Anti-ice & Inflight Engine Restart???

[AeroTech]

Hi,

In case of engine failure/shutdown/fire in twinjet, the plane will fly at lower altitudes where it MAY encounter icing problem. If this scenario is possible, can the operative engine provide the needed pneumatic power for the pack valve(s)[2 or only 1 pack valve is supplyed by air ??], anti-ice (wing, engine), ADPs (if the plane is fitted with it like 767, 777...), etc? After driftdown at lower altitude, can the APU provide the pneumatic power to assist the operative engine? (up to 17000 ft for 737-NG, I don't know for other aircrafts?)
-In such case and icing condition, is the operative engine providing air (for anti-ice) for the failed engine and the opposite wing?

-In different context here another question: in certain inflight engine restart procedures, the pilot must turn on engine anti-ice before restaring engine. why this procedure is required? is this procedure required for certain aircrafts only?

Feedback appreciared. Thank you in advance.
Best regards.

P.S: it seems to me that making research for certain subjects (in the archive) is difficult and time consuming since the "search" feature is removed, or may be I missing something?

[aidey_f]

In general, the cowl anti-ice air comes from the on-side engine directly, and isn't driven off the main pneumatic system, so if you are running on one engine with the anti-ice on, the other engine won't be deiced.

whether or not you can use the APU to supply bleed air depends on the APU - some will only supply bleed air up to about FL200ish.

Hope that helps

[virginpaul]

Why would you be bothered about anticing the intake of a dead engine? It's dead!

[PRNAV1]

in case of engine failure/shutdown/fire in twinjet, the plane will fly at lower altitudes where it MAY encounter icing problem. If this scenario is possible, can the operative engine provide the needed pneumatic power for the pack valve(s)[2 or only 1 pack valve is supplyed by air ??],
well, yes and no. it depends...
if it's a normal shut down or eng failure without use of the fire handles then the operative eng can supply both pack valves no problem.
but on the other hand if the fire handle has been pulled it becomes more complicated...depending on the aircraft and how the bleed system is designed affects whether you can supply both packs by 1 eng. in my case, i can only supply both packs by the eng bleed of the remaining eng if it's fire handle for eng no.2 that has been pulled.
i.e eng 2 fire!
but vis versa and its a no go due to contamination from the eng bleed system.
anti-ice (wing, engine)
eng ice is not a factor. selection is norm indevidual for each eng so you just don't select it for the dead eng, simple. again there's abit more...if you have both packs avail on the good eng, you select 1 pack off, in my case, to supply the wing a/ice. this is to avoid major loss of eng bleed. you don't want to over load the remaining eng with 2packs, eng+wing a/ice. an if you only have 1pack then you have no choice anyway.
After driftdown at lower altitude, can the APU provide the pneumatic power to assist the operative engine?
yes! but like some1 has already stated, only up to a certain altitude.
both packs on my type can be supplied up to FL200. 1pack+wing a/ice upto FL150 but generator load is not a prob upto max ceiling of my type.
(with certain limatations)
-In such case and icing condition, is the operative engine providing air (for anti-ice) for the failed engine and the opposite wing?
as i've explained, norm the eng+wing a/ice for each side are individual selections. eng a/ice is norm blead straight from the respective eng....self explanitory...no eng, no bleed, no eng a/ice for that eng.
however, wing a/ice can be supplied to the dead eng side by the live eng with the above mentioned limitations.
in certain inflight engine restart procedures, the pilot must turn on engine anti-ice before restaring engine. why this procedure is required? is this procedure required for certain aircrafts only?
can't help...might have something to do with increasing/decreasing bleed in someway or another??? don't know...
hope this helps :ok:

[AeroTech]

Hi,

Thank you for your answers.
-According to the posts it is possible to use anti-ice (wings and engine) within certain limits after engine failure/shutdown/fire. Is this also valid after engine bleed trip-off in a twinjet?
If the operating engine cannot provide the needed pneumatic power, can assymetric anti-ice be used?

-In certain flight manual, there is a note:Above FL 350 wing anti-ice could cause a bleed trip-off with BOTH bleeds working.
Is it usual to encounter icing conditions at FL 350 or is it very rare? At what altitude pilots usually encounter anti-ice?

-In certain inflight engine restart procedures (like on MD 80), the pilot must turn on engine anti-ice before restaring engine (along with turning off the EDP and the IDG in order to reduce load on engine during restart). Can someone enlight me how using engine anti-ice reduce load on engine and improve restart? Is this procedure required for all aircraft?

Feedback appreciated. Thank you.
Best regards.