AST 473 Cessna Citation Oxygen System Dr. Kurt Barnhart.

AST 473 Cessna Citation AST 473 Cessna Citation Oxygen SystemOxygen System

Dr. Kurt BarnhartDr. Kurt Barnhart

Oxygen SystemOxygen System

OverviewOverview– System consists of crew and pax. Distr. Syst.System consists of crew and pax. Distr. Syst.– Ox. Available to crew continuouslyOx. Available to crew continuously– Ox. Available to pax. Automatically above Ox. Available to pax. Automatically above

13,500 ft. C.A. or13,500 ft. C.A. or– ManuallyManually– Normally used for emerg.Normally used for emerg.


Components:Components:– Ox. Storage cylinder w/ integral shutoff valve & Ox. Storage cylinder w/ integral shutoff valve &

press. Regulatorpress. Regulator– Servicing fittingServicing fitting– Crew & Pax. MasksCrew & Pax. Masks– Altitude press. SwitchAltitude press. Switch– Overboard discharge disc.Overboard discharge disc.– Control selector on pilot’s consoleControl selector on pilot’s console


Components:Components:– Ox. Cylinder installed in tailcone immediately aft Ox. Cylinder installed in tailcone immediately aft

of access door- either 22 or 64 ft(3) capacityof access door- either 22 or 64 ft(3) capacity– Shutoff valve and press. Regulator on bottle on Shutoff valve and press. Regulator on bottle on

cylinder controls ox. Flow to distr. Sys.cylinder controls ox. Flow to distr. Sys.– Shutoff valve normally open- regulator reduces Shutoff valve normally open- regulator reduces

line press. To 70 psi.line press. To 70 psi.


Pressure gauge- direct gauge on co-pilot’s Pressure gauge- direct gauge on co-pilot’s panel (rt.)- reads cylinder pressure panel (rt.)- reads cylinder pressure regardless of position of shutoff valve on regardless of position of shutoff valve on cylindercylinder

Fully serviced- 1,600 – 1,800 psiFully serviced- 1,600 – 1,800 psi Service anytime gauge reads out of greenService anytime gauge reads out of green MUST service if below 400 psi & must be MUST service if below 400 psi & must be

Purged of bottle goes empty.Purged of bottle goes empty.


Controls- Ox. Cnt’l on pilot’s consol (left) Controls- Ox. Cnt’l on pilot’s consol (left) controls flow to CREW ONLY, NORMAL controls flow to CREW ONLY, NORMAL (pax. And crew), and MANUAL DROP(pax. And crew), and MANUAL DROP– Mechanically position control valve for distr. As Mechanically position control valve for distr. As

desired abovedesired above– Early models- Ox controlled via 2 levers instead Early models- Ox controlled via 2 levers instead

of rotary valveof rotary valve


Overboard discharge-Overboard discharge-– Green disc. Aft of tail-cone access door on Green disc. Aft of tail-cone access door on

exterior of fuselage (fwd. rt. Side on older exterior of fuselage (fwd. rt. Side on older models)models)

– Provides visual indication of overpressure- Provides visual indication of overpressure- bottle emptybottle empty

– Mx. Required before flightMx. Required before flight


Oxygen MasksOxygen Masks– Either standard (w. 22 cu. Ft. bottle) or optional Either standard (w. 22 cu. Ft. bottle) or optional

sweep-on mask w. optional 64 cu. Ft. bottlesweep-on mask w. optional 64 cu. Ft. bottle– Standard mask- microphone & Ox. RegulatorStandard mask- microphone & Ox. Regulator– Regulator can be set to diluter demand of 100% Regulator can be set to diluter demand of 100%

flow- can be quick donning if worn around neck- flow- can be quick donning if worn around neck- should be set to 100%should be set to 100%


Optional sweep-on mask is quick-donning- integral Optional sweep-on mask is quick-donning- integral microphone & 3 pos. regulatormicrophone & 3 pos. regulator

Selecting EMER. on mask regulator- steady flow Selecting EMER. on mask regulator- steady flow to maskto mask

In 100% position- user assured ox. being received In 100% position- user assured ox. being received if no breathing restrictions presentif no breathing restrictions present

Norm position- diluter demandNorm position- diluter demand Must stow on clip aft of side window to be quick- Must stow on clip aft of side window to be quick-

donning- Use EMER pos. for smokedonning- Use EMER pos. for smoke Pax. Masks- auto drop- lanyard pull starts Ox.Pax. Masks- auto drop- lanyard pull starts Ox.


Operation:Operation:– With Ox. Selector in NORMAL low press. Ox. @ 70 psi. With Ox. Selector in NORMAL low press. Ox. @ 70 psi.

avail. To both crewavail. To both crew– Solenoid valve normally spring-loaded closed blocking Solenoid valve normally spring-loaded closed blocking

flow to pax.flow to pax.– At C.A. of 13,500 ft. alt. press. Switch energizes At C.A. of 13,500 ft. alt. press. Switch energizes

solenoid valve opensolenoid valve open– Ox. Press. Flowing pushes on overhead doors releasing Ox. Press. Flowing pushes on overhead doors releasing

themthem– If cabin press restored- solenoid de-energizes @8,000 ft If cabin press restored- solenoid de-energizes @8,000 ft

shutting off flowshutting off flow


If D.C. fail- solenoid valve cannot route Ox. If D.C. fail- solenoid valve cannot route Ox. To pax.- Place OXYGEN selector to To pax.- Place OXYGEN selector to MANUAL DROP routes Ox. Through MANUAL DROP routes Ox. Through manual cont’l valve dropping masksmanual cont’l valve dropping masks

In CREW position only crew has Ox.In CREW position only crew has Ox. Obviously- no smoking when using Ox.- oil, Obviously- no smoking when using Ox.- oil,

grease, soap, lipstick & other fatty materials grease, soap, lipstick & other fatty materials pose a serious fire risk when using Ox.pose a serious fire risk when using Ox.

THE ENDTHE END

AST 473 Cessna Citation Oxygen System Dr. Kurt Barnhart.

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