SEP - 7 2012 

RA-12-03853 

U.S. Department of Transportation 

Docket Operations, M-30 

1200 New Jersey Avenue, S.E. 

John A. Hamilton 

Lead Administrator 

Regulatory Administration 

Commercial Airplanes 

Room W12-140, West Bldg. Ground Floor 

Washington, DC 20590-0001 

The Boeing Company 

P.O. Box 3707 MC 03-56 

~)EFt-\'Ffi1vti~\~fbf8124-22o7 

-i1ANSPORTATION 

:·:(\(CT 0°ERATIONS 

ZO! l SEP I 0 P I: 2 b 

Subject: Petition for Exemption from Title 14 Code of Federal Regulations 

Section 25.841(a)(2) and (a)(3) atAmendment 87 with Respect to 

Uncontained Engine Failure · 

Model: 787-9 

The Boeing Company respectfully submits this petition for exemption from Title· 

14 Code ofFederalRegulations Section 25.841(a)(2) and (a)(3) at Amendment 

87 for the 787-9 as described in the summary below. The enclosure to this letter 

provides the details of the petition in accordance with Title 14. Code ofF ederal· 

Regulations Section 11. 81. The following summary is provided for the Federal 

Register in accordance with Title 14 code of federal Regulations Section 

11.81(f). 

Summary for Federal Register 

Petitioner: The Boeing Company. 

Section of 14 CFR Affected: Section 25.841(a)(2)(3) 

Description of Relief Being Sought: 

Boeing is requesting relief from the requirements of Title 14 Code ofFedetal 

Regulations Section 25.84l(a)(2) and (a)(3) pertaining to cabin decompression 

· following certain extremely rare uncontained engine failures for the Boeing 

Model 787-9. If granted, this·exemption will allow operators the ability to operate 

the 787-9 where it is most efficient and therefore not face higher operating costs 

due. to increased fueL bum. Furthermore, reduced fuel burn will lead to lower 

engine emissions resulting in a positive impact to the environment. By granting 

this petition for exemption the true benefits of the 787-9 will be realized, causing 

no adverse effect on safety. 
~DEI.NG 

Page2 

RA-12-03853 

Sincerely, 

;ZM~~rr Director, Regulatory Administration 

Deputy Lead Administrator 

(425) 237-1383, MC03-52 

FAX: ( 425) 294-9340 

Enclosure: Petition for Exemption from 14 CFR 25.841, Amendment 87 

cc 

Name 

Ken Schroer 

Doug Tsuji 

Letter 

Paper/SP 

SP 

Enclosures 

SP 

SP 

Comments 

ANM-106B· 

ANM-106B 
Petition for Exemption from 14 CFR 25.841, Amendment 25-87 

Enclosure to RA-12-03853 

Page1 of17 

(a) Name and Address of the Petitioner 

Doug Lane, Director, Regulatory Administration Deputy Lead Administrator 

The Boeing Company 

PO Box 3707 

Seattle, Washington, 98124 

(b) Section(s) ofthe Regulations from which Relief is Sought: 

(c 

25.84l(a)(2) and 25.841(a)(3) With Respect to Uncontained Engine Failures. 

§ 25.841 

(a)(2) The airplane must be designed so that occupants will not be exposed to a 

cabin pressure altitude that exceeds the following after decompression from any 

failure condition not shown to be extremely improbable: 

(i) Twenty-five thousand (25,000) feet for more than 2 minutes; or 

(ii) Fmiy thousand (40,000) feet for any duration. 

(a)(3) Fuselage structure, engine and system failures are to be considered in 

evaluating the cabin decompression. 

) The Extent of Relief Sought and Reason(s) 

Regulation Requires: Relief is Necessary because: 

14 CFR 25.841 (a)(2) and Compliance to be shown with Direct compliance would limit maximum 

(a)(3) cabin pressure altitude limits for aircraft altitude to less than 40,000ft and 

Amendment 25-87 uncontained engine failure would: 

A) create an economic impact to 

operators associated with higher fuel 

bum 

B) have an environmental impact due to 

increased engine emissions associated 

j 

with higher fuel burn 

C) reduce competitiveness of the 787-9 

in the aircraft marketplace 

(d) Description of Issue 

The 787-9 aircraft is being designed to operate at a maximum cruise altitude of 43,100 ft. 

Amendment 25-87, Reference (1 ), established new requirements in § 25.841 (a) intended to·upgrade 

the airplane and equipment airworthiness standards for subsonic transport airplanes operated above 

40,000 feet. These were based in part on special conditions that had been used on type ce1iification 
Enclosure to RA-12-03853 

Page 2 of 17 

of executive business airplanes for many years. Specifically, Amendment 25-87 created three 

requirements in§§ 25.84l(a)(2)(i), 25.84l(a)(2)(ii), and 25.84l(a)(3) governing the cockpit/cabin 

environment: 

§ 25.84l(a) subpart; 

(2) The airplane must be designed so that occupants will not be exposed to a cabin pressure 

altitude that exceeds the following after decompression from any failure condition not shown 

to be extremely improbable: 

(i) Twenty-five thousand,(25,000) feet for more than 2 minutes; or 

(ii) Forty thousand (40,000) feet for any duration. 

(3) Fuselage structure, engine and system failures are to be considered in evaluating the cabin 

decompression. 

The Boeing Company respectfully submits that compliance with §§ 25.841 (a)(2), and 25.841 (a)(3) · 

as written, with respect only to the consideration of an uncontained engine failure, provides no 

increase in safety with respect to modern transport category jet aircraft when considering the safety 

record of the fleet over the last 53 years. The fleet has a demonstrated safety record with mi I! ions of 

hours at altitudes similar to the maximum cruise altitude proposed for the 787-9. Despite the 

improved descent capability of the 787-9 over previously certificated aircraft of similar category and 

class, compliance with 25.841 (a)(2)(i) following an uncontained engine failure would limit the 787-9 

maximum ce1iificated altitude. In addition, The Boeing Company assessment of the §25.841 (a), 

Amendment 87, impact on overall fleet safety raised concerns about several unintended 

consequences. One such consequence is higher density air traffic at altitudes below 40,000 feet as a 

result of limiting new aircraft with wing mounted engines to altitudes below 40,000 feet. This may 

result in additional cost to maintain an adequate level of safety for the air traffic system. 

The 787-9 is designed to fly at cruise altitudes that will maximize fuel efficiency. The reduction in 

maximum cruise altitude resulting from compliance with §§25.841(a)(2) and 25.841(a)(3) for 

uncontained engine failure would significantly impact the marketability of the 787-9. This concern 

is shared by other manufacturers of airplanes with wing-mounted engines seeking new or amended 

Type certification. No transport category airplane with wing-mounted engines ce1iificated today for 

operation above 39,000 feet can meet the new cabin altitude limits within the current §§25.84l(a)(2) 

and 25.841(a)(3) without an exemption. 

The 787-9 incorporates new technology, lessons learned from previous and current production 

airplanes, and complies with the latest airworthiness standards throughout to provide a safer, more 

efficient transportation option for airlines and airline passengers. Grant of this petition provides the 

public the benefits of the 787-9 airplane. 

As stated in the Mechanical Systems Harmonization Working Group (MSHWG) rep011, there is an 

inherent physiological risk to humans when exposed to high cabin altitudes. In the 787-9 design, 

The Boeing Company mitigates risk to high cabin altitude exposure by reasonable design 

requirements, proven design methodologies and operational considerations regardless ofthe cause of 

the decompression event. It is intended that the proposed exemption addresses the intended concern 
Enclosure to RA-12-03853 

Page 3 of 17 

for safety without imposing the operational economic penalties driven by §§25.841 (a)(2) and 

25.841 (a)(3) as currently written. In the following, The Boeing Company provides: 

• a background of the current rule and activities to harmonize it 

• a review of the safety history ofhigh altitude commercial flight 

• a discussion of hypoxia physiology data upon which rule making activities are based 

• a discussion of the impact of compliance with uncontained engine rotor burst aspects of 

existing rule, as related to economics, environmental, and air traffic considerations. 

• proposed risk mitigation 

• statements addressing public interest and no adverse impact to safety. 

Background on 14 CFR § 25.84l(a)(2)(3), Amendment 25-87 

Amendment 25-87 to§ 25.84l(a) was made effective July 5, 1996. The focus of the rule was to 

codify the special conditions formerly used in the certification of high altitude operation, generally 

applied to general aviation and transport category business jets covering operation up to 51 ,000 feet. 

This section was changed without being harmonized with the Joint Aviation Authorities (JAA) or 

now the European Aviation Safety Agency (EASA). It is noteworthy that the .JAA and EASA have 

not adopted the same regulations as levied in 14 CFR §25.84l(a) as promulgated in Amendment 25-

87 and lists §25.841 (a) as a significant difference for concurrent F AAI .JAA or F AA/EASA 

cetiification programs. The JAA INT/POL/25/16, Issue 1, Date: 0 1.06.03, "Airworthiness Standards 

for Subsonic Transport Aeroplanes to be operated above an altitude of 41 ,000 ft," states, with respect 

to evaluation of engine rotor burst, "It is JAA opinion that turbine engine installations failures should 

be assessed against the specific requirement of JAR 25.903(d) and should not be part of the present 

Special Conditions, this is to allow a consistent approach at the aircraft level ... " 

The provisions of §§25.841 (a)(2) and 25.841 (a)(3) of Amendment 25-87 effectively limit new 

transport category airplanes with wing-mounted engines to operating altitudes well below 40,000 

feet. This has major cost impacts since new airplane models may not be able to compete with 

existing certificated airplanes or derivative airplanes, which do not have §25.841 (a), Amendment 25-

87 as pati of their certification basis. The existing airplanes can cruise at altitudes above 40,000 feet 

where they are more fuel-efficient. 

The Aerospace Industries Association (AlA) and European Association of Aerospace 

Industries/ Association Europeenne des Constructeurs de Materiels Aeronautique (AECMA) 

petitioned the Federal Aviation Administration to amend 14 CFR 25.841(a), Amendment 25-87, 

pressurized cabins, and the associated Advisory Circular 25-20. It was suggested that the proposed 

amendment be addressed through the auspices ofthe Aviation Rulemaking Advisory Committee 

(ARAC). The petitioners recommended that hannonization with the Joint Airworthiness 

Requirements and Transport Canada's standards be accomplished simultaneously through the ARAC · 

process. 

The petitioners represented the manufacturers of transport category airplanes in the United States 

and Europe. As such, they have an interest in this rulemaking proposal because new and derivative 

airplanes designed to meet 14 CFR Part 25 as amended at Amendment 25-87 will have significantly 

higher design and operating costs than currently certificated airplanes, with no measurable increase 

in safety. These higher costs, impact the ability of manufacturers to develop new airplanes that can 

compete with previously approved airplanes. The petitioners also identified that the economic 
Enclosure to RA-12-03853 

Page 4 of 17 

evaluation conducted by the FAA did not consider the costs associated with applying this new 

standard to changes to existing type certificates (derivative models) when assessing the costs and 

benefits accruing from the amendment, nor whether the new requirement itself could be met by any 

practical means for any new or derivative airplane. 

In July 2001, the FAA assigned the ARAC and the Mechanical Systems Harmonization Working 

Group (MSHWG) the task of addressing various concerns with the regulation, raised by industry, 

and of reaching a consensus among medical experts, representatives from the FAA, JAA, Air 

Transport Association (AT A), ALPA, AF A and Aircraft Manufacturers (members with 

representation in the AlA, AECMA or GAMA). The MSHWG agreed that the existing standard 

may be conservative relative to engine related failures when considering the associated risks and 

exposure to safety. The issuance of an FAA Draft Interim Policy, published in the Federal Register, 

June 2003, Reference (2) is consistent with this position, as is the MSHWG working group repoti, 

Reference (3), which identified the existing requirements as being conservative relative to safety. In 

consideration of comments received on the draft Interim Policy and the acceptance of the MSHWG 

report by TAEIG,. the FAA worked with manufacturers to establish appropriate criteria for 25.841 (a) 

with respect to an uncontained engine failure. The following proposal is consistent with those 

criteria and similar to exemptions granted for the 787-8, 747-8, 747-8F, A380, ERJ 170, and ERJ 

190. 

Safety History 

The original 14 CFR §§25.841 (a)(2) and 25.841 (a)(3) had the goal of ensuring that no fatalities or 

permanent physiological harm occurred following a rapid depressurization event. However, the 

MSHWG believed that there is an inherent risk to occupant health and safety associated with any 

rapid depressurization event. The MSHWG concluded that all occupants are at some level of risk 

during a decompression event and the resulting emergency descent, flight, and landing. Fatalities 

may occur during the initial event (i.e., from impact ofuncontained engine debris or from being 

ejected from the airplane). In addition, some cases of permanent physiological harm could result 

from hypoxia among those occupants at increased risk due to pre-existing health factors (e.g., age, 

chronic and acute medical conditions, etc.). The following is presented to establish the demonstrated 

risk to safety due to rapid depressurizations is non-significant when compared to other risks to 

safety. 

Previously certificated large transp01i aircraft incorporating established design practices have safely 

operated at altitudes in excess of 40,000 feet for more than 30 years, representing many millions of 

flight hours. Historically, relatively few accidents or incidents have occurred during cruise. 

According to the statistics, for the period 1959 - 1996, only 6.8 percent of accidents in the worldwide 

commercial fleet history have occurred during cruise; even though the highest percentage of the 

flight time (57%) is at cruise (Reference ( 4)). See Figure 1-1. More recent statistics, show only 6.0 

percent of accidents have occurred during cruise for the period 1994- 2003, (Reference (5)) and 11 

percent of accidents have occurred during cruise for the period 2002- 20 II (Reference (16)). See 

Figure 1-2 and 1-3 respectively. 
Fatalities 

\1\forld~'vide Commercial Jet Fleet- 1959- 1996 

Enclosure to RA-12-03853 

Page 5 of 17 

Exposure percentage based on flight duration of 1. 5 hours 

18.3% 

Percentage of fatalities 

Load, Takeoff lnttial Climb Cruise 

taxi, climb 

unload 

20% 7.3% 11.0% 17.4% 6.8% 

1% 1% 

~ 

./ 

Flaps retracted 

/ 

14% 57% 

22.6% 

Descent lnttial Final Landing 

approach approach 

11.7% 21.2% 18.2% 4.4% 

----......, ---~ 

~ w~~~-~ Nav fb< Outer marker I 

11% 1 12% I 3% , % 

Exposure, percentage of flight time 4,578 

Figure 1-1, Fatalities, Worldwide Commercial Jet Fleet -1959- 1996 
Enclosure to RA-12-03853 

Page 6 of 17 

Accidents and Onboard Fatalities by Phase of Flight 

Hull Loss and/or Fatal Accidents- Worldwide Commercial Jet Fleet- 1994-2003 

Accidents 

Fatalities 

100 

Hull 80 

loss 

and/or 60 

fatal 

accidents40 

20 

16 

Taxi, 

load, 

parked Takeoff 

5% 12% 

0% 8% 

1% 

Taxi, load, Takeoff 

parked 

17% 

Initial 

climb 

5% 

14% 

22% 

1% 

• Hull loss and/or fatal accidents 

Percentage of accidents/fatalities 

Climb 

(flaps up) Cruise 

Initial 

Descent approach 

8% 6% 3% 

25% ~--------~12~~Yo~-----h_ 

I I 

Exposure = percentage of flight time 

based on flight duration of 1.5 hours 

14% 57% 

Distribution of accidents and fatalities 

1,619 

7% 

51% 

18% 

1% 

93 

Initial Final Landing 

approach approach 

D On board fatalities 

2000 

1500 

Fatalities 

1000 

500 

2003 STATISTICAL SUMMARY, MAY 2004 rti-BD'Ei'.NG 

Figure 1-2, Fatalities, Worldwide Commercial Jet Fleet -1994- 2003 
Enclosure to RA-12-03853 

Page 7 of 17 

Fatal Accidents and Onboard Fatalities by Phase of Flight 

Worldwide Commercial Jet Fleet- 2002 Through 2011 

1ft 

.-..., ,_, 

'FINI ~~ 

, ..... ..... C:lnll lnlllll 

taw r....,rr .. ,..,. .. , Cldle 0- .,,.,.c~~ .,.... t.IO't _._.. 11t. 10W. n. "' 11t. .... 14t. 1ft 20fo 

, ...... Ql, 111. "' 101a ..1... 221. 2'11 19'11 1ft 1ft 

1ft / t"""'" ·•E 

' 28'11. v -::lis 

nfllgN fou 1CJ~j 19\ 1411 e,'Jfl 

·Y-~ 11" 1 1~ • 111 flghQ 

..... ,, ...... _......,...,_lal!ftllldiW, 

Figure 1-3, Fatalities, Worldwide Commercial Jet Fleet- 2002- 2011 

Olbollll 

, ..... 

Figure 2 shows fatal accidents by category for the world commercial jet fleet for the period of 1992 

to 2001. Note for this period, of the 7,171 fatalities from all causes, none were due to hypoxia 

resulting from in-flight rapid decompression events at altitudes greater than 25,000 feet. Relative to 

other causes, decompressions resulting in hypoxic fatalities are not a significant accident contributor. 
2,500 

2,000 

~ 1,500 

"' .z 1,000 

500 

0 

Sources: 

Fatalities by Accident Categories 

Enclosure to RA-12-03853 

Page 8 of 17 

Fatal Accidents. World Commercial Jet Fleet -1992 Through 2001 

w Total fatalities 112001 fatalities 

Boeing Airplane Safety Engineering (ASE) and Safety Information System (SIS), National Transportation Safety Board (NTSB) 

Figure 2: Fatal Accidents by Category 

Additionally, an assessment of decompressions since the 200 I completion of the above study 

through 2011, confirmed there were tio additional fatalities due to hypoxia resulting from in-flight 

rapid decompression. There were 121 additional fatalities related to hypoxia from a single event; 

the Helios Airways Flight HCY522 accident which was not a decompression event, but a failure of 

the flight crew to properly configure the pressurization system and a subsequent failure to recognize 

that the aircraft was not pressurized after takeoff, Reference ( 15). There were no additional deaths or 

injuries resulting in permanent physiological harm and only two additional incidents were recorded 

as having resulted in minor barotrauma injuries. 

It should also be noted that very few rapid decompression events, if any, have exposed aircraft 

occupants to cabin pressure altitude profiles that run the risk of permanent harm to occupants. 

Industry experience shows that very few cases of decompressions at high altitude resulting in death 

or permanent physiological harm have occurred. The FAA cited 3 cases as examples of uncontained 

engine failure for consideration. In one case, a DC-I 0 (cruise flight near Albuquerque, New 

Mexico) reported several cases of initial decompression sickness apparently with no permanent 

injuries. However, it was noted that 24 passengers and crewmembers were brought to the hospital at 

Kirtland AFB for treatment of symptoms including, barotraumas (ear problems), minor abrasions, 

and smoke inhalation. Because there was no known follow-up on these occupants, there is no way 

to assess the extent of physiological injuries sustained during this decompression event. The NTSB 

report, (Reference (6), NTSB report NTSB-AAR-75-2) concluded that the rotor burst occurred due 

to the fact that "The flight crew (was), in effect, performing an untested failure analyses on the auto 

throttle system." In the second case (Sioux City, Iowa), the aircraft damage was aft of the pressure 

bulkhead, thus no rapid decompression occurred. The FAA cites this event to estimate the damage if 

the debris field had been forward of the pressure bulkhead. In the third case (Pensacola, Florida), the 

airplane was performing a takeoff (not cruise) when the event occurred and the flight deck crew 

successfully performed a rejected takeoff. Thus, this case did not encounter a rapid decompression. 

It should be noted that the FAA cited these three cases (Reference (7)) because they were "data rich" 
Enclosure to RA-12-03853 

Page 9 of 17 

events. In addition to the "data rich" events discussed above, there have been nine other uncontained 

engine failures at cruise identified to the FAA, Reference (8), however, none of these other events 

caused a cabin decompression. 

The events experienced to date as discussed above were associated with I st generation engine 

technology. Safety enhancement initiatives with respect to critical rotating parts (inspecting for 

cracks in disks and using continually updated maintenance data to refine disk inspection criteria), as 

well as improvement in engine technology, lessons learned, and 2nd /3rd generation engine design 

practices have resulted in a reduction in uncontained engine failure events. The uncontained engine 

failure rates of 211d/3rd generation engines compared to 1st generation engines has improved by 

approximately 95% based on historical Boeing data on uncontained engine failures. 

As noted previously regarding the three ''data rich events" (the Albuquerque, Sioux City, and 

Pensacola events), only the Albuquerque event resulted in a decompression. Furthermore, the 

Albuquerque event remains an inappropriate event as a "decompression'' model, particularly since 

the NTSB noted that "The flight crew was, in effect, performing an untested failure analyses on the 

autothrottle system" prior to the engine failure, Reference (6), NTSB repmi NTSB-AAR-75-2. 

Figure 3 depicts pressurization events by cause. Note that uncontained engine failure is an 

insignificant contributor to the total number of events. 

4.00E-06 

3.50E-06 

3.00E-06 

2.50E-06 

2.00E-06 

1.50E-06 

1.00E-06 

S.OOE-07 

O.OOE+OO 

Decompression Events by Cause 

$/ 

Pressurization Events per Hour and per Flight, by Cause 

jm # Ev/Hr • # Ev/Fit I 

Sources: Boeing Airplane Safety Engineering (ASE) and Safety Information System (SIS), National Transportation Safety Board (NTSB) 

Engine Events Are Rare Contributors To Decompression Events 

cp_-.OEI_G. 

Figure 3, Pressurization Events by Cause per Flight Hour 

Jn conjunction with the above data, it should be noted that very few decompression events exposed 

the aircraft occupants to cabin pressure altitude profiles which run the risk of permanent 

physiological harm. Figure 4 summarizes significant transport category decompression events 
Enclosure to RA-12-03853 

Page 10 of 17 

resulting in fatalities or incapacitation (in red). Note that while fatalities were incurred, none would 

have been prevented by the intent of§ 25.841 (a), Amendment 25-87 which was promulgated in 

large part to prevent death or permanent physiological harm from hypoxia as a result of a rapid 

decompression caused by a large hole in the pressure vessel from an uncontained engine failure. 

The only fatal event since this data was taken has been the previously discussed Helios event. 

Cl> 

'0 

.a 

;:; 

< 

c 

:c 

ro 

0 

E 

:I 

E 

';( 

ro 

== 

45,000 

40,000 

35,000 

30,000 

25,000 

20,000 

15,000 

10,000 

5,000 

0 

• 

• 

All Pressurization Events with associated 

Fatality, Incapacitation or Injury 

I• Fatality/Incapacitation • Injury! 

• • A lA 

• A. ••• • 

• • ... • • • '"': ... ...... -. • .... 

• 

• 

• 

• 

• 

0 5,000 10,000 15,000 20,000 25,000 30,000 35,000 40,000 45,000 50,000 

Event Altitude 

Figure 4: Pressurization Events with Fatality, Incapacitation or Injury 

Notes: A total of2866 pressurization events were reported between 1959-2001 on 

Transport Category Airplanes over 60,000 Jbs. 873 of these included Event 

Altitude and Cabin Altitude reports. 

Sources: Boeing Airplane Safety Engineering (ASE) and Safety Information System (SIS), 

National Transportation Safety Board (NTSB) 

Of the 18 events that resulted in fatalities, I 0 events were at cabin altitude exposures less than those 

altitudes addressed by§ 25.84l(a)(2), Amendment 25-87. In four of the remaining eight events, 

fatalities were due to injury directly attributed to the event rather than from hypoxia (one 

catastrophic structure loss, two engine failures, and one wheel burst). The remaining four events 

were attributed to crew error, un-annunciated loss of pressurization, and oxygen system failure. 

Current generation aircraft, (1980s through 2000s) introduced higher performance permitting higher 

altitude flight in response to the need for increased fuel efficiency and avoidance of increasingly 

crowded airspace at altitudes below 40,000 feet. The MSHWG report, Reference (3) concluded for 

the world commercial jet fleet for the period of 1992 to 2001, no hypoxia related fatalities were due 

to in-flight decompression events. This safety record has been maintained even as newer airplanes 

fly at these higher altitudes more often than older airplanes (see Figure 5). As stated previously, an 

assessment of decompressions since the 200 I completion of the above study through 20 II 

confirmed there were no additional fatalities or permanent physiological harm due to hypoxia 

resulting from in-flight rapid decompression, and only two additional incidents resulting in minor 
Enclosure to RA-12-03853 

Page 11 of 17 

barotrauma injuries. As discussed previously, the Helios Airways Flight HCY522 accident was not 

a decompression event, but a failure of the flight crew to properly configure the pressurization 

system and a subsequent failure to recognize that the aircraft was not pressurized after takeoff. 

Based on these facts, the MSHWG report conclusions remain valid. Three separate studies have 

recently been made to illustrate the extent of air traffic operations at high altitude in today's air 

traffic system. While today's numbers are significant, the new generation of airplanes as exemplified 

by the 787-9 are being designed to cruise at altitudes above 37,000 feet for even longer portions of 

their mission. 

Altitude Reports By Airplane Model 

FAA's Enhanced Traffic Management System (ETMS) Reports for U.S. 

Commercial Aircraft above 28,000 feet 

45% 

40% 0 

35% 

~ First Flight of Type Prior to 1980 ~ 

30% 

{! 25% 

0 

c. 

~ 20% 

15% 

10% 

5% 

f--

'--

0% 

'\<Y 

;- -

n rGi ..n 

• Data represents reports from one week in Sept. 2000 

• Based on position reports every 3 minutes. 

Iii! Above 40.000 ft [ 

0 Above 37,000 ft : 

;-

1-

rf--

1 I 1-n I r.n 

-

-

- -

- -

- 1--

- i--

- 1- - -

0 I I 

-

-

r-- '--

~ 

-

Figure 5: Frequency of Flights above 37,000 ft. and 40,000 ft. Altitude of New Design Aircraft 

vs. Older Design Aircraft. 

Aerospace Hypoxia Physiology Data 

The FAA, and other qualified experts agree that the severity of hypoxia exposure to rapid 

depressurization is determined by the pressure field and duration of the event. This is predicated on 

observations made from flight physiological and medical experiments. The cabin altitude limits in 

Amendment 25-87 were developed by the FAA based in pati on recommendations from the FAA's 

Civil Aeromedical Institute (CAM\), which were based on the concept of"Time of Safe 

Unconsciousness'· (TSU) documented by James G. Gawne in his 1970 paper. The study concluded 

with the statement that," ... a plea must be made for collection of better data." Gaume's 1970 paper 

is only one source in establishing safety basis. It should be understood that the proposed TSU 

criteria was established as a compensating consideration to the elimination of the passenger oxygen 

system. Today's commercial transport are required to provide an emergency oxygen system 

providing additional margin of safety. 
Enclosure to RA-12-03853 

Page 12 of 17 

The MSHWG agreed additional data based on further study would benefit the establishment of new 

standards. In lieu of new data the MSHWG established physiological exposure limits that are 

conservative with respect to the data available. The MSHWG considered the available physiological 

exposure research which included several papers that have been circulated in the aerospace medical 

community, all with the objective of establishing physiological limits to occupants following cabin 

decompression. lt was based on these papers, and consideration of the overall risk to decompression 

exposure that the MSHWG documented its recommendations in the Reference (3) TAEIG accepted 

report. The following are summaries of the reports from recognized Aerospace Medical Doctors 

addressing physiological information that was considered by the MSHWG: 

- James Gawne (Aerospace Medicine) authored a paper substantiating the new rule. 

According to Gawne, during an emergency descent from 42,000 feet to 5,000 feet for 

adequate recovery of unconscious passengers without any supplemental emergency 

oxygen to the occupants, with an aircraft emergency descent of 6200 feet per minute and 

with cabin altitude exceeding 33,000 feet, no more than I minute and 42 seconds is 

considered acceptable. Reference (9): "Factors Influencing the Time of Safe Unconsciousness (TSU) for Commercial Jet Passengers Following Cabin Decompression" 

by James Gawne, Aerospace Medicine, April 1970. 

- Dr. Stanley R. Mohler, a former director of CAM! (FAA's Civil Aeromedical Institute), 

analyzed a number of actual decompression cases, including data from studies by BaiTOn, 

Reference (I 0), and Gaume. He concluded that brain damage in the absence of oxygen 

starts after about four minutes, and that three minutes above 25,000 feet is a reasonable 

limit to protect against permanent physiological damage from a cabin decompression 

occurring at up to 45,000 feet. Reference (11 ): "Sudden High Altitude Cabin 

Decompression Immediately Threatens Safety of Aircraft Crew and Passengers" by Dr. 

Stanley Mohler, Flight Safety Foundation, Human Factors & Aviation Medicine, 

December 1994. 

- Dr. Robert Garner, Research Physiologist, Protection and Survival Laboratory at CAM!, 

agrees that limiting cabin altitude exposure to 25,000 feet for up to three minutes and 

never allowing it to exceed 45,000 feet would provide an acceptable level of safety. His 

views on this matter have been communicated to the FAA Transport Standards Staff. 

- Draft White paper issued by CAMJ - FAA Civil Aerospace Medical Altitude Rule: 

presented in the MSHWG in July 2002, Reference (12), Page 13, states that exposure: if 

unprotected, passengers to a 41,000 feet altitude would be approximately equal to 

exposure at a 40,000 feet altitude. 

- "Neurological Study of Simulated Decompression in Supersonic Transport Aircraft," 

Aerospace Medicine, .J.B. Brierley and A. N. Nicholson, August, 1969, Reference (13), 

concluded that cabin altitude exposure above I 0,000 feet not more than eight minutes up 

to peak of 36,000 feet does not cause brain damage. 

- "Neurological Sequelae of Prolonged Decompression," Aerospace Medicine, A. N. 

Nicholson and J .R. Ern sting, Apri I 1967, Reference (14) concluded that cabin altitude 
Enclosure to RA-12-03853 

Page 13 of 17 

exposure above 40,000 feet with time exposure of 1 minute and 30 seconds caused brain 

damage. 

In consideration of the above studies, comments received on the draft Interim Policy, and the 

acceptance of the MSHWG repoti by TAEIG, the FAA established appropriate criteria for 

§25.841 (a) with respect to an uncontained engine failure. These criteria are more conservative than 

those established by MSHWG report. In lieu of any other standard, Boeing will comply with these 

criteria as presented in the Proposed Risk Mitigation discussion provided later in this petition. 

Impacts of Compliance with the Uncontained Engine Failure Aspect of Rule 

The Boeing Company's 787-9 will fully comply with the latest airworthiness standards including 

§§25.841 (a)(2) and 25.841 (a)(3 ), Amendment 25-87 in all regards, except as related to an 

uncontained engine failure event as defined herein. 

With respect to uncontained engine failure events, the impact of §25.841 (a), Amendment 25-87 to 

the aviation industry and the flying public is significant. The "impact" of compliance takes three 

forms (1) economic which lead to (2) reduced potential for overall safety improvements and (3) 

environmental. 

(1) While it is difficult to place an exact dollar amount on the impact ofthese new 

requirements on the 787-9, it is clear that not granting the proposed exemption would have 

severe impact. This conclusion is based on the reduction in maximum cruise altitude that 

compliance with §§25.841(a)(2) and 25.841(a)(3), Amendment 25-87 as relates to 

uncontained engine failure would result in. This reduction in maximum cruise altitude would 

result in significantly higher operating costs, based on the significant increased fuel burn due 

to operations at altitudes not optimum for these airplanes. These higher costs will adversely 

impact the ability of the Boeing 787-9 to compete with previously certificated airplanes 

which can operate at the more economical cruise altitudes typically in excess of 37,000 feet. 

In addition, restricting airplane operations to lower altitudes will increase traffic congestion. 

Three separate studies have shown that the number of operations above 37,000 feet are 

significant today and the trend is for newer airplanes to cruise at these altitudes for even 

longer portions oftheir mission. Limiting operation of new generation airplanes to lower 

altitudes will result in higher traffic density, which in turn will result in higher cost of safety 

in order to maintain established air traffic vertical and horizontal separation requirements. 

(2) Since the release of Amendment 25-87, a number of amendments to 14 CFR 25 have 

been released. Each of these amendments has the intent of an increase in aviation safety. 

The Boeing 787-9 will meet the latest amendments in effect at the time of application, 

except as noted in the 787-9 Certification Basis. The net result is that the 787-9 incorporates 

the safety advancements as intended within these later amendments. Any significant impact 

to the marketability of the 787-9 will, at a minimum, result in a reduced number of aircraft 

with this higher level of safety as compared with the previous generation of aircraft, or at a 

maximum, preclude the manufacture of this new generation of aircraft. In either case, 

Amendment 25-87 results in a reduced potential for overall aviation safety improvements. 
Enclosure to RA-12-03853 

Page 14 of 17 

(3) As stated in (I) above, the restriction to maximum cruise altitude imposed upon the 787-9 

due to compliance with §§25.841 (a)(2) and 25.841 (a)(3), Amendment 25-87 as relates to 

uncontained engine failure has a significant adverse impact on 787-9 fuel burn. This 

additional fuel burn not only increases 787-9 operating costs, but will also increase engine 

emissions (e.g. C02). 

Proposed Risk Mitigation 

It is The Boeing Company assessment that the risk to safety which is attempted to be mitigated by 

the new rule §§ 25.841 (a)(2) and 25.841 (a)(3), creates unintended consequences. The existing fleet 

has demonstrated safe operations via millions of hours of flight at altitudes similar to those proposed 

for the 787-9. The risk of rapid depressurization following an uncontained engine failure is better 

mitigated by a combination of proven design practices established through years of airplane industry 

experience combined with today's improved technical capabilities. It is intended that the proposed 

risk mitigation measures augment this exemption request and address the intended concern for safety 

without the non-commensurate impacts driven by current requirements of §§25.841 (a)(2) and 

25.841 (a)(3). 

It must be reiterated that this request for exemption for §§25.841 (a)(2) and 25.841 (a)(3) is limited to 

only uncontained engine failures. For other sources of rapid depressurization, including system 

failures and specific structural failures §§25.841 (a)(2) and 25.841 (a)(3) will be complied with as 

amended by Amendment 25-87. All mechanical and/or functional interfaces that could potentially 

violate the physiological limits imposed by §25.841 (a) are considered. Robust structural and 

systems design, and the ability for the airplane to rapidly descend, are key to assuring the safety of 

airplane occupants and are an inherent part of the 787-9 design. The Boeing Company design 

practices refine the requirements into sub-requirements for systems, structures, aerodynamics, and 

performance in order to assure airplane level compliance. 

Other threat minimization philosophies employed in the 787-9 design include an automatic pressure 

demand mask (FAA approved for 45,000 feet) for the pilots which will be certified to § 25.1441 (d), 

separation and redundancy of key systems such as electrical power, passenger oxygen, cabin 

pressure control and spoiler actuation. 

The following more specifically addresses The Boeing Company proposed means of compliance for 

rapid depressurizations related to uncontained engine failures. Using the FAA established criteria 

(Reference (2)), The Boeing Company proposes to mitigate the risk to occupants from exposure to 

high cabin altitudes resulting from uncontained engine failure, in part, by implementing the 

following design requirements on the 787-9 airplane: 

• Design Requirement 

The airplane must be designed so that occupants will not be exposed to a cabin pressure 

altitude that exceeds the following after decompression from any engine failure condition 

not shown to be extremely improbable: 

(i) Forty-five thousand (45,000)feetfor any duration; or 

(ii) Forty thousand (40.000)feetfor one minute: or 

(iii) Twenty:five thousand (25, 000) feet for more than three minutes; or 
(iv) Ten thousand (1 0, 000) feet for more than six minutes. 

Enclosure to RA-12-03853 

Page 15 of 17 

In calculating the descent capability of the airplane in order to meet the cabin altitude requirements, 

the loss of the failed engine's contribution as a source of power to the systems enabling the descent 

need be considered. (i.e. If losing power on one engine results in loss of a hydraulic system, and that 

in turn reduces the number of spoilers that are available, the descent rate must be based on the 

capabilities of the degraded system.) Systems degradation due to debris damage from an 

Uncontained Engine Failure need not be considered. The 787-9 aircraft descent profile will be 

generated by analysis based on 787-8 flight test airplane descent performance data, and data 

establishing equivalency of the 787-8 and 787-9 emergency descent capabilities. 

References 

I) Amendment 25-87 Final Rule, Docket 26070, Federal Register Volume 61, Number I 09, 

June 5, 1996 

2) FAA Interim Policy, ANM-03-112-16, Subject: INFORMATION: Interim Policy on 

Amendment 25-87 Requirements FR Doc. 03-13541, Issued May 15, 2003 

3) Mechanical Systems Harmonization Working Group (MSHWG) Final Report on FAR 

25.841 (a)(2,3), dated August 2003, submitted to FAA October 21, 2003 

4) Statistical Summary of Commercial Jet Airplane Accidents, Worldwide Operations, 

1959-2002, Published by Boeing Commercial Airplane, May, 2003 

5) Statistical Summary of Commercial Jet Airplane Accidents, Worldwide Operations, 

1959-2003, Published by Boeing Commercial Airplane, May, 2004 

6) NTSB-AAR-75-2, AIRCRAFT ACCIDENT NATIONAL AIRLINES, JNC.,DC-10-10, 

N60NA NEAR ALBUQUERQUE, NEW MEXICO, November 3,1973 

7) Uncontained Engine Failure Fuselage Hole Analysis, Draft Technical Note, October 200 I 

8) Uncontained Engine Damage Database, ACCESS 2000 Database, FAA UED v001, June 

10,2002 

9) Factors influencing the time of Safe Unconsciousness (TSU) for commercial passengers 

Following Cabin Decompression, Gamne, J., 1970. Aerospace Medicine, April 1970, 

382-385 

10) Barron, C. and Cook, T., Effects of Variable. Decompressions to 45000 feet, Aerospace 

Medicine, May 1965, 425.430 

11) Mohler, Dr. Stanley, "Sudden High Altitude Cabin Decompression Immediately 

Threatens Safety of Aircraft Crew and Passengers," Flight Safety Foundation, Human 

Factors & Aviation Medicine, December 1994 

12) Draft White paper issued by CAMI- FAA Civil Aerospace Medical Altitude Rule: 

presented in the MSHWG in July 2002 

13) "Neurological Study of Simulated Decompression in Supersonic Transport Aircraft,'' 

Aerospace Medicine, J.B. Brierley and A.N. Nicholson, August, 1969 

14) "Neurological Sequelae of Prolonged Decompression,'' Aerospace Medicine, A.N. 

Nicholson and J.R. Ernsting, April 1967 

15) Hellenic Republic Ministry of Transport & Communications, AAIASB Aircraft Accident 

Report, Helios Airways Flight HCY522, Boeing 737-31S At Grammatiko,.Hellas on 14 

August 2005, Dated 11/2006 
Enclosure to RA~12-03853 

Page 16 of 17 

16) Statistical Summary of Commercial Jet Airplane Accidents, Worldwide Operations, 

1959-2011, To be published by Boeing Commercial Airplane 

Statement of Public Interest 

The Boeing Company Model 787-9 fully complies with the latest airworthiness standards including 

§§25.84l(a)(2) and 25.84l(a)(3), Amendment 25-87 in all regards, except as related to an 

uncontained engine failure event as defined herein. Specific features have been incorporated into the 

787-9 design to mitigate the safety risk to occupants due to a decompression resulting from an 

uncontained engine failure. Improvements in engine technology, application of lessons learned, and 

2nd 13rct generation engine design practices have resulted in a reduction in uncontained engine failure 

events and the risk of a rapid depressurization. As stated above, the Boeing 787-9 will meet all the 

latest amendments in effect at the time of application. The net result is that the 787-9 incorporates 

all the safety advancements as intended within these later amendments. The 787-9, therefore, offers . 

a higher level of safety than do previously certificated transport category airplanes. 

In addition, the 787-9 will provide industry-leading operating economics, and environmental 

improvements. Granting this petition of exemption is in the public interest because it will improve 

safety relative to previously ce1tificated airplanes, while reducing operational costs by reducing the 

amount of fuel consumed. The cost of maintaining the level of safety within the existing air traffic 

management system will not be adversely impacted by continuing to allow operation in the less 

congested altitudes typically well above 37,000 feet. The reduction in fuel consumed will also result 

in reduced emissions. These benefits will accrue with no decrease in safety. 

(e) Statement of No Adverse Effect on Safety 

The exemption requested will not adversely affect safety. As previously discussed, the 787-9 

complies with §25.841 (a) in all other aspects of a rapid depressurization. In the unlikely event of an 

uncontained engine failure, the 787-9 preserves an even higher level of safety relative to previously 

ce11ificated airplanes due to its higher descent capability and other design features. As concluded 

herein, and based on the MSHWG report, the world commercial jet fleet has had no hypoxia related 

fatalities due to in-flight decompression events caused by an uncontained engine failure. This safety 

record has been maintained even as newer airplanes fly at higher altitudes more often than older 

airplanes. In keeping with time-above-altitude FAA guidance and the recommendations of the 

MSHWG repmt, as adopted by TAIEG, Boeing has incorporated design features that appropriately 

address the risk to safety following an uncontained engine failure. Therefore, granting of the 

exemption will not compromise safety to the airplane occupants. 

(f) Request to 'Waive Publication and Comment' 

Boeing requests to waive the requirement for publication and comment based on similar exemptions 

granted to the following aircraft: 787-8, 747-8, 747-8F, A380, ERJ 170, and ER.J 190. 

The 787-9 is a stretch derivative of the 787-8. The 787-9 aircraft differences that affect compliance 

to §§25.841 (a)(2) and 25.841 (a)(3) are: 
Enclosure to RA-12-03853 

Page 17 of 17 

The lengthened fuselage sections use similar design and construction techniques as the 787-

8. The lengthened fuselage increases the pressurized volume for the 787-9. 

The 787-9 design weight will be increased approximately 10% relative to the 787-8. This 

increased design weight will have an effect on the aircraft's emergency descent performance. 

The 787-9 engine thrust is increased relative to the 787-8 via revised ratings, as these engines 

were designed to accommodate 787-9 thrust requirements. The increased thrust will have an 

effect on the aircraft's emergency descent performance. 

Although these differences between the 787-8 and the 787-9 have an effect on showing compliance 

to §§25 .841 (a)(2) and 25.841 (a)(3 ), they do not change the rationale for granting the 787-9 an 

exemption similar to the 787-8 and other aircraft. 

(g) Privileges of the Exemption Outside the United States 

Per 14 CFR 11.81(h), Boeing requests that the privileges ofthis exemption be extended outside the 

United States. This extension of privileges is necessary for operations based within foreign countries 

having bilateral agreements with the United States accepting FAA 14 CFR part 25 as their 

airworthiness standards for transp01i category aircraft. The 787-9 is intended for the global market 

place. 

(h) Conclusion 

The information in this petition for exemption provides evidence that compliance with §§ 

25.841 (a)(2), and 25.841 (a)(3), with respect to an uncontained engine failure, provides no increase in 

safety. The 787-9 provides advancements in technology and safety relative to previously certified 

aircraft. Grant of this petition provides the public the benefits of the 787-9 airplane. Operators will 

be able to operate the 787-9 where it is most efficient and therefore will not face higher operating 

costs due to increased fuel burn. FUiiher more, reduced fuel burn will lead to lower engine 

emissions resulting in positive impact to the environment. By granting this petition for exemption 

the true benefits of787-9 will be realized, causing no adverse effect on safety. 

(i) Summary to be Published in the Federal Register 

PETITIONER: Boeing Commercial Airplanes 

SECTION OF 14 CFR AFFECTED: 14 CFR 25.841 (a)(2)(3) 

DESCRIPTION OF RELIEF SOUGHT: To allow relief from the requirements pertaining to 

cabin decompression following certain extremely rare uncontained engine failures for the Boeing 

Model 787-9.