MOONEY
M20TN - MODEL TYPE-S
SECTION VII
AIRPLANE AND SYSTEM DESCRIPTION
7 -- 34
AIRPLANE FLIGHT MANUAL
ORIGINAL ISSUE -- 04-02-2008
OXYGEN SYSTEM
AVOX OXYGEN SYSTEM
A four--place oxygen system provides supplementary oxygen necessary for continuous flight at
high altitude. An oxygen cylinder is located in the equipment bay, accessible through a remov-
able panel on the aft wall of the baggage compartment, or through the standard external, right
side, panel in the tailcone. A combined pressure regulator/shutoff valve, attached to the cylinder,
automatically reduces cylinder pressure to the delivery pressure required for operating altitude.
The oxygen cylinder filler valve is located under a spring loaded door aft of the baggage door.
NOTE:
For the PRECISE FLIGHT OXYGEN SYSTEM (Optional)
Refer to Section IX for Supplemental Data
A pilot’s oxygen panel contains a cylinder pressure gauge, on the pilot’s arm rest, effectively a
quantity gauge, and a control knob, below arm rest, which is mechanically connected to the shut-
off valve at the cylinder. The supply of oxygen can thus be shut off from the cockpit when not
required. When the control is in the “ON” position, sufficient oxygen flow is available at the maxi-
mum airplane operating altitude (see Section II Limitations) while at lower altitudes the reducing
valve automatically economizes the flow to conserve oxygen for longer duration or for future
availability, without requiring any action by the pilot (See Fig. 7--12 or Fig. 7--13).
Four oxygen outlets are provided in the overhead panel between the pilot’s and co--pilot’s seat
for the convenience of all occupants. Oxygen flows from the outlets only when a mask hose is
connected. Four partial re--breathing type masks are provided, each with vinyl plastic hoses and
flow indicators. The three passenger masks are of the disposable type. The pilot’s mask is a per-
manent type with a built--in microphone for ease of radio communication while using oxygen. To
use the mask--microphone, connect its lead to the microphone jack located left of the instrument
panel, in place of the aircraft or headset microphone lead, and key the switch on the control yoke.
The oxygen cylinder, (composite) when fully charged, contains either a 77.1 ft.
3
or 115.7 ft.
3
of
aviator’s breathing oxygen (Spec No. MIL--0--27210) under a pressure of 1850 PSI at 21
o
C (70
o
F).
Filling pressures will vary, however, due to ambient temperature in filling area, and the rise of
temperature resulting from compression of the oxygen. Because of this, merely filling to 1850
PSI will not necessarily result in a properly filled cylinder. Fill to pressures indicated on Fig. 7--11
for ambient temperatures.
--WARNING--
Oil, grease or other lubricants in contact with oxygen create a serious fire hazard,
and such contact must be avoided when handling oxygen equipment.
Ambient
Temperature
o
F
Filling Pressure
PSIG
Ambient
Temperature
o
F
Filling Pressure
PSIG
0
1650
50
1875
10
1700
60
1925
20
1725
70
1975
30
1775
80
2000
40
1825
90
2050
FIGURE 7--11 OXYGEN FILLING PRESSURES
NOTE:
The oxygen cylinder should not be run down to less than 100 PSI. Below this
pressure, atmospheric contamination of the cylinder may occur, requiring valve
removal and cylinder cleaning and inspection at an FAA approved repair station.
Revision B -- 11-21-2014