RA-11-03359 Enclosure 

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Boeing Proposal for Deviation from 

FAA Partial Exemption No 9943 and Issue Paper ES-13 

747-8 Program 

Reference

a) Exemption No. 9943, “The Boeing Company for an exemption from 25.841(a)(2) and 

25.841(a)(3) of Title 14, Code of Federal Regulations,” dated October 19, 2009 

b) FAA IP ES-13 Stage 4, “747-8 Crew and Passenger, and 747-8 Freighter (747-8F) 

Crew and Supernumerary, Oxygen Equipment for Use Above 40,000 Feet,” dated April 

7, 2011 

c) Boeing letter RA-11-02860, “747-8F Boeing Proposal for Emergency Descent Altitude 

Limitation,” dated June 7, 2011. 

Executive Summary

On May 16, 2011, Boeing conducted two certification flight test profiles to demonstrate 

the 747-8 Freighter (747-8F) emergency descent capability. Per Federal Aviation 

Administration (FAA) Partial Exemption No 9943 (Reference a), the goal of the test was 

to show that after decompression due to a rotor burst event at an airplane indicated 

operating pressure altitude of 43,000 feet (ft), the cabin pressure altitude will not exceed 

40,000 feet for more than 1 minute and 25,000 ft for more than 3 minutes. 

In reference c) Boeing provided results of two 747-8F certification flight descent profiles 

showing that at the 3-minute mark, the airplane was approximately 900 ft above the 

25,000 ft target. Boeing therefore recommended using the certification flight test data to 

lower the 747-8F maximum operating altitude limit from 43,100 ft to 42,100 ft 

commensurate with the approximately 900 ft miss. 

Although the partial exemption refers to an airplane indicated operating pressure altitude 

of 43,000 ft and the recommended 747-8F airplane operating pressure altitude will be 

42,000 ft (42,100 ft maximum operating pressure altitude), Boeing believes that this is an 

administrative change and therefore a change to the exemption would be of no real value. 

The important requirement is the time exposure of the aircraft occupants to pressure 

altitudes, in this case between the original operating altitude and 25,000 ft. Boeing has 

demonstrated that the 747-8F meets the time exposure requirement by using an airplane 

maximum operating altitude of 42,100 ft rather than 43,100 ft. However, if the 

exemption must be revised, Boeing recommends that the certification flight data as 

summarized in this letter and further explained in reference c) be used as support for the 

FAA’s desire to revise Partial Exemption No 9943 to change the referenced maximum 

operating altitude from 43,000 ft to 42,100 ft. 

Similarly, the issue Paper ES-13 (Reference b) addressing the use of oxygen over 40,000 

ft, notes the 43,000 ft airplane operating altitude. Boeing recommends that there be no 

changes to issue paper ES-13 because by limiting the altitude of the airplane to 42,100 ft, 

the requirements of issue paper ES-13 are met. If issue paper ES-13 must be revised then 

the only change needed is to revise the 43,000 ft airplane operating altitude to 42,100 ft 

airplane operating altitude. 
RA-11-03359 Enclosure 

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Certification Flight Data

Two Boeing 747-8 Freighter certification flights were conducted on May 16, 2011 per the 

partial exemption airplane and environmental operational boundaries. Additionally, the 

test procedure took into account a 17 second initial crew reaction time from the start of 

the simulated decompression event to commanded initiation of the rapid emergency 

descent, so the allotted descent time requirement to reach the 40,000 ft mark was 43 

seconds and the time requirement to reach the 25,000 ft mark was 163 seconds. 

The certification flight data shows that both descents were at the 40,000 ft mark in less 

than 43 seconds. However, both descents missed the 25,000 ft mark by approximately 11 

seconds. In further review of the data, at the 163 seconds requirement, both descents 

were above the 25,000 ft mark by: 

 Certification flight test #1: altitude at 163 seconds: 25,891 ft (891 ft exceedance) 

 Certification flight test #2: altitude at 163 seconds: 25,932 ft (932 ft exceedance) 

Based on this data, Boeing recommends lowering the 747-8F maximum operating 

altitude limit by 1,000 ft from 43,100 ft to 42,100 ft to compensate for the descent 

altitude exceedance in order to meet the conditions set forth in Exemption No. 9943. 

Compliance will be documented using interpolation of the above certification flight test 

data in combination with lowering the maximum operating altitude limit as mentioned 

above, to show that the airplane is capable of being at or under 25,000 ft in 3 minutes, 

while maintaining compliant capability of being at or under 40,000 ft in 1 minute. 

Request

Although Boeing believes that the intent of the exemption is met and that no change is 

required to the exemption, if a change is required then Boeing an expedited revision to 

the partial exemption using the information provided in this letter in support of showing 

compliance to the reference (a) partial exemption, by reducing the maximum operating 

altitude of the Boeing 747-8 Freighter from 43,100 ft to 42,100 ft based on the May 16, 

2011 certification flight test data.