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DEPARTMENT OF TRANSPORTATION

RlN 2120-AA64

Federal Aviation Administration

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

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ACTION: Notice of proposed rulemaking (NPRM).

(Regional Jet Series 900) Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

100 & 440) Airplanes; Model CL-600-2CIO (Regional Jet Series 700, 701, & 702)

Ainvorthiness Directives; Bombardier, Inc. Model CL-600-2B19 (Regional Jet Series

Airplanes; Model CL-600-2D15 (Regiooal Jet Series 705) and Model CL-600-2D24

[Docket No. FAA-2010-*****; Directorate Identifier 201O-NM-014-AD)

14 CFR Part 39

listed above. This proposed AD results from mandatory continuing airworthiness .~

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

and correct an unsafe condition on an aviation product. The MeAl describes the unsafe ROUTlN'HYMIIQl

condition as:

Following five reported cases of balance washer screw failure on similar

ADOs [aiHiriven generators]/ram air turbines installed on other aircraft

types, investigation by Hamilton Sundstrand determined that a specific

batch of the screws had a metallographic non~confonnity 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 ADG structural failure (including blade failure), loss

of ADG electrical power and structural damage to the aircraft and, if

deployment was activated by a dual engine shutdown, could also result in

loss ofbydraulic power for the flight controls [and consequent reduced

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DEPARTMENT OF TRANSPORT AnON

Fl'dend Aviatiun Administration

14 CFn. Part 39

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lJ)ocket No.•.•.AA-2010-*"'***; Directorate Identifier 20tO-NM-OI4·ADl

RIN 21211-AA64

Airworthiness Directives; Bombardier, Inc. Model CL-600-2B 19 (Regional Jet Series A'N'I~~~"7't,

100 & 440) Airplanes; Model CL-600-2CIO (Regional Jet Series 700, 701, & 702)

Airplanes; Mode! CL-600-2DI5 (Regional Jet Series 705) and Model CL~600-2D24

(Regional Jet Series 900) Airplanes

AGENCY: Federal Aviation Administration WAA). DOT.

ACTION: Notice ufproposed mlemaking (NPRM).

SUMMARY: We propose (0 adopt a new airworthiness directive (AD) for the products

listed above. This proposed AD resu.lLsfrom mandatory continuing air\\lorthiness

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

and correct an unsafe condition all an aviation product The MeAl de!>cribesthe unsafe

conditioll m;:

Following five reported cases of balance washer screw failure on similar

ADGs lair-driven generalors)/ram air turbines inslalled on other aircraft

types. investigation by Hamilton Sundstrand determined that a spcciHc_

balch or the screws had a Illctallographic non-confonnily that increased

their susce.plibility to brittle 1i'"',JclUre.* * *

Failure ora balance washer screw can result in loss of the 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 a dual engine shutdown, could also result in

loss of hydraulic power for the flight controls.

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