DEC-21-201 0 14:2 5 Fflf l RENTO N P.02/0 7

Exemptio n No . 1017 5 UNITE D STATE S O FAMERIC A DEPARTMEN T O FTRANSPORTATIO N FEDERA L AVIATIO N ADMINISTRATIO N RENTON , WASHINGTO N 98057-335 6 • — 5



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# Pi ^ C O UA J In th e matte r

o f th e petitio n o f Bombardie r

Aerospac e for a n exemptio n fro m§ 25.981(a)(3 ) o f Titl e 14 , Cod e o f

Federa l Regulation s Regulatory Docke t No . FAA-2010-028 7

GRAN T O FEXEMPTIO N B y lette r date dFebruary 25,2010 , an dadditional informatio n date dMa y 14,2010 , Mr . C . Nham , Senio r Projec t Manager , Fixe dWin g Larg e Transport Aircraft , Nationa l Aircraf t Certification , Civi l Aviation , Transport Canada , Aircraf

t Certificatio n Branc h (AARDE) , 3'* ' Floor , Towe r C , Plac e D e Ville , 30 0 Spark s Street , Ottawa , Ontario , Canad aK l A 0N8 , petitione dth e FAA , o n behal f o f Bombardie r

Aerospace , for

apartia l exemptio n fromth e requirement s o f § 25.981(a)(3 ) o f Titl e 14 , Cod e o f

Federa l Regulation s (1 4 CFR) . Thi s exemption , i f granted , woul dpermi t relie f fromth e faul t

toleranc e ftiel tan k

ignitio n preventio n reqxiirement s for it s Mode l CL-600

- 2 E 2 5 (CR J 1000 ) serie s airplane s allowin g the mt o (1 ) demonstrat e that th e structura l desig n provide s tw o independent , effectiv e an dreliabl e mean s o f lightnin g strike protection , an d(2 ) demonstrat e complianc e wit h thi s requiremen t

b y 2 4 month s afte

r typ e certificatio n o f

th e airplane . Th e petitione r

request s relie f

fro mth e followin g regulation : Sectio n 25.981(a)(3 ) a s amende db y Amendmen t 25-102 : (a ) N o ignitio n sourc e may b e presen t a t eac h poin t

i n th e fiiel tan k

o r fuel tan k syste m wiiere catastrophic failure coul doccu r du e t o ignitio n o f

fuel o r vapors . Thi s mus t

b e show n by : (3 ) Demonstratin g that

an ignitio n sourc e coul dno t resul t fromeac h singl e failure , from eac h single failur e i n combinatio n with eac h laten t failure conditio n no t

show n t o b eDEC-21-201 0 14:2 5 FRf l RENTO NP.03/0 7

extremel y remote , an dfromal l combination s o f failure s not

show n t o b e extremel y improbable . Th e effect s o f manufacturin g variability , aging , wear , corrosion , an dlikel y damag e mus t

b e considered . Th e petitione r

support s it s reques t

wit h th e followin g information : Thi s sectio n quotes , i n part , th e relevan t informatio n fromth e petitioner' s documentation . Th e complet e documentatio n i s availabl e at th e Departmen t

o f Transportation' s Federa l Docke t Managemen t

System , o n th e Interne t

at http://regulations.gov , i n Docke t No . FAA-2010-0287 . A s explaine di n FA A polic y memo ANM-112-08-002 , before amendmen t 25-102 , th e concep t o f lightnin g protectio n o f

th e fiiel tank s wa s normall y applie di n preventin g ignitio n o f

vapor s i n th e tank

area . Ther e wa s n o consideratio n o f desig n failures , aging , wea r o r maintenanc e induce derror s t o th e fiiel tank structure . A s aresult , th e FA A polic y no w specifie s tha t

complianc e wit

h 1 4 CFRPart

25.981(a)(3 ) woul dtypicall y requir e adesig n with thre e highl y reUable , independen t an dredimdan t

protectiv e feature s t o preven t ignitio n i n th e event

o f alightnin g strike . Th e structura l elements o f th e win g tan k desig n o f th e Bombardie r

Aerospac e (BA ) CL-600-2E2 5 (CRJIOOO) d o no t compl y with thi s requirement . I t was note di n th e polic y mem o tha t th e FA A determine dtha t i n certai n case s i t

wa s i n th e publi c interes t

t o gran t a n exemptio n fo

r structural relate delement s provide dtha t certai n condition s ar e me t ensurin g a

n acceptabl e leve l o f

safety . I n vie w o f

thi s allowance , B A i s applyin g for atwo-part

exemptio n fo

r th e structura l element s o f th e fuel tan k design . Firstly , t o demonstrat e tha t th e desig n complie s with th e requiremen t eve r with onl y tw o independent , effectiv e an drehabl e mean s o f lightnin g strik e protection . Secondly , that

th e demonstratio n o f

complianc e t o thi s requiremen t b e mad e afte

r typ e certificatio n o f

th e CRJIOOO . B A ha s implemente dacomplianc e pla n t o mee t th e requirement s o f

th e FA A polic y i n support o f thi s exemptio n application , however , i t ha s bee n conclude dtha t

th e analyses / assessments , compilatio n an ddocumentatio n o f th e substantiatin g dat acanno t b e complete di n tim e for

CRJIOO O typ e certificatio n o n th e basi s tha t som e o f th e tes t dat a require dt o sho w complianc e woul dno t b e availabl e prio r

t o thi s date . A schedul e ha s bee n include da s part

o f thi s complianc e plan outlinin g th e milestone s toward s th e completio n o f

thi s deliverabl e b y th e middl e o f Septembe r

2012 . Fue l tan k ignitio n preventio n i s ensure dthroug h lo w fuel tan k flammability exposur e an d th e preclusio n o f

ignitio n source s withi n th e tank . Th e preventio n o f ignitio n soiirce s i s substantiate db y analysi s o f al l potentia l ignitio n sources , usin g th e guidanc e o f A C 25.981-1 B (notin g that

thi s A C di dno t

addres s th e "structura l lightning " aspects ) an dth e developmen t

o f airworthines s limitations , bot h fiael syste mmandatory inspection s an dby definin g critica l desig n configuratio n contro l limitation s (CDCCLs) . A s adde dsafet y justification , desig n change s require dto sho w complianc e with SC A H2002-0 3 hav e bee nDEC-21-201 0 14:2 5 FRf l RENTO NP.04/0 7

accomplished . Al l th e resultin g mandator y modification s ar

e include da s an integra l part o f th e CRJIOO

O typ e design . Lo w ftiel tan k flanunability exposur e ha s bee n demonstrate d fo r FA R26.3 3 complianc e a s per FA A guidanc e A C 25.981-2 A an dPa n 25 , Appendi x N . B A consider s th e desig n o f th e CRJIOO

O win g asaf

e design , witi i goo dservic e history an dmeet s authority expectation s fo r a n aluminu mwin g design . B A believe s grantin g thi s exemptio n ha s n o impac t

o n safety . Federa l Registe r

YnbMcatio n A simimai y o f

th e petitio n was publishe di n th e Federa l Registe r o n Septembe r

20 , 201 0 (7 5 FR 57328) . N o comment s wer e received . Th e FAA' s analysi s In May 2001 , th e FA A issue dth e "Transport Airplan e Fue l Tan k

Syste mDesig n Review , Flammability Reduction , an dMaintenanc e & Inspectio n Requirements " final rul e (Docke t FAA- l 999-6411 , effectiv e Jime 6,2001 ) tiiat vra s adopte da s Amendmen t 25-102 . Thi s amendmen t

adde dspecifi c ignitio n preventio n requirement s an dane w flammability minimizatio n requiremen t t o § 25.981 . Th e amende dignitio n preventio n requirement s i n § 25.981(a)(3 ) requir e consideratio n o f factor s suc h a s aging , wear , an dmaintenanc e error s a s wel l a s th e existenc e o f singl e failures , combination s o f

failures , an dlaten t

failure s that

ma y b e th e caus e o f

ignitio n source s in fuel tanks . Sectio n 25.981 , a s amende db y Amendmen t 25-102 , require s tha

t airplan e design s b e protecte d fro mth e effect s o f

structura l lightnin g wit

h feamre s that

are failure tolerant . Prio r t o thi s amendment , onl y § 25.95 4 hadbee n apphe dt o lightnin g protectio n o f fue l tanks . That

provisio n require s onl y that

th e airplan e desig n prevent s ignitio n o f vapor s i n th e tank

with n o consideratio n for

anticipate ddesig n failures , aging , an dwear , o r maintenanc e errors . System s with potentiall y catastrophi c failure mode s woul dtypicall y mee t th e requirement s o f § 25.981(a)(3 ) b y providin g at leas t tripl e redundanc y i n thei r protectiv e feature s with periodi c inspections , o r

dual redundan t

feature s v^it

h continuou s syste mmonitorin g t o reduc e th e latenc y period . Dual redundan t

desig n scheme s coul donl y compl y wit h § 25.981(a)(3 ) whe n combine d with eithe r

regular inspection s at

ver y shor t interval s o r

amonitorin g devic e t o verif y th e fimctionality o f

th e protectiv e features . Inspectio n o f th e variou s desig n feature s ma y b e difficul t o r impossibl e i f

th e featur e i s internal t o th e fiiel tan k an dpart o f th e win g structure . Whe n § 25.98 1 was applie dt o th e structural Ughtnin g aspect s o f ne w airplan e designs , applicant s foimdi t wa s impractica l t o mee t

th e standardan dincorporat e additiona l protectiv e features . W eDEC-21-201 0 14:2 5 Fflf l RENTO N P.05/0 7

issue dtw o exemption s an ddevelope dne w policy . Th e tw o exemption s wer e fo r th e Dassaul t Falco n IX , signe do n Apri l 20 , 2007 , an dth e othe r wa s fo r th e Hawke r

4000 , signe do n Augus t 28,2008 . O n May 26,2009 , followin g apublic-commen t period , w e adopte dne w polic y tha t define dcriteri atha t

w e woul dconside r

regardin g grantin g o f

exemption s an dissuanc e o f specia l condition s for

structural lightnin g protection . A s discusse di n th e preambl e t o Amendmen t 25-102 , conventional , unheated , aluminu mwin g tank s minimiz e fiiel tan k

flammability exposure , a s require db y § 25.981(c) . Eve n i f alaten t failure o f aprotectiv e featur e occurre dfor suc h atank , th e risk

o f lightnin g induce dfiiel tan k explosion s i s relativel y lo w whe n th e tank i s fuele dwith lo w volatility fuel s suc h a s Je t A , a s demonstrate db y th e servic e experienc e o f thes e tanks . Becaus e o f

th e impracticality o f

ftill complianc e with §25.98 1 (a)(3 ) fo r lightnin g protectio n an dth e reduce dflammability exposur e o f thes e tanks , w e behev e grantin g an exemptio n i s i n th e publi c interes t i f applicant s can sho w tha t thei r desig n provide s practica l dual protectiv e feature s for fiiel-tank structural lightnin g protectio n that

ar e both independen t

an drobust , an dsho w th e probability o f fiiel tan k ignitio n t o b e extreniel y improbabl e fo r an y non-fault-toleran t

features . Bombardie r

provide dinitia l dat ai n support o f thei r exemptio n reques t

that shows , pendin g th e result s o f testin g an dadditiona l analysis , thei r desig n shoul dmee t

th e criteri ao f

th e FA A policy . Bombardier' s reques t

for a n exemptio n state s the y wil l demonstrat e tha t th e structura l desig n provide s tw o independent , effectiv e an dreliabl e mean s o f lightnin g strik e protection . Suc h faul t toleran t feature s may b e practica l fo r fasteners . However , simila r design s hav e include dsingl e failure s o f

structur e tha t

coul dresul t

i n afue l tank ignitio n sourc e durin g certai n lightnin g strik e events . A s state dabove , FA A polic y allow s for acceptin g singl e failure s whe n certai n criteri ai n th e polic y mem o hav e bee n met . Thi s include s demonstratin g th e probability o f fuel tan k ignitio n t o b e extremel y improbabl e fo r any suc h non-fault-toleran t features . W e anticipat e after fiirther analysi s Bombardie r

may identif

y suc h singl e failure s i n th e desig n o f th e CL-600-2E2 5 (CRJ 1000) . I f

singl e failure s exis t

i n th e design , Bombardie r woul dnee dt o modif

y thei r exemptio n reques t

t o expan dth e scop e t o includ e singl e failure s a s provide dfor i n thi s polic y an dsummarize dbelow: . Faul t toleranc e i s no t

require dfor

an y specifi c desig n feature if : a . providin g faul t

toleranc e i s show n t o b e impractica l fo r tha t feature , an d b . fiiel tan k

vapo r ignitio n becaus e o f

tha t feature an dal l othe r

non-fault-toleran t features , whe n thei r

fiiel tan k vapo r ignitio n even t

probabiUtie s ar e summed , i s show n t o b e extremel y improbable .DEC-21-201 0 14:2 5 Fflf l RENTO NP.0&/0 7

O n Novembe r

2 , 2010 , Transport

Canad aCivi l Aviatio n (TCCA ) issue dan exemptio n allowin g Bombardier , unti l Octobe r 29,2012 , t o complet e di e necessary certificatio n testing , mitigation , analysi s an ddocumentatio n t o sho w th e CL-600-2E2 5 (CRJ 1000 ) complie s with th e TCC A certificatio n requirement s fo r structura l Ughtning protectio n under AWM 525.981(a)(3) . That sam e dat awil l b e use dt o sho w di e CL-600-2E2 5 (CRJ 1000 ) doe s mee t th e FA A sft-uctura

l lightnin g policy . Th e CL-600-2E2 5 (CR J 1000 ) airplan e typ e certificatio n programi s near completion . Witiiou t thi s exemption . Bombardie r woul dno t

receiv e FA A desig n approval fo r th e aircraf

t i n atimel y maimer , puttin g i t

a t a n unfai r disadvantag e with it s competitors . Thi s coul dals o caus e disruptio n t o severa l majo r

corporation s i n th e worl dthat ar e anticipatin g th e imminen t delivery o f

th e CL

600-2E2 5 (CRJ 1000 ) airplan e t o inee t thei r busines s needs . Thes e Bombardie r customers may nee dt o findalternative s for thei r aviatio n need s i f

thi s exemptio n i s ho t

granted . W e further

not e tha t Bombardie r

ha s indicate dthat

n o U.S . operator s hav e place dorder s fo r th e CL-600-2E2 5 (CRJ 1000 ) airplane . Th e FAA' s Decisio n I n consideratio n o f

th e foregoing , I findthat

agran t o f exemptio n i s i n th e publi c interest . Therefore , pursuan t

t o th e authority containe di n 4 9 U.S.C . § § 4011 3 an d44701 , delegate dt o m e b y th e Administrator , Bombardie r i s hereb y grante da

n exemptio n fromth e requirement s o f 1 4 CF R§ 25.981(a)(3 ) a s i t

relate s Mode l CL-600-2E2 5 (CRJ 1000 ) serie s airplan e fiiel-tank structura l lightnin g protectio n with th e followin g provisions : 1 . Instea do f

complianc e with th e requirement s o f § 25.98 1 (a)(3) . Bombardie r mus t sho w tha t th e desig n include s a

t leas t tw o independent , effective , an dreliabl e lightnin g protectio n feature s (o r

set s o f features ) suc h tha

t fault toleranc e t o preven t

lightning

relate dignitio n source s i s provide dfo r eac h are ao f

th e structural desig n tha t the y hav e shov man dFA A ha s determine dt o b e impractica l fo r fiill compliance . a . Bombardie r

mus t identif y al l feature s tha t

mee t thi s two-laye r

protectio n provisio n an dal l feature s tha t d o not includ e two-layers. . b . I f an y feature s d o no t

mee t thi s two-laye r

protectio n provision . Bombardie r mus t petitio n t o expan dthi s exemptio n t o includ e th e non-faul t toleran t provisio n describe di n FA A PoUcy Memorandu mANM-112-08-002 , Polic y o n Issuanc e o f

Specia l Condition s an dExemption s Relate dt o Lightnin g Protectio n o f

Fue l Tan k Structure , date dMay 26 , 2009 . 2 . Bombardie r

mus t performa

n analysi s t o sho w that

th e design , manufacturin g processes , an dairworthines s limitation s sectio n o f th e instruction s for

continue dairworthines s includ e al l practica l measure s t o prevent , an ddetec t an dcorrect , failure s o f

structura l lightnin g protectio n feature s becaus e o f manufacturin g variability , aging , wear , corrosion , an dlikel y damage .DEC-21-201 0 14:2 6 Fflf l RENTO N P.07/0 7

3 . Bombardie r

mus t demonstrat e complianc e wit h provision s 1 an d2 o f

thi s exemptio n withi n 2 4 month s after

typ e certificatio n o f

th e airplane . 4 . I f Bombardie r

i s unabl e t o demonstrat e complianc e wit h provision s 1 an d2

- o f

thi s exemptio n withi n 2 4 month s afte r typ e certificatio n o f

th e airplane , th e FA A wil l not issu e further

airworthines s certificate s unti l Bombardier show s tha t

th e condition s ar e met . Issue di n Renton , Washington , o n DE C 1 4 201

0

Michae l J . Kaszycki Actin g Manager , Transport Airplan e Directorat e Aircraf t Certificatio n Servic e

TOTfl L P.0 7