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ROUTING S\'MHOL IWfE [Docket No. FAA-20IO-++++; Directorate Ide[tifier 2010-NM-095-AD] RlN 2120-AA64 Airworthiness Directives; Learjet Inc. Model 4 Airplanes AGENCY; Federal Aviation Administration (FtA), DOT. ACTION; Notice ofproposed rulemaking (NPRM). SUMMARY: Wepropose to adopt anew airwokhiness directive (AD) forcertain I Learjet Inc. Model 45 airplanes. This proposed

# tD would require replacing aluminum "OUT"aSYMBOL fire extinguisher discharge tubes with new, impTved tubes; checking the fire INITIALS'SIG extinguisher container for certain serial numbers; replacing fire extinguisher containers 

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# o,;~o that have affected serial numbers; inspecting thelpressure indicator on certain fire 

# RO~,(:;'.,nJD extinguisher containers fordiscrepancies; and

### pf(rforming corrective act~onifnecessary.

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# ov ,I I I ].5'". This proposed AD results from areport ofaCCidfntaldischarge ofafire extinguisher container and damage to an aluminum dischargl tube. Investigation revealed that 

# .,~,'3;y, following the discharge an inaccurate pressure in Idicatioll, due to the indicator dial being f h 'N[TLAlqIG incorrectly staked_showed that the contamer war Ullyc arged. We are proposing this AD to prevent inaccurate pressure readings and fubsequent damage to the discharge tub 

# :sm during operation, which could result in failure ofthe fire extinguisher system and an ROun~\""M"OI, 14CFR Part 39 Federal Aviation Administration DEPARTMENT OF TRANSPORTATION

uncontained fire inan emergency situation. INITIM"/jIG DATES: We must receive comments onthis priPosed AD by [INSERT DATE 45 DAYS AFTER DATE OF PUBLICA nON INTHE FEDERAL REGISTER]. ADDRESSES: You may send comments by anJ ofthe following methods:

• Federal eRulemaking Portal: Go to httJ://Vo."Nw.regUlations.gOv. Follow the D.HE

instructions for submitting comments.DEPARTMENT OF TRANSPORTATION /491O-13-Pj

14CFR Part 39 Federal Aviation Administration 

## IDocket No. FAA-2010·++++j Directorate IdCrtifier 2010-NM-095-ADI RIN 2120-AA64 "'" 

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## oK lD Airworthiness Directives; LemjetInc.Model4$Airplanes n,1 , .~ -. "~l. 

# pn. AGENCY: Federal Aviation Administration (Fr)' DOT. 

# "".~o.,,"~£, ACTION: Notice ofproposed rulcmaking (NPRM). ['""m 

# I "Y·/~ SU~MARY: WeproposetoadoPt.anewairworthiness directi~e(AD)~orcertai~ 

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< Learyet Ine. Model 45 airplanes. This proposed ~D would reqUIre replaemg alummum ,.

# fr~;.,£ fire extinguisher diseharge tubes with new, imprLed tubes; ebecking the fire 

# ""'0- _If) extmb'Uisher cuntainer for certain serial numbers! replacing fire extinguisher containers 

# l[r',-, that have affeeted senal numbers; inspectmg the rressure indicator on eertain fire extinbruisher containers for discrepancies; and performing corrective achon 

### ifnecessa This proposed AD results from areport of accidJntal discharge ofa fire extinguisher eontainer and damage to an aluminum diseharge rUbe. Investigation revealed that following the discharge an inaccurate pressure in(lication. due to the indicator dial bein incorrectly staked, showed that the container wJ fully charged. Weare proposing this "o;'''''JS'''''(;(lL AD to prevent inaccurate pressure readings and SlbSeqUent damage to the discharge tu es"".L3!S'[,"'''L'~E during operation, which could result in failure oJthe fire extinguisher system and an uncontained fire in an emergency situation. DATES: We must receive comments on this proposed AD by [fNSERT DATE 45 I DAYS AFTER DATE OF PUBLICA nON INjHE FEDERAL REGISTER]. ADDRESSES: You may send comments by any ofthe following methods:

• Federal eRulemaking Portal: Go to http.//www.rcgu1<llioIlS.goV. Follow the 

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# "'1 n''''rr. :;,",'OO[ .",,,",-~., $;(""""" , instructions for submitting comments.

\ (l.S. GOVEflNMUJr PAIUTING onlC( 1m 169·~11 FAA Form 1360-14.1 (6-89)