What is derate in aviation?
Derate is where the thrust at both take-off and climb is reduced because you don’t need all the thrust the engine would be able to produce (for example, if the take-off weight less than maximum, or if its a cold day etc…).
What is derate climb?
Aircraft engines are sized and power managed to meet takeoff field length and climb rate requirements at the maximum takeoff gross weight (TOGW). When operating at reduced TOGW, reduced thrust (derate) may be used in both takeoff and climb to extend engine life and reduce maintenance cost.
What is flat rated temperature?
The flat-rated temperature is that temperature where the engine can still produce the rated thrust with a safety factor margin so the turbine blades and vanes are not damaged. For hydromechanical control (non FADEC) engines, the engine’s thrust is controlled by the crew’s positioning of the power levers.
How does increasing OAT outside air temperature affect gas turbine engine thrust?
This increase occurs partly because the energy required per pound of airflow to drive the compressor varies directly with the temperature, leaving more energy to develop thrust. In addition, the thrust output increases since the air at reduced temperature has an increased density.
What is the difference between assumed temperature and derate takeoff?
In Assumed Temperature takeoff thrust, the pilots are allowed to advance the thrust levers to full rated takeoff thrust. However, in Derated takeoff thrust, the levers should not be increased beyond the fixed decate limit, otherwise a engine failure may result in loss of directional control.
When to use derated takeoff thrust on a 737?
Derated takeoff thrust (fixed derate) may be used for takeoff on a wet runway and on a runway contaminated with standing water, slush, snow, or ice. The Boeing 737 FCTM has a nearly identical description.
Which is less granular, derate or assumed temperature?
The derate method is typically less granular than assumed temperature — you have two or maybe three derate setting you can select, and that’s that. But those steps may be pretty big steps.
How many pages is an assumed temperature thrust reduction?
All of the information, photographs & schematics from this website and much more is now available in a 374 page printed book or in electronic format. What is an Assumed Temperature Thrust Reduction ?