For a single-engined turbine aeroplane whose pressurisation system energy source is lost (e.g., bleed air inflow), what happens to the cabin pressure altitude after an engine failure, and what does this allow the flight crew to do?

The cabin pressure altitude increases at a rate dependent upon the pressurisation system design and the cabin pressure leak rate, and it will remain below 13,000 ft for a certain duration, which should allow the flight crew to descend at the best gliding speed during this period.

GM1 CAT.IDE.A.235(c) Supplemental oxygen

Q: For a pressurised aeroplane without automatically deployable oxygen-dispensing units, what is the required basis for the amount of supplemental oxygen if it was first issued with an individual CofA after 8 November 1998 and has a maximum certified cruising altitude above 25,000 ft?

The amount of supplemental oxygen should be based on a cruising altitude of 25,000 ft, as CAT.IDE.A.235(c) limits the operations of such aeroplanes to that altitude.

Q: In the event of a loss of engine power during SET-IMC operations, what specific descent conditions must be assumed when calculating the required supplemental oxygen for all occupants?

The descent must be performed at the best-range gliding speed and in the best gliding configuration, assuming the maximum cabin pressure leak rate, during the entire flying time when the cabin pressure altitude exceeds 13,000 ft.

Q: What is the intent of CAT.IDE.A.235(c) regarding the cabin pressure altitude potentially increasing above 13,000 ft after an engine failure during SET-IMC operations?

The intent is to ensure that this does not result in any unsafe conditions for the passengers, as well as not jeopardise the safety of operations approved in accordance with Subpart L (SET-IMC) of Annex V (Part-SPA) to Regulation (EU) No 965/2012 by maximising the chances of reaching an appropriate landing site.

Q: For pressurised aeroplanes without automatically deployable oxygen-dispensing units, what is the maximum cabin pressure altitude threshold below which supplemental oxygen is not required during the entire flying time after a loss of engine power?

Supplemental oxygen is required during the entire flying time when the cabin pressure altitude exceeds 13,000 ft; below that threshold, it is not required.

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GM1 CAT.IDE.A.235(c) Supplemental oxygen – pressurised aeroplanes

ED Decision 2017/004/R

AEROPLANES WITHOUT AUTOMATIC DEPLOYABLE OXYGEN-DISPENSING UNITS

For operations approved in accordance with Subpart L (SET-IMC) of Annex V (Part-SPA) to Regulation (EU) No 965/2012, should a loss of engine power occur, it is required that sufficient supplemental oxygen for all occupants is available to allow descent from the maximum certified cruising altitude, performed at the best-range gliding speed and in the best gliding configuration, assuming the maximum cabin pressure leak rate, during the entire flying time when the cabin pressure altitude exceeds 13 000 ft.

In the case of pressurised aeroplanes first issued with an individual certificate of airworthiness (CofA) after 8 November 1998, with a maximum certified cruising altitude above 25 000 ft, and not fitted with automatically deployable oxygen-dispensing units, the amount of supplemental oxygen should be based on a cruising altitude of 25 000 ft as CAT.IDE.A.235(c) limits the operations of such aeroplanes to the aforementioned altitude.

For such single-engined turbine aeroplanes, with the energy source of the pressurisation system being lost (this is at least the case of pressurisation systems relying on bleed air inflow), the cabin pressure altitude increases at a rate dependent upon the pressurisation system design and the cabin pressure leak rate.

Therefore, following an engine failure during such operations, the cabin pressure altitude will remain below 13 000 ft for a certain duration, which should allow the flight crew to descend at the best gliding speed during this period.

The intent of the CAT.IDE.A.235(c) requirement is to ensure that this does not result in any unsafe conditions for the passengers, as the cabin pressure altitude might increase above 13 000 ft, as well as not jeopardise the safety of operations approved in accordance with Subpart L (SET-IMC) of Annex V (Part-SPA) to Regulation (EU) No 956/2012 by maximising the chances of reaching an appropriate landing site.

Details

Source-Title: GM1 CAT.IDE.A.235(c) Supplemental oxygen - pressurised aeroplanes View latest amendments

Erulesid: ERULES-1963177438-12784 Compare versions

Domain: Air operations

Applicabilitydate: 10 March, 2017

Entryintoforcedate: 10 March, 2017

Regulatorysource: ED Decision 2017/004/R Navigate

Regulatorysubject: Part-CAT

Typeofcontent: GM to IR (Guidance material to implementing rule)

Parentir: CAT.IDE.A.235 Supplemental oxygen - pressurised aeroplanes

Origin: EASA

Category: EAR