Document ID: chunk:federal_register_of_legislation:F2009L02258:body:0:p2
Version: federal_register_of_legislation:F2009L02258
Segment Type: other
Provision Reference: 
Character Range: 2893–4207

April 2009 refers.
Compliance:  Within 1600 flight hours or within 18 months after the effective date of this AD, whichever comes first.
             This Airworthiness Directive becomes effective on 2 July 2009.
Background:  A specific batch of NLG and NLG door selector valves, part number (P/N) 601R75146-1 (Kaiser Fluid Technologies P/N 750006000), may have had their end caps incorrectly lock-wired and/or incorrectly torqued during assembly.  This condition can lead to the end cap backing off, with consequent damage to a seal and internal leakage within the valve.  Subsequently, if electrical power is transferred or removed from the aircraft before the NLG safety pin is installed, any pressure, including residual pressure, in the No. 3 hydraulic system can result in an uncommanded NLG retraction and/or uncommanded opening of the NLG doors.  There have been six cases reported on CL600-2B19 aircraft, one of which resulted in the collapse of the NLG at the departure gate.

             This AD mandates a check of the NLG and NLG door selector valves installed on all aircraft in the Applicability section above.  Depending on the results, replacement, rework and/or additional identification of the valves may be required.

James Coyne
Delegate of the Civil Aviation Safety Authority

22 May 2009