Top Case Repairs (CFM56 Series)

Topcase is a procedure that is carried out when an engine is removed off wing and the repair is carried out at the engine facility at an airport or Maintenance Repair Organisation. This versus sending the engine back to the Engine Original Equipment Manufactures saves the operator many thousands of pounds in downtime and logistics cost. The procedure can be carried out on CFM56 series, GE90 series, CF6 series and CF34 series engines.

The procedure allows for the Top and Bottom High Pressure Compressor Cases to be removed to expose the High Pressure Compressor Blade. This allows the engineers to identify damage blades that could not have been repaired in-situ via the Borescope Blade Blend Technique i.e. Dent in Dim “R” that exceeds the Approved Maintenance Manual Limits. Utilising the procedure from the Engine Shop Manual the engineer can remove and replace the damaged blade with a new blade. The engine is then put back together, replaced on the wing and run through a series of tests before being put back into service.