[491O-13-PI

14CFR Part 39 DEPARTMENT OFTRANSPORTATION 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 ofproposed rulemaking (NPRM). SUMMARY: We propose to adopt anew 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 /ji'v/f) ~

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• l1I'lNG S\1olllOL and correcl an unsafe condition on an aviation product. The MeAl describes the unsafe NI1I,usISKl condition as: Following five reported cases ofbalance 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 ametallographic non-conformity that increased their susceptibility to brittle fracture" 

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## * * Failure ofa balance washer screw can result in loss ofthe 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 adual engine shutdown, could also result in loss ofhydraulic power forthe flight controls [and consequent reduced ability of the flightcrew to maintain the safe flight and landing ofthe airplane].



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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.;; IaiHln veil gcnaalurs liwill air tmbincs installed on mhl.":rAJrcr:rfl lypL';;. invl:sligaliull hy Ilalll1ltun SlIIllISIl"aild dcl..:rmillcd thJt i\ spetilic h'll..:h oCllle s..:re\Vshad fill1d,il\(lgr:lpl1ic Ilon-conformity thai il1cJ"(,';I:;cd llicii" SIIS..:..:plihilil)' to bl'lltk ti"'ldUl'e.•• " •• '"'"'' "'"'t" 

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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"CnirtlJllJ. if tkphlYlllL·nt \\"asactivaled by ,IJlt,ll cngim: shutdown. elml.:l ul:;(\result ill Illss ,It hydrmd i.: power for UK' llight cIJIltrub.


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