Exe mption No. 14821

UNITED STATES OF AMERICA DEPARTMENT OF TRANSPORTATION FEDERAL AVlATION ADMINISTRATION RENTON, WASHINGTON 98057-3356

In the matter of th e petition of
The Boeing Company
for an exemption from§ 25.841(a)(2) and (a)(3) of Title 14 , Code o f Federa l Regulations Regulatory Docket No. F AA-2015-3366

PARTIAL GRANT OF EXEMPTION By letter no. RA-1 5

- 02563 , received June 25 , 20 15 , Mr. Gary E. Nagai, Project Adm inistrator , T h e Boeing Company , P.O. Box 3707 , Seattle, WA 98 124-220 7 , pet iti o ned to exempt the Model 787-10 airp lane from th e requirements ofTitle 14 , Code of Federal R eg ul at ions (14 CFR) 25.84 1 (a)(2) and (a)(3), as a mended by Ame ndm ent 25 -87. If granted , the exempt ion would re l ieve these a irpl anes from the re quire ment that , during a decompression ca u sed b y an un containe d fa il ure of one of the engines , airpl a ne cabin pressure altitude d oes not e xceed 25 , 00 0 feet for more than two minu tes, or exceed 40, 0 00 feet for any duration

. In ad dition to th e materials Boein g s ubmitted, wh ich were po sted in the docket , Boein g also prov ided the F AA a dditional proprietary information. This information i s used in th e FAA's analysis ofthis exe mption. The petitioner reque sts relief from th e following re g ulations: Section 25.84 1 (a)(2) at Amendment 25-87 , requires that " Th e airpl ane must be designed so that occ upants will not be expo sed to a cabin pressure altit ud e that exceeds the follow in g afte r decompression from any failur e cond itio n not s hown to be extremely improbabl e: (i) Twenty-five thousand (25 , 000) feet for more than 2 minutes; or ( ii) F orty thousand (40 , 000) feet for any duration. " Se ction 25.841(a)(3) at Amendm ent 25-87 , requires that "F uselage structure, engine and system failur es are to be considered in eva lu at in g the cabi n decompression. "The petitioner supports its request with the following information: This sec t io n summarize s the petitioner's request. The complete petition i s available at the Departm ent of Transportation 's Federal Docket Man agement System, on the Internet at http: // regulatio ns.go v, in docket no. F AA

- 20 15-3366.

The Boeing Model 787-10 airplane i s designed to opera te at a maximum cruise altitude of 41,100 feet pre ssu re altitude. Should an uncon ta in ed engine -rotor burst event occur, it is po ss ible that the cabin pressure could exc eed the limit s contained in current regulation s. Boeing offers the following justification in support of its petition for exe mption. Some of this justification is based on cabin-decompression eval uation s p erformed and report ed by the Mechanical Systems Harmoni zation Working G roup (MS HWG ) under the auspice s of the Avia tion Rulemaking Adv i sory Committee (ARAC). 1 The Boeing Company requests an exe mption from compliance with§§ 25. 84l(a)(2), and 25.84 1 (a)(3) for cabin depressuri zat ion that can occur from uncont ain ed e ngine-rotor failu res that result in large hol es in the fuselage. Boeing states that , based on fleet service exper ie nce, these even ts are rare. The Model 787-10 airplane complies with the latest FAA requirement s a nd , therefore , offers a significantl y higher basic level of safety than previously certified transport-category airplanes. Modern transport-category airplanes have a 53-year safety record with millions of hours at altitudes similar to the maximum cru i se altitude proposed for the Mod e l 787-10 airplane. In addition , Boeing claims th at ne ither the Joint Airworthiness Aut horiti es nor the European Aviation Safety Adm ini stration h ave implemented s imilar restriction s
. Boeing notes that very few, if any , d ecompression incidents have exposed an airplane cab in to pressure-altitude profiles that pose a ri sk of injury to pas senge r s. T ransportcategory-airplan e industry history reveals that few cases of catastr ophic decompressions at hi gh altitude h ave occurred , and those that have occurred have typically involv ed sma ll business jets, acco rdin g to Boeing. The FAA has cited a few cases of rotor burst in cruise, according to Boeing. In one s uch in stance, the c r ew of a DC-I 0 cross in g New Mexico reported several case s of initial decompression sickness, apparently with no permanent mJunes. In addition, Boeing acknowledges 121 additional fatalities related to hypoxia from the H e lios Airways Fli ght HCY522 accide nt. Ho wever, Boeing correctly states that this accident was not due to a system , st ructural , or engine-failure event , but a failure of the flightcrew to prop e rl y configur e the pressurizat ion sys tem , and a s ub se quent failure to recognize that th e airp lane was not pressurized after takeoff

. Boe ing supplied the results of analysis for the Model 787-10 airplane , powered by RollsRoyce Trent and Gen e ral Electric G E nx engines, and provided information on the likelihood of various engine-fail u re eve nts. In it s d eco mpression analysis, Boeing included a measure of the severity of exposure for occupants, based on a Depressurization Exp osure Integral (DEI) from the Mechanical Systems Harm onization Working Group report on 25.841(a)(2) and (3). Boeing u sed th e r e l at ion ship between

1 The Final Report of the MSHWG , dated August 2003, was approved by a majori ty of the members of ARAC's Transport A irplane Engine Issues Group (TAE IG ). Seven members ofTAE IG vo ted to submi t th e report as a recommendation to the FAA , two members voted against s ubmittin g the report , and one member abstained.

2cabin pressure and the Depressuri zation Sever it

y Indicator (DS I) , which is a measure of the partial pressure of oxygen , as was proposed by the Mechanical Systems Harmonization Working Group. The petitioner s howed that, for the fai lure modes reviewed for thi s exempti on, the resultant DSI levels were much less than the critical valu e specified by the MSHWG. The analysis considers certain design and operational features of the Model 787-10 airplane that would mitigate the effects of an increase in cabin pressure altitude. These desi gn features include redundancy of key systems, such as electrical power, pa sse nger oxygen , cab in pressure control, and spoi ler actuation. The Model 787- 1 0 airplane is des igned to fly at cruise altitudes that will maximize fuel efficiency. The reduction in maximum cruise a ltitude resulting from comp liance with §§ 25.84l(a)(2) and 25.841(a)(3) for uncontained engine failure i s a concern shared by other manufacturers of airplanes with wing-mounted engines seeking new or amended type certification. No transport-category airplane with wing-mounted engines certificat e d today for operation above 39 , 000 feet can meet the new cabin a lti tude limi ts w ithin the current§§ 25.841 (a)(2) and 25.841(a)(3) without an exemption. The Bo e in g Company mitigates risk to hi g h cabin-altitude exposure by reasonable design requirements , proven design methodo log ies , and operational considerations regardless of the cause of th e decompression event. It is intended that the proposed exemption addresses the intended concern for safety without imposing the operational economic penalties driven by §§25.84 1(a) (2) and 25.84 l(a)(3) as currently written. Safety enhancement initiatives with re s pect to critica l rotating parts (inspecti n g for cracks in disks and u s ing continually updated maintenance data to refine disk-inspection criteria), as well as improvement in engine techno logy, lessons learn ed, and second

- or third -generatio n eng ine-design practices, have resulted in a reduction in uncontained engine

- failure events. The uncontained eng ine-failure rate s of second- or third-generation engines compa red to fir st -generation engi n es , have impro ved by ap proximately 95 percent based on historical Boein g data on uncontained eng i ne fai lures. Restricting airplane operations to lowe r a ltitudes will increase traffic congestion. Limiting operation of new generation airplanes to lower a lti tudes will result in higher traffic density , which, in turn , will result in higher cost of safety to maintain established air-traffic vertical and horizontal separation requirements. The Model 787-10 airplane will meet the latest amendments in effect at the time of application , exce pt as noted w ithin the Model 787-10 airplane certification basis. The net result is that the Model 787-10 airplane incorporates all the safety advancements as intended within these l ater amendment s
. Boeing states that any s ig nifi cant impact to the marketabi l ity of the Model 787-10 airplane will , at a minimum , result in a reduced number of airplanes with this higher level of safety as compared with the previous generation of a irplanes , or at a maximum , prevent the manufacture of this new generation of airplanes. In either case, Amendment 25-87, according to Boeing , results in a reduc ed potential for overall aviation safety impro vemen ts. Boeing ' s petition reiterates that this request for exemption from §§ 25.841 (a)(2) and 25.84 1 (a)(3 ) is li mited to only uncontained engine fa ilure s. For other sou rc es of rapid depressurization , including system failure s and spec ifi c structural fai lures , §§ 25.84 1 (a)(2) and 25 .841 (a)(3) will be compl ied w i th as amended by Amendment 25-

387. All mechanical or functional interfaces that could potentiall y violate the physiological limit s imposed by 

### § 25.841(a) are cons idered. Robust struc tural 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 ofthe Model787-IO airplane design. The Boeing Company states that its design practices refine the req uirements into sub-requirements for systems, structures , aerodynamics , and performance to assure airp lane-level compliance. Other threat minimization philo sop hi es employed in the Model 787-1 0 airplane design include an automatic pressure demand mask (FAA-approved for 45,000 feet) for the pilots, which will be certified to§ 25. 144l(d) ; and separat ion and redundancy ofkey systems suc h as e lectrica l power , passenger oxygen , cabin-pressure control, and spoiler act u ation. The petitioner's statement of public interest: With respect to uncontained engine-failure events, the impact of§ 25.84 1 (a), Amendment 25 -87 , to the aviation industry and the flying public is significant. The "i mpact " of comp l iance takes three forms: (1) increase in air traffic congestion , (2) reduced potential for overa ll safety improvemen ts , and (3) e nvironmental. I

. Restricting a irplane operations to lower altitudes will increa se traffic congestion. Boeing cited three studies s howing that the numbers of transport-category airplane operations above 37 , 000 feet are significant today and the trend i s fo r newer airplanes to cruise at these altitudes for even long er portions of their mission. Limiting o p eration of new-generation airplanes to lower altitudes wi ll res ult in hi gher traffic density , w hi ch, in turn , will result in higher cost of safety to maintain es t ablished air-traffic vertical and horizontal separation requirements. 2. Since th e re lease of Amendment 25-87, a number of amendm e nts to 14 CFR part 25 have been released. Each of these amendments has the int ent of an increase in aviation safety. The Model 787-10 airplane wi II meet the l atest amendments in effect at the time of application, except as noted in the 787-10 certification basis. The net result is that the Model 787-10 airplane incorpora tes the safety a dvancem ents as intended within these lat er ame ndmen ts. Any s ign ificant imp act to the marketab ility of the Model 787-10 airplane will, at a minimum, result in a reduced numb er of airplane with this higher level of safety as compared with the p revious generation of airplane , or at a maximum, preclude the manufacture of this new generation of airplane. In either case , Ame ndme nt 25-87 results in a reduced potential for overall aviation safety improvements. 3. The restriction to maximum cruise altitude imposed upon the Model 787-10 airplane due to compliance with§§ 25.84l(a)(2) and 25.841(a)(3), Amendment 25-87, as re lates to uncontained engine fai lure , has a significant adverse impact on Model 787-10 airplane fuel bum. This add iti onal fuel burn will increase engin e emissions , such as C02. Federa l Register publication The FAA has determined that good cause exists for waiving the requirement for Federal Register publication for public comment because the request is identical in all material respects to

4previously gran ted exem pt io n s; the exempt io n , if granted, wou ld no t set a p recede n t; and any d e la y in act in g on this petition wo uld be detrimental to B oei n g. The FAA's analysis Th e Boeing Co mpany provided the fo ll owing information t o suppo rt it s application fo r exemption f ro m §§ 25.841 (a)(2)( i) and (ii) a nd 25.841 (a)(3):

• a background of th e c urrent rule and recent acti v iti es t o harmoni ze it ;
• a review of the safe ty history of hi g h-altitude commercial flight ;
• a discussion of h y p ox ia physiolo gy data upon which recent rulemakin g activ itie s are based;

• a discussion of the impact o f compliance with unc o nt a ined engine-rotor-burst aspect s of the ex i st in g rule;

• e n vi ronmenta l and ai r traffic considerations; and,

• state m e nts address ing pub li c int e r

es t a nd n o adverse impact to safety. Boein g provided company proprietary data o n the es timated cabin pressur e altitude and airplane fli ght-a lti tude- time hi s tory plots that follow e d decompress ion s per emergency descent procedur es, an d a description of the Bo e in g methodology of eva luating the threat from an un contained e n g ine - rotor burst. 1. Need for exemption B oeing requests relief fro m § 25.84 1 (a)(2)( i), w hich s p ec ifi es th a t ca bin pr ess ur e altitude m ay not exceed 25,00 0 feet for more than two minut es after d e c o mpr ess ion fro m any fa ilure condition not s h own to b e ex tremely improbab le
. A g rant of exe mption from thi s regulation would allow the M ode l 787-1 0 a irpl ane, to take longer than two minute s to descend from 41, I 00 f ee t to 25 , 000 feet after suc h decompression. B oeing a l so requests re l ief fro m § 25.841 (a)(2)( ii ), w hi c h speci fies tha t cabin pressure altitude may not excee d 40 , 000 feet for any durat io n after decompr ess ion from any failure con diti on not shown to b e ex tremel y improbable. A grant of exe mption from thi s regulation wo uld allow th e Mod e l 787- 1 0 cabin pr ess ur e a ltitud e to exceed 40,000 feet after s uch decompression. Boeing h as state d that th e 787- 1 0 design will meet the requirements of§ 25.841 (a)(2)(i) and (i i) for all system and structural fai lure s, but not for a ll types of engine fa ilur es. For some uncon t ained eng in e-rotor fa il ures th a t resu lt in pressure
- vessel p e netrat ion by fragmen ts , the desi g n of the Model 787-10 a irpl ane do es not mee t the requ irements of§ 25.84 1 (a)(2)(i) and (i i). A grant of exe mpti on from this regulation would allow the Mode l 787-10 airp lane to operate up to 41 , 1 00 feet , which could briefly expose cabin occup an t s to this altitude in the event of a worst-case decompression: a rotor burst creating a large hole in the fuse lage. Finally , Boeing requests relieffrom § 25.84 I (a)(3), which requires that an airp lan e manu facturer consider fu se la ge structure, e ngine , and sys t e m failures whe n eva luating th e cab in pressur e alt itude fo llowing a d ecompress i on due to one of th ese fa ilu re eve nts. A s noted in the preamb le to this regulation:

5Possible modes of failure to be evaluated include malfunctions and damage from external sources such as tire burst, wheel failure, uncontained engine failure, engine fan, compressor or turbine multi blade failure, and loss of antennas

... The FAA's analysis shows that Boeing did consider these failures in its analysis. Therefore, the petition e r comp li es with § 25.84 1 (a)(3), eliminating the need for an exemptio n from it. 2. Analysis under FAA policy The FAA reviewed this petition, in the context of the MSHWG Final Report on§ 25.84l(a)(2) and FAA policy memorandum ANM-03-112- 1 6, dated March 24, 2006, on Amendment 25-87 requirements. The polic y applies only to decompression events that are du e to uncontained engine-rotor failure. Th e basis of the po li cy is data from research on the response of humans and other primates to changes in ambient pressure. Evaluation of this data indicate s a direct correlation between the alveolar partial pressure of oxygen time integral and the likeliho od of fata liti es or permanent physiological damage to those exposed to such pressure changes. That is , as the value of the integral increases , the likelihood of fatalities or permanent physiological damage also increases. The FAA polic y contains a table of altitudes and cumu lative exposure times in lieu of the pres s ure-time integral. The values of altitude and time in the table , and the results of the pressure-time integral method, are in agreement. Accordingly, our policy focuses on minimizing the likelihood that, if a person i s exposed to high-altitude cabin pressure from any failure not shown to be extremely improbable, they wi ll suffer permanent physio log ical damage. To ana lyze petitions for exemption from§ 25.84l(a)(2) , the FAA requires informat ion about emergency descent rates , any design features that incr ease such rates , other design features that offset the inherent increased risk of expos ure to highaltitude cabin pressure, and operational procedures. As stated above and in the policy, the FAA acknowledges a lack of relevant data on the effects of exposure to high-a ltitude cabin pressure following decompr ess ion and , particularly, those effects on people of vario u s ages , peop le wit h c i rculatory or re spiratory diseases , or certa in other medical cond itions. Our review of the Boein g petition indicate s that Boeing used the criteria recommended in the FAA's pol icy. Boeing's de s ign incorporated these limits to e nsure airp l ane descent performance. Thi s methodology is conservative because it assumes a lower partia l pressure of oxygen than wou ld lik ely be present dur ing decompressio n at 41,100 feet. Bo eing provided descent profiles for the Model 787-10 airp lane, based on conservative estimates of descent performance for failure scenario s, as described in the FAA's policy; d escen t profiles indicate that the Model 787-10 airplane can descend rapidly from 41 , 10 0 feet to be low 25,000 feet. Boeing also performed a depressurization analysis on both types of engines used on the Model 787-10 airplane , Roll s-Royce Trent and General Elec tri c GE nx engi ne s , whic h were based up o n maximum cru i se fli g ht conditions

. It defined the envelope of vulnerability of passengers following fai lures that result in a decompression

. In addition , Boeing identifi ed design and operationa l features of the Mode l 787-10 airplane that would mitigate the effects of an increase in cabin pressure altitude.

6The decompression analysis used several measures recommended in the MSHWG Final R eport. Specifically , Boein g es tim ated th e severity of exposur e to high-altitude cabin pr ess ure for occup ants , based on ca lcul at ion of a DEI. T he ana ly s i s al so co n s idered the r e lati o nship b etwee n ca bin pressure a nd th e DSI , a measure of the partial pr essure of oxygen
. T he an a lys i s indi cates that the phys io logi cal effec t of a s light increase in the length of time spent above 25,00 0 feet is wi thin the uncertainty band of avai lable physiological dat a. The Boeing analysis also shows that , for the failure modes re v iewed for this exemption , re s ultant DSI levels were muc h less than the critical value recommend e d by the MSHWG. The FAA rev iewed inform ation Boein g prov ided about design feat ures and operationa l procedures that would miti ga te the thre at of a high

- al t itude rapid decompression as it relates to maint ai nin g the descent capab ility of the Mode l 787- 1 0 a irp lane and to e n sure occupant surv i va l. We conc lud ed that the design features and operat ional procedures associated with rapid decompress ion , followed by an emergency d esce nt , support a finding that g ra nting the exemption would not adverse l y affect sa f ety. 

### 3 . Review of historica l da t a an d researc h The F AA rev iewe d databases fro m its Natio n a l Av iat ion Safety Data Analysis Ce nter, cove ri ng 195 9 to 20 1 2. Approximately 3,00 0 in stances of loss of cab in pressure h ave occurred s inc e 1 959. System fa ilures , such as cabin-pressurization-controller fa i lures and valve fa ilures; and structural failur es , s uch as door

- sea l fa il ure s , have c au se d the vast majority of these events , which typic a ll y have b een recognized at low altitude within a few minutes after takeoff

. Pil ot erro r has also contributed to the number of eve nts
. The majority of these events have not s ubj ected the occupants to expos ur es above 25,000 feet (an altitude co n si dered physio l og ica ll y s i gnificant). The cabin pressure altitude in most events did not exceed 15 , 000 fee t (the cabin pressure a ltitude at which passenger o xyge n ma s ks are depl oye d). Similarly , uncontain e d e n g in e -rotor-bur st failures tend to be very rare. A simple calculation shows that grou pin g a ll eng in es and transport airplanes together y ield s an average probability of an un co ntained e ngine fa ilu re at cruise of a pproximatel y 1 x 1 

## o- 7 per eng i ne hour. New engine design s a ppear to redu ce thi s probability by an o rd e r of magnitude. We found , as noted in the MSHWG report on§ 25.841 (a), that no fatalities from hypoxia were due to in-flight rapid decompress ion events a s e nvisioned by Amendme nt 25 -87

. The data indicat e that decompress io n is not a sig nificant cause of fatalities. It i s because the se events a re so rare th at the FA A consider s the risk to be acceptab le. In a ddit io n , Boeing provided the FAA with propr i etary data from its analysis of uncontained eng in e-rotor fai lure s , and the size and number of hol es in the fuse lage resu lting fro m such fa ilur es. Us in g historica l serv ice data and theoretical values , Boeing perform ed decompress io n analysis for seve ral scenarios. Boeing ana lyzed th e probability of uncont ained e ng ine

- ro to r fai lure and of penetration of the fuse l age o f the Model 787 -1 0 airp lan e from fragments of var io u s sizes , from both engine s, resulting from s uc h failures. Thi s ana l y sis was used to assess t h e threat of s uch an eve n t to occupa nt s ofthe airp lane. T h e F AA did not agree with Boeing ' s excl u s i on o f data in the ir a n a ly sis th at conce rn ed large ho les in the fuselage ca using decompression. However , Boeing's ana lys i s was conducted i n a manner consistent with the recommendations w i t hin the MSHWG r epor t , a nd the ir data s howe d that even for the largest s urv ivable hole, th e Model 787 -1 0 airplane wo ul d be ab le to meet the FAA ' s po l icy cri te ria.

7The 17 J\J\ concurs with the pe t itio ner that un co ntained eng in e -rotor failures a r c rare events. F

urth e rm o re, our anal ys is in this case is s imil a r to our anal ys is of an ea rli er pe tition for exemp ti o n , f rom a different applicant, fo r an a irpl ane wi th a n intended crui se a ltitude of 41,000 tee t. Th e petition submitted by this pr evious applicant included es timat es or the probability or occurrence of a n uncontain ed e ngine-r oto r fa ilu re. In that case. the altitude exc ur s io n above 4 0

. 000 feet wa s less tha n 1. 000 feet. We co n c lud e d that th e risk associated wi th ex posur e of the occupants to the slightly hi g her altitude was esse ntiall y th e sa me as the ri s k of ex p os ure at 40.000 t ee t. In other wo r d s. the ri s k tl·om ex posu r e at altitud e was esse ntiall y the sa me with or without th e gran t of the exe mption

. Therefor e
. th e rar it y of uncontained engine-rotor failure s did not sig ni ticantly enter into consideration r ega rding the pr ev io u s grant of exemption. 4. Usc of s uppl e m e nt a l oxygen As discu sse d below. the 

## r J\J\ has anal yze d th e Boeing petition in the cont ex t or the MSHWG recomm e ndations , th e part 25 requirem e nt s pertaining to s upplemental oxygen. and certain technical s tandard s for s uppl emen tal- oxygen equipme nt. Sec tion 25.1441 (d) requ ir es approval o r oxygen eq uipment for airplanes that are app r ove d to operate above 40.000 feet a ltitude. Section 25.1443 specif i es th e minimum ma ss tl ow or supp lem en ta l oxyge n for f 1i g ht c rew and passenger oxygen sys te m s up to a cabi n altitude of 40.000 feet. Part 25 d oes not contain s ta ndards for oxygen sys tem s abo ve 40.000 feet. Howev e r, FAA Techni ca l Standard Order s ( T SOs) pro v id e re quireme nt s for tlightcrew di Iuter demand pressure breathin g regulators (TSO-C89a) and tlight crew dema nd oxygen masks (TSO-C78a) up to 45.000 feet. In additi on
. th e Soc iety of A ut o mo ti ve E ngineers (SJ\E) S tandard AS 8027 pro v id es spec ification s for diluter demand pre ss ur e brea thing reg ulat ors u se d by th e flightcrew up to 45,000 f ee t. As pa rt o r the certification for the Mod e l 787-10 airplane. Boeing must s ub s tantiat e the ad eq uac y o f the t1 ightcrev, , supp le me nta l-oxygen sys t e m for operation above 40.000 fe e t. Flight c rcw pressure-b rea thin g eq uipm e nt is ge ne ra ll y us e d to provide hy po x ia pr o tection a t hi g h cab in pr essu re altitudes and req uire s training to ens ure eftec ti ve u se
. Pr ess ure breathing requires ph ys ical ef f or t to exha le and minimal effort t o inhal e. Thi s reversal of the normal br e athin g cycl e can lead to hyperve ntilation. The fAA co n s ider s the trainin g of passengers to u se pressur e breathing equipme nt safely to be impr act ic al. The FAA d e te rmin ed that a n acceptable mean s of compliance for the fixed and portable oxy ge n sys tem s u sed by Oight attenda nt s and passeng e rs wou ld be t o in s tall oxygen eq uipment that is certificated to 40 .000 feet and limit ex posur e to the reduced pressu re e nv ironme nt above 40.000 feet v ia airpl ane-desce nt performance. Th e FAA believes that. ultimate ly . occupant survival during a decompression eve nt depe n ds upon swift descent to a lower altitude. In it s review of th e petitioner's a irpl a n e -d escen t profi le
. the F A/\ finds th at th e Mod e l 787- 10 airpla ne can descend at acceptable rat es
. 5. Co nclu s ion ofF AA analysis Pe rm itting ai rplan es to tly a b ove 40.000 feet o f fe rs real and tangible benefits to the aerospace industry, the traveling public. and the U.S. eco nomy by reducing congestion, improving fue l economy. a nd reducin g poll ution. I f compliance w ith § 25.84 1 at Amendment 25 -87 we re to limit a irpl ane operati ons to a maximum alt itud e of 40.000 f ee t , it wo uld imp ose a significant disadvant age on new ly d es i g ned airplan es th at ha ve man y sa fet y advantages ove r older a irpl anes currently a ll owe d to opera te at hi g he r a ltitud es. Thi s wo uld de lay th e introduc ti o n of th ese airp lanes and the safe ty benefi t s of their more
- ad va nc ed technology

.

8B ased upo n eva lu ati o n of th e data an d analys is Boe i ng p r ovided. th e FAA has de t e rmin ed that g rantin g thi s exe m pt io n wo uld no t ad ve rse ly affec t sa f e ty . is in th e pub li c int e res t , and t he re f o re that th e r e i s s uffic ie n t j u s t i fica tio n f o r a p art ia l g rant o f exe mp ti o n fr o m 

# * 25.84 1 (a)(2)( i) and ( ii ). T hi s partia l grant or exemption does not provide relie f from 14 CF R 25.841 (a) for any o th e r sys t e m a nd s tru c tu ra l fa il u r e eve nts no t s h ow n to be ext r e me ly i mpro b able. T h e pe titi o ne r mus t de mons trate co mp li a nce fo r those f a il u r e eve nt s
. a nd th is pa rti a l g rant i s p red i ca t ed on th e cond it io n that th e pe ti tio ne r s uc ce ss f u ll y de mo n s trates c o mp li anc e f or t he B oe in g Mode l 787

- 10 ai r pl ane. As no t e d in the M S HWG r e p ort o n § 25 .8 4 l (a)

. a t i re b urst in flig ht is not ex treme ly i mp r obab l e
. as de m ons tr ated by hi s tor ic data. Th e ground loads for tires are no t app l icab le in tl ight a nd f o r thi s co ndi t ion tires are extre m ely rob u s t. Acco rd in g to the preamble of § 25

.729(1)( I ) and hi s toric da ta
. t ir e burs t s occu r in fl ig ht. It is ve ry di ffic ult t o de mo n s tr ate th a t tir es c an no t be bur s t in case of o verh eat. It ca nn o t be d e mo n s trated tha t ti r es do no t bu rs t in hi g h

altit ude fl igh t. The re for e, th e t i re- burs t eve nt mu s t be c o n s id e re d in the de pr ess uri z at ion anal ys i s. I n addi ti o n
. press ure-vesse l ope ni ngs res ulti ng f ro m loss of a nte nn as or sta l l wa rni ng vanes. o r any system

**f~1 ilur** 
**e** co nd iti ons tha t are not s how n to be ex tre mely i mp robable. mus t be co n s idered. T h e e f fects of s uc h da mage
. w h ile o pera tin g u n de r max imum no r ma l cab in pr ess ure di tTe r en ti a l, mu s t be eva lu ated. A lso, s tru c tur a l c rac k s mu s t be ad dre sse d as per the ex i s ti ng A me ndm e nt 25 -87 pr ea mb le, i.e. , T he max imum press ure-vessel ope nin g resu ltin g f ro m a n ini t ia ll y detec tab le crack propaga ting l o r a per iod e ncompassi ng fo ur normal i ns pect io n i n terva ls. Mid p ane l cracks a n d cracks th r o ugh s ki n str inge r a nd s ki n l'ra m e co m b in at i ons m u st be eva lu ate d

. In ad d ition. th is p ar ti a l g ra nt of exe mp tion is pred ic at e d o n th e r e quire m e nt tha t th e B oe in g Mod e l 787

- 10 a irpl a ne s uccess full y d e mo n s tra t es co m pli ance to§§ 2 5

. 14 4 1. 25. 1443 ,2 5

. 14 45, 25 .1 44 7 a nd 25. 144 9

. T h is p artial g r a nt of exemp tion takes int o accou n t ope rat ing ru les i n 14 CF R parts 9 1 , 1 2 1 . and 135 w h i c h r e quire (a) tha t one pilot wea r an d u se an oxyge n mas k w hen operati n g above 4 1 .000 f ee t a lti tude and (b) tha t an adeq u ate qu a ntit y o f oxyge n i s p r ov ide d f or c r ew o pe r a tio n s. T hi s p ar tia l g r a n t o f exe m pt io n is al so pr e mi se d o n th e con d it io n s th at : I

. The cer ti fi cat io n tl ig ht tes t co ndu c ted. to prov id e data tha t co rr obo rate th e desce nt p ro fil es used in th e applica n t· s analysis

. and to show tha t. after decomp ression at an ai r plane i ndicated operat i ng p r essure altitude of 41, I 00 feet, the cabi n pressure alt i tude will not exceed 25

. 000 feet for mo re tha n 3 mi n utes or 40,000 fee t f or more than I m i nu te, s ho ul d be co nd uc ted w ith th e e n g in e - powe r se tti ng o f the r a il e d e ng in e se t at id le
. Du e t o th e un ce rta int y o f' th e s t a t

e o f a n e n g ine fo ll owi ng a n unco nt a ined e ng ine fa il ure, it is no t poss i b le t o acc u ra t e ly s imu late th e resulting aerody nam ic engi ne- nace ll e drag as wou ld occur in !lig h t. R at her than requi re multip le flig ht tests or ana lyses to address th is issue, the FAA has dctcnnined tha t se tt ing the fa i led e ngine t o i d l

e th r ust provides an accep tab l e configu rat ion. 2

. If d ispa tc h i s d ee m ed ap p ro pr iate w ith a mal fu ncti o nin g syste m th at is r e quire d to e n s ure th at th e a ir p l a ne is ca pab le o f pc r fo nn i ng a n e me rgen c y d escen t (i.e

.. s p o il e rs full y de pl oy ed

. if app ropria t e: max im um desce n t rate : maximum ope r ating l imi t VM o/Mi\
· Jo speed). th e Maste r

9Minimum E quipm e n t List (MME L) mu s t l imit d ispatc h t o a max inwm flight altitude of 40 ,00 0 f ee t. unless o th e r regulation s o r lim i tation s r equi r e a lower a ltitu de. Though V ;.., of Mt- 1 

### o is norm a ll y th e bes t speed for a rapid decomp ress ion de scen t , the pi lots s ho uld follow the recomm e nd ed e me rgency desc e nt procedures in th e A i rplan e Fli g ht Manu a l (/\F M). Rath e r th an plac e an MMEL di s p atc h li m itat io n as an explicit cond iti o n of granting th e exemp tion. the FAA ha s determined tha t it is appropriat e for th e FAA F li gh t Ope rat io n s E

va l ua ti on Bo ard to evaluate th e matter of dispa t c h wi th a malfun ct io ning sys t e m that is requir ed to ens ure that th e a irplan e is capable of pe rforming an e m e rgency desce nt. 3. T he appl icab le rap id d eco mpression p r oce du res tor the t li ghtcr ew mu st be in c l uded in th e emergency procedures sect io n ofthe A f M. This in fo rma ti o n s ho uld a lso be in c l uded in the 13 oe ing Fl igh t C re w Oper atin g Manual. No t e that ini tial and recurren t e m e r gency training for all crcwme mb e r s. in accordance wi th §§ 1 2 1. 39 7. 121.417. and 12 1. 427

. mu s t include training l o r a rapid decompres s io n and do nn ing of oxyge n ma s ks
. R

egarding th e pro v isions of§ 25.841 (a)(3)

. the petiti o ne r inclu ded in its anal ys i s conside rat io n of e n g ine failures. In additi o n. as part of th e normal ce rtification process, th e petitione r will cons id e r fuse lage structure and sys te m failures. Therefore , reli ef f rom thi s requireme nt is not necessa r y. Th e partial gran t of exemption from § 25.841 (a)(2)(ii) permi t s cab in p ressure a ltitud e to exceed 40.000 feet lor one minute (but not to exceed 41.1 00 fee t fo r an y duration ) a ft er deco mpression fr o m any un conta in e d eng in e failure condi t ion not s hown to be ex tre m e ly im probable

. The pa r tia l gra nt of exe mpt i on fi·om

**~** 25.841 (a)(2)( i) p e rm i t s cab i n pr ess ure a l ti tu de to e xceed 25,000 feet l or more than 2 minutes (b ut no t more th an three minute s) afte r decompression fr o m any uncont aine d engine -f a ilur e co ndition not s hown to be extre me ly improbable. allow in g time fo r the ai rplan e to d escend from an altitud e of 4l.l 00 feet to 25.000 fee t. Th e F AA 's d ec i s ion In considerat io n of the foregoing. I find th at a p a rti al g rant of exem pti o n is in th e public int erest r egarding 14 C FR 25 .8 4 1 (a)(2)( i) a nd 25 .84 1 (a)(2)(ii). as a mended by Ame n dment 25

- 87. Th ereto re
. pur s u a nt to the a uth o rit y con t ai ned in 49 U .S.C

. 401 1 3 a nd 44 701. de legated t o me by the A dmini s trator. th e petition o r B oe in g fo r an exe mp tion f rom th e re qu i re me nt s of

**~§** 25 .84 l(a)(2)(i). and 25.84 1 (a)(2)( ii ). 

### as amended by Amendmen t 2 5-87. is gra nted for Boe in g lode! 787-10 a irplane s
. T hi s part ia l g r a nt of exemption is subject to the following co nditi o n s: I

. The A i rplane Flight Manual fo r the Boei ng Mod e l 787 -1 0 a irplane mu s t indica t e that the maximum indica t ed ope ratin g pressu re alti tude is 4 1.1 00 feet. 2. The Airpl a ne Flig ht Manua l mu s t conta in a ppli cab le fli g htd eck c r ew proce dure s for a rap id deco mp ress io n eve nt

. T he sec tion o f th e A irpl ane Flight Manual tor the B oe in g Mo del 787-10 airplane. which pe rtain s to actions in the eve nt or a decomp ression. must state that the flightd eck crew shou ld initiat e a desce nt at the maximum rate of descent and safe d esce nt speed. w hich is t ypica ll y the maximum operat in g spee d (VMo/ M r-.
. ,o). assuming s tructural integrity of the ai r plane.

10

### 3

. T he p e t it io n er mu s t s ub mit ce rti li cat io n tl ig ht

- tcst da t a lor th e Boeing Model 787

- I 0 that co rrobora t e t he desce nt p r ofiles u se d in th e analysis, to s how th at afte r decompression at an a irpl ane indicat ed operat i ng pressu r e altitude of 4 1.1 00 feet. the cabin pressure a lt itu de w ill no t exceed 25,000 feet for mo r e than 3 minute s o r 40.000 tee t for more than I minut e
. 

## JAN 1 2 2016

Michae l Ka szycki Ac ting Manage r. Tra nsport A irplan e Dir ec tora t e Air c raft Certi l ication Service

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