AST 473 Cessna Citation Oxygen System Dr. Kurt Barnhart

Oxygen System  Overview –System consists of crew and pax. Distr. Syst. –Ox. Available to crew continuously –Ox. Available to pax. Automatically above 13,500 ft. C.A. or –Manually –Normally used for emerg.

Oxygen System  Components: –Ox. Storage cylinder w/ integral shutoff valve & press. Regulator –Servicing fitting –Crew & Pax. Masks –Altitude press. Switch –Overboard discharge disc. –Control selector on pilot’s console

Oxygen System  Components: –Ox. Cylinder installed in tailcone immediately aft of access door- either 22 or 64 ft(3) capacity –Shutoff valve and press. Regulator on bottle on cylinder controls ox. Flow to distr. Sys. –Shutoff valve normally open- regulator reduces line press. To 70 psi.

Oxygen System  Pressure gauge- direct gauge on co-pilot’s panel (rt.)- reads cylinder pressure regardless of position of shutoff valve on cylinder  Fully serviced- 1,600 – 1,800 psi  Service anytime gauge reads out of green  MUST service if below 400 psi & must be Purged of bottle goes empty.

Oxygen System  Controls- Ox. Cnt’l on pilot’s consol (left) controls flow to CREW ONLY, NORMAL (pax. And crew), and MANUAL DROP –Mechanically position control valve for distr. As desired above –Early models- Ox controlled via 2 levers instead of rotary valve

Oxygen System  Overboard discharge- –Green disc. Aft of tail-cone access door on exterior of fuselage (fwd. rt. Side on older models) –Provides visual indication of overpressure- bottle empty –Mx. Required before flight

Oxygen System  Oxygen Masks –Either standard (w. 22 cu. Ft. bottle) or optional sweep-on mask w. optional 64 cu. Ft. bottle –Standard mask- microphone & Ox. Regulator –Regulator can be set to diluter demand of 100% flow- can be quick donning if worn around neck- should be set to 100%

Oxygen System  Optional sweep-on mask is quick-donning- integral microphone & 3 pos. regulator  Selecting EMER. on mask regulator- steady flow to mask  In 100% position- user assured ox. being received if no breathing restrictions present  Norm position- diluter demand  Must stow on clip aft of side window to be quick- donning- Use EMER pos. for smoke  Pax. Masks- auto drop- lanyard pull starts Ox.

Oxygen System  Operation: –With Ox. Selector in NORMAL low press. 70 psi. avail. To both crew –Solenoid valve normally spring-loaded closed blocking flow to pax. –At C.A. of 13,500 ft. alt. press. Switch energizes solenoid valve open –Ox. Press. Flowing pushes on overhead doors releasing them –If cabin press restored- solenoid ft shutting off flow

Oxygen System  If D.C. fail- solenoid valve cannot route Ox. To pax.- Place OXYGEN selector to MANUAL DROP routes Ox. Through manual cont’l valve dropping masks  In CREW position only crew has Ox.  Obviously- no smoking when using Ox.- oil, grease, soap, lipstick & other fatty materials pose a serious fire risk when using Ox.

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