There is always a Maximum limit to the takeoff thrust. But when it’s hot and high, there are some ways the #A320 could get “a little more out of the engine’s”.
🧵 On Thrust Bump.
Thrust Bump : is an increased takeoff thrust which is occasionally used when the basic maximum takeoff thrust does not provide the required performance.
(There is no possibility to set an intermediate thrust between the basic maximum takeoff thrust and the bump)
Thrust bump provides between 6 and 10% more thrust than the basic one. It was available on both IAE (SCN18) and CFM (5BL) but only certified for the IAE engines.
The bump is activated by two guarded pushbuttons, placed on the thrust levers only once both engines have started. Thrust bump becomes active when thrust lever is set above MCT position. It remains engaged (armed) for the entire flight.
It disarm’s at engine shutdown
on the ground by depressing either bump pushbutton and thrust levers are not
above FLX/MCT.
The principle :
On early V2500-A1s, IAE devised a method to increase the thrust by pushing more fuel into the engine once the take-off roll had started. As the a/c moved forward the ram air reduces the depression in the inlet thereby increasing mass airflow.
As this occurs, with a set EPR, the EGT would reduce. Therefore at this point the FADEC automatically introduces more fuel to give higher thrust and 'recover' the lost EGT. Hence more thrust.
US Airways used it on their IAE powered A321’s to depart out of Phoenix.
MyTravel Airways needed it out of Corfu to get over the hill at the end of RWY 35.
The IAE-A5 engines on newer A320’s and A319’s no longer have thrust bump. The A321’s with IAE engines do have thrust bump as an option.
Pratt and Whitney, which currently offers a Pure Power Geared Turbo Fan engine on the A321neo with 33,000 pounds of thrust, has announced a 2,000 pound increase via a thrust bump.
noticiaslatamsales.com/noticias/may-june-2014/a321neo-goes-hot-and-high-pratt-whitney/
Credits :
bit.ly/3laY7Ar : Flex/Derate, Engine Bump and Derated climb by Airbus
bit.ly/3wdxZeO : Getting to grips to
“High Elevation Airport Operations” project by Airbus
Arjun Singh
@chainsawrocks
Airline Pilot A320 | B737 | Flight Sim Enthusiast. (Views and comments are personal)