J'ai posé la même question sur le fofo d'ED et voilà ce que l'on m'a répondu:
Pourtant avant de poser ma question j'ai fouillé dans le manuel du L-39 mais je n'ai rien trouvé, bon je vais de nouveau relire ce manuel car là je suis comme un boulet...FUEL DELIVERY LIMITER
The fuel delivery to the engine is continuously cut down to
protect the engine from surge when the gun is firing. Once the
armament system is selected and ready for gun firing, the fuel
delivery is limited the whole time when the trigger is
squeezed either the gun fires or not.
WARNING:
If the trigger is squeezed for more than a few seconds,
the RPM will drop down to 42% either the gun fires or
not. When the trigger is released, the RPM increase
back to preselected value by the throttle.
Merci encore, Skull.