What are Bumps and de rate in an Airbus?

Question

Pilots that fly Airbus' check the Bump/ De Rate. but what are these things they are checking?

Answer 1

I assume with 'bump' you mean what airbus calls a 'detente'

The derate, or FLEX temp, is a temperature used to make the engines run at less than 100% power. This is done to reduce engine wear.

The 'bumps' are the detentes on the throttle. On takeoff, the throttles are moved from the idle detente through the full range, to the CLB (climb) detente then to the FLX detente. If full power is required there is a further forward detente labelled TO/GA. While moving through the detentes a clicking can be heard.

What pilots are checking is that the correct thrust derate has been set, and the correct engine power selected on the throttles by being in the correct detente.

Answer 2

Yes as above. Just to add that the de-rate figure will have been entered at setup, so when the thrust levers are advanced to FLEX the power will go to that pre determined figure. De-rate is allowed legally up to 25% less than the rated power (assuming runway length, altitude, etc are not limiting factors).