14 CFR ParI 39

DEPARTMENT OF TRANSPORTATION

Federal AviatioD Administration

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[Docket No. FAA-2010-*****; Directorate Identifier 201O-NM-041-AD]

14910-I3-P]

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R1N 2120-AA64

Airworthiness Directives; Bombardier, Inc. Model BD-700-1AIO and BD-700-lAII

Airplanes

AGENCY: Federal Aviation Admimstration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

ROUTING SYMBOL

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

listed above. This proposed AD results from mandatory continuing airworthiness

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

RCl<.!J"TNG :;;VMBOL

and correct an unsafe condition on an aviation product. The MeAl describes the unsafe "mAl..SlSl~

condition as:

Following five reported cases of balance washer screw failure on similar

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

types, an investigation * * * determined that a specific batch of the screws

had a metallographic non-conformity that increased their susceptibility to

brittle fracture. * * *

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

washer, with consequent turbine imbalance. Such imbalance could

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

of RAT 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].

ROlJTTNG SYMBOL

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'O\Jf1NG SYMIIOL

OUTING SVMOOL

NITIALS;SIG

DATE

* * * * * * *
DEPARTMENT OF TRANSPORTATION

Federal A,"ialioll AdminiSlr:Hion

14 CIi'J{ 1):\I·t 39

1491O-13-PI

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[Docket No. FAA-2010-*****; Dircdllralc Identifier 20IOvNM-041-AI>]

Aim"OI·thillc.~~ Directives; Bombardier, Inc. Model BD~ 700-1A 10 [Jnd 13D-700-11\ 11

Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed wlemaking. (NPRM).

SUMMARY: We propose to adopt a new airworthiness directive (AU) for the products

lisled above. This proposed AD results from Itmndalory continuing airworthiness

information (MeAl) originated byan aviation authority of another counlry to identify

ami correct an unsafe condition on ,m aviation product. The MeAl describes the uns~d'c

condition as:

Following live repOlted cases of balance washer screw failure llil simililr

RATs lram air lurbincsJ/air driven generators installtld on olher uin.:.rilft

types, I1ninvcsrigalioll '" '" '" determined that a specific batch o('l.he screw:;

had [l. lIlctallographic non~c{)nforl11itylhat increased their susceptibility to

brittle fracture, * * *

Failure of {1 b~lance washer screw can rcsult in loss ofthc related balance

washer, with consequcnt turbine imbalance. Such imbalance could

potenlially result in RAT structural failure (including blade failure). loss

of RAT electrical power and structural damage to the ain:.raftl.lnu, if

deployment was activated by a dunl enginc shutdown, could also rcsult in

loss of hydraulic power for the nighl controls [and conscquel1\ reduced

ability of lhe flightcrew to mailltain lhe sale nighl and landing oCthe

airpluncl·

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ANt>171

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