FYI... (Not specific to the Oxygen issue, rather to Engine Out...)
VOLUME 4 AIRCRAFT EQUIPMENT AND OPERATIONAL AUTHORIZATIONS
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Engine-Out En route Limit. At an altitude of 1,000 feet above all obstacles within 10 miles of the course to be flown, the airplane must be able to climb at a rate specified as follows...
1) Airplanes certified under CAR 4B must be able to climb at .079-(.106/N) Vso2, expressed in feet per minute, where N is the number of engines. For a four-engine airplane with a stall speed of 100, the following formula applies: .079-(.106/4)1002 and .079-.0265 * 10,000 and .0525 * 10,000 = 525 FPM
2) Airplanes certified under CAR 4A must be able to maintain a rate of climb of .026Vso2 , expressed in feet per minute. For an airplane with a stall speed of 50, the following formula applies: .026*502 = 65 FPM
3) Instead of meeting the climb requirement, the operator may substitute an approved diversion.
The procedure must be approved by the POI and published in a CFM or a portion of the GOM.
When an operator proposes such a procedure, the airplane must be able to maintain an altitude of 2,000 feet above any obstacle within 5 miles of track after the assumed failure.
The rate of climb used to show this capability must be taken from the AFM and diminished by .079- [.106/N]Vso2 for CAR 4B airplanes or by .026 Vso for CAR 4A airplanes to compute a net gradient.
The operator’s proposed procedure must define a point at which the airplane is assumed to pass over the critical obstacle.
The operator’s procedure must define this point by means of an approved navigational fix.
The airplane must also be able to meet the required rate of climb at an altitude of 1,000 feet above the alternate airport. The procedure must provide an account of winds and temperatures forecast in the area. Fuel may be jettisoned to meet these requirements.
An en route alternate airport to which the airplane could divert, which meets the prescribed weather minimums, must be specified on the flight release when these procedures are used.