22 January 2004
AFT Pressure Bulkhead Damage
Transport Canada has learned through the review of Bombardier All Operator Message (AOM) No. 746, of several reports where damage was caused to the aft pressure bulkhead at FS 621, a Principal Structural Element. This damage appears to have been inflicted while carrying out the generic Repair Engineering Order (REO) 601R-25-53-005, and during the replacement of the bulkhead liner around the cargo door track.
View on the forward side for FS 621
REO 601R-25-53-005 allows for the installation of a new Stainless Steel angle at FS 621, WL73, that picks up on the existing structure. During the installation, personnel are drilling the angle and allowing the drill bit to penetrate the bulkhead behind the supporting structure.
Another area of concern is the in-service replacement of the bulkhead liner around the cargo door track. During the replacement of these liners, many aircraft were found with additional holes drilled adjacent to the original holes.
View of FS 621 at door track
Bombardier AOM No.746 states, "Damage Tolerance Analysis, for aircraft that are affected by the inadvertent damage incurred during these types of repair configuration, will as a result, impact the damage tolerance of the pressure bulkhead such that the required threshold and repeat inspections will be significantly reduced".
Transport Canada strongly recommends operators inspect for damage to the aft pressure bulkhead in the area of the Stainless Steel angle and the door track liner. Removal of the liner and the angle may be necessary to facilitate this inspection. This should be done at the operators' earliest convenience.
Any defects or further occurrences should be reported by sending a Service Difficulty Report to Transport Canada, Continuing Airworthiness, Ottawa.
For further information, contact a Transport Canada Centre, or Mr. Steve Dudka, Continuing Airworthiness, Ottawa, telephone (613) 952-4361, facsimile (613) 996-9178 or e-mail email@example.com.
For Director, Aircraft Certification
Chief, Continuing Airworthiness
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