View Full Version : Engine Surge and Anti Ice

4th Sep 2012, 15:39
Greeting to all!

Just a quick question among many, in IAE (or rather any other type) if a surge occurs, the QRH says to ON the ENG ANTI ICE and WING ANTI ICE.

Why is it necessary to activate anti ice during a surge?

The manual also says, orange flame can be seen from the inlet in a severe case, so why the TAI supplied by Piccolo tube system (ENG ANTI ICE) should be "ON" ?

Thanks in advance!

Code 0

4th Sep 2012, 16:11
Increased bleed air extraction from the engine causes the combustor to operate at a higher fuel-to-air ratio, which reduces the probability of flameout.Increased engine bleed air extraction does provide a large increase in the margin to flameout.

in my opinion.

4th Sep 2012, 16:37
Anything that lowers the back pressure in the compressor like more bleed air helps a tired engine avoid the natural surge line. Of course the turbine efficiency suffers and its temperature will rise for most controlling functions

4th Sep 2012, 17:10
Thanks a trillion for the fast answers!

But for that purpose there are VBVs, TBVs right? so what you mean in the ANTI ICE system act as a indirect backup system for a engine Surge re-stabilization?



5th Sep 2012, 00:21
Reguardless, I believe the point is to lower high stage compressor pressure thus allowing the engine to suck bang and boom out the tailpipe. A.I is high stage air as it is hot. When VBV's/VSV's etc lack flow due to turbine speed, engines stall. I suppose A.I. would reduce the pressure, helping the ability of air to flow as the engine is designed.

de facto
5th Sep 2012, 09:45
But for that purpose there are VBVs, TBVs right?

Nearly.The Variable Stator Vanes (VSV) and Transient Bleed Valve (TBV) prevent HPc and LPC stall,the Variable bleed valves do some else,,running out of battery..so till next time:E

Eric Janson
5th Sep 2012, 12:24
We had an issue at high altitude where the bleed pressure would drop to the point that the bleed system would switch from the IP to HP valve causing the engine to surge as the valves opened and closed.

Anti ice increased the bleed pressure and prevented this from happening.