(AW 600-29-2485 and AW 300-29-0211) – Operators have reported cases where certain hydraulic system clamps have shown premature deterioration of the cushion material on Challenger 604 (5301 to 5665) and 605 (5701 to 5990) aircraft.  The failures have been found to be when the cushion material has broken down prematurely, and in some cases, enough to allow the metal clamp band to contact and chafe the tubing/piping.

The Advisory Wire (AW) issued previously pertains to blue Adel clamps (p/n M85052/2). Bombardier has conducted an airworthiness review of the reports and has determined there is no immediate safety impact.  However, operators should be aware of this condition and at the next convenient opportunity, inspect and replace any clamps whose cushion material may be showing signs of deterioration to avoid possible hydraulic line damage.  Particular attention should be given to clamps in the aft compartment.

While this Advisory Wire has been out for quite some time, operators may not be aware of the issue. West Star Aviation recommends replacement of all blue Adel clamps to the upgraded purple clamps. They are an improved material that does not deteriorate when in contact with Skydrol.