# ~OEING John A. Hamilton Lead Administrator Regulatory Administration Commercial Airplanes The Boeing Company P.O. Box 3707 MC 03-56 Seattle, WA 98124-2207



## MAR -4 2013

RA-13-00845 U.S. Department ofTransportation Docket Operations West Building Ground Floor, Room W 12-140 1200 New Jersey Avenue, S.E. Washington, D.C. 20590
Subject:

Model: RA Project No.: EASA ProjectNo.: EASA Level: Branch/Panel No.: Branch/Panel Name: Response Due: Reference(s): Special Instructions:
This letter is to submit: Petition for Exemption from 14 CFR 25.841 (a)(2) and (a)(3), Pressurized CabinsUncontained Engine Failure 767-2C PS09-0863 N/A N/A ANM-106B Certification Services June 4, 2013 (a) PS-ANM-03-112-16, Interim Policy on High Altitude Cabin Decompression N/A

(X) Petition for Exemption This letter is being sent for: (X) Posting to the Federal Docket ;,.,.,.,\

j 

### en 

### J>

.(J'j

The Boeing Company hereby petitions for an exemption for relieffrom 14 CFR 25.84I(a)(2) and (a)(3), as amended by Amendment 25-87, with respect to uncontained engine failure. This petition is made in accordance with the reference (a) FAA Policy. Waiver.from Public Comment As allowed by 14 CFR 11.87, The Boeing Company respectfully requests a waiver from the publication and public comment period ofthe Exemption

# rzi-aoEI.IVG Page2 Mr. A. Xidias RA-13-00845 requirements of 14 CFR 11.85 and 1J.89 as this petition wi II not set a precedent and the reliefrequested is identical to exemptions previously granted. To supp01t the 767-2C program schedule, The Boeing Company respectfully requests that the enclosed information be processed byJune 4, 2013. Furthermore, The Boeing Company requests to be notified when the enclosed petition processing has completed. Please contact this office or the following individuals ifyou have further questions: Project Administrator (PA): Program Manager Cert.ification Specialist: S. Gordon P. Guilford T. Howorth N. Jolly 425-237-6068 425-237-5981 425-717-9847 425-266-7499 The information being forwarded to the FAA by or with this correspondence is for the exclusive purpose ofsupport ofapplications for or amendments to Type Ce1tificates. Sincerely,

ForDouglas M. Lane ODA Deputy Lead Administrator (425) 237-1383, MC 03-56 FAX: (425) 294-9340

Enclosures: Petition for Exemption

cc Name Jim Cashdollar Angelos Xidias Letter EDT EDT Enclosures Comments EDT ANM-IOOB EDT ANM-1008RA-13-00845 Enclosure (A) Page I of 17

Petition for Exemption from Title 14 Code ofFederal Regulations 25.841, Amendment 25-87

Narne and Address ofthePetitioner DougLane, Director, Regulatory Administration Deputy Lead Administrator The Boeing Company , PO Box 3707 Seattle, Washington, 98124
Section(s) ofthe Regulations from which Reliefis Sought 

### §§ 25.841(a)(2) and 25.84l(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 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 2minutes; or (ii) Forty thousand (40,000) feet for any duration. (a)(3) Fuselage structure, engine and system failures are to be considered in evaluatingthe cabin decompression.

TheExtent ofReliefSoughtand Reason(s) Regulation Requires: Reliefis Necessary because: 

### §25.84l(a)(2) and (a)(3) Compliance to be shown with Direct compliance would limit maximum Amendment 25-87 cabinpressure altitude limits aircraft altitude to less than 40,000ft and for**uncontain~d** engine failure would: A) create an economic impactto operators associated withhigher fuel bum B) have an environmental impact due to increased engine emissions associated withhigher fuel bum C) reduce competitiveness ofthe 767-2C in the aircraft marketplace

1RA-13-00845 Enclosure (A) Page 2of 17 Description of

### Issue The 767-2C aircraft is being designed to operate at a maximum cruise altitude of40,100 ft. Amendment 25-87, Reference (1), established newrequirements in§ 25.841(a) intended to upgrade the airplane and equipment airworthiness standards for subsonic transport airplanes operated above 40,000 feet. These werehased in parton special conditions that had been used on type certification ofexecutive business airplanes for many years. Specifically, Amendment 25-87 created three requirements in§§ 25.841(a)(2)(i), 25.841(a)(2)(ii), and 25.841(a)(3) governing the cockpit/cabin environment: § 25.841(a) subpart; (2) The airplane must be desigried so that occupants will notbe 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) Fortythousand (40,000) feet for any duration. (3) Fuselage structure, engine and system failures .are to be considered in evaluatingthe cabin decompression. The Boeing Companyrespectfully submits that compliance with§§ 25.841(a)(2), and 25.841(a)(3) as written, with respect onlyto 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 millions ofhours at altitudes similarto the maximum cruise altitude proposed for the 767-2C. Despitethe improved descent capability ofthe 767-2C overpreviously certificated aircraft ofsimilar category and class, compliance with§ 25.841(a)(2)(i) following an uncontained engine failure would limit the 767-2C maximum certificated altitude. In addition, The Boeing Company assessment ofthe§ 25.841(a), Amendment 87, impact on overall fleet safetyraised 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 cost to maintain an adequate level ofsafety for the airtraffic system. The 767-2C 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 767-2C. 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 certificated today for operation above 39,000 feet can meet the new cabin altitude limits within the current§§ 25.841(a)(2) and 25.841(a)(3) without an exemption. The 767-2C incorporates new technology, lessons learned from previous and currentproduction airplanes, and complies with the latest airworthiness standards (except as noted in 767-2C Certification Basis)throughoutto provide a safer, more efficienttransportation option for operators and occupants. Grant ofthis petitionprovides the public the benefits ofthe 767-2C airplane.



## .. 2RA-13-00845 Enclosure (A) Page 3 of17

As stated in the Mechanical Systems Harmonization Working Group (MSHWG) report, there is an inherentphysiological riskto humans when exposed to high cabin altitudes. In the 767-2C design, The Boeing Company mitigates riskto high cabin altitude exposure byreasonable design requirements, proven design methodologies and operational considerations regardless ofthe cause ofthe decompression event. Itis intended that the proposed exemption addresses the intended concern for safety without imposing the operational economic penalties driven by §§ 25.841(a)(2) and 25.841(a)(3) as cuJ;Tently written. In the following, The Boeing Company provides:·

• a background ofthe currentrule and activities to harmonize it • a review ofthe safetyhistory ofhigh altitude commercial flight • a discussion ofhypoxiaphysiology data upon 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 • proposedrisk mitigation • statements addressingpublic interest and no adverse impactto safety Background on 14 CFR25.841(a)(2)(3), Amendment25-87 Amendment 25-87 to § 25.841(a) was made effective July 5, 1996. The focus ofthe rule was to codifythe special conditions formerly used in the certification ofhigh altitude operation, generally applied to general aviation and transport category businessjets covering operationup to 51,000 feet. This section was changed without being harmonized with the Joint Aviation Authorities (JAA) ornow the European Aviation SafetyAgency (EASA). It is noteworthy that the JAA and EASA have not adopted the same regulations as levied in 14 CFR 25.841(a) as promulgated in Amendment 25-87 and lists§ 25.841(a) as a significant difference for concurrent FAA/JAA orFAAJEASA certificationprograms. 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 that turbine engine installations failures should be assessed against the specific requirement of JAR 25.903(d) and should not bepart ofthe 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) ofAmendment 25-87 effectively limitnew transport category airplanes with wing-mounted engines to operating altitudes well below40,000 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 part oftheir certificationbasis. The existing airplanes can cruise at altitudes above40,000 feet where they are morefuel-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 CFR25.841(a), Amendment 25-87, pressurized cabins, and the associated Advisory Circular 25-20. Itwas suggested thatthe proposed amendmentbe addressed through the auspices ofthe Aviation Rulemaking Advisory

·3RA-13-00845 Enclosure (A) Page 4 of 17 Committee (ARAC). The petitionersrecommended that harmonization with the Joint Airworthiness Requirements and Transport Canada's standards be accomplished simultaneously through the ARAC process. Thepetitioners represented the manufacturers oftransport 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 CFRPart 25 as amended at Amendment 25-87 will have significantlyhigher design and operating costs than currently certificated airplanes, with no measurable increase in safety. These higher costs, impactthe ability ofmanufacturers to develop new airplanes that can compete withpreviously approved airplanes. The petitioners also identified that the economic evaluation conductedby the FAA did not considerthe costs associated with applying this new standard to changes to existingtype certificates (derivative models) when assessing the costs and benefits accruing from the amendment, norwhether the new requirement itselfcould be metby anypractical 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 ofaddressing various concerns with the regulation, raised by industry, and ofreaching a consensus among medical experts, representatives from the FAA, JAA, Air Transport Association (ATA), ALPA, AFA and Aircraft Manufacturers (members with representation in the AlA, AECMA or GAMA). The MSHWG agreed thatthe existing.standard maybe conservative relative to engine related failures when considering the associated risks and exposure to safety. The issuance ofan FAA Interim Policy, March 2006, Reference (2) is · consistent with this position, as is the MSHWGworking group report, Reference (3), which identified the existingrequirements as being conservative relative to safety. In consideration of comments received on the draft Interim Policy and the acceptance ofthe MSHWGreport by TAEIG, the FAAworked 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 similarto exemptions granted for the 787-8, 747:.8, 747-8F, A380, ERJ 170, and ERJ 190. Safety History The original§§ 25.841(a)(2) and 25.841(a)(3) had the goal ofensuring that no fatalities or permanentphysiological harm occurred following a rapid depressurization event. However, the MSHWGbelievedthat there is an inherent risk to occupanthealth 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 occur duringthe initial event (i.e., from impact ofuncontained engine debris orfrom being ejected from the airplane). In addition, some cases ofpermanentphysiological 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 riskto safety due to rapid depressurizations is non-sigilificant when comparedto otherrisks to·safety. · · Previously certificated large transport aircraft incorporating established design practices have safely operated at altitudes in excess of40,000 feet for more than 30 years, representing many

4RA-13-00845 Enclosure (A) Page 5of 17 millions offlight hours. Historically, relatively few accidents or incidents have occurred during cruise. According to 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 

### 2002-2011 (Reference 

### (16)). See Figure 

### 1-2 and 

### 1-3 respectively.



## Fatalities Worldwide Commercial Jet Fleet-1959-1996

Exposure percentage based on flight duration of 1.5hours

Load, taxi, unload 2.0% 18.3%**~------** Percentage offatalnies Takeoff lnnial Climb Cruise climb 7.3% 11.0% 17.4% 6.8%

/

### ~Flaps retracted

1% 1% 14% 57% 22.6%

....**~** Descent lnnial Final Landing approach approach 11.7% 21.2% 18.2% 4.4%**~~**

## ~**~--~** Nav fb< Outer marker 

# I

11% 1 12% 

# I 3% 1% Exposure, percentage offlight time 4,578

Figure 1-1, Fatalities, Worldwide Commercial Jet Fleet -1959 -1996

5RA-13-00845 Enclosure (A) Page 6 of 17


### Accidents and Onboard Fatalities by Phase of Flight Hull Loss and/or Fatal Accidents- Worldwide Commercial Jet Fleet -1994-2003

17%

# -~**~;:**

# ...**~-=- 1~:**  FataiiUes 0% 8% 

# l

100
Hull· 80 loss and/or ao fatal accldents40
20 r----
..**:.~--/1**

1% 1% Percentage ofaccidents/fatalities 51% Climb (flaps up)

8% Cruise 6% Descent 3% Initial Final 

# I approach ; approach Landing I

. 7% 

### J 6% 45% 12% 

### I I Exposure= percentage offlight time based on flight duration of 1.6 hours Initial approach

fix 14% 57% 11%

# v

Distribution ofaccidents and fatalities 1 619 

## ·-**~--·~;;-r···--;·;;··-··**
18%



# I
J 1%

93

Descent Initial Final Landing approach approach ll Hull loss andlorfatal accidents 0 Onboand fatalities 2000

1500

FatallUes 1000

500

16 2003 STATISTICAL SUMMARY, MAY 2004 rlJ.-,HIIEI,NG 

### Figure 1-2, Fatalities, Worldwide Commercial JetFleet-1994-2003

6

### RA-13-00845 Enclosure (A) Page 7 of17 

## FatalAccidents and Onboard Fatalitiesby Phase of Flight Worldwide Commercial Jet Fleet- 2002 Through 2011

Taxi, load/ 16% Percentage of fat"! accidents and onboard**f~talitie~ unload~** 

par1<ed,**tn~ial** Climb

tow Takeoff climb (flaps up) Fatal accidenls 11% 10% 1 6% 6% Onboard fata lilies Oo/o 10%

Exposure

· (Percent8ge offlight time estimated fora 1.5 hour flight) 

# ! 1% 1% I 14%

.. J Cruise 

# IDescent 11% 4% 

# + 22% 2%

57% 37%

100**r-----------------------------------------------------------~~** so Fatal 60 11ccidents 40 D felolecciderts 00nboordfaloliies Distnoulion of fatal accidents and onboard fatalities

1001 1500 Onboard 1000 fatalities

20 lOll STAJISTIC!<l SlMofJIRY.JUHE2011 

### Figure 1-3, Fatalities, Worldwide CommercialJetFleet- 2002-2011 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 hypoxiaresulting from in-flight rapid decompression events at altitudes greaterthan 25,000 feet. Relative to othercauses, decompressions resulting in hypoxic fatalities are not a significant accident contributor.

7RA-13-00845 Enclosure (A) Page 8of 17

2,500 2,000 

### '" :! 1,500 !.1,000
500 Fatalities byAccident Categories Fatal Accidents·World Commercial Jet Fleet -1992 Through 2001 jaTotal fatalities • 2001 fatalities J

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

### Figure 2: FatalAccidents by 

### Category Additionally, an assessment ofdecompressions since the 2001 completion ofthe above study through 2011, confirmed there were no additional fatalities due to hypoxia resulting from inflight rapid decompression. There were 121 additional fatalities related to hypoxia from a single event; the Helios Airways Flight HCY522 accidentwhich was not a decompression event, but a failure ofthe flight crew to properly configure the pressurization system and a subsequent failure to recognize thatthe aircraft was notpressurized 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 minorbarotrauma injuries.
It should also be noted that very few rapid decompression events, ifany, have exposed aircraft occupants to cabin pressure altitude profiles that run the risk ofpermanent harm to occupants. Industry experience shows that very few cases ofdecompressions athigh altitude resulting in death orpermanentphysiological harm have occurred. The FAA cited 3 cases as examples of uncontained engine failure for consideration. In one case, a DC-10 (cruise flight near Albuquerque, NewMexico) reported several cases ofinitial decompression sickness apparently with no permanentinjuries. However, it was noted that 24 passengers and crewmembers were brought to the hospital at Kirtland AFB for treatment ofsymptoms 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 ofphysiological injuries sustained during this decompression event. The NTSB report, (Reference (6), NTSB reportNTSB-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 event to estimate the damage ifthe 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 successfullyperformed a rejected takeoff. Thus, this case did not encounter a rapid decompression. It should be noted that

8RA-13-00845 Enclosure (A) Page 9 of 17 the FAA citedthese three cases (Reference (7)) because they were "datarich" events. In addition to the "datarich" events discussed above, there have been nine otheruncontained engine failures at cruise identified to the FAA, Reference (8), however, none ofthese other events caused a cabin decompression. The events experiencedto date as discussed above were associated with 1st 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 of2nd;3rd generation engines comparedto 1st generation engines has improved by approximately 95% based on historical Boeing data on uncontained engine failures. · · As noted previouslyregarding the three "datarich events" (the Albuquerque, Sioux City, and Pensacola events), only the Albuquerque eventresulted in a decompression. Furthermore, the Albuquerque eventremains 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"priorto the engine failure, Reference (6), NTSB report NTSB-AAR-75-2. Figure 3 depicts pressurization events by cause. Note thatuncontained 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 5.00E-07 O.OOE+OO

## Decompression Events by Cause

Pressurization Events per Hour an.d per Flight, by Cause IC # Ev/Hr • # Ev/FitI

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

Engine Events Are Rare Contributors To Decompression Events**~.BDEIND'"** 

### Figure 3, Pressurization Events by 

### CauseperFlightHour

9RA-13-00845 Enclosure (A) Page 10 of 17
In conjunction with the above data, it should be noted thatvery few decompression events exposed the aircraft occupants to cabinpressure altitude profiles whichrun the risk ofpermanent physiological harm. Figure 4 summarizes significanttransport category decompression events resulting in fatalities orincapacitation (inred). Note that while fatalities were incurred, none would have been prevented bythe intent of§ 25.841(a), Amendment 25-87 which was promulgated in large part to prevent death orpermanentphysiological 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 thisdatawas taken has beenthe previously discussed Helios event.

CD "0 :I :1::: 

### 5i c :a I'll u E :I E ';( I'll :E 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 

# J• Fatality/Incapacitation • lnjuryJ


# •

...... 

# • • _A 

## • 

# ••••**~___.**



### ... 

# • : l • 

# • A 

# ·: '

.. -..-."-rl> 

# ;-.-t-& • 

# • • •

I 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 orInjury
Notes: Total of2866 pressurization events reported 1959-2001. Transport Category Airplanes over 60,000 lbs. EventAltitude and Cabin Altitude were reported for 873 events. Sources: BoeingAirplane Safety Engineering (ASE) and Safety Information System (SIS), National Transportation Safety Board (NTSB) Ofthe 18 events that resulted in fatalities, 1 0 events were at cabin altitude exposures less than those altitudes addressed by§ 25.841(a)(2), Amendment 25-87.lnfour ofthe remaining eight events, fatalities were due to injury directly attributed to the eventratherthan 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 ofpressurization, and oxygen system failure. Current generation aircraft, (1980s through 2000s) introduced higherperformance 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 MSHWGreport, 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**saf~ty** record has been maintained

10RA-13-00845 Enclosure (A) Page 11 of 17

even as newer airplanes fly at these higher altitudes more often than older airplanes (see Figure 5). As statedpreviously, an assessment ofdecompressions since the 2001 completion ofthe above studythrough 2011 confirmed there were no additional fatalities orpermanent physiological harm due to hypoxia resulting from in-flightrapid decompression, and only two· additional incidents resulting in minorbarotrauma injuries. As discussed previously, the Helios Airways Flight HCY522 accident was not a decompression event, buta failure ofthe flight crew to properly configure the pressurization system and a subsequent failure to recognize thatthe aircraft was not pressurized after takeoff. Based on these facts, the MSHWGreport conclusions remain valid. Three separate studies have recently beenmade to illustrate the extent ofairtraffic operations at high altitUde in today's airtraffic system. While today's numbers are significant, the new generation ofairplanes as exemplified by the 767-2C are being designed to cruise at altitudes above 37,000 feet for even longerportions oftheir mission.

45%

40%

35%

30% 

### t! 25% 0 Q.**~** 20%

15%

10%

5%

0% 

### Altitude Reports 

## By Airplane Model FAA's Enhanced Traffic Management System (ETMS) Reports for U.S. Commercial Aircraft above 28,000 feet

... ---- --·· ···-· i r-

; 

## IIJAbove 40,000 ft 

# I
IJAbove 37,000 ft**~** First Flight ofType Priorto 1980**~** 

## - 1-**~** 1-rr- r- r-

,_ r- 1- 

## - r-- r- 

### - i-- 

### ·- 1- 1- 

### - 

# I r- '-- 

# I r- r- r- ,_ - _n rE 

## n 

# n I.-- 

# ill 

# ill**~~~~~~~,~~-~~~~,,~,/** <§1 Q**~** .... '
• Data represents reports from one week in Sept 2000 • Based on position reports every 3 minutes. ,...-



### Figure 5: Frequency ofFlights above 37,000 ft. and**40~000** 

### ft. AltitudeofNew Design Aircraftvs. OlderDesign Aircraft.
Aerospace Hypoxia Physiology Data The FAA, and otherqualified experts agree that the 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 FAAbased in part onrecommendations from the FAA's Civil Aeromedical Institute (CAMI), which were based onthe concept of"Timeof Safe Unconsciousness" (TSU)documentedby James G. Gaume in his 1970 paper. The study concluded with the statementthat,""

... a plea mustbe made for collection ofbetter data."

11RA-13-00845 Enclosure (A) Page 12 of 17 Gaume's 1970paper is only one source in establishing safetybasis. It shouldbe understood that the proposed TSU criteria was established as a compensating consideration to the elimination of the passenger oxygen system. Today's commercial transport arerequired to provide an emergency oxygen systemproviding additional margin ofsafety. The MSHWG agreed additional databased on further study would benefitthe establishment of new standards. In lieu ofnew data the MSHWG established physiological exposure limits that are conservative with respect to the data available. The MSHWG consideredthe available physiological exposure research which included several papers that have been circulated in the aerospace medical community, all with the objective ofestablishingphysiological limits to occupants following cabin decompression. Itwas based on these papers, and consideration ofthe overall risk to decompression exposure thatthe MSHWG documented its recommendations in the Reference (3) TAEIG accepted report. The following are summaries ofthereports from

. recognized AerospaceMedical Doctors addressingphysiological informationthat was consideredbythe MSHWG:

- ·James Gaume (Aerospace Medicine) authored a paper substantiatingthe newrule. According to Gaume, during an emergency descent from 42,000 feet to 5,000feet for adequate recovery ofunconscious passengers without any supplemental emergency oxygento the occupants, with an aircraft emergency descent of6200 feet perminute and with cabin altitude exceeding 33,000 feet, no more than 1 minute and 42 seconds is considered acceptable. Reference (9): "Factors Influencingthe Time ofSafe Unconsciousness (TSU) for Commercial JetPassengers Following Cabin Decompression" by James Gaume, Aerospace Medicine, April 1970.

- Dr. StanleyR. Mohler, a former director ofCAMI (FAA's Civil Aeromedical Institute), analyzed a number ofactual decompression cases, including data from studies by Barron, Reference (10), 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 againstpermanentphysiological damage from a cabin decompression occurring at up to 45,000 feet. Reference (11): "Sudden HighAltitude Cabin Decompression Immediately Threatens Safety ofAircraft Crew and Passengers" byDr. Stanley Mohler, Flight Safety Foundation, Human Factors & Aviation Medicine, December 1994.
Dr. Robert Gamer, Research ·Physiologist, Protection and Survival Laboratory at CAMI, agrees that limiting cabin altitude exposure to 25,000 feet for up to three minutes and never allowing itto exceed 45,000 feet wouldprovide an acceptable level ofsafety. His views on this matterhave been communicatedto the FAA Transport Standards Staff. DraftWhitepaper issued by CAMI- FAA Civil Aerospace Medical Altitude Rule: presented in the MSHWG in July 2002, Reference (12), Page 13, states that exposure: ifunprotected, passengers to a 41,000 feet altitude would be approximately equal to exposure at a 40,000 feet altitude. ·

12RA-13-00845 Enclosure (A) Page 13 of 17

- "Neurological Study ofSimulated Decompression in Supersonic Transport Aircraft," Aerospace Medicine, J.B. Brierley and A. N. Nicholson, August, 1969, Reference (13), concluded that cabin altitude exposure above 10,000 feet notmore 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. Emsting, April1967, Reference (14) concluded that cabin altitude exposure above 40,000 feet with time exposure of 1minute and 30 seconds caused brain damage.
In consideration ofthe above studies, comments received on the draft Interim Policy, and the acceptance ofthe MSHWGreport by TAEIG,theFAA established appropriate criteria for § 25.841(a) with respect to an uncontained engine failure. These criteria are more conservative than those established by MSHWGreport. 

### In lieu ofany other standard, Boeingwill comply with these criteria as presented in the Proposed Risk Mitigation discussion provided later in this petition. Impacts ofCompliance with the Uncontained EngineFailure Aspect ofRule The Boeing Company's 767-2C will fully comply with the latest airworthiness standards (except

.as noted in the 767-2C Certification Basis) 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" ofcompliancetakes 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 onthe impact ofthese new requirements on the 767-2C, it is clearthat 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 itrelates to uncontained engine failure would result in. This reduction in maximum cruise altitude would result in significantly higher operating**costs~** based onthe significant increased fuel burn due to operations at altitudes not optimum for these airplanes. These higher costs will adversely impactthe ability ofthe Boeing 767-2C to compete with previously certificated airplanes which can operate at the more economical cruise altitudes typically in excess of37,000 feet. In addition, restricting airplane operations to lower altitudes will increase traffic congestion. Three separate studies have shown thatthe number of operations above 37,000 feet are significant today and the trend is for newer airplanes to cruise at these altitudes for even longerportions oftheir mission. Limiting operation of new generation airplanes to lower altitudes will result in highertraffic density, which in tum will result in higher cost·ofsafety in order to maintain established air traffic vertical and horizontal separation requirements.

13RA-13-00845 Enclosure (A) Page 14 of 17 (2) Since the release ofAmendment 25-87, a number ofamendments to 14 CFR 25 have been released. Each ofthese amendments has the intent ofan increase in aviation safety. The Boeing 767-2C will meetthe latest amendments in effect at the time ofapplication, except as noted in the 767-2C Certification Basis. The net result is thatthe 767-2C incorporates the safety-advancements as intended within these later amendments. Any significant impactto the marketability ofthe 767-2C will, at a minimum, result in a reduced number ofaircraft with this higher level ofsafety as compared with the previous generation ofaircraft, orat a maximum, preclude the manufacture ofthis new model series ofaircraft. Ineither case, Amendment 25-87 results in a reduced potential for overall aviation safety improvements. (3) As stated in (1) above, the restriction to maximum cruise altitude imposed upon the 767-2C due to compliance with§§ 25.841(a)(2) and 25.841(a)(3), Amendment 25-87 as itrelates to uncontained engine failure has a significant adverse impact on 767-2C fuel bum. This additional fuel bum not only increases 767-2C operating costs, but will also increase engine emissions (e.g. C02). Proposed Risk Mitigation
It is The Boeing Company assessmentthat the risk to safety which is attempted to be mitigated by the newrule§§ 25.841(a)(2) and 25.841(a)(3), creates unintended consequences. The existing fleet has demonstrated safe operations viamillions ofhours offlight at altitudes similarto those proposed for the 767-2C. The risk ofrapid depressurization following an uncontained engine failure is bettermitigated by a combination ofproven design practices establishedthrough years ofairplane industry experience combined with today's improved technical capabilities.**I~** 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 25.84l(a)(3). Itmust 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 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/or functional interfaces that could potentially violate the physiological limits imposedby§ 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 ofairplane occupants and are an inherentpart ofthe 767-2C 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 minimizationphilosophies employed in the 767-2C design include an automatic pressure demand mask for the pilots which will be certified to§ 25.1441(d), separation and redundancy ofkey systems such as electrical power, cabinpressure control and spoiler actuation. The following more specifically addresses The Boeing Companyproposed means ofcompliance for rapid depressurizations related to uncontained engine failures. Using the FAA established criteria (Reference (2)), The Boeing Companyproposes to mitigate the risk to occupants from

14RA-13-00845 Enclosure (A) Page 15 of17
exposure to high cabin altitudes resulting from uncontained engine failure, in part, by implementingthe following design requirements onthe 767-2C airplane:

• Design Requirement The airplane mustbe designedso thatoccupants willnotbe exposedto a cabin pressure altitude that exceeds thefollowing afterdecompression from any engine failure condition notshown to be extremely improbable: (i) Forty-five thousand (45,000)feetfor anyduration; or (ii) Forty thousand (40,000)feet for one minute; or· (iii) Twenty-five thousand (25, 000)feet for more than three minutes; or (iv) Ten thousand (JO,OOO)feetfor more than sixminutes. In calculatingthe descent capability ofthe airplane in order to meet the cabin altitude requirements, the loss ofthe failed engine's contribution as a source ofpowerto the systems enabling the descent needbe considered. (i.e. Iflosing power on one engine results in loss ofa hydraulic system, and that in tumreduces 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. References 1) Amendment 25-87 Final Rule, Docket 26070, Federal Register Volume 61, Number 109, June 5, 1996 2) FAA Interim Policy, ANM-03-112-16, Subject: Interim Policy on High Altitude Cabin Decompression (Reference Amendment 25-87) Issued March 24, 2006 3) Mechanical Systems Harmonization Working Group (MSHWG) Final Report on FAR25.841(a)(2,3), dated August 2003, submitted to FAA October 21,2003 4) Statistical Summary ofCommercial JetAirplane Accidents, Worldwide Operations, 1959-2002, Published by Boeing Commercial Airplane, May, 2003 5) St3;tistical Summary ofCommercial JetAirplane Accidents, Worldwide Operations, 1959-2003, PublishedbyBoeing Commercial Airplane, May, 2004 6) NTSB-AAR-75-2, AIRCRAFT ACCIDENTNATIONALAIRLINES, INC.,DC-10- 10, N60NANEARALBUQUERQUE, NEW MEXICO, November 3,1973 7) Uncontained Engine Failure Fuselage Hole Analysis, Draft Technical Note, October 2001 8) Uncontained Engine Damage Database, ACCESS 2000 Database, FAA UED vOO 1, June 10, 2002 9) Factors influencing the time ofSafe Unconsciousness (TSU) for commercial passengers Following Cabin Decompression, Gaume, J., 1970. Aerospace Medicine, April1970, 382-385 10)Barron, C

..and Cook, T.,-Effects ofVariable Decompressionsto 45000 feet, Aerospace Medicine, May 1965,425.430 11)Mohler, Dr. Stanley, "Sudden High Altitude Cabin Decompression Immediately Threatens Safety ofAircraft Crew and**Passeng~rs,"** Flight Safety Foundation, Human Factors & Aviation Medicine, December 1994

15RA-13-00845 Enclosure (A) Page 16 of 17 12)Draft White paperissued by CAMI

- FAA Civil Aerospace Medical Altitude Rule: presented inthe MSHWG in July 2002 13) ''Neurological Study ofSimulatedDecompression 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. Emsting, April1967 15)Hellenic Republic Ministry ofTransport & Communications, AAIASB Aircraft AccidentReport, Helios Airways FlightHCY522, Boeing 737-31S At Grammatiko, Hellas on 14 August 2005, Dated 1112006 16) Statistical Summary ofCommercial JetAirplane Accidents, Worldwide Operations, 1959-2011, To be published by Boeing Commercial Airplane 

### StatementofPublicInterest The Boeing CompanyModel 767-2C fully complies with the latest airworthiness standards (except as noted in 767-2C CertificationBasis) 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. Specific features ofthe 767-2C design mitigate the safety riskto occupants due to a decompression resulting from an uncontained engine failure. Improvements in engine technology, application oflessons learned, and 2nd13rd generation engine design practices have resulted in a reduction in uncontained engine failure events and the risk ofa rapid depressurization. Asstated above, the Boeing767-2C will meet all the latest amendments in effect at the time ofapplication, except as noted in the 767-2C Certification Basis. The netresult is thatthe 767-2C incorporates the safety advancements as intended within these later amendments. The 767-2C, therefore, offers a higherlevel ofsafetythan do previously certificatedtransport category airplanes. In addition, the 767-2C willprovide industry-leading operating economics, and environmental improvements. Granting this petition ofexemption is in the public interest because itwill improve safety relative to previously certificated airplanes, while reducing operational costs by reducing the amount offuel consumed. The cost ofmaintainingthe level ofsafety withinthe 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. 

### StatementofNo AdverseEffect on Safety The exemptionrequested will not adversely affect safety. Aspreviously discussed, the 767-2C will comply with§ 25.841(a) in all other aspects ofa rapid depressurization. Inthe unlikely event ofan uncontained engine failure, the 767-2C design incorporates a high level ofsafety due to its descent capability and otherdesign features. As concluded herein, and based onthe MSHWGreport (Reference (3)), and the Interim Policy (Reference (2)), the world commercial jetfleet has had no hypoxiarelated 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

16RA-13-00845 Enclosure (A) Page 17 of 17 guidance and the recommendat"ions ofthe MSHWGreport, as adopted by TAIEG, Boeinghas 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. Request to 'Waive Publication and Comment' Boeingrequests to waive the requirement for publication and comment based on sim'ilar exemptions granted to the following aircraft: 787-8, 747-8, 747-8F, A380, ERJ 170, and ERJ 190. Privileges ofthe Exemption Outside the United States Per§ 11.81(h), Boeingrequests that the privileges ofthis exemption be extended outside the United States. This extension ofprivileges is necessary for operations based within foreign countries havingbilateral agreements with the United States accepting FAA 14 CFRpart 25 as their airworthiness standards for transport category aircraft. The 767-2C is intended for the global marketplace. Conclusion The information in this petition for exemptionprovides 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 767-2C provides advancements in technology and safety relative to previously certified aircraft. Grant ofthis petitionprovides the public the benefits ofthe 767-2C airplane. Operators will be able to operate the 767-2C where it is mostefficient and therefore will not face higher operating costs due to increased fuel burn. Furthermore, reduced fuel bum will lead to lower engine emissions resulting in positive impact to the environment. By granting this petition for exemption the true benefits of'767-2C will be realized, causing no adverse effect on safety.
Summary to be Published in the Federal Register PETITIONER: Boeing Commercial Airplanes SECTION OF 14 CFRAFFECTED: 14 CFR25.841(a)(2)(3)

. > DESCRIPTION OFRELIEF SOUGHT: To allowrelieffrom the requirements pertainingto cabin decompression following certain extremely rare uncontained engine failures for the Boeing Model 767-2C.

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