Anti-ice valve

[Jacek]

I'm taking a closer look at anti-ice valve. My general question is, what is the position of valve if electrics fails? I found on EMB170 maint cbt, that this valve is fail safe and becomes open, at MD10 I found that after el. fail, valve regulates automatically, and in FAA handbook I found that it becomes closed. What is your opinion about this matter? Please shear your experience.

Kind regards,
Jacek

[lomapaseo]

Typical fail safe is to protect against ice. The downside is that it uses bleed from the engines and also raises the metal temp on a hot day to areas of concern.

My narrow memory is that the unwanted increase in temperature as well as the engine performance loss is acomadated in the aircraft in flight, while it may have a backup "off" condition on takeoff

[dixi188]

Most aircraft that I've worked on have Engine anti-ice valves that fail open to protect the engine with only a small loss of permormance, and Airframe anti-ice valves that fail closed since they are not often required and can overheat the leading edges on the ground.
Hope this helps.

[BullHughes]

Several turbine helicopters I've worked on also have the same.
The P2 bleed air valves are powered closed. Total loss of AC electrical power will de-energise the solenoid and drop the valve thus leaving engine anti-ice 'ON' with the associated engine performance penalty.

[Mecaniquito84]

Engine antiice valve are fail open, when in flight should the valve fail, to protect engine of a possible ice formation in engine inlet cowls with subsequent ingestion and F.O.D. The same applies for wing antiice, if ice is formed in the wings, the air flow is disrupted and sustantation is lost. When plane come back, should it is not possible to fix the problem. The decision to depart with valve in override open or override closed position is taken by pilots in dependence of forecast. As a rule of thumb, they will most of the times play safe and select open position, so severe performance penalties applies since you are extra bleeding engines. Air flow to wings antiice on ground may be controlled opening/closing engines air bleed and/or crossfeed valves. There is no way to control air flow for engine antiice, it is taken upstream the air bleed valve, so even with air bleed valve closed, if you deactivated engine antiice to open, you will have antiice air bleed. The only thing you may control is the time the engine is running, for instance, starting the engine in the taxi run instaed of during pushback.
Rgds