03/16/201 0 14:3 8 316946410 7 WICHIT AAG O PAG E 02/0 5 

# Federa l Aviatio n Administratio n 

# Memorandu m Date : Marc h 16,201 0 From : Tin aL . Mille r Progra mManager , ACE-117 W Wichit aAircraf

t Certificatio n Offic e To : U.S . Dep t

o f Transportatio n Docke t Managemen t

Syste m Prepare d by : Tin aL . Mille r Subject : ACTION : Cessn aAircraf t Compan y Reques t

for Exemptio n fro mth e Requirement s o f 1 4 CF R Sectio n §25.1447(cXl) , 15,00 0 ft Cabi n Pressur e Altitud e

Cessn aAircraf

t Compan y ha s submitted , throug

h th e Wichit

aAhcrai t Certificatio

n Office , thei

r reques t for exemption t o th e requirement listed above a s pertain s t

o automati c display o f

oxyge n befor e th e cabi n altitud e exceed s 15,00 0 feet . Attached fo

r yo u actio n i s th e origina

l cop y o f Cessn alette

r L390-10-0656 , dated Marc

h 1,2010 . W

e will appreciat e you keepin

g thi s offic e infonned regarding an

y action s take

n fo r thi s request . A cop y o f thi s transmioa

l memorandu

man d Cessna' s reques t

i s bein g sen

t to th e Transpor

t Airplan e Directorate . Th e Projec

t Office r fo r th e Cessn aMode

l 68 0 i s Rick

Morris , ANM-113 . I f yo u hav e an y questions , pleas e advise . Tin aL . Mille r Attachmen t cc : Ric

k Morris , ANM-11 303/16/201 0 14:3 8 316946410 7 WICHIT A AG O PAG E 03/0 5



### C^ssr a A T«KU« n Compan y 0 1 Marc h 201 0 I N REPLY , REFE

R TO : L390-10-065 6 Federa l Aviation Administration Wichit aAircraf t Certification Offic

e 180 1 Airpor

t Roa d Wichita , Kansa s 6720 9 < 1

^ 

# J ^

ATTENTION : SUBJECT : Ms . Tin aMille r Cessn aProgra

mManage r Mode l 680 , Petitio n fo

r Exemption firomth e Requirement s o f 1 4 CF R 25.H47(c)(l) , 15,00

0 ft Cabi n Pressur e Altitud e Dea r Ms . Miller : Cessn areqiies t

relie f fromthe followin

g regulations : Section 25.1447(cXl ) states ; "Ther e mus t b e a n oxyge n dispensing uni t

connecte d t o oxyge

n suppl y terminal s immediatel

y availabl e t

o eac h occupant , whereve

r seated , an d a t leas t tw o oxyge n dispensing unit s cormecte d t o oxyge n terminal s i

n eac h lavatory . Th

e tota l numbe r o f dispensin g unit s an d outlet s in th e cabi

n roust excee d th e numbe

r o f seat s by a t leas t 1 0 percent . Th e extr aunit s mus t

b e a s uniforml

y distribute d throughou

t th e cabin a s practicable . I

f certification fo

r operatio n above 30,000 fee t i s requested , the dispensing imit s providin g th e require d oxyge

n flow mus t

b e automaticall

y presente d t o th e occupant s befor e th e cabin pressur

e altitud e exceed s 15,00

0 fee t Th e crew mus t

b e provide d wit

h amanua l mean s o f making th e dispensin g imit s immediatel

y availabl e i n the even

t o f afailur e o f th e automati c system. " A n exemptio n i s requeste d t o th e portio n requirin g th e dispensin g unit s t o b e automaticall y presente d t o the occupant s befor e the cabin pressur

e altitude exceed s 15,00

0 fee t Th e presen t aircraf t use s Transpor

t Airplane Directorat

e (TAD ) Equivalen

t Leve l o f Safet y (ELOS ) Mem

o TC2548WI-T-SG- 1 t o addres s suppression o f th e 10,00 0 foo t cabin pressur

e altitud e warning require d b

y 25.841(b)(6 ) whe

n operating t o an

d firomairport s wit

h afield elevatio n fiom8,00

0 fee t t o 14,00 0 fee t03/16/201 0 14:3 8 316946410 7 WICHIT AAG O PAG E 04/0 5 L390-10-065 6 Pag e 2 of 3 T o avoid nuisanc e warning s whe n operating t o an

d fiomairport s wit

h afield elevatio n from 8,00 0 fee t t o 14,00 0 feet , a n exemption i s requeste d t o allo w us e o f a">14K " switc

h t o shif t the cabi n altitud e warnin g to 15,75 0 feet . Th e petitione r support s it s reques t

wit h the following : A ne w airpor t i s unde r constructio n in N^qu , Chin ai n th e northwes t portio n o f th e Qinghai

Tibe t Plateau . Th

e airpor t i s scheduled fo

r completion in 201 0 an

d ha s alandin g field elevatio n o f 14,63 9 fee t above se alevel . The custome r ha s requested th e aircraf

t b e capable o

f operation s a t thi s and othe

r airport s wit

h field elevatio n abov e 14,00 0 fee t (witi i anticipate d barometri c pressur e variations ) u

p to 15,00 0 feet I n orde r fo r th e Mode l 68 0 Sovereign t o provid

e th e additiona l capabilit y fo r landing a t airport s u p t o 15,00 0 fee t pressur e altitude , th e Cabi

n Pressur e Control Syste

m(CPCS ) an

d Passenge r Oxyge n Control Syste

m(POCS ) wil l b e modifie

d t o allo w th e cabi

n interna l pressur e altitud e t o reach a s higj i a s 15,15 0 +/-15 0 fee t durin g ">14K " operations . Manua

l contro l o f

th e oxyge n syste mi s no t affecte d an d ca n b e activate d a

t an y tim e th e crew deeir\s necessary . Publi c Interes t

Statement : Cessna' s leadershi

p positio n in the globa

l busines s je t

marke t i s du e t o th

e effort s o f it s nearl y 8,00 0 employee s i

n manuiacturin g plants , completion centers , an d servic e center s acros s th e Unite d States . Thi s fiirthcr

include s th e man

y vendor s located acros s th e United State s tha t provid e th e numeroii s aircraf

t piece s suc h a s avionics , oxyge

n components , a s wel

l ath e modifie d CPC S component s tha

t would b e used fo

r th e aircraf t t o operat e a t thi s high elevation , Cessn acompete s fo

r ne w busines s al l ove

r th e world . Althoug

h th e curren

t econom y ha s slowed , Cessn ai s strivin g har d t o gai n internationa

l market s fo

r it s busines s jets . Thi s increased marke t directl y affects th e viabilit

y o f Cessn aan d would ai d i n th e stabilizatio n o f th e jo b marke

t a s well a s the growt

h o f the America

n economy , whic

h i s directly i n th e interes t

o f th e public . Supporting Information : A requiremen

t fo r automati c presentatio n o f

masks fo r airplane s certified t o operat e above 30,00 0 feet

originated i

n §4b-65I(d)(3)(i ) o f

th e Civil Aviation Regulation s (CAR ) an d wa s carrie d ove

r a s §25.1447(c)(1 ) whe

n par t 2 5 wa s codified . Th

e CA R requiremen

t di d no t specif y the maximu

mcabi n altitud e pressur e allowed prio r

t o presentation . Th

e requiremen

t tha t th e oxyge n equipmen

t b e automaticall

y presente d befor

e th e cabi n pressur e altitude reache s 15,00

0 fee t wa s adde d a t Amendmen

t 25-41 , effective Septembe

r 1,1977 . Thi s additiona

l requiremen

t recognized the hazar

d o f oxyge n deprivation on th e averag e huma n bein g an d it s effec t o n carrying ou

t action s unde

r stressfu l conditions . Th e oxyge n mas k presentatio n a

t 15,75 0 +/

- 25 0 fee

t i s onl y selecte d ^^e n a">14K " switch i s activate d by the pilot . A

n indication ligh

t indicatin g tha

t th e aircraf t i s i n ">14K " mod

e i s als o provided . Thi s featur

e assist s i n limitin g us e o f

thi s mod e t o condition s whe

n th e airplan

e wil l operat e fromairfield s wit

h a n elevatio n greate

r tha n 14,00 0 feet . Th e activatio n poin

t fo r th e03/16/201 0 14:3 8 315945410 7 WICHIT AAG O PAG E 05/0 5 L390-10-065 6 Pag e 3 of 3 cabi n altitud e warnin g i s als o shifte d with th e sam e switc h t o avoi d nuisanc e alert s whe n operatin g t o an d fromairport s a t a n altitud e greate r

tha n 14,00 0 feet . Appropriat e procedure s wil l b e provide d i n th e Airplan e Fligh t Manual t o addres s prope r operatio n o f

th e ">14K " switc h fimction. Thes e feature s wil l hav e th e flight cre w selec t

thi s fimctio n whe n descendin g t o lan d at a n airfiel d elevatio n greate r tha n 14,00 0 fee t

an d t o reselec t

th e ">14K " switc h bac k

t o th e "Normal " mod e whe n climbin g after takeof f froma n airpor

t wit h afield elevatio n greate r

tha n 14,00 0 feet

Th e procedur e wil l minimiz e th e time th e aircraf t i s i n th e elevate d altitud e t o tha t require d t o safel y lan d and/o r takeof f fixmi airport s wit

h afield elevatio n greate r

than 14,00 0 feet . I f yo u requir e additional informatio n o r hav e an y questions , pleas e d o not hesitat e t o contac t Donn aDeBuh r

a t 316-517-0689 , emai l ddcbuhr(3!cessna . textron.co m Sincerely ,

/ - Carlo s Ayal a T C OD A Administrato r Cessn aAircraf

t Compan y ODA-100129-C E