[4910-I3-P]

DEPARTMENT OF TRANSPORT AnON 

### Federal Aviation Administration 

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14CFR Part 39 

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# O;}..7:3 [Dockel No. FAA-;lOO9-'*'**; [)jrcclorale Idenlifier 2009-NM-134-AD[ DurIN SI"MBOL ANE·11l RIN 2120-AA64 Airworthiness Directives; Bombardier Model DHC-8-400 Series Airplanes AGENCY; Federal Aviation Administration (FAA), DOT. ACTION: Nolice ofproposed rulemaking (NPRM). SUMMARY: We propose to adopt anew airworthiness directive (AD) for the product 1 isted above. This proposed AD results from mandatory continuing airworthiness UTIN~",mOL ANE-170
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# • Two in·service incidents have been reported on DHC-8 Series 400 aircraft in which the nose landing gear (NLG) trailing ann pivot pin retention bolt (part numher NAS6204-l3D) was damaged. One incident involved the left hand NLG tire which ruptW'ed on take-off. Investigation determined that the retention bolt failure was due to repeated contact ofthe castellated nut with the towing device including both the towbar and the towbarless rigs. The loss ofthe retention bolt allowed the pivot pin to migrate from its normal position and resulted incontact with and rupture ofthe tire. The loss ofthe pivot pin could compromise retention ofthe trailing ann and could result in aloss ofdirectional control due to loss ofnose wheel steering. The loss ofan NLG tire or the loss ofdirectional control could adversely affect the aircraft during take offor landing.


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# "®" h The proposed AD would require actions that are intended to address the unsafe conditio ~;~ 'tJ\ 1'1t\fln.1 

# 11110 described inthe MeAl. infonnation (MeAl) originated byan aviation authority of another country to identify 

### , and correct an unsafe condition on an aviation product. The MeAl describes the unsafe 

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14910-13-PI DEPARTMENT OF TRANSPORTATION Federal Aviation Administration 14CFR Part 39 IDocket No. FAA-2009-'"""'u,t,; Directorate Identifier 2009-NM~134-ADJ IlIN Z120-AA64 Ainvorthiness Directives; Bombardier Model DHCw8-400 Series Airplanes AGENCY: Federal Aviation Administration (FAA), DOT. 

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and eOITect all unsafe condition on anaviation product. The MeAl describes the unsafe cundition us: (>1m"" 'YMrIOI. LJ;fj-Arf'&

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# • Two ill-service incidents have been reported on DHC·8 Series 400 aircraft inwhich tile nose landing gear (NLG) trailing arm pivot pin retention bolt (part number NAS6204-13D) was damaged. One incident involved the left hand NLG tire which ruptured on take-off. Investigation dctennined that the retention bolt failure was due to repeated contact of the castellated nut with the towing device including both the towbar and the towbarless rigs. The loss of the retention bolt allowed the pivot pin to migrate from its nonnal position and resulted incontact with and rupture of the tire. The loss ofthe pivot pin could compromise retention ofthe trailing ann and could rcsult in a loss ofdirectional control due to loss ofnose wheel sleering. The loss ofanNLG tireortheloss ofdirectional control could adversely affect the aircraft during take ofTor landing
. listed above. This proposed AD results from mandatory continuing airworthiness infonnalion (MeAl) originated byan aviation authority ofanother country to identify ACTION: Notice ofproposed rulemaking (NPRM). SUMMARY: We propose toadopt anew airworthiness directive (AD) for the produc

The proposed AD would require actions thal aTC intended to address the unsafe conditio m described in the MeAl.