# AmericanAirline s MAINTENANC E & ENGINEERIN G CENTE R 

## ^^RTMENT O Novembe r23 , 201 0
. ^i'^SPORTATlO N ^AciOPFRATiON S U
. S
. Department o fTransportatio n Docke t Operation s ' i O f'Q V2 b AiO

- 3 8 West Buildin g Groun d Floor , Roo m W12-14 0 120 0 Ne wJerse yAvenue , SE
. Washingto n DC , 2059 0 Subject : Reques t fo rExemptio n t o Section s o f1 4 CF R Part s 121 , an d 121.344(f) : America n Airtines , Inc
. v^^ould lik e t o petitio n th e Federa l Aviatio n Administratio n fo ra time limite d exemptio n o f1 8 month s fro m Decembe r6 , 2010 , t o 1 4 CF R 121.34 4 t o continu e 1 4 CF R 12 1 operation s o ffou r737-82 3 serie s aircraf t usin g a fligh tdat a recorde rsyste m tha tdoe s no t full ycompl ywit h th e recordin g interva l requirement s fo rth e left elevato rsurfac e positio n parameter , als o know n a s "Primarypitc h contro l surfac e position. " Applicabl e Sections : Thi s exemptio n reques t onl yinvolve s paramete r"(15 ) Primarypitc h contro l surfac e position " a s liste d i n 1 4 CF R 121.34 4 paragrap h (a)
. 1 4 CF R 121.34 4 (f ) state s To ral l turbine-engine-powere d transpor tcategor yairplane s tha t ar e manufacture d afte rAugus t 19 , 2002.(1 ) Th e parameter s liste d i n paragrap h (a ) (1 ) throug h (88 ) o fthi s sectio n mus t b e recorde d withi n th e ranges , accuracies , resolutions , an d recordin g interval s specifie d i n Appendi xM o fthi s part"
. 1 4 CF R 121.34 4 Appendi xM (Not e 18 ) state s "Fo ral l aircraf t manufacture d o n o rafte r Decembe r6 , 2010 , th e second s pe rsamplin g interva l i s 0.125
. Eac h inpu tmus tb e recorde d a t thi s rate
. Alternatel ysamplin g input s (interleaving ) t o mee t thi s samplin g interva l i s prohibited"
. Exten t o fRelie f Thi s time-limite d exemptio n woul d allo wfo rth e continue d domesti can d internationa l operation s o fth e followin g America n Airline s operate d B737-82 3 serie s aircraf t(se e Tabl e 1 ) fo r1 8 month s afte rDecembe r6 , 2010 , withou t th e full ycomplian t recordin g interva l o fth e leftelevato rsurfac e positio n paramete r(Se e Tabl e 2) :
Mak e / Mode l Boein g / 737-82 3 Boein g / 737-82 3 Boein g / 737-82 3 Boein g / 737-82 3 Tabl e 1 (Aircraf t Applicabl e t o thi s Exemption )

Seria l # 3090 3 3111 1 2955 4 4058 4 Line #

348 1 348 7 349 3 349 9 Reaistratio n #

N863N N N864N N N865N N N866N N Tabl e 2 121.344(f ) Paramete r# 1 5 (Syste m Signal s no trecorde d Appendi xM Reauiremen t Pitc h Contro l Surfac e Positio n b y th e Digita l Fligh t Dat a Recorder ) Inou t t o DFDA U Left Elevato rPositio n Dat a ( 1 sampl e o fth e 8 H z se t every5 seconds ) Pag e 1 o f4 M D P.O
. BOX582809 , TULSA , OKLAHOMA74159-2809 , CABL E ADDRES S AMAI RAmerica n Airline s - 737N G Exemptio n Reques t

Novembe r23 , 201 0 Reaso n fo rrelie f Thi s exemptio n i s necessitate d b yth e Aircraf t Manufacture r(Boeing ) an d th e Digita l Fligh t Dat a Acquisitio n Uni t(DFDAU ) syste m / softwar e supplier' s (Teledyne ) nee d t o develop , validate , an d integrat e th e enhance d syste m softwar e int o th e aircraf t typ e design
. Thi s enhance d softwar e wil l provid e fo rth e DFDA U recordin g o fal l regulatoryrequire d parameter s an d allo wAmerica n Airline s tim e t o instal l th e softwar e withou t significantl yaffectin g fligh toperations
. Backgroun d Summary : A737N G Fligh tDat a Recorde rSyste m (FDRS ) anomal ywa s discovere d durin g Boein g fligh t lin e airplan e operations
. Th e FDR S configuratio n include d a Teledyn e Digita l Fligh t Dat a Acquisitio n Uni t(DFDAU ) wit h th e 737- 7 dat a fram e enabled
. Th e dat a fram e i s a 51 2 word s pe rsecon d dat a fram e tha twa s certifie d i n Apri l o f201 0 t o mee tth e lates t FAAregulation s ( § 121.34 4 (f ) Appendi xM) , whic h ar e effectiv e De c6 , 2010
. Th e followin g describe s th e anomal y an d discusse s Boeing' s pla n t o correc t th e discrepancy
. Discussion : O n 10/19/2010 , a n anomal ywa s reporte d o n a Boein g productio n 737N G airplane
. Thi s detaile d a proble m wit h th e displa yo fth e left elevato rpositio n o n th e Cente rLowe rDispla yUni twhic h wa s laggin g whe n compare d t o th e righ televato rpositio n o n tha tdisplay
. Th e Commo n Displa y Syste m (CDS ) retrieves surfac e positio n dat a fro m th e DFDA U fo roptiona l fligh tcre wdisplay
. Th e displa yo felevato rpositio n i s NO Trequire d t o mee tcertificatio n regulation s an d support s a n optiona l Maintenanc e Groun d Operatio n t o ai d i n airplan e dispatch
. Th e displa yo fth e elevato rposition s (alon g wit h othe rprimaryfligh tcontro l positions ) o n th e CD S i s a custome r option
. Whe n th e anomal ywa s reported
. Fligh t Dat a Recorde r(FDR ) dat a wa s downloade d an d analyze d t o determin e i fth e proble m see n o n th e CD S wa s als o presen ti n th e FD R elevato rpositio n data
. Pe rFAAregulation s ( § 121.34 4 (f ) Appendi xM (paramete rgrou p 15)) , a s o fDe c6 , 201 0 th e FDR S mus trecor d left an d righ televato rpositio n at8 sample s pe r second
. FD R dat a analysi s showe d tha t a ttimes , 1 o fth e 8 sample s o fleftelevato rpositio n data , i n a give n second , coul d b e stal e ( a previou s sample ) an d i s visibl e i fther e i s a rapi d movemen t o f th e elevato rposition
. Th e anomalou s leftelevato rpositio n dat a i s usuall ypresen t onl yonc e every5 second s (i.e
. onc e every5 second s ther e ar e onl y7 vali d sample s an d on e invali d sampl e i n a on e secon d acquisitio n perio d (Su b frame))
. Righ televato rpositio n dat a wa s show n no t t o b e effecte d byth e anomaly
. I t i s possibl e t o deduc e a correcte d left elevato r positio n sampl e fro m compariso n o fthi s paramete rt o th e righ televato rpositio n an d linea r interpolatio n betwee n correc t left elevato rpositio n sample s aroun d th e anomaly
. Th e operatio n o fth e righ t an d left elevator s typicall ytrac k th e movemen to feac h othe rdu e t o th e mechanic s o f th e elevato rsystem
. I n summary , thi s anomal yca n b e addresse d i n groun d processin g o fth e data
. Th e roo t caus e o fthi s anomal yi s foun d i n a DFDA U softwar e acquisitio n timin g error . Periodically , i n a give n paramete racquisitio n cycle , th e DFDA U i s requestin g th e acquisitio n o f mor e paramete rdat a tha n i tha s tim e t o complet e i n tha tacquisitio n cycle
. Becaus e paramete r acquisitio n doe s no t hav e tim e t o complet e th e previou s vali d sampl e i s use d i n th e recordin g rathe rtha n th e desire d curren t sample
. Pag e 2 o f4America n Airline s - 737N G Exemptio n Reques t

Novembe r23 , 201 0 Th e DFDA U softwar e i s softwar e loadabl e an d Teledyn e ha s informe d Boein g tha tthi s anomal y ca n b e fixe d wit h a mino rsoftwar e revisio n resultin g i n ne wsoftwar e partnumbers
. Pla n t o Correc tAnomaly : Boein g ha s verball ynotifie d th e FAAan d i s i n th e proces s o ffilin g a "Reporto fNoncomplianc e wit h Part 2 5 Ainworthines s Regulations " wit h th e FAAstatin g tha t th e anomal ydoe s no t represen t a safet yissu e fo rcontinue d operation
. Boein g ha s a pending contrac t in-wor k wit h Teledyn e an d afte rit s acceptanc e th e pla n i s t o certif yth e ne wDFDA U softwar e i n approximatel y5- 6 months
. Th e dat e o fcertificatio n i s contingen t o n wha ti s foun d durin g tes twhic h ma ycaus e th e schedul e t o mov e eithe rleft o rth e right
. I n an ycase , Boein g i s activel yworkin g t o accelerat e th e certificatio n o fcorrecte d software
. Upo n receip to fth e Boein g Servic e Bulleti n an d certifie d software , America n Airtine s wil l instal l thi s softwar e withi n 9 0 days , terminatin g th e nee d fo rth e exemption
. Publi cInteres t Th e grantin g o fthi s exemptio n woul d b e i n th e publi cinteres tbyallowin g America n Airline s t o continu e providin g servic e t o domesti can d internationa l destination s utilizin g th e B737-82 3 serie s aircraf t liste d i n Tabl e 1
. Failur e t o gran t thi s exemptio n woul d requir e America n Airline s t o cance l flight s an d disrup t schedule s causin g significan t financia l los s a s wel l a s impos e inconvenienc e an d potentia l lost tim e cos t t o th e travelin g public
. Affec t o n th e Leve l o fSafet y Th e fac t tha t th e FDR S i s missin g 1 recorde d sampl e every5 second s doe s no t hav e a n advers e affect o n th e norma l o rirregula roperatio n o fth e aircraft
. I ti s possibl e t o deduc e a correcte d leftelevato rpositio n sampl e fro m compariso n o fthi s paramete rt o th e righ televato r positio n wit h linea rinterpolation
. Th e operatio n o fth e righ t an d leftelevator s typicall ytrac k th e movemen t o feac h othe rdu e t o th e mechanic s o fth e elevato rsystem
. I n summary , thi s anomal yca n b e addresse d i n groun d processin g o fth e data
. Th e manufacture ro fth e aircraf t (Boeing ) ha s reviewe d thi s exemptio n an d ha s determine d "th e issu e i s no t considere d t o b e a ris k t o curren t an d futur e operatio n o fth e airplane. " Summar yfo rth e Federa l Registe r A s describe d i n 1 4 CF R 11.87 , America n Airline s request s tha tthi s exemptio n no tb e publishe d i n th e Federa l Registe ran d follo wwit h reques t fo rcomment s du e t o th e ensuin g dela yo f potentiall ygrantin g th e exemption
. America n Airtine s i s requestin g a n exemptio n fro m 1 4 CF R Part 121.34 4 t o allo wfo rth e continue d operatio n o fB737-82 3 serie s aircraf t i n domesti can d internationa l revenu e servic e withou t th e installe d Digita l Fligh tDat a Acquisitio n Uni t (DFDAU ) recordin g al l 8 sample s o fth e left elevato rpositio n data
. Thi s exemptio n shal l allo wth e Aircraf t Manufacture r(Boeing ) an d th e DFDA U Syste m Softwar e Provide r(Teledyne ) tim e t o develop , validate , an d certifyth e softwar e t o correc t th e DFDA U anomal yan d allo wAmerica n Airtine s tim e t o instal l th e softwar e wit h minima l interruptio n t o fligh t scheduling
. Pag e 3 of4America n Airline s - 737N G Exemptio n Reques t

Novembe r23 , 201 0 Additiona l Informatio n Boein g ha s verball ynotifie d th e FAAan d i s i n th e proces s o ffilin g a "Report o fNoncomplianc e wit h Part 2 5 Airworthines s Regulations " wit h th e FAAstatin g tha tth e anomal ydoe s no t represen t a safet yissu e fo rcontinue d operation
. Us e o fth e Exemptio n outsid e th e Unite d State s America n Airiine s woul d lik e t o utiliz e th e privilege s o fthi s exemptio n outsid e th e Unite d States
. Th e primaryschedule d operation s fo rthi s mode l aircraf t i n America n Airiine s flee tinclude s internationa l operation s primaril yi n Mexico , Canada , Centra l America , Sout h Americ a an d th e Caribbean
. You rconsideratio n o fth e foregoin g an d expedite d approva l o fthi s reques ti s appreciated
. I fyo u hav e an yquestion s regardin g thi s request , pleas e fee ! fre e t o contac t thi s office
. Sincerely ,
Willia m M
. Cavit t Vic e Presiden t Engineering , Performanc e & Qualit yAssuranc e
O n behal fof : America n Airiines , Inc
.

Ai rCarrie rCertificat e AALA025 A 390 0 N Ming o Rd,M D 18 3 Tulsa , O K7411 6 Phone : 918-292-290 2 Fax : 918-292-183 0 Email : bill.cavitt@aa.co m
cc : Federa l Aviatio n Administratio n AA LCertificat e Managemen tOffic e c/ o Mr
. Willia m T
. Satterfield , PA I 1480 0 Trinit yBlvd , St
. 10 0 FortWorth , Texa s 7615 5 Th e Boein g Compan y B
. C
. Groenewegen , Manager , Continue d Ain/vorthines s Twi n Aisl e Program s P.O
. Bo x370 7 Seattl e W A98214-220 7

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