AD/CL-600/77 Engine Exhaust Nozzle (Cth)

AIRWORTHINESS DIRECTIVE

For the reasons set out in the background section, the CASA delegate whose signature appears below issues the following Airworthiness Directive (AD) under subregulation 39.001(1) of CASR 1998.  The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.

Bombardier (Canadair) CL-600 (Challenger) Series Aeroplanes

AD/CL-600/77 Engine Exhaust Nozzle 9/2007

Applicability:

Bombardier Inc. CL-600-2B19 Regional Jet (CRJ), aircraft serial numbers 7003 through 7067, and 7069 through 7947.

Requirement:

1.    Inspect both left and right exhaust nozzles in accordance with the Accomplishment Instructions, Part A of Bombardier SB 601R-78-021 dated
2 June 2006 or later NAA approved revisions.

a.     If a bolt is missing or fractured on the engine exhaust nozzle, before further flight, replace the existing engine exhaust nozzle attachment hardware with new hardware in accordance with Requirement 3 of this AD.

b.    If no bolt is missing or fractured, no further action is required until the next inspection.

2.    Repeat Requirement 1 of this AD.

3.    Replace the existing engine exhaust nozzle attachment hardware with new hardware in accordance with the Accomplishment Instructions, Part B of Bombardier SB 601R-78-021 original issue or later NAA approved revisions.

Completion of Requirement 3 of this AD constitutes terminating action for Requirements 1 and 2 of this AD for the applicable engine exhaust nozzle.

Note:  Transport Canada AD CF-2006-19 dated 28 July 2006 refers.

Compliance:

1.    Within 1500 flight hours after the effective date of this AD, unless previously accomplished.

2.    At intervals not to exceed 1500 flight hours.

3.    Within 4000 flight hours after the effective date of this AD.

This Airworthiness Directive becomes effective on 30 August 2007.

Background:

There have been three reported incidents of CL-600-2B19 (CRJ) aircraft engine exhaust nozzle and fairing departure in flight.  Investigation on the failed retaining bolts revealed the bolts attaching the engine exhaust nozzle to the engine flange offered less than desirable stress margins.  Loss of the engine exhaust nozzle during flight could result in damage to the aircraft and create a hazard to persons and property on the ground.

In order to rectify this problem, Bombardier has issued service bulletin (SB)
601R-78-021 to introduce an inspection and replacement of the hardware attaching the engine nozzle to the engine flange.

David Punshon
Delegate of the Civil Aviation Safety Authority

25 June 2007