UNITED STATES OF AMERICA 

DEPARTMENT OF TRANSPORTATION 

FEDERAL AVIATION ADMINISTRATION 

RENTON, WASHINGTON 98057-3356 

In the matter of the petition of 

Exemption No. 11621 

Cessna Aircraft Company Regulatory Docket No. FAA-2015-0449 

for an exemption from§ 25.1447(c)(1) of 

Title 14, Code of Federal Regulations 

PARTIAL GRANT OF EXEMPTION 

By letter dated February 16, 2015, Mr. Brian Richardet, Airworthiness Manager, Cessna Aircraft 

Company, One Cessna Boulevard, Wichita, Kansas, 67277-7704, petitioned the Federal Aviation 

Administration (FAA) for an exemption from the requirements of§ 25.1447(c)(1) of Title 14, 

Code of Federal Regulations (14 CFR). This exemption, if granted, would permit relief from the 

requirement that oxygen dispensing units must be automatically presented to occupants before 

the cabin pressure altitude exceeds 15,000 feet on Cessna Model 750 airplanes. 

The petitioner requests relief from the following regulation(s): 

Section 25.1447(c)(1) requires, in pertinent part, that there must be an oxygen-dispensing 

unit connected to oxygen-supply terminals immediately available to each occupant, 

wherever seated. If certification for operation above 30,000 feet is requested, the 

dispensing units providing the required oxygen flow must be automatically presented to 

the occupants before the cabin-pressure altitude exceeds 15,000 feet, and the crew must 

be provided with a manual means to make the dispensing units immediately available in 

the event of failure of the automatic system. 

The petitioner supports its request with the following information: 

This section quotes the relevant information from the petitioner's request, with minor edits for 

clarity. The complete petition is available at the Department of Transportation's Federal Docket 

Management System, on the Internet at http://regulations.gov, in Docket No. FAA-2015-0449. 
Background 

Cessna Aircraft Company requests an exemption from the portion of§ 25.1447(c)(1) that 

requires the oxygen dispensing units to be automatically presented to the occupants 

before the cabin pressure altitude exceeds 15,000 feet. 

The present aircraft uses Transport Airplane Directorate equivalent level of safety 

(ELOS) memo TC0002WI-T-SG-8 to address suppression of the 10,000 foot cabin 

pressure altitude warning required by§ 25.841(b)(6) when operating to and from airports 

with a field elevation between 8,000 and 14,000. 

To avoid nuisance oxygen mask deployments when operating to and from airports with a 

field elevation greater than 14,000 feet, an exemption is requested to allow use of an 

"Elevation > 14K" button to shift the oxygen mask deployment altitude to 15,750 ± 250 

feet. (The petitioner incorrectly referred to cabin altitude warning at 14, 700 feet in this 

paragraph. We corrected this erroneous information based on the entirety of the petition.) 

The Petitioner Supports its Request with the Following 

China currently has four airports with elevations in excess of 14,000 feet, including 

Daocheng Yading Airport at 14,472 feet. It is requested that the aircraft be capable of 

operations at these and other airports with field operations above 14,000 feet (with 

anticipated barometric pressure variations) and up to 15,000 feet. In order for the Model 

750 Citation X+ to provide the additional capability for operation at these airports, the 

cabin pressure control system (CPCS) and passenger oxygen control system (POCS) will 

be modified to allow the cabin pressure altitude to reach as high as 15,150 ± 150 feet. 

Manual control of the oxygen system is not affected and can be activated at any time the 

crew deems necessary. 

Public Interest Statement 

Cessna's leadership position in the global business jet market is due to the efforts of its 

nearly 8,000 employees in manufacturing plants, completion centers, and service centers 

across the United States. This further includes the many vendors located across the 

United States that provide the numerous aircraft pieces such as avionics, oxygen 

components, as well as the modified CPCS components that would be used for the 

aircraft to operate at this high elevation. Cessna competes for new business all over the 

world. Although the current economy has slowed, Cessna is striving to gain international 

markets for its business jets. This increased market directly affects the viability of Cessna 

and would aid in the stabilization of the job market, as well as the growth ofthe 

American economy, which is directly in the interest of the public. 

Supporting Information 

A requirement for automatic presentation of masks for airplanes certified to operate 

above 30,000 feet originated in § 4b.651 ( d)(3 )(i) of the Civil Aviation Regulations (CAR) 

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and was carried over as§ 25.1447(c)(1) when part 25 was codified. The CAR 

requirement did not specify the maximum cabin pressure altitude allowed prior to 

presentation. The requirement that oxygen equipment be automatically presented before 

the cabin pressure altitude reaches 15,000 feet was added at Amendment 25-41, effective 

September 1, 1977. This additional requirement recognized the hazard of oxygen 

deprivation on the average human being and its effect on carrying out actions under 

stressful conditions. It should be recognized that in travel requiring use of the 

Elevation> 14K mode, the persons on the aircraft will be disembarking at an altitude near 

15,000 feet. Therefore, the cabin altitude conditions are comparable to the environmental 

conditions to which they will be exposed. 

The oxygen mask presentation at 15,750 ± 250 feet is only selected when an "Elevation> 

14K" button is activated by the pilot. The button will remain illuminated and an advisory 

ELEV > 14K message will be displayed to indicate that the plane is in Elevation> 14K 

mode. These features assist in limiting the use of this mode to conditions when the 

airplane will be operating at airfields with an elevation greater than 14,000 feet. The 

activation point for the cabin altitude warning is also shifted to avoid nuisance alerts. 

Appropriate procedures will be provided in the airplane flight manual to address proper 

operation of the Elevation> 14K mode. These procedures will instruct the flight crew to 

select this mode when descending to land at an airfield with an elevation greater than 

14,000 feet, and to reset the "Elevation> 14K" button back to the "normal" mode while 

climbing after takeoff. These procedures will minimize the duration of the elevated cabin 

altitudes. These procedures are for China-based aircraft and will be similar to those for 

the previously certified Model 680 high altitude option. 

Federal Register publication 

The FAA has determined that good cause exists for waiving the requirement for Federal Register 

publication for public comment because the request is identical in all material respects to 

previously granted exemptions; the exemption, if granted, would not set a precedent; and any 

delay in acting on this petition would be detrimental to the Cessna Aircraft Company. 

The FAA's analysis 

The FAA considers that granting the petition is in the public interest for the reasons stated by the 

petitioner and because the exemption is effectively identical to previously granted exemptions to 

§ 25.1447(c)(l). 

The petitioner requests an exemption for Cessna Model 750 airplanes and seeks relief from the 

requirement in§ 25.1447(c)(l), which states that oxygen dispensing units must be automatically 

presented to occupants before the cabin pressure altitude reaches 15,000 feet. A requirement for 

automatic presentation of oxygen masks for airplanes certificated to operate above 30,000 feet 

originated in § 4b.651 ( d)(3)(i) of the Civil Aviation Regulations (CAR) and was carried over as 

§ 25.1447(c)(1) when 14 CFR part 25 was codified. The CAR requirement did not specify the 

maximum cabin pressure altitude allowed prior to presentation. The requirement that the oxygen 

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dispensing units be automatically presented before the cabin pressure altitude reaches 15,000 feet 

was added at Amendment 25-41 , effective September 1, 1977. 

For operation of the Cessna Model 750 airplane into and out of an airport with a landing field 

above 14,000 feet, the flightcrew must activate the "Elevation > 14 K" button. This results in 

automatic deployment of the passenger oxygen masks when the cabin pressure altitude is 15,750 

feet, ± 250 feet. This feature is necessary to reduce the occurrence of inadvertent deployment of 

oxygen masks. 

The FAA's decision 

In consideration of the foregoing, I find that a partial grant of exemption is in the public interest. 

Therefore, pursuant to the authority contained in 49 U.S.C. §§ 40113 and 44701 delegated to me 

by the Administrator, I grant Cessna Aircraft Company an exemption from the requirement of 

14 CFR 25.144 7( c )(1) that the passenger oxygen equipment must be automatically presented 

before the cabin pressure altitude exceeds 15,000 feet. For Cessna Model 750 series airplanes, 

this grant of exemption will permit passenger oxygen masks to be automatically presented before 

the cabin pressure altitude exceeds 16,000 feet when operating into and out of airports with 

altitudes above 14,000 feet. This exemption is granted to the extent necessary to reduce the 

occurrence of inadvertent deployment of oxygen masks. 

Issued in Renton, Washington, on HAY 1 5 2015 

~~ Michael Kaszycki 

Acting Manager, Transport Airplane Directorate 

Aircraft Certification Service 

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