# <A A Ronal d J . Hinderberge r Lea d Adminislralo r Regulator yAdministratio n Commercia l Airplane s Th e Boein g Compan y P. O Bo x370 7 M C 03-5 6 Seattle , W A98124-220 7 

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### % 1 201 1 KA-n-0484 7

U.S . Departmen t

o f Transportatio n Docke t Operation s Wes t Buildin g Groun dFloor , Roo mW12-14 0 120 0 Ne w Jerse y Avenue , S.E . Washington , D C 2059 0 C O Dear Si r o r Madam , Subject : Petitio n for Exemptio n t o Title 1 4 Cod e o f Federa l Regulation s (CFR ) Part 25.86 3 I n accordanc e wit hth e provision s o f Titl e 1 4 Cod e o f

Federa l Regulatio n §11.61(b) , Th e Boein g Company , herei n petition s for an exemptio n from1 4 CF R §25.863 , tiie exemptio n petitio n onl y addres s 1 4 CF RPart 25.863 , i n accordanc e withth e agreemen t

i n th e Referenc e b ) FA A Letter . Th e exemption , i f

granted , applie s t o th e followin g airplane s whe n owne dand/o r operate db y Boeing :

Mode l 73 7 Typ e

-600/-700/-700C/-800/-900/-900E R Petitio n fo r

Exemptio n I n accordanc e withth e requirement s o f 1 4 CF R§11.81(a)-(g) , w e provid e th e followin g detaile dinformatio n i n support o f ou r petition : Contac t Information : Ro n Hinderberge r VP , Regulatory Administratio n Boein g Commercia l Airplane s P.O . Bo x 3707 , M/C 03-3 7 Seattle , W

A 98124-220 7 e-mail : ron.j.hinderberfg.boeing.co m Th e specifi c section s o f

1 4 CF Rfro mwhic hw e see k a n exemption : Boein g i s seekin g relie f

fromth e followin g regulatio n for th e mai n engin e exhaus t plu g installatio n o n th e 737-600/-700/-700C/-800/-900/-900E Rmodels : 1 4 CFR§25.86 3 Flammabl e fluidprotection . (a ) I n eac hare awher e flammable fluids o r vapor s might

escap e b y leakag e o f afluidsystem , ther e mus t b e mean s t o minimiz e th e probabilit y o f^ . 

## fgr^£Af£ P Pag e 2 U.S . Departmen t

o f Transportatio n Docke t Operation s RA-11-0484 7 ignitio n o f

th e fluids an dvapors , an dth e resultan t hazard s i f

ignitio n doe s occur , (b ) Complianc e wit

hparagrap h(a ) o f

this sectio n mus t

b e show n by analysi s o r tests , an dth e followin g factor s mus t b e considered : (J ) Possibl e source s an dpath s o f fluidleakage , an dmean s o f detectin g leakage . (2 ) Possibl e ignitio n sources , includin g electrica l faults , overheatin g o f equipment , an dmalfunctionin g o f protectiv e devices . Th e exten t

o f relie f w e ar e seeking , an dth e reaso n w e ar e seekin g th e relief : Exten t o f Relie f Th e CFM56-7 B engin e installatio n o n th e 737-600/-700/-700C/-800/-900/

- 900E Rmodel s use s acor e exhaus t nozzl e an dplu g t o contro l th e flow o f th e exhaus t gase s fro mth e engine . Th e CFM56-7 B engin e incorporate s acente r ven t tub e that exhaust s ai r

int o th e plu g cavity . Th e plu g ha s a4. 8 inc hopenin g in th e af t en dt o allo w th e engin e ven t ai r t o e)diaus t

overboard . Th e engin e als o incorporate s adrai n for

th e mai n bearin g af

t oi l sump that

discharge s int o th e plu g cavity . Ther e ar e no t designe ddrainag e provision s for th e plu g cavity o f

th e 314A2620- 1 plu g installation . Boein g i s seekin g relie f

fro m§25.86 3 (a) , (b)(1) , (b)(3 ) a s i t applie s t o th e interna l cavit y o f

th e 314A2620- 1 plu g installatio n o n certai n 737-600/-700/

- 700C/-800/-900/-900E Rairplanes . Engin e oi l and/o r fiiel can b e directe dt o th e plu g cavit y b y th e af

t sump drai n and/o r

th e cente r

ven t tube . Ther e ar e n o drainag e provision s i n th e 314A2620- 1 plu g installation . Th e plu g surfac e temperature s ca n excee dth e auto-ignitio n temperatur e o f engin e oi l an dfuel . Consequentl y direc t

complianc e for

th e 314A2620- 1 plu g installatio n canno t no w b e show n t o §25.86 3 (a) , (b)(1) , (b)(3) . Th e 314A2620- 1 plu g installatio n wa s previousl y foun dcomplian t with§25.863(a) , (b)(1) , (b)(3 ) i n error . A t Lin e No . 3762 , Boein g introduce dane w exhaus t installatio n includin g ane w plu g tha t wa s complian t

with§25.863 . However , th e ne w typ e desig n coul dno t b e approve dwithth e 314A2620- 1 plu g installatio n a s a n interchangeabl e spar e for th e ne w exhaust . Consequently , installation o f th e 314A2620- 1 plu g i s no t allowe do n 737-600/-700/-700C/-800/-900/-900E Rmodel s fromLin e No . 376 2 an don . Boein g i s seekin g relie f fromth e regulation vi aexemptio n t o allo w th e installation . Publi c Interes t Exemptio n from§25.863(a),(b)(l) , (b)(3 ) forth e 314A2620- 1 plu g installatio n o n Lin e No . 376 2 an do n woul db e i n th e publi c interest . Th e inability t o us e th e 314A2620- 1 plu g o n asub-grou p o f airplane s withi n an airlin e operator' s fleet create s asignifican t

interchangeability issue . Ther e ar e currentl y ove r 7,00 0 o f th e 314A2620- 1 plug s i n servic e operation . Typicall y th e exhaus t i s installe da s par t o f th e spar e engin e ki t

t o minimiz e th e engin e chang e tim e o n th e flightline. Operator s hav e informe dBoein g that th e interchangeability restrictio n wil l^ . Pag e 3 U.S . Departmen t

o f Transportatio n Docke t Operation s RA-11-0484 7 increas e operationa l cost s arisin g fromth e additiona l inventory contro l processe s that wil l b e needed , an dpotential delays i f th e correc t

exhaus t part numbe r i s no t immediatel y available . Thes e cost s wil l eventuall y b e passe do n t o th e public . Removin g th e restrictio n wil l allo w greate r flexibility an dincrease defficienc y for th e operato r

t o bette r serv e th e public . Safet y Exemptio n from§25.863(a),(b)(l) , (b)(3 ) forth e 314A2620- 1 plu g installatio n o n Lin e No . 376 2 an do n woul dno t adversel y affec t

publi c safety basedo n th e feature s summarize dbelow . Th e FAA-SAC O agree dwit hasimilar assessmen t in 2009 . Th e airplan e i s protecte dfromth e effect s o f apotential fire withi n th e exhaus t plu g b y th e followin g desig n an dconstructio n features : Th e plu g i s considere dfireproof Ther e i s a4. 8 inc hdiamete r openin g i n th e af

t en do f th e plu g t o provid e for

ventilatio n flow. Thi s openin g i s approximatel y 6 0 inche s af t fromth e locatio n wher e fluidwoul dcollec t at th e forwar den do f

th e plug . Th e plu g i s shielde dfromth e airplan e surface s alon g mos t o f it s lengthb y th e exhaus t nozzle , whic hi s als o considere dfireproof. Ther e i s ahea t

shiel ddirecfl y abov e an daf t o f th e exhaus t

that protect s th e af

t stru t fairing . Th e hea t

shiel di s considere dfireproof Th e lowe r

surface s o f

th e win g withi n on e nacell e diamete r o f th e fire zone , includin g th e contro l surfaces , ar e fire resistant . Th e vertica l distanc e fro mth e openin g i n th e af t en do f th e pu g t o th e af

t fairin g i s 1 1 inches ; t o th e undersurfac e o f th e win g i s 3 6 inches . Th e horizonta l distanc e t o th e win g rear

spar i s 4 8 inches . Failure s o f

th e engin e tha t

coul dresul t

i n evacuatio n o f

th e oi l syste mint o th e plu g cavity wil l b e indicate dt o th e Fligh t Cre w b y alo w oi l pressur e indication . Th e Boein g Fligh t

Cre w Operation s Manua l (FCOM ) instruct s th e cre w t o performan engin e shutdow n for lo w oi l pressur e indication . A potentia l fire in th e plu g cavity wil l b e identifie dan daddresse db y th e Fligh t an dGroun dcrew s i n th e sam e manne r a s atraditiona l fuel-fe dtailpip e fire. Th e installatio n i s currentl y operatin g o n ove r 3,50 0 airplane s an dha s accumulate dove r

6 6 millio n hour s an d3 5 millio n cycle s a s o f Apri l 2011 . Operatio n an dinstallatio n o f th e 314A2620- 1 plu g installatio n o n post-Lin e No . 376 2 airplane s i s identica l t o th e installation s tha t hav e safel y accumulate dthes e hours/cycles .( ^ Pag e 4 U.S . Departmen t

o f Transportatio n Docke t Operation s RA-11-0484 7 Summar y o f

Petitio n Petitioner : Boein g Commercia l Airplane s Sectio n o f

1 4 CF Raffected : 1 4 CF R25.863(a) , (b)(1) , (b)(3 ) Descriptio n o f

Relie f Sought : T o permi t

installation o f

th e 314A2620- 1 exhaus t plu g o n 737-600/-700/-700C/-800/-900/-900E Rmode l airplanes , Lin e No . 376 2 an don . Reques t t o Waiv e Publicatio n an dCommen t In som e cases , th e FA A may waiv e th e requiremen t for publicatio n an d comment . On e potential reaso n i s that th e relie f requeste di s identica l t o previousl y grante dexemptions . Give n tha t th e installatio n o f

th e 314A2620- 1 exhaus t plu g i s currentl y operatin g o n ove r 3,50 0 airplane s an dha s accumulate d ove r 6 6 millio n hour s an d3 5 millio n cycle s a s o f Apri l 2011 , Boein g request s that th e FA A waiv e th e requiremen t for publicatio n an dcomment . Nee dt o Exercis e th e Exemptio n Outsid e o f th e Unite dState s 737-600/-700/-700C/800/-900/-900E Rmode l airplane s fromLin e No . 376 2 an d o n ar e anticipate dt o b e operate din man y foreig n countries . T o provid e for maximu mefficienc y an dflexitility for foreig n operators , Boein g request s tha t th e FA A allo w th e us e o f

th e petitione dexemptio n outsid e o f th e Unite dStates . Shoul dyo u hav e question s o r requir e additiona l information , pleas e d o no t hesitat e t o contac t

th e undersigne do r

Debr aDean at

debra.a.deanfg,boeing.co m o r (425 ) 717-1165 . Very trul y yours .

Timoth y P . Dowlin g RA Progra mManage r

Flee t Support (206 ) 766-3885 , M C 03-5 6 FAX : (425)294-934 0