# SEP - 72012 RA-12-03853 U.S. Department ofTransportation DocketOperations, M-30 1200NewJerseyAvenue, S.E. JohnA. Hamilton Lead Administrator Regulatory Administration Commercial Airplanes



### RoomW12-140, WestBldg. GroundFloor 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 I0 

## P I: 2 b

Subject: Petitionfor Exemptionfrom Title 14 Code ofFederalRegulations Section25.841(a)(2) and (a)(3) atAmendment 87 withRespectto Uncontained Engine Failure · 

### Model: 787-9

TheBoeing Companyrespectfully submitsthis petition for exemptionfrom Title· 14 Code ofFederalRegulations Section25.841(a)(2) and (a)(3) at Amendment 87 for the 787-9 as described inthe summary below. The enclosureto this letter provides the details ofthepetitionin accordance withTitle 14.Code ofF ederal· Regulations Section 11.81. The following summary is providedfor the Federal Registerin accordance with Title 14 code offederalRegulations Section 11.81(f). 

### SummaryforFederalRegister Petitioner: The Boeing Company. Sectionof14 CFRAffected: Section25.841(a)(2)(3) Description ofReliefBeing Sought: Boeingis requesting relieffrom the requirements ofTitle 14 Code ofFedetal Regulations Section25.84l(a)(2) and (a)(3) pertainingto cabin decompression
·following certain extremelyrare uncontained engine failures forthe Boeing Model 787-9. Ifgranted, this·exemption will allow operators the ability to operate the 787-9 where itismostefficientandtherefore not face higheroperatingcosts due.

## to increasedfueLbum. Furthermore, reduced fuel burnwillleadto lower engine emissions resulting ina positive impactto the environment. By granting thispetitionfor exemptionthe true benefits ofthe 787-9 will berealized, causing no adverse effect on safety.

# ~DEI.NG Page2 RA-12-03853

Sincerely,

# ;ZM~~rr Director, RegulatoryAdministration DeputyLeadAdministrator (425) 237-1383, MC03-52 FAX: (425) 294-9340 Enclosure: Petition for Exemption from 14 CFR25.841,Amendment 87

cc Name Ken Schroer DougTsuji Letter Paper/SP SP Enclosures SP SP Comments ANM-106B· ANM-106B

### Petition for Exemption from 14 CFR25.841, Amendment25-87 Enclosure to RA-12-03853 Page1 of17



### (a) Name and Address ofthe Petitioner Doug Lane, Director, Regulatory Administration Deputy Lead Administrator The Boeing Company PO Box 3707 Seattle, Washington, 98124 

### (b) Section(s) oftheRegulations from which Reliefis Sought:

(c 25.84l(a)(2) and 25.841(a)(3) With Respectto Uncontained Engine Failures. 

### §25.841 (a)(2) The airplane mustbe designed so that occupants will not be exposed to a cabin pressure altitude that exceedsthe 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 evaluatingthe cabin decompression.


### ) The Extent ofReliefSought and Reason(s)

Regulation Requires: Reliefis 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 ofthe 787-9 in the aircraft marketplace



### (d) Description ofIssue The 787-9 aircraft is beingdesigned to operate at a maximum cruise altitude of43,100 ft. Amendment 25-87, Reference (1), established newrequirements in 

### § 25.841(a) intended to·upgrade the airplane and equipmentairworthiness standards for subsonic transport airplanes operated above 40,000 feet. These were based in parton special conditionsthat had been used on type ce1iificationEnclosure to RA-12-03853 Page 2 of 17

ofexecutive 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 mustbe designed so that occupants will not be exposed to a cabin pressure altitude that exceedsthe following after decompression from any failure condition not shown to be extremely improbable: (i) Twenty-fivethousand,(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 ofan uncontained engine failure, provides no increase in safety with respect to modern transport categoryjetaircraft when considering the safety record ofthe fleet overthe last 53 years. The fleet has a demonstrated safety record with miI!ions of hours at altitudes similarto the maximum cruise altitude proposed for the 787-9. Despite the improved descent capability ofthe 787-9 overpreviously certificated aircraft ofsimilarcategory 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 ofthe §25.841(a), Amendment 87, impact on overall fleet safety raised concerns about several unintended consequences. One such consequence is higher density airtraffic at altitudes below 40,000 feet as a result oflimiting new aircraft with wing mounted engines to altitudes below 40,000 feet. This may result in additional costto maintain an adequate level ofsafety for the airtraffic 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 impactthe marketability ofthe 787-9. This concern is shared by other manufacturers ofairplanes with wing-mounted engines seeking new oramended 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 efficienttransportation option for airlines and airline passengers. Grant ofthis petition provides the public the benefits ofthe 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 concernEnclosure to RA-12-03853 Page 3 of 17

for safety without imposingthe 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 ofthe current rule and activities to harmonize it • a review ofthe safety history ofhigh altitude commercial flight • a discussion ofhypoxia physiology dataupon which rulemaking activities are based • a discussion ofthe impact ofcompliance with uncontained engine rotor burst aspects of existing rule, as related to economics, environmental, and airtraffic considerations. • proposed risk mitigation • statements addressing public interest and no adverse impactto safety. 

### Background on 14 CFR §

### 25.84l(a)(2)(3), Amendment 25-87 Amendment25-87to§ 25.84l(a) was made effective July 5, 1996. The focus ofthe rule wasto codify the special conditions formerly used in the certification ofhigh altitude operation, generally applied to general aviation and transport category businessjets covering operation up to 51 ,000 feet. This section was changed without beingharmonized with the Joint Aviation Authorities (JAA) or now the European Aviation Safety Agency (EASA). Itis noteworthy thatthe .JAA and EASA have not adopted the same regulations as levied in 14 CFR §25.84l(a) as promulgated in Amendment25- 87 and lists §25.841(a) as a significantdifference for concurrentFAAI.JAA or F AA/EASA cetiification programs. The JAA INT/POL/25/16, Issue 1, Date: 01.06.03, "Airworthiness Standards for Subsonic Transport Aeroplanes to be operated above an altitude of41 ,000 ft," states, with respect to evaluation ofengine rotor burst, "It is JAA opinion thatturbine engine installations failures should be assessed against the specific requirement ofJAR 25.903(d) and should not be part ofthe present Special Conditions, this is to allow a consistent approach atthe aircraft level

..." The provisions of§§25.841 (a)(2) and 25.841(a)(3) ofAmendment 25-87 effectively limit new transport category airplanes with wing-mounted engines to operating altitudes well below40,000 feet. This has majorcost 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), Amendment25- 87 as patioftheir 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 ofAerospace 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 Circular25-20. It was suggested thatthe proposed amendment be addressed through the auspices ofthe Aviation Rulemaking Advisory Committee (ARAC). The petitioners recommended that hannonization with the JointAirworthiness Requirements and Transport Canada's standards be accomplished simultaneously through the ARAC · process. The petitioners represented the manufacturers oftransportcategory 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 CFRPart 25 as amended at Amendment25-87 will have significantly higher design and operating coststhan currently certificated airplanes, with no measurable increase in safety. These higher costs, impactthe ability ofmanufacturersto develop new airplanes thatcan compete with previously approved airplanes. The petitioners also identifiedthatthe economicEnclosure 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 whetherthe new requirement itselfcould be met by any practical means for any new orderivative airplane.
In July 2001, the FAA assigned the ARAC and the Mechanical Systems Harmonization Working Group (MSHWG)the task ofaddressing various concerns with the regulation, raised by industry, and ofreaching a consensus among medical experts, representatives from the FAA, JAA, Air TransportAssociation (ATA), ALPA, AFA and AircraftManufacturers (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 ofan FAA Draft Interim Policy, published in the Federal Register, June 2003, Reference (2) is consistentwith this position, as is the MSHWG working group repoti, Reference (3), which identified the existing requirements as being conservative relative to safety. In consideration ofcomments received on the draft Interim Policy and the acceptance ofthe 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 consistentwith those criteria and similarto 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 ofensuringthat no fatalities or permanent physiological harm occurred following a rapid depressurization event. However, the MSHWG believed that there is an inherent riskto occupant health and safety associated with any rapid depressurization event. The MSHWG concluded that all occupants are at some level ofrisk during a decompression event and the resulting emergency descent, flight, and landing. Fatalities may occurduring the initial event (i.e., from impact ofuncontained engine debris orfrom being ejected from the airplane). In addition, some cases ofpermanent 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 otherrisksto safety. Previously certificated large transp01i aircraft incorporating established design practices have safely operated at altitudes in excess of40,000 feet for more than 30 years, representing many millions of flight hours. Historically, relatively few accidents or incidents have occurred during cruise. Accordingto the statistics, for the period 1959

- 1996, only 6.8 percent ofaccidents in the worldwide commercial fleet history have occurred during cruise; even though the highest percentage ofthe flight time (57%) is at cruise (Reference (4)). See Figure 1-1. More recent statistics, show only 6.0 percent ofaccidents have occurred during cruise for the period 1994- 2003, (Reference (5)) and 11 percent ofaccidents have occurred during cruise for the period 2002- 20II (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 1.5hours 18.3% Percentage offatalities Cruise Load, Takeoff lnttial Climb 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 offlight time 4,578



### Figure 1-1, Fatalities, Worldwide CommercialJet Fleet -1959- 1996Enclosure 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/orfatal accidents Percentage ofaccidents/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 ofaccidents and fatalities 1,619 7% 51%

18%

1%

93

Initial Final Landing approach approach D Onboardfatalities 2000

1500

Fatalities 1000

500

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

### Figure 1-2, Fatalities,Worldwide CommercialJetFleet-1994- 2003Enclosure to RA-12-03853 Page 7 of 17


## FatalAccidentsand Onboard Fatalitiesby 

## Phase of Flight WorldwideCommercial

### Jet Fleet- 2002 Through2011
1ft 

# .-..., ,_, 'FINI**~~** 

# , 

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# "' 101a ..1... 221. 2'11 19'11 1ft 1ft 1ft 

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Figure 

### 1-3, Fatalities,Worldwide CommercialJetFleet- 

### 2002- 2011 Olbollll 

# , 

# .....

Figure 2 shows fatal accidents by category for the world commercialjetfleet for the period of 1992 to 2001. Note for this period, ofthe 7,171 fatalities from all causes, none were due to hypoxia resulting from in-flight rapid decompression events at altitudes greaterthan 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) 

### Figure2: FatalAccidents by 

### Category Additionally, an assessment ofdecompressions since the 200I completion ofthe 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 crewto 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 permanentphysiological 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, ifany, have exposed aircraft occupantsto cabin pressure altitude profiles that run the risk ofpermanent harm to occupants. Industry experience shows thatvery few cases ofdecompressions at high altitude resulting in death orpermanent physiological harm have occurred. The FAA cited 3 cases as examples ofuncontained engine failure for consideration. In one case, a DC-I0 (cruise flight near Albuquerque, New Mexico) reported several cases ofinitial 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 ofsymptoms including, barotraumas (earproblems), minor abrasions, and smoke inhalation. Because there was no known follow-up on these occupants, there is no way to assess the extentofphysiological injuries sustained during this decompression event. TheNTSB report, (Reference (6), NTSB report NTSB-AAR-75-2) concluded thatthe 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 ofthe pressure bulkhead, thus no rapid decompression occurred. The FAA cites this eventto estimate the damage if the debris field had been forward ofthe 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 thatthe 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 ofthese otherevents caused a cabin decompression. The events experienced to date as discussed above were associated with Ist 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 of211d/3rd generation engines comparedto 1st generation engines has improved by approximately 95% based on historical Boeing data on uncontained engine failures. As noted previously regarding the three ''datarich events" (the Albuquerque, Sioux City, and Pensacola events), only the Albuquerque eventresulted in a decompression. Furthermore, the Albuquerque event remains an inappropriate event as a "decompression'' model, particularly since the NTSB noted that "The flight crewwas, in effect, performing an untested failure analyses on the autothrottle system" priorto the engine failure, Reference (6), NTSB repmiNTSB-AAR-75-2. Figure 3 depicts pressurization events by cause. Notethat uncontained engine failure is an insignificant contributorto the total number ofevents.

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. Figure3, Pressurization Events by

### CauseperFlightHour 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 ofpermanent physiological harm. Figure 4 summarizes significanttransport category decompression eventsEnclosure to RA-12-03853 Page 10 of 17
resulting in fatalities orincapacitation (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 preventdeath or permanentphysiological harm from hypoxia as a result ofa 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 

### Figure4: Pressurization Events with Fatality,Incapacitation orInjury
Notes: A total of2866 pressurization events were reported between 1959-2001 on Transport Category Airplanes over 60,000 Jbs. 873 ofthese included Event Altitude and Cabin Altitude reports. Sources: Boeing Airplane Safety Engineering (ASE) and Safety Information System (SIS), National Transportation Safety Board (NTSB) Ofthe 18 eventsthat resulted in fatalities, I0 events were at cabin altitude exposures less than those altitudes addressed by§ 25.84l(a)(2), Amendment 25-87. In four ofthe 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 crewerror, un-annunciated loss ofpressurization, 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 ofincreasingly crowded airspace at altitudes below 40,000 feet. The MSHWG report, Reference (3) concluded for the world commercialjetfleet 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 atthese higher altitudes more often than older airplanes (see Figure 5). As stated previously, an assessment ofdecompressions since the 200I completion ofthe above study through 20II confirmed there were no additional fatalities orpermanent physiological harm due to hypoxia resulting from in-flightrapid decompression, and only two additional incidents resulting in minorEnclosure to RA-12-03853 Page 11 of 17

barotrauma injuries. As discussed previously, the Helios Airways Flight HCY522 accidentwas not a decompression event, but a failure ofthe flight crewto properly configure the pressurization system and a subsequent failure to recognize that the aircraft was not pressurized aftertakeoff. Based on these facts, the MSHWG report conclusions remain valid. Three separate studies have recently been made to illustratethe extent ofair traffic operations at high altitude in today's air traffic system. While today's numbers are significant, the new generation ofairplanes as exemplified by the 787-9 are beingdesigned 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 ofType 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 40.000ft [ 0 Above 37,000ft :

;-

1-


### rf--



# I 1 1- 

# n Ir.n 

### -

-



## -

-



## - -



## - 1--



## - i--



## - 1- 

## - -

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# I -

-

r-- '--**~**



## -

Figure 5: FrequencyofFlights above 37,000 ft. and 40,000 ft. Altitude ofNew Design Aircraft vs. OlderDesign Aircraft.
Aerospace Hypoxia Physiology Data The FAA, and otherqualified experts agree thatthe severity ofhypoxia exposure to rapid depressurization is determined by the pressure field and duration ofthe 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 pation recommendations from the FAA's Civil Aeromedical Institute (CAM\), which were based on the conceptof"Time ofSafe 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 ofbetter data." Gaume's 1970 paper is only one source in establishing safety basis. Itshould be understood that the proposed TSU criteria was established as a compensating consideration to the elimination ofthepassengeroxygen system. Today's commercial transport are required to provide an emergency oxygen system providing additional margin ofsafety.Enclosure to RA-12-03853 Page 12 of 17

The MSHWG agreed additional data based on further study would benefitthe establishmentofnew standards. In lieu ofnew data the MSHWGestablished physiological exposure limits that are conservative with respectto the data available. The MSHWG considered the available physiological exposure research which included several papersthat have been circulated in the aerospace medical community, all with the objective ofestablishing physiological limits to occupants following cabin decompression. ltwas based on these papers, and consideration ofthe overall risk to decompression exposurethatthe MSHWG documented its recommendations in the Reference (3) TAEIG accepted report. The following are summaries ofthe reports from recognized Aerospace Medical Doctors addressing physiological information that was considered by the MSHWG:

- James Gawne (Aerospace Medicine) authored a paper substantiatingthe new rule. According to Gawne, during an emergency descent from 42,000 feet to 5,000 feet for adequate recovery ofunconscious passengers without any supplemental emergency oxygen to the occupants, with an aircraft emergency descent of6200 feet perminute 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 ofSafe Unconsciousness (TSU) for Commercial Jet Passengers Following Cabin Decompression" by James Gawne, Aerospace Medicine, April 1970.

- Dr. Stanley R. Mohler, a former director ofCAM! (FAA's Civil Aeromedical Institute), analyzed a number ofactual decompression cases, including data from studies by BaiTOn, Reference (I0), and Gaume. He concluded that brain damage in the absence ofoxygen 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 ofAircraft Crew and Passengers" by Dr. Stanley Mohler, Flight Safety Foundation, HumanFactors & 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 ofsafety. 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 ofSimulated Decompression in Supersonic TransportAircraft," Aerospace Medicine, .J.B. Brierley and A. N. Nicholson, August, 1969, Reference (13), concluded that cabin altitude exposure above I0,000 feet not more than eight minutes up to peak of36,000 feet does not cause brain damage.

- "Neurological Sequelae ofProlonged Decompression," Aerospace Medicine, A. N. Nicholson and J.R. Ernsting, ApriI 1967, Reference (14) concluded that cabin altitudeEnclosure 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 ofthe above studies, comments received on the draft Interim Policy, and the acceptance ofthe 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 ofany other standard, Boeing will comply with these criteria as presented in the Proposed Risk Mitigation discussion provided later in this petition.


### Impacts ofCompliancewith the Uncontained EngineFailureAspect ofRule 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" ofcompliancetakesthree 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 clearthat not grantingthe 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 impactthe ability ofthe Boeing 787-9to compete with previously certificated airplanes which can operate at the more economical cruise altitudes typically in excess of37,000 feet. In addition, restricting airplane operationsto lower altitudes will increase traffic congestion. Three separate studieshave shown that the number ofoperations above 37,000 feet are significanttoday and the trend is for newer airplanes to cruise atthese altitudes for even longerportions oftheirmission. Limiting operation ofnew generation airplanes to lower altitudes will result in highertraffic density, which in turn will result in higher cost ofsafety in orderto maintain established airtraffic vertical and horizontal separation requirements. (2) Since the release ofAmendment25-87, a number ofamendments to 14 CFR 25 have been released. Each ofthese amendments has the intent ofan increase in aviation safety. The Boeing 787-9 will meetthe latest amendments in effect atthe time ofapplication, except as noted in the 787-9 Certification Basis. The net result is thatthe 787-9 incorporates the safety advancements as intended within these later amendments. Any significant impact to the marketability ofthe 787-9 will, at a minimum, result in a reduced number ofaircraft with this higher level ofsafety as compared with the previous generation ofaircraft, or at a maximum, preclude the manufacture ofthis new generation ofaircraft. In eithercase, 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, butwill also increase engine emissions (e.g. C02). 

### Proposed Risk Mitigation Itis The Boeing Company assessmentthat 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 ofhours offlight at altitudes similarto those proposed for the 787-9. The risk ofrapid depressurization following an uncontained engine failure is better mitigatedby a combination ofproven design practices established through years ofairplane industry experience combined with today's improved technical capabilities. It is intended that the proposed risk mitigation measures augmentthis exemption request and address the intended concern for safety withoutthe 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. Forother sources ofrapid 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/orfunctional 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 partofthe 787-9 design. The Boeing Company design practices refine the requirements into sub-requirements for systems, structures, aerodynamics, and performance in orderto assure airplane level compliance. Otherthreat 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 ofkey systems such as electrical power, passengeroxygen, cabin pressure control and spoiler actuation. The following more specifically addresses The Boeing Company proposed means ofcompliance for rapid depressurizations related to uncontained engine failures. Using the FAA established criteria (Reference (2)), The Boeing Company proposes to mitigate the riskto 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 designedso that occupants willnotbe exposedto a cabinpressure altitude thatexceeds thefollowing after decompression from anyenginefailure condition notshown to be extremely improbable: (i) 

### Forty-five thousand(45,000)feetfor anyduration; 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)feetfor more than sixminutes. Enclosure to RA-12-03853 Page 15 of 17

In calculating the descent capability ofthe airplane in orderto meetthe cabin altitude requirements, the loss ofthe failed engine's contribution as a source ofpowerto the systems enablingthe descent need be considered. (i.e. Iflosing power on one engine results in loss ofa hydraulic system, and that in turn reduces the number ofspoilers that are available, the descent rate must be based on the capabilities ofthe degraded system.) Systems degradation due to debris damage from an Uncontained Engine Failure need not be considered. The 787-9 aircraft descentprofile will be generated by analysis based on 787-8 flight test airplane descentperformance data, and data establishing equivalency ofthe 787-8 and 787-9 emergency descent capabilities.



### References I) Amendment 25-87 Final Rule, Docket 26070, Federal Register Volume 61, Number I09, June 5, 1996 2) FAA Interim Policy, ANM-03-112-16, Subject: INFORMATION: Interim Policy on Amendment 25-87 Requirements FRDoc. 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 ofCommercial Jet Airplane Accidents, Worldwide Operations, 1959-2002, Published by Boeing Commercial Airplane, May, 2003 5) Statistical Summary ofCommercial Jet Airplane Accidents, Worldwide Operations, 1959-2003, Published by Boeing Commercial Airplane, May, 2004 6) NTSB-AAR-75-2, AIRCRAFT ACCIDENTNATIONAL AIRLINES, JNC.,DC-10-10, N60NA NEAR ALBUQUERQUE, NEW MEXICO, November 3,1973 7) Uncontained Engine Failure Fuselage Hole Analysis, Draft Technical Note, October200I 8) Uncontained Engine Damage Database, ACCESS 2000 Database, FAA UED v001, June 10,2002 9) Factors influencing the time ofSafe Unconsciousness (TSU) for commercial passengers Following Cabin Decompression, Gamne, J., 1970. Aerospace Medicine, April 1970, 382-385 10)Barron, C. and Cook, T., Effects ofVariable. Decompressions to 45000 feet, Aerospace Medicine, May 1965, 425.430 11) Mohler, Dr. Stanley, "Sudden High Altitude Cabin Decompression Immediately Threatens Safety ofAircraft 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 ofSimulated Decompression in Supersonic Transport Aircraft,'' Aerospace Medicine, J.B. Brierley and A.N. Nicholson, August, 1969 14) "Neurological Sequelae ofProlonged Decompression,'' Aerospace Medicine, A.N. Nicholson and J.R. Ernsting, April 1967 15) Hellenic Republic Ministry ofTransport & Communications, AAIASB Aircraft Accident Report, Helios Airways Flight HCY522, Boeing 737-31S At Grammatiko,.Hellas on 14 August 2005, Dated 11/2006Enclosure to**RA~12-03853** Page 16 of 17
16)Statistical Summary ofCommercial Jet Airplane Accidents, Worldwide Operations, 1959-2011, To be published by Boeing Commercial Airplane



### StatementofPublicInterest 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 riskto occupants due to a decompression resulting from an uncontained engine failure. Improvements in engine technology, application oflessons learned, and 2nd 13rct generation engine design practices have resulted in a reduction in uncontained engine failure events and the risk ofa rapid depressurization. As stated above, the Boeing 787-9 will meet all the latest amendments in effect at the time ofapplication. 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 ofsafety than do previously certificated transport category airplanes.
In addition, the 787-9 will provide industry-leading operating economics, and environmental improvements. Granting this petition ofexemption is in the public interest because it will improve safety relative to previously ce1tificated airplanes, while reducing operational costs by reducing the amount offuel consumed. The cost ofmaintaining the level ofsafety within the existing airtraffic management system will not be adversely impacted by continuingto 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) StatementofNo AdverseEffect 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 ofa rapid depressurization. In the unlikely event ofan uncontained engine failure, the 787-9 preserves an even higher level ofsafety 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 commercialjetfleet 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 ofthe 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 ofthe exemption will not compromise safety to the airplane occupants. 

### (f) Requestto 'WaivePublication and Comment' Boeing requests to waive the requirement for publication and comment based on similarexemptions 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 ofthe 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 enginethrust 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 descentperformance. Although these differences between the 787-8 and the 787-9 have an effecton showing compliance to §§25.841 (a)(2) and 25.841(a)(3), they do not change the rationale for grantingthe 787-9 an exemption similarto the 787-8 and other aircraft. (g) 

### Privileges ofthe Exemption Outside the United States Per 14 CFR 11.81(h), Boeing requests thatthe privileges ofthis exemption be extended outsidethe United States. This extension ofprivileges is necessary for operations based within foreign countries having bilateral agreements with the United States accepting FAA 14 CFRpart 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 evidencethatcompliance 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 ofthis petition provides the publicthe benefits ofthe 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 grantingthis 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 CFRAFFECTED: 14 CFR 25.841 (a)(2)(3) 

### DESCRIPTION OF RELIEF SOUGHT: To allow relieffrom the requirements pertaining to cabin decompression following certain extremely rare uncontained engine failures for the Boeing Model 787-9.