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14 CFR Part 39

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

OLl39

[Docket No. FAA-2010-*****; Directorate Identifier 2010-NM-029-AD]

RTN 2120-AA64

Airworthiness Directives; Bombardier, Inc. Model CL-600-2B16 (CL-604 Variants

(Includi.ng CL-60S Marketing Variant) Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

SUMMARY: We propose to adopt a new airworthiness directive (AD) for the product

listed above. This proposed AD results from mandatory continuing ajrworthiness

infonnation (MeAl) originated by an aviation authority of another country to identify

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and correcl an unsafe condition on an aviation product. The MeAl describes the unsafe NI1I,usISKl

condition as:

Following five reported cases of balance washer screw failure 011 similar

ADGs [air-driven generators]/ram air turbines installed on other aircraft

types, investigation by Hamilton Sundstrand detcnnined that 8: specific

batch of the screws had a metallographic non-conformity that increased

their susceptibility to brittle fracture" * * *

Failure ofa balance washer screw can result in loss of the related balance

washer, with consequent turbine imbalance. Such imbalance could

potentially result in ADG structural failure (including blade failure), loss

of ADG electrical power and structural damage to the aircraft. and, if

deployment was activated by a dual engine shutdown, could also result in

loss of hydraulic power for the flight controls [and consequent reduced

ability of the flightcrew to maintain the safe flight and landing of the

airplane].

* * * * * * *

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1lEI'AJ-rI"r\l ENT {)F TR,\NSI'OrnATION

Fl'dcl':11 ;\\'iatiUli Administr;}lion

l-t ('FH Part 39

jllockd Nil. F;\;\-2010-*'"'***; Dirccturatl' ldcnlifit'l· 2010-NM-029-ADI

RIN 2120-.'\/\6.:1

Ain,orthincss Dircdinll; Bombarclicr.lnc. ~'lodcl CL·600·2BI6 (CL-604 V;!.fi:lni~

(incJllllin,!! l'l.-605lvbrkcling V,mant» Airpl'll1c~

A(;ENey: I'cderal AvjationAdministraliul\ (FAA), 00r.

ACI'ION: NUlicc of proposed rukmaking (NPRM).

Sl !MMARY: We propoS(' ll\ adopt a I1C\\'airwllnhincss clircctivl: (AD) for the prndu(:ls

li!iled 'lbuvc. 'J-his proposed AD resull ...•from mUml.lIOl)' cotllill\ling airwonhincss

inhlflllatitJll (Ml"AI ~origiJl<licd by un L1vimbn authorilY 01",mother Coulliry It' l(klllily

and l:nlTccl an unsafe C\lllliilinl\ on <Ill<\\'i,ltiun product. The MeAl describc_,>lhl.: Ull$<IIi.'

condition as:

l:nllowlI1g flv<..'rcporto.'J C:lses nrhulalll.:c washcr ~crcw fail\lr~ on similar

/\ I)G.;; Iai Hln veil gcnaalurs liwill air tmbincs installed on mhl.":r AJrcr:rfl

lypL';;. invl:sligaliull hy Ilalll1ltun SlIIllISIl"aild dcl..:rmillcd thJt i\ spetilic

h'll..:h oCllle s..:re\Vs had fill1d,il\(lgr:lpl1ic Ilon-conformity thai il1cJ"(,';I:;cd

llicii" SIIS..:..:plihilil)' to bl'lltk ti"'ldUl'e.•• " ••

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l"ailun.: ul' a bnlam:e wasl1el' SClTW C,m result ill los~ of th..:rdat<:d 1)<lI[[n..:..:

w'l"h<:1". with ClHls<.:ym:nt lurbul<.' 1I11!l;II'1I1C<':.Such imbalancc cmtlJ

PUI('lllial1y rC:"lllt in ADO structural f:'til11I"<': (including blade faillln.::), l".,;s

(It"I\D(; ek,Aric'I!I)ilwcr and slrll",lllral dmnagc to (h..: llil"Cnirt lJllJ. if

tkphlYlllL·nt \\"as activaled by ,I Jlt,ll cngim: shutdown. elml.:l ul:;(\ result ill

Illss ,It hydrmd i.: power for UK' llight cIJIltrub.

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