What are the types of aircraft you are referencing?
Have you filled out a CSIR for this issue?
We have seen several fuel system designs on different aircraft that do NOT meet the required specifications as per Rotax installation instructions and are causing fuel pump issues. to ensure the reliability of the fuel pumps, make sure your fuel system is designed as per the Rotax installation manual as this is very critical!
-fuel line size
-fuel tank outlet port size
-fuel selector/shut off restrictions and location of the fuel shut-off /selector valve
-mounting location of fuel pumps
-fuel filter mesh and micron size
-fuel system bypass line with metered orifice between feed and return side
-gascolator type
-fuel tank vent size
-fuel return port location relative to the outlet port
-fuel system temperature specification & testing data
-electrical wiring size
-etc. etc. etc.
If the fuel system design is not within the specifications as per the Rotax installation manual it must be rectified. Read the installation manual and cross-reference it with your fuel system. If you did not design the fuel system, contact your airframe manufacture and have them cross-reference their system with the Rotax installation manual and ask them for the fuel system testing data (flow rate, temperature limitations, etc.) and ask them for the fuel system schematic.
We have yet to see a failed fuel pump that has been accompanied by a well-designed, well-tested, and conforming fuel system as per the Rotax installation manual.
