.
Fuel Fill Port and Dust Cap
Fig. 8, CNG Fuel Panel
Fuel
47
Business Class M2 Maintenance Manual, August 2015
47/9
Property of American Airlines
