because a siezed engine has less drag than a windmilling one.
Just what I want to clarify Old Smokey,
I know this is true for Propeller airplane but according to A340 FCOM a windmilling engine has less drag than a rotor locked case.
From the FCOM for ferry flight:
The performance data are provided for the rotor locked case. Fuel consumption for the windmilling case is about 3% lower.
Best Regards,
Guclu