Oxygen System

Gulfstream GVII

Eddie sez:

The oxygen system is similar to previous versions but more fool proof. The primary switch is guarded on, for example.

For a quick refresher or a good intro, be sure to see Ivan Luciani's notes: Oxygen System.

There are also a few flash cards here: G500 Flashcards and Quizlet.

Everything here is from the references shown below, with a few comments in an alternate color.


Photo: The GVII oxygen system, Eddie's drawing
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How it works . . .

The components in greater detail . . .

Limitations and Abnormal Procedures . . .

Last revision:


How it works . . .

Getting and storing the oxygen


An oxygen service panel is mounted on the right side of the fuselage forward of the wing. There is a gage for each cylinder and a filler valve that services both bottles simultaneously.


There are two oxygen bottles located below the cabin floor, forward of the wing, which are made of composites and are lined with aluminum. Each cylinder has 123.4 cubic foot volume and are normally charged to 1800 ± 50 psig aviator's oxygen. So long as there is at least 250 psgi, crew oxygen is regulated to 55 to 80 psig. (Below 250 psig, no pressure is given to the supply lines.

System Test


Photo: G500 Passenger oxygen system test, PAS, p. 12-15
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[PAS, p. 12-15] Passenger Oxygen System Test

  • Master Test switch on DU Ctrl / Test page. Press and release. Test latches until de-selected. When selected, O2 annunciator lights illuminate, therapeutic cyan on, ALT SELECT amber HIGH ALT, and the Pax O2 shown below.

  • Passenger Oxygen O2 test switch: accessed via DU Ctrl / Test → System Test. Press and hold: passenger Oxygen O2 test switch → Green, passenger Oxygen On. 2 aural CAS bongs, 2 Master Warning “CAUT” lights. PASS OXYGEN ON light → Rt Side console, NO SMOKING signs / icons illuminate, aural doorbell chime over speakers if NO SMOKING switch not selected ON. Test ends when switch released.

The components in greater detail . . .

Crew Masks


Photo: G500 Crew masks, PAS, p. 12-5
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[PAS, p. 12-5]

  • There are three crew masks (pilot, copilot, and jump seat) that are quick donning (capable of donning and sealing within 5 seconds).

  • Each mask contains an inflation harness that is activated by squeezing both red tabs together. This inflates the harness for placement over head. When tabs are released, harness deflates and conforms to head and tension secures mask against face.

  • The comfort control is a gray, 2-stop button on front of mask. When pressed to first stop, the harness inflates slowly. Release the button when at desired comfort level. When pressed to the second stop the harness will deflate.


Photo: G500 Crew masks, PAS, p. 12-6
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[PAS, p. 12-6]

  • The mask microphone is integrated into breathing area of mask and is activated by selecting MASK on COMM JACKS panel. This activates cockpit overhead speakers and the mic is keyed with Push-To-Talk on sidestick or CCD.

  • The N / 100% control switch on mask / regulator allows for selection of:

    • Pull OUT → “N” (Normal) → Diluted O2 (regulated by altitude and demand; pressurized 100% O2 supplied at 35K’ cabin altitude)

    • Press IN → 100% O2 (100% O2 supplied at all altitudes, manufacturer recommends to keep in this setting)

  • EMERGENCY / PRESS TO TEST knob (3 functions)

    • Pressed IN momentarily: Verifies if regulator can supply constant pressure O2; Used in conjunction with PRESS-TO TEST switch on storage compartment for Oxygen System preflight test

    • NORMAL setting (fully counterclockwise position): Allows regulator to provide diluter-demand flow

    • EMERGENCY setting (fully clockwise position): Provides constant pressure 100% O2 if N / 100% switch is in 100%


Photo: G500 Crew masks, PAS, p. 12-7
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[PAS, p. 12-7]

  • There are three smoke goggles, one each under the front of each pilot's seats and one for the jump seat in a storage box in the floor just aft of center pedestal.

  • Remove the goggles from their holders and attach to masks: place goggles locking mechanism in front of receptacle on mask and push into receptacle until it clicks locked.


Photo: G500 Crew masks, PAS, p. 12-8
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Photo: G500 Crew masks, PAS, p. 12-9
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[PAS, p. 12-9]

  • The flow blinker indicates oxygen flow when yellow, no flow when black.

  • The PRESS-TO-TEST AND RESET control switch may be used while the mask is in the stowed position. The flow blinker displays yellow momentarily then turns black indicating leak-tight. If blinker remains yellow, suspect a leak and investigate.

  • The RESET position closes the shutoff valve to stop oxygen flow. The shutoff valve opens when compartment doors open.

  • To remove mask from storage compartment, grasp mask by red tabs, quickly pull mask from compartment. This will inflate the harness and activates the flow of oxygen to the mask.

Oxygen Bottles


Photo: G500 Oxygen bottles, PAS, p. 12-3
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[GVII-G500 Description Manual, §] The onboard oxygen system is supplied by two 123.4 cubic foot, aluminum lined, composite oxygen cylinders located below the cabin floor, forward of the wingbox. Oxygen Cylinder. The cylinders are normally charged to 1800 ±50 psig of aviators breathing oxygen. There is a regulator mounted on the cylinder. For cylinder pressure above 250 psig, the crew oxygen supply is regulated to 55 - 80 psig. If cylinder pressure drops below 250 psig, there will be no pressure in the supply lines. The regulator has HP and LP relief port. The relief ports are tied together and vent to the overboard discharge indicator on the right side of the fuselage. The LP relief port vents oxygen when regulator supply pressure exceeds 90 psig. The LP relief port resets at 90 psig. The HP relief port vents oxygen when cylinder pressure exceeds 2775 psig. The HP relief port resets at 2500 psig. The regulator has a refill port plumbed to the oxygen service panel and a port for remote indication for cylinder charge pressure.

[PAS, p. 12-3]

  • The bottles are rupture resistant, manufactured from seamless aluminum, wrapped in Kevlar fabric.

  • Each bottle is equipped with a shutoff valve and a low pressure regulator on the neck of each bottle to maintains a nominal delivery pressure of 55 to 80 psi.

  • There is a direct reading gauge at the O2 service panel. High pressure relief valve rated at 2775 maximum psi. A low pressure relief valve alerts crew when low pressure O2 < 45 psi:

    • Crew Oxygen Off

    • Passenger Oxygen Off


Photo: G500 Oxygen service panel, Eddie's aircraft
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[PAS, p. 12-4]

  • The Oxygen Service Panel is located on the right side of the aircraft opposite main door.

  • The Oxygen High Pressure Relief Disc is located just forward of service panel. A green disc that caps overboard discharge line. Crew or passenger O2 vented here to relieve pressure due to over pressure (regulated pressure > 90 psi, O2 bottle pressure > 2500-2775 psi. Vented O2 will blow out green disc to alerts crew during preflight of O2 discharged overboard.



Photo: G500 oxygen system panel, Eddie's drawing
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Oxygen System Panel

[PAS, p. 12-12] Oxygen System Panel

  • Located on copilot side console.

  • CREW / PASS guarded green toggle switch does not require electrical power. When ON, O2 flow provided to Crew / Pax O2 system. Normally left in ON position after aircraft shutdown. When OFF, O2 flow to system is inhibited.

  • THERAPEUTIC OXYGEN guarded switch is normally OFF (dark). When ON (Blue), allows flow of O2 to therapeutic port in cabin. CAS message: Therapeutic Oxygen On.

Passenger Oxgyen Panel

[PAS, p. 12-13] Passenger Oxygen Panel

  • PASSENGER OXYGEN rotary knob, 3 position rotary knob, does not require electrical power

    • AUTO (normal position), enables auto deployment of pax O2 masks, dependent upon ALT SELECT switch setting. Flow of O2 to masks regulated based on cabin altitude.

    • OFF: Inhibits flow of O2 to pax O2 system.

    • MAN: Manually deploys pax O2 masks, O2 flows to masks at a constant preset flow.

  • Green PASS OXYGEN ON indicator light: normally dark, indicates green when flow of O2 to pax masks is sensed. CAS message: Passenger Oxygen On.

  • OXYGEN SUPPLY PRESSURE gauge: does not require electrical power, displays O2 supply pressure available to crew and pax. Shows the regulated pressure after leaving O2 bottles. Actual pressure in O2 bottles can be read via TSCs and synoptic pages.


Photo: G500 Boom / Mask Mic Switch, PAS, p. 12-14
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[PAS, p. 12-14]

  • ALT SELECT guarded switch requires PASSENGER OXYGEN switch AUTO. OFF (dark) → Out position (normal position), Pax O2 masks auto deploy → Cabin alt 14,750' +/- 250'. Amber “HIGH ALT” → IN position, used when flying in / out of airport elevation > 14,000', Pax O2 masks auto deploy → Cabin alt 15,750' +/- 250'

  • ALT TEST port → Used for MX testing of Pax O2 masks deploy

  • Boom / Mask Mic Switch located on left and right COMM JACKS panels. When selected to MASK, activates O2 mask mic, activates cockpit overhead speakers. Mic is keyed with Push-To-Talk on sidestick or CCD. Jump seat uses RADIO / ICS toggle switch on its COMM JACKS panel.

Oxygen service panel

[GVII-G500 Description Manual, §] An external HP oxygen servicing panel is mounted on the right side of the fuselage forward of the wing-to-body fairing. Located within the servicing panel is a single HP filler valve with integral check valve and direct reading pressure gages for the crew and passenger oxygen cylinders. The filler valve will service both oxygen cylinders simultaneously. The filler valve is protected from contamination by a dust cap that is secured to the frame by a chain. The direct reading pressure gages display pressure directly from the crew and passenger cylinders. The servicing panel gages have a range of 0 - 2000 psig. A door switch controls the servicing panel light and provides a door open signal to EICAS.

[GVII-G500 Description Manual, §] An overboard discharge indicator, located on the right side of the aircraft just forward of the oxygen servicing panel, indicates when oxygen cylinder pressure has been relieved overboard. The HP burst disk will become dislodged from the retaining ring at pressures between 20 and 90 psig. The cylinder regulator vents LP relief when supply line pressure exceeds 90 psig. The regulator assembly will also vent HP relief when cylinder pressure exceeds 2775 psig.

Passenger Oxygen Masks


Photo: G500 Passenger masks, PAS, p. 12-10
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[PAS, p. 12-10] Passenger Overhead Masks

  • Yellow cup-like masks commonly used in airline operations. The number installed must exceed number of occupants by at least 10%.

  • Located in compartments overhead each seat, lavatories, and galley.

  • Deployed automatically by cabin depressurization or manually from a switch on cockpit oxygen control panel.

  • The passenger must pull on a lanyard to remove a flow pin, which allows a low flow O2 to flow into retaining bag.

[PAS, p. 12-10] Therapeutic Mask

  • An outlet is installed in the cabin, usually near the divan. The mask and hose provided for medical emergencies are normally stowed in a divan storage compartment.

Protective Breathing Equipment (PBE)


Photo: G500 PBE, PAS, p. 12-11
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[PAS, p. 12-11]

  • There are two, one in the cockpit behind pilot's seat and one in the cabin in the aft lav cabinet in wall above the toilet seat.

  • The PBE is designed to safeguard wearer from effects of smoke, CO2, harmful gases, and O2 deficiency. Helps to manage inflight fires, smoke or fume emergencies, improves visibility in smoke filled compartments, protects head / face from melting / dripping plastics, shields head against brief exposure to heat / flame.

  • Contains 2 oxygen cylinders which combined to hold a minimum of 36 liters of oxygen.

  • Battery powered Service / End-of-Service Indicator light, mounted slightly below eye level on left inner side of hood. Green → Equipment functioning properly. Red → Service life has ended.

  • O2 remains in hood for full 15 mins of total usage time.

  • Preflight requirement: replace PBE if beyond usability date or humidity indicator → Pink. (Normal → Blue)




Photo: Oxygen duration, crew of three, masks on NORMAL, AFM, §01-35-10, fig. 1
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Photo: Oxygen duration, crew of three, masks on 100%, AFM, §01-35-10, fig. 2
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[AFM, §01-35-20]




  • Above Flight Level 250, crew masks must be in the quick-donning position which allows donning within 5 seconds.

  • Crew and passenger oxygen masks are not approved for use at greater than 40,000 feet cabin altitude.

See Also:

Gulfstream GVII-G500 Airplane Flight Manual, Revision 4, August 29, 2019

Gulfstream GVII-G500 Production Aircraft Systems, Revision 3, July 15, 2019

Gulfstream GVII-G500 System Description Manual, Revision 2, December 15/19