COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Bombardier (Canadair) CL-600 (Challenger) Series Aeroplanes AD/CL-600/33 Overwing Emergency Exit Hatches 6/99 Applicability: Bombardier Inc. (formerly Canadair) CL-600-2B19 'Regional Jet' aircraft, serial numbers 7003 through 7292. Requirement: Remove the insulation blankets surrounding the overwing emergency exit hatches in accordance with the Accomplishment Instructions of Bombardier Alert Service Bulletin A601R-25-152 dated 26 December 1998. Note: Transport Canada Airworthiness Directive CF-99-01 refers. Compliance: Unless already accomplished, before 17 July 1999. This Airworthiness Directive becomes effective on 17 June 1999. Background: During maintenance within one hour after the last flight of the day, an operator experienced problems removing the overwing emergency exit hatches on three RJ aircraft. Investigation showed that the problem was due to freezing of moisture in the fibreglass/foam insulation installed in the aircraft.