[4910-I3-P]

DEPARTMENT OF TRANSPORT AnON

Federal Aviation Administration

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14 CFR Part 39

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[Dockel No. FAA-;lOO9-'*'**; [)jrcclorale Idenlifier 2009-NM-134-AD[ DurIN SI"MBOL

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RIN 2120-AA64

Airworthiness Directives; Bombardier Model DHC-8-400 Series Airplanes

AGENCY; Federal Aviation Administration (FAA), DOT.

ACTION: Nolice of proposed rulemaking (NPRM).

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

1isted above. This proposed AD results from mandatory continuing airworthiness

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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 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

normal position and resulted in contact with and rupture of the tire. The

loss of the pivot pin could compromise retention of the trailing ann and

could result in a loss of directional control due to loss of nose wheel

steering. The loss of an NLG tire or the loss of directional control could

adversely affect the aircraft during take off or landing.

•

condition as:

* * * * *

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

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described in the MeAl.

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

,

and correct an unsafe condition on an aviation product. The MeAl describes the unsafe 0U11::S~~"OL{p

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14910-13-PI

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR 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. ~,~

ANE-111

and eOITect all unsafe condition on an aviation product. The MeAl describes the unsafe

cundition us:

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Two ill-service incidents have been reported on DHC·8 Series 400 aircraft

in which 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 in contact with and rupture of the tire. The

loss of the pivot pin could compromise retention of the trailing ann and

could rcsult in a loss of directional control due to loss of nose wheel

sleering. The loss of an NLG tire or the loss of directional 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 of another country to identify

ACTION: Notice of proposed rulemaking (NPRM).

SUMMARY: We propose to adopt a new 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.