Hello,

Regarding the bypass to derate the pump:

-Install a "T" fitting in the line between the pump and engine.
-On the 3th exit of the "T" fitting install a regulable needle valve.
-The exit of the valve can be routed directly to the fuel tank or, trough another "T" fitting, to the input of the pump. The idea is to have some of the fuel pumped going back to the pump input.

Once installed, fully close the needle and start the engine.

Set the engine at full power and slowly open the bypass. The engine rpm will drop and the fadec will increase the pump power to recover. The goal is that at full power the indicated pump power (value under the temperature) be between 600 and 800 units at full power.

Once this adjusted, return to idle slowly. Surely the engine will stop if set too fast, as the fadec should recalibrate itself with the new behaviour of the pump. If the engine stop, that's OK, no problem, on next start the fadec will recalibrate.

As the pump now will be less efficient, it is posible that on next start the ramp of the pump must be increased to have a fast start, this should be experimented after adjusting the bypass. Acceleration time could need some tweaking too.

It is important to adjust the bypass ONLY at full power, and once adjusted, fix it and don't touch anymore.

PLEASE NOTE THAT THIS IS NOT AN APPROVED PROCEDURE BY WREN NOR SIMJET. USE ONLY AT YOUR OWN RISK.

Regards,

Gaspar