] o f4 G E Aviatio n -X^- H • I - ' .^ i Genera l Electri cCompany , BBC1 5 P . O . Bo x156301 , On e Neuman n Wa y , - , . , . ^

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Cincinnati , O H 45215-630 1 ' i: - J , 51 3 243-947 8 51 3 243-947 8 FAX Emai l Paul.Hill1igge.co m bcc : File/L B GEnx/PAH/034/1 1 Jul y25 , 201 1 U.S . Departmen to fTransportation , DocKetManagemen tSystem , 40 0 7* ^ Street , SW. , Roo m P L401 , Washington . D C 20591-000 1 GO : Federa l Aviatio n Administratio n Ne wEnglan d Regio n 1 2 Ne wEnglan d Executiv e Par k Burlington , M A0180 3 Subject : Petitio n fo rExemptio n t o FA R 33.83(d ) fo rGEnx-2 B (al l models ) Aircraf tEngine s Gentlemen : I n Jul y201 0 Genera l Electri cwa s grante d a n amende d typ e certificat e whic h include d th e GEnx GEnx-1B54 . GEnx-1B57 , GEnx-1B64 , GEnx-1B67 , GEnx-1B7 0 an d GEnx-2B6 7 turbofa n engines . I n Octobe r201 0 G E mad e applicatio n fo rsevera l GEnx-2B6 7 derivativ e models . Thes e model s ar e ye tt o b e certifie d derivative s o fth e currentl ycertifie d GEnx-2B6 7 whic h i s liste d o n typ e certificat e E00078NE . Wit h th e pursui to fincrease d fue l efficienc yan d subsequen ttechnolog yenhancement s o f moder n commercia l aircraf tsom e olde rsection s o fth e FA R ar e no ti n lin e wit h moder n aircraf t an d turbin e engin e desig n philosophies . On e o fthes e section s i s 33.83(d ) [vibratio n survey ] whic h wa s introduce d i n th e 1960's . Airframe rdesigne d engin e inlet s ar e designe d t o optimiz e aircraf taerodynami can d acoustica l efficiencie s thu s enhancin g aircraf tfue l efficiency . I n som e case s th e engin e inlet s ar e designe d suc h tha tairflo wint o th e inle t separate s abov e certai n cros$win d level s thu s causin g increase d engin e fa n blad e an d engin e fa n outle tguid e van e (OGV ) vibratorystress . Thi s i s th e case fo rth e Boein g 747- 8 (al l models ) an d th e GEnx-2 B (al l models) . A tcrosswind s abov e 2 5 knot s an d a t lo wrelativ e aircraf tforwar d velocitie s (take-of f roll ) th e airframe rdesigne d inle tca n hav e separate d ai rflo wthu s causin g a transien tviolatio n of 33.8 3 (d ) fo rth e engin e fa n blade s an d engin e fa n outle t guid e vane s (OGV's) . Background : Fo rth e GEnx-2 B (al l models)/Boein g 747- 8 (al l models ) application s th e airframe rha s requeste d th e abilit yt o take-of fa tcrosswind s u p t o 4 5 knots .2 o f4

G E i s requestin g a n exemptio n t o CF R 1 4 Par t3 3 Sectio n 33.8 3 (d ) fo rth e GEnx-2 B (al l models) . Sectio n 33.83(d ) states : "(d ) Excep ta s provide d b yparagrap h (e ) o fthi s section , th e vibratio n stresse s associate d wit h th e vibratio n characteristic s determine d unde rthi s section , whe n combine d wit h th e appropriat e stead ystresses , mus tb e les s tha tth e enduranc e limit s o fth e material s concerned , afte rmakin g du e allowance s fo roperatin g condition s fo rth e permitte d variation s i n propertie s o fth e materials . Th e suitabilit yo fthes e stres s margin s mus tb e justifie d fo reac h par tevaluated . I fi t i s determine d tha t certai n operatin g conditions , o rranges , nee d t o b e limited , operatin g an d instailatio n limitation s shal l b e established. " Specific s o fth e Exemptio n Request : G E request s tha tth e GEnx-2 B (al l models ) fa n blade s an d fa n OGV' s b e exempte d fro m th e requirement s i n bol d below . '(d ) Excep ta s provide d b yparagrap h (e ) o fthi s section , th e vibratio n stresse s associate d wit h th e vibratio n characteristic s determine d unde rthi s section , whe n combine d wit h th e appropriat e stead ystresses , mus t b e les s tha tth e enduranc e limit s o fth e material s concerned , afte rmakin g du e allowance s fo roperatin g condition s fo rth e permitte d variation s i n propertie s o fth e materials. " I tha s bee n determine d tha ta n equivalen tleve l o fsafet yt o th e requirement s o f33.8 3 (d ) stil l exist s fo rth e GEnx-2 B (al l models ) fa n blade s an d fa n OGV's . Reaso n fo rRequest : Thi s exemptio n i s bein g requeste d t o accommodat e a transien tengin e inlet , fa n blade , an d OG V vibrator yinteractio n a tcrosswind s abov e 2 5 knots . Th e Genera l Electri cCompan yha s determine d vi a analysi s that , eve n thoug h materia l enduranc e limit s ar e exceede d transientl y durin g take-off , th e level s o fstres s encountere d o n th e fa n blad e an d OGV s resul ti n Lo wCycl e Fatigu e (LCF ) cycli clive s wel l i n exces s o fth e require d minimu m LC F cycli clive s neede d t o preclud e a n airworthines s limitatio n o n thos e parts . Grantin g o fthi s exemptio n i s i n th e publi cinteres tbecaus e i twill : (1 ) No tadversel yaffec t fligh t safet ysinc e a leve l o fsafet yequivalen tt o tha t ensure d b y1 4 CF R Par t3 3 Amendmen t21 , Sectio n 33.8 3 (d ) ha s bee n determined . (2 ) Allo wfo rth e continue d us e an d grovrt h o fhig h by-pas s turbofa n engines . Hig h Bypas s rati o turbofa n engine s ar e fue l efficien tan d extremel yeconomica l t o operat e fo rth e world s airline s an d allo wfo rlon g rang e engin e operatio n a s i n th e Boein g 78 7 an d 747- 8 aircraft . Increasingl ylonge rroute s wit h increasingl ylarge raircraf tan d payload s ar e requirin g increase s o fengin e thrus tlevels . Wit h improve d aerodynamic , mor e fue l efficien t an d nois e reducin g aircraf tdesign s it ha s becom e difficul tt o sta ywithi n materia l enduranc e limit s a tcrosswind s abov e 2 5 knot s an d lo wrelativ e aircraf tvelocities .3 o f4

(3 ) Maintai n a positiv e effec to n th e U S economy . Ther e i s a potentia l fo radvers e impac tt o engine/airplan e sales . Not e tha tth e GEnx-2B6 7 engin e i s th e sol e engin e fo rth e B747- 8 Growt h airplane , a s suc h ther e i s n o domesti ccompetitio n engine . Th e competitio n fo r th e 747-8/GEnx-2B6 7 marke ti s solel youtsid e o fth e Unite d States . Thu s th e los s o fa campaig n wil l b e t o a non-U S business . ABoein g 747 , includin g th e engine s ha s a valu e o f$150-18 0 million ; a typica l sal e woul d includ e 6-1 0 aircraft . Wit h a produc t a s larg e a s th e Boein g 74 7 an d th e GEnx-2B6 7 engines , an ysal e o fth e produc tha s a clea rpositiv e impac tt o th e U.S . public . Th e additiona l sale s o fth e produc t wil l b e i n th e publi cinteres t a s th e sal e ha s th e impac to fretainin g curren temployment , wit h th e potentia l o fincreasin g employment . I n addition , increasin g th e numbe ro fairplan e engin e sale s t o foreig n countrie s wil l hav e a positiv e impac tt o th e U S econom yan d balanc e o ftrade . (4 ) Decreas e administrativ e burde n t o th e FAAan d t o GE . Th e inten to f33.83(d ) i s t o sho wtha tth e engin e hardwar e wil l no tfai l du e t o vibratio n induce d stresses . Th e critica l ite m i s th e capabilit yo fth e aircraf tt o mee tth e require d performanc e characteristic s while , a tth e sam e time , ensurin g tha tth e engin e hardwar e doe s no tfail . Airframe rdesigne d engin e inlet s fo rhig h bypas s rati o turb o fa n engin e an d larg e airplan e application s ar e designe d t o optimiz e aircraf t aerodynami can d acousti c efficiencie s thu s enhancin g overal l aircraf tfue l efficienc yand , typically , engin e manufacturer s d o no thav e a n inpu tint o th e inle tdesign . Separate d flo wengin e fa n blad e an d fa n OG Vvibratio n ofte n occur s a thig h cros s win d level s an d lo wrelativ e aircraf t velocities . Arulin g i n favo ro fthi s reques tfo rexemptio n woul d eliminat e th e nee d fo rG E t o pursu e a n ELO S an d fo rth e FAAt o writ e issu e paper s fo rfutur e GEnx-2B6 7 engin e derivative s thu s decreasin g administrativ e burde n t o th e FAAan d t o GE . Base d o n th e abov e justification , ful l complianc e wit h th e "i n service " aircraf t requirements , an d publi cinterestGenera l Electri crequest s exemptio n fro m th e "mus tb e les s tha tth e enduranc e limit s o fth e material s concerned " requiremen t withi n FA R 33.8 3 (d ) fo rth e GEnx-2B6 7 engin e model s (al l models) . Summar y(fo rPublis h i n Federa l Reqister ) pe rFA R Par t 1 1 Sectio n 11.81(f ) Petitio n fo rExemptio n I n Jul y201 0 Genera l Electri cwa s grante d a n amende d typ e certificat e whic h include d th e GEnx 1 B an d 2 8 turbofa n engin e models . I n Octobe r201 0 G E mad e applicatio n fo rGEnx-2 B derivativ e models . Thes e model s ar e ye t t o b e certifie d derivative s o fth e currentl ycertifie d GEnx-2B6 7 whic h i s liste d o n typ e certificat e E00078NE . Wit h th e pursui to fincrease d fue l efficienc yan d subsequen ttechnolog yenhancement s o f moder n commercia l aircraf tsom e olde rsection s o fth e FA R ar e no t i n lin e wit h moder n aircraf t desig n philosophy . On e o fthes e section s i s 33.8 3 (d ) [vibratio n survey ] whic h was introduce d i n th e 1960's . Airframe rdesigne d engin e inlet s ar e designe d t o optimiz e aircraf taerodynami can d acoustica l efficiencie s thu s enhancin g aircraf tfue l efficiency . I n som e case s th e engin e inlet s ar e designe d suc h tha tairflo wint o th e inle tseparates , thu s causin g increase d engin e fa n blad e an d engin e fa n outle tguid e van e (OGV ) vibration . Thi s i s th e cas e fo rth e 747- 8 (al l models ) an d th e GEnx-2 B (al l models) . A tcrosswind s abov e 2 5 knot s th e airframe rdesigne d inle tca n hav e4 o f4

separate d ai rflowthu s causin g a transien tviolatio n o f33.8 3 (d ) fo rth e engin e fa n blade s an d engin e fa n OGV's . Genera l Electri crequest s exemptio n fro m th e "mus tb e les s tha tth e enduranc e limit s o fth e material s concerned " requiremen twithi n FA R 33.8 3 (d ) fo rth e GEnx-2 B (al l models ) engin e model s fa n blade s an d fa n OGV's . 14CF R Part3 3 Amendmen t2 1 Sectio n 33.8 3 (d) ) states : Excep ta s provide d b yparagrap h (e ) o fthi s section , th e vibratio n stresse s associate d wit h th e vibratio n characteristic s determine d unde rthi s section , whe n combine d wit h th e appropriat e stead ystresses , mus tb e les s tha tth e enduranc e limit s o fth e material s concerned , afte r makin g du e allowance s fo roperatin g condition s fo rth e permitte d variation s i n propertie s o fth e materials . Genera l Electri ci s requestin g a n exemptio n t o th e "mus tb e les s tha tth e enduranc e limit s o f th e material s concerned " requiremen tsinc e i tha s bee n determine d tha ta n equivalen tleve l o f safet yexists . En d Summar y 

### Sincerely , 

# fl^ l^ ^ Pau l A . Hil l FAA-DE R Principa l Engineer , Airworthiness&Certificatio n