Enclosure to RA

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1 Petition for Exemption from 14 CFR 25.841 , Amendment 25

- 87

Name and Address of the Petitioner

Doug Lane, Director, Regulatory Administration Deputy Lead Administrator The Boeing Company PO Box 3707 Seattle, Washington, 98124

Section(s) of the R egulatio ns from which R elief is S ought : §§ 25.841(a)(2) and 25.841(a)(3) With Respect to Uncontained Engine Failures.

§ 25.84 1 (a)(2) The airplane must be designed so that occupants will not be exposed to a cabin pressure altitude that exceeds the following afte r 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.

(a)(3) Fuselage structure, engine and system failures a re to be considered in evaluating the cabin decompression.

The Extent of Relief S ought and R eason(s) Regulation Requires : Relief is Necessary because: 14 CFR 25. 841(a)(2) and (a)(3) Amendment 25

- 87 Compliance to be shown with cabin pressure altitude l imits for uncontained engine failure Direct compliance would l imit maximum aircraft altitude to less than 40,000ft and would : A) create an e conomic impact to operators associated with higher fuel burn B) have an e nvironmental impact due to i ncrease d engine emi ssions associated with higher fuel burn C) reduce competitiveness of the 787

- 10 in the aircraft marketplaceEnclosure to RA

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2 

### Table of Contents Description of Issue

................................ ................................ ................................ .............................. 2 Background on 14 CFR § 25.841(a)(2)(3), Amendment 25

- 87

................................ ............................ 3 Safety History

................................ ................................ ................................ ................................ ....... 4 Aerospace Hypoxia Physiology Dat a

................................ ................................ ................................ . 10 Impacts of Compliance with the Uncontained Engine Failure Aspect of Rule

................................ .. 12 Proposed Risk Mitigation

................................ ................................ ................................ ................... 13 Statement of Public Interest

................................ ................................ ................................ ................ 14 Statement of No Adverse Effect on Safety

................................ ................................ ......................... 14 Request to ‘Waive Publication and Comment’

................................ ................................ ................... 14 Privileges of the Exemption Outside the United States

................................ ................................ ...... 15 Conclusion

................................ ................................ ................................ ................................ .......... 15 Summary to be Published in the Federal Register

................................ ................................ .............. 15 References

................................ ................................ ................................ ................................ ........... 16

**Description of Issue**
The 787

- 10 aircraft is bein g design ed to operate at a maximum cruise altitude of 41 ,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 a bove 40,000 feet. These were based in part on special conditions that had been used on type certification of executive business airplanes for many years. Specifically, Amendment 25

- 87 created three requirements in §§ 25.841(a)(2)(i), 25.841(a)(2)(ii), an d 25.841(a)(3) governing the cockpit/cabin environment:

§ 25.841(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 decom pression.

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 c ategory jet aircraft when considering the safety record of the fleet over the last 53 years. The fleet has a demonstrated safety record with millions of hours at altitudes similar to the maximum cruise altitude proposed for the 787

- 10 . Despite the improv ed descent capability of the 787

- 10 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

- 10 maximum certificated 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 aircraf t 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.Enclosure to RA

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3 The 787

- 10 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 airplane . This concern is shared by other manufacturers of airplanes wit h wing

- mounted engines seeking new or amended t ype 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 25.8 41(a)(3) without an exemption.

The 7 87

- 10 incorporate s new technology, lessons learned from previous and current production airplanes, and compl ies with the latest airworthiness standards throughout to provide a safer, more efficient transportation op tion for airlines and airline passengers. Grant of this petition provides the public the benefits of the 787

- 10 airplane.

As stated in the Mechanical Systems Harmonization Working Group (MSHWG) report, Reference (3), there is an inherent physiological ris k to humans when exposed to high cabin altitudes. In the 787

- 10 design, The Boeing Company mitigates risk to high cabin altitude exposure by reasonable design requirements, proven design methodologies and operational considerations regardless o f the

cause of the depressurization event. It is 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 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 of high altitude commercial flight

• a discussion of hypoxia physiology data upon which rulemaking 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.

• Analysis supporting the petition for exemption

• proposed risk mitigation

• statements addressing pu blic interest and no adverse impact to safety.

• Emergency descent r ate design improvements

**Background on 14 CFR § 25.841(a)(2)(3), Amendment 25**

**- 87**  Amendment 25

- 87 to § 25.841(a) was made effective July 5, 1996. The focus of the rule was to codify the spec ial 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 §25.841(a) as promulgated in Amendment 25

- 87 and lists §25.841(a) as a signific ant difference for concurrent FAA / JAA or FAA/EASA certification 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 of 41,000 ft,” states, with respect
to e valuation 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 appr oach at the aircraft level...”Enclosure to RA

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4 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 d o not have §25.841(a), Amendment 25

- 87 as part of their certification basis . The existing airplanes can cruise at altitudes above 40,000 f eet where they are more fuel

- efficient.

T he Aerospace Industries Association (AIA) and European Association of Aerospace Industries/Association Européenne des Constructeurs de Maté riels Aeronautique (AECMA) petition ed the Federal Aviation Administration t o amend 14 CFR 25.841(a) , Amendment 25

- 87,
p ressurized cabins, and the associated Advisory Circular 25

- 20 . It was suggested that the proposed amendment be addressed through the auspices of the Aviation Rulemaking Advisory Committee (ARAC). The petitioner s recommend ed that harmonization with the Joint Airworthiness Requirements and Transport Canada’s standards be accomplished simultaneously through the ARAC
process.
The petitioners represent ed the manufacturers of transport category airplanes in the Unite d States and Europe. As such, they have an interest in this rulemaking proposal because new and derivative airplanes designed to meet 14 CFR P art 25 as amended at Amendment 25

- 87 will have significantly higher design and operating costs than currently cer tificated 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 t he economic 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 itse lf could be met by any practical means for any new or derivative airplane.

In July 2001, the FAA assigned the ARAC and the M echanical S ystems H armonization W orking G roup (MSHWG) the task of addressing various concerns with the regulation, raised by indust ry, and of reaching a consensus among medical experts , representatives from the FAA, JAA, A ir T ransport A ssociation (ATA) , ALPA, AFA and Aircraft Manufacturers ( members with representation in the AIA, AECMA or GAMA ) . Th e MSHWG agreed that the existing sta ndard may be conservative relative to engine related failures when considering the associated risk s and exposure to safety. The issuance of a n FAA Draft Interim Policy, published in the Federal Register

, June 2003 , Reference (2) is consistent with this po sition , as is the MSHWG working group report, 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 T AEIG, 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 737

- 7/

- 8/

- 9, 787

- 8 /

- 9

, 767

- 2C 747

- 8, 747

- 8F, ERJ 170, ERJ 190

, A380 and A350.

**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. How ever, 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 leve l of riskEnclosure to RA

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5 during a depressurization event and the resulting emer gency descent, flight, and landing. Fatalities may occur during the initial event (i.e., from impact of uncontained 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 w hen compared to other risks to safety. Previously certificated large transport aircraft incorporating established design practices have safely operated at altitudes in excess of 40,000 feet for more than 3 0 years, representing many millions of flight hours . Historically, relatively few accidents or incidents have occurred during cruise. According to the statistics, f or the period 1959

- 1996, only 6.8 percent of accidents in the worldwide commercial fleet history have occurred during cruise; even though th e 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 hav e occurred during cruise for the period 2002

– 2011 (Reference (16)) . See Figure 1

- 2 and 1

- 3 respectively

.

Figure 1

- 1: Fatalities, Worldwide Commercial Jet Fleet

– 1959

- 1996Enclosure to RA

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6 

### Accidents and Onboard Fatalities by Phase of Flight
Hull Loss and/or Fatal Accidents

- Worldwide Commercial Jet Fleet

- 1994

- 2003

Hull loss and/or fatal accidents Onboard fatalities Taxi, load,

parked Takeoff Initial climb Climb Fa t lie s

Cruise Descent Initial approach Final approach Landing 11
3 25 Hull loss and/or fatal accidents 539

11 17 1,619

788

13 7 14 1,066

13 Initial approach

7%

13%

12% Descent

3%

8%

11% Final approach

6%

16%

3% Percentage of accidents/fatalities

Takeoff

12%

8%

1% Initial climb

5%

14%

1% Landing

45%

2%

1% Taxi, load, parked

5%

0% Climb (flaps up)

8%

25%

14% Cruise

6%

12%

57% 17% 51%

22% 18% Accidents

Fatalities

Initial approach fix Exposure = percentage of flight time based on flight duration of 1.5 hours

Distribution of accidents and fatalities

0 20 40 60 80 100

0 500 1000 1500 2000

902

541 93

161 Fatalities

865 Final approach fix

16 2003 STATISTICAL SUMMARY, MAY 2004 Figure 1

- 2: Fatali ties, Worldwide Commercial Jet Fleet

– 1994

– 2003

Figure 1

- 3 : Fatalities, World wide Commercial Jet Fleet

– 2002

- 2011Enclosure to RA

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7 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 hypoxia resulting from in

- flight rapid depressurization events at altitudes greater than 25,000 feet. Relative to other causes, depressurizations resulting in hypoxic fatalities are not a significant accident contributor.

Fatalities by Accident Categories Fatal Accidents - World Commercial Jet Fleet - 1992 Through 2001

0 500 1,000 1,500 2,000 2,500

Lost control CFIT Midair collision In-flight fire Fuel tank Landing Takeoff config Rwy incursion Ice/snow Windshear Misc. fatality Fuel exhaust RTO Turbulence Decompression UnknownFatalities Total fatalities 2001 fatalities

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

(Hypoxia) >25Kft

Figure 2 : Fatal Accidents by Category

Additionally, an assessment of depressurizations since the 2001 completion of the above study through 2011

, confirmed there were no additional fatalities due to hypoxia resulting fr om in

- fl ight rapid depressurization . There were 121 additional fatalities related to hypoxia from a single event; the Helios Airways Flight HCY522 accide nt which was not a depressurization event, but a failure of the flight crew to properly configure the pressu rization system and a subsequent failure to recognize that the aircraft was not pressurized after takeoff , Reference (15). T here were no additional deaths or injuries resulting in permanent physiological harm and only t wo additional incidents were recorded as having resulted in minor barotrauma injuries.

It should also be noted that very few rapid depressurization events, if any, have exposed aircraft occupants to cabin pressure altitude profiles that run the risk of permanent harm to occupants. Industry experience shows tha t very few cases of depressurizations 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

- 10 (cruise f light 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 sympt oms 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 autoEnclosure to RA

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8 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 airpla ne 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 (Referen ce (7) ) because they were “data rich” 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 1 st generation engine technology. Safety enhancement initiatives with respect to critical rotating parts (inspecting for cracks in disks and using continually updated m aintenance data to refine disk inspection criteria)

, as well as improvement in engine technology, lessons learned, and 2 nd /3 rd generation engine design practices have resulted in a reduction in uncontained engine failure events . The uncontained engine f

ailure rates of 2 nd /3 rd generation engines compared to 1 st 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, Si oux 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 report NTSB

- AAR

- 75

- 2.

Figure 3 depict s pressurization events by cause. Note that uncontained engine failure is an insignificant contrib uto r to the total number of events

.


### Decompression Events by Cause

Pressurization Events per Hour and per Flight, by Cause

0.00E+00 5.00E-07 1.00E-06 1.50E-06 2.00E-06 2.50E-06 3.00E-06 3.50E-06 4.00E-06

Unknown Press. Sys. Door/Seal Structural Procedural Engine Shootdown/Bomb # Ev/Hr # Ev/Flt

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

Engine Events Are Rare Contributors To Decompression Events

Figure 3 : Pressurization Events by Cause per Flight HourEnclosure to RA

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9 In conjunction with the above data, it should be not ed that very few decompression ev ents expose d the aircra ft occupants to cabin pressure altitude profiles which run the risk of permanent physiological harm

. Figure 4 summarize s significant transport category decompression events resulting in fatalities or incapacitation (in red). Note that while fatalities we re 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 p ressure vessel from an uncontained engine failure. The only fatal event since this data was taken has been the previously discussed Helios event

.

.

Figure 4 : Pressurization Events with Fatality, Incapacitation or Injury

Notes: Total of 2866 pressurizat ion events reported 1959

- 2001. Transport Category Airplanes over 60,000 lbs. Event Altitude and Cabin Altitude were reported for 873 events. Sources: Boeing Airplane Safety Engineering (ASE) and Safety Information System (SIS), National Transportation S afety Board (NTSB)

Of the 1 8 events that result ed in fatalities, 10 events were at cabin altitude exposures less than those altitudes addressed by § 25.841(a) (2) , Amendment 25

- 87 . In four of the remaining eight events, fatalities were due to injury direc tly 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.

C urrent 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 MSH WG 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 hig her altitudes more often than older airplanes (see Figure 5). As stated previously, an assessment of decompressions since the 2001 completion of the above study through 2011 All Pressurization Events with associated Fatality, Incapacitation or Injury

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

0 5,000 10,000 15,000 20,000 25,000 30,000 35,000 40,000 45,000 50,000
Event AltitudeMaximum Cabin Altitude Fatality/Incapacitation Injury All Pressurization Events with associated Fatality, Incapacitation or Injury

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

0 5,000 10,000 15,000 20,000 25,000 30,000 35,000 40,000 45,000 50,000
Event AltitudeMaximum Cabin Altitude Fatality/Incapacitation InjuryEnclosure to RA

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10 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 barotrauma injuries. As discussed previously, the Helios Airways Flight HCY522 accident was not a decompression event, but a failure of the flig ht crew to properly configure the pressurization system and a subsequent failure to recognize that the aircraft was not pressurized after takeoff. Based on these fact s , 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

- 10 are being designed to cruise at altitudes above 37,0 00 feet for even longer portions of their mission.

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

**Aerospace Hypoxia P hysiology 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 part on recommendations from the FAA’s Civil Aeromedical Institute (CAMI), which were based on the concept of “Time of Safe Unconsciousness” (TSU) docume nted by James G. Gaume 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 T SU 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. 

### Altitude Reports By Airplane Model FAA’s Enhanced Traffic Management System (ETMS) Reports for U.S.

0% 5% 10% 15% 20% 25% 30% 35% 40% 45%

707 DC - 8 727 DC

- 9/717 737 747 DC - 10 A300 MD - 80 767 757 A310 A320 MD - 11 A340 A330 777 A319 737NGReports Above 40,000 ft Above 37,000 ft First Flight of Type Prior to 1980 Commercial Aircraft above 28,000 feet

• Data represents reports from one week in Sept. 2000

• Based on position reports every 3 minutes.Enclosure to RA

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11 The MSHWG agreed addit ional data based on further study would benefit t he 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 physio logical exposure research which included s everal papers that have been circulated in the aerospace medical community , all with the objective of establishing physiological limits to occupants following cabin decompression. It 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 r ecognized Aerospace Medical Doctors address ing physiolo gical information that was considered by the MSHWG:

− James Gaume (Aerospace Medicine) authored a paper substantiating the new rule. According to Gaume, during an emergency descent from 42,000 feet t o 5,000 feet for adequate recovery of unconscious passeng ers without any supplemental emergency oxygen to the occupants, with an aircraft emergency descent of 6200 f eet p er m inute and with cabin altitude exceeding 33,000 feet, no more than 1 minute and 42 seconds is considered acceptable. Reference (9) : “ Factors Influencing the Time of Safe Un

c onsciousness (TSU) for Commercial Jet Passengers Following Cabin Decompression ” by James Gaume, Aerospace Medicine, April 1970.

− Dr. Stanley R. Mohler, a former director of CAM I (FAA ’ s Civil Aeromedical Institute), analyze d a number of actual decompression cases, including data from studies by Barron

, Reference (10), 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 li mit to protect against permanent physiological damage from a cabin decompression occurring at up to 45,000 feet. R eference (11) : “ Sudden High Altitude Cabin Decompression Immediately Threatens Safety of Aircraft Crew an d Passengers ” by Dr

. Stanley Mohler, Flight Safety Foundation, Human Factors & Aviation Medicine, December 1994.

− Dr. Robert Garner, 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 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 CAM I

- FAA Civil Aerospace Medical Altitude Rule: presented in the MSHWG in July 2002, Reference (12), P age 13, states that exposure: if unprotected

, passengers to a 41,000 feet altitude would be approximately equal t o exposure at a 40,000 feet altitude.

− “ Neurological Study of Simulated Decomp ression 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 f ee t not more than eight minutes up to peak of 36

, 000 f ee t does not cause brain damage.Enclosure to RA

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12 − “ Neurol ogical Sequelae of Prolonged Decompression, ” Aerospace Medicine, A. N. Nicholson and J.R. Ernsting, April 1967 , Reference (14) concluded that cabin altitude exposure above 40

, 000 f ee t with time exposure of 1 min ute and 30 seconds caused brain damage.

In c onsideration of the above studies, comments received on the draft Interim Policy, and the acceptance of the MSHWG report by TAEIG, the FAA established appropriate criteria for § 25.841(a) with respect to an uncontained engine failure. These criteria are mo re 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 Uncontain ed Engine Failure Aspect of Rule**  The Boeing 787

- 10 will fully comply with the latest airworthiness standards , except as noted in the 787

- 10 Certification Basis. This statement is inclusive of compliance to §§25.841(a)(2) and 25.841(a)(3), Amendment 25

- 87 i n 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) I t is clear that not granting the proposed exemption would have severe impact. This conclusion is based on the reduction in maximum cruise altitude that would result by compliance to §§25.841(a)(2) and 25.841(a )(3), Amendment 25

- 87 as related to uncontained engine failure

. This reduction in maximum cruise altitude would result in significantly higher operati ng costs base d on 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

- 10 to compete with previously certificated airplanes which can operate at the more economical cruise alt itudes typically in excess of 3 7 ,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 3 7 ,000 feet is significa nt today and the trend is for newer airplanes to cruise at these altitudes for even longer portions of their mission. Limiting operation of new generation airplanes to lower altitudes will result in higher traffic density, which in turn will result in hig her 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

- 10 will meet the latest amendments in effect at the time of application

, except as noted in the 787

- 10 Certification Basis

. The net result is that the 787

- 10 incorporates the safety advancements as intended within these later amendments. Any significant impact to the marketability of the 787

- 10 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, pre clude 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

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13 (3) As stated in (1) above, the restriction to maximum cruise altitude imposed upon the 78 7

- 10 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

- 10 fuel burn. This additional fuel burn not only increases 787

- 10 operating costs, but will also increase engine emissions (e.g. CO 2 )

.

**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 existin g fleet has demonstrated safe operations via millions of hours of flight at altitudes similar to those proposed for the 787

- 10

. The risk of rapid depressurization following an uncontained engine failure is better mitigated by a combination of proven desig n 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 safe ty 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. R obust 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

- 10 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

- 10 design i nclude 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 actuatio n.
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 t he 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

- 10 airplane :

• Design Requirement

The airplane must be designed so that occupants wi ll 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) feet for any duration; or (ii) Forty thousand (40,000) feet for o ne minute; or (iii) Twenty

- five thousand (25,000) feet for more than three minutes; or (iv) Ten thousand (10,000) feet for more than six minutes.Enclosure to RA

- 15

- 02567 Page 14 of 16

14 In calculating the descent capability of the airplane in order to meet the cabin altitude requirements, the loss of the f ailed 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 des cent 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.

**Statement of Public Interest** The Boeing Company M odel 787

- 10 fully complies with th e latest airworthiness standards , except as noted in the 787

- 10 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. Specific features h av e been incorporated into the 787

- 10 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 2 nd /3 rd generation engine de sign practices have resulted in a reduction in uncontained engine failure events and the risk of a rapid depressurization. As stated above, th e Boeing 787

- 10 will meet all the latest amendments in effect at the time of application except as noted in the 7 87

- 10 Certification Basis

. The net re sult is that the 787

- 10 incorporates all the safety advancements as intended within these later amendments

. The 787

- 10 , therefore, offers a higher level of safety than do previously certificated transport category airp lanes.

In addition , the 787

- 10 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 certificated 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 a ltitudes 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.

**Statement of No Adverse Effect on Safety** The exemption requested will not adversely af fect safety. As previously discussed, the 787

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

un con tained engine failure, the 787

- 10 preserves an even higher level of safety relative to previously certificated 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 b y 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 report, as adop ted 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.

**Request to ‘**  **Waive Publi cation**  **and Comment’**  Boeing requests to waive the requirement for publication and comment based on similar exemption s granted to the following aircraft: 737

- 7/

- 8/

- 9,787

- 8/

- 9, 767

- 2C 747

- 8, 747

- 8F, ERJ 170, ERJ 190, A380, and A350.Enclosure to RA

- 15

- 02567 Page 15 of 16

15 **Privileges of the Exemptio n**  **Outside the United States** 
Per 14 CFR 1 1.81(h), Boeing requests that the privileges of this exemption be extended outside the United States. This extension of privileges is necessary for operations based within foreign countries having bilateral agreemen ts with the United States accepting FAA 14 CFR part 25 as their airworthiness standards for transport category aircraft. T he 7 8 7

- 10 is intended for the global market place.

**Conclusion**
The information in this petition for exemption provides evidence that c ompliance with §§ 25.841(a)(2), and 25.841(a)(3), with respect to an uncontained engine failure, provides no increase in safety. The 787

- 10 provides advancements in technology and safety relative to previously certified aircraft. Grant of this petition p rovides the public the benefits of the 787

- 10 airplane. Operators w ill be able to operate the 787

- 10 where it is most efficient and therefore will not face higher operating costs due to increased fuel burn. Further more, reduced fuel burn will lead to lo wer engine emissions resulting in positive impact to the environment. By grant ing this petition for exem ption the true benefits of 787

- 10 will be realized, causing no adverse effect o n safety

.

**Summary to be Published**  **in the Federal Register**

PETITIONER : Boeing Commercial Airplane s

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 fai lures for the B oeing Model 787

- 10

.Enclosure to RA

- 15

- 02567 Page 16 of 16

16 **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: INFORMATION : Interim Policy on Amendment 25

- 87 Requirements FR Doc. 03

- 13541, Iss ued 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, Pub lished 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 ACCI DENT NATIONAL AIRLINES, INC. ,DC

- 10

- 10, N60 NA NEAR ALBUQUERQUE, NEW MEXICO

, N ovember 3,1973 7) Uncontained Engine Failure Fuselage Hole Analysis, Draft Technical Note, October 2001 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

, Gaume , 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 an d Passengers
, ” Flight Safety Foundation, Human Factors & Aviation Medicine, December 1994 12) Draft White paper issued by CAM I

- 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 Decompressio n, ” 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 11/2 006 16) Statistical Summary of Commercial Jet Airplane Accidents, Worldwide Operations, 1959

- 2011, To be published by Boeing Commercial Airplane