# .+. Transport Canada Transports

Canada No. CF-2010-01 Issue Date TP 7245E



# I 1/2 

# AIRWORTHINESS 18January 2010 

# DIRECTIVE ~~1~~f~'~#~o~~'i~1'S~l

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### Compliance: Background:

Corrective Actions: CF·2010·01

Ram Air Turbine (RAT)
- NonwConforming Balance Washer Screws 16 February 2010 Bombardier Inc. Models BD-700-1A10 and BD-700-1A11. Serial Numbers (SINs) 9002 and subsequent. As indicated below, Following five reported cases of balance washer screw failure on similar RATs/air driven generators installed on other aircraft types, an investigation by Hamilton Sundstrand determined that a specific batch of the screws had a metallographic non-conformity that increased their susceptibility to brittle fracture. Subsequently, itwas established that 187 RATs [Part Number (PIN) GL456-1101-7 and Hamilton Sundstrand PINs in the 762826 series) had non-conforming screws installed either during production or possibly during maintenance or repair at Hamilton Sundstrand repair stations. Failure of a balance washer screw can result in loss ofthe related balance washer, with consequent turbine imbalance_Such imbalance could potentially result in RAT structural failure (induding blade failure), loss of RATelectrical power and structural damage tothe aircraft and, ifdeployment was activated by a dual engine shutdown, could also result in loss of hydraulic powerfortheflight controls. This directive mandates checking ofthe RATand replacing the balance washer screws, if required, Italso prohibits future insta!lation of unmodified RATs. Part I: Identification Check Appiicable to BD-700-1A10and BD-700-1A11 aircraft, SINs 9002through 9380. Prior to the next scheduled in-flight operational test ofthe RAT after the effective date of this directive, unless already accomplished, check the SIN of the installed RAT. This check may be conducted visually. which requires the RAT to be lowered, or by checking the delivery and maintenance records. A Ifthe RAT SIN is not listed in paragraph 1A ofthe applicable Bombardier Aerospace Service Bulletin (SB) detailed below, or later revision approved by the Chief, Continuing Airworthiness, Transport Canada, nofurther action is required, other than compliance with Part III ofthis directive.

B, Ifthe RAT SIN islisted in paragraph 1.A. ofthe applicable Bombardier Aerospace SB detailed below, or later revision approved by the Chief, Continuing Airworthiness, Transport Canada. inspect the RAT identification plate.

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1) If symbol "24-7" is marked on the RAT identification plate. the balance washer screws have already been replaced. No further action is required, other than compliance with Part III of this directiv8_ 2) Ifsymbol "24-7" is notmarked on the RAT identification plate, replacement ofthe balance washer screws is required_ Proceed to Part II of this directive.
Part II: Replacement of the Balance Washer Screws and Identification of the RAT Applicable to BD-700-1A10and BD-700-1A11 aircraft, SINs 9002through 9380. Priortothe next scheduled in-flight operational test ofthe RATafterthe effective date of this directive, unless already accomplished: Replace all of the balance washer screws, and mark the RAT identification plate with symbol "24-7", in accordance with the Accomplishment Instructions in the applicable Bombardier Aerospace S8 detailed below, or later revision approved by the Chief, Continuing Airworthiness, Transport Canada.

Note: Part II isonlyapplicable if required by Part I, Paragraph B.2. ofthis directive. Part III: Replacement Parts Applicable to BD-700-1A10and BD-700-1A11 aircraft, SINs 9002 and subsequent After the effective date ofthis directive: It is not permitted to install a replacemenUspare RAT [PIN GL456-1101-7; Hamilton Sundstrand PINs inthe 762826 series] with one ofthe SINs listed in paragraph 1.Aofthe applicable Bombardier Aerospace S8 detalled below, or later revision approved by the Chief, Continuing Airworthiness, Transport Canada, unless it is identified with the symbol "24-7" on the identification plate.

Authorization: For Minister ofTransport, Infrastructure and Communities

ORIGINAL SIGNED BY Derek Ferguson, Chief, Continuing Airworthiness


### Contact: Mr. Richard Topham, Continuing Airworthiness, Ottawa, telephone 613-952-4357,

facsimile 613-996-9178 or e-mail CAW Web Feedback@tc.gc.ca or any Transport Canada Centre.