Bartholomew
Bartholomew
First OfficerFirst Officer
Joined: Dec 15, 2004 Posts: 172 Location: LYBE
Asked

So my 727 manual tells me the engine anti-ice must be on when icing conditions are anticipated or at any time the OAT is below 8C (46F), and either moisture is visible or the OAT and dewpoint are within 3C (5F) of each other.

It also says the minimum N1 setting for penetrating icing conditions is 55%, and heavy icing 70%.

So considering that (and the bold bit), are you supposed to have the engine anti-ice on when the OAT is way below zero but you're cruising at 85% or more of N1??? 😳

Please help.

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Jonathan (99jolegg)
Jonathan (99jolegg)
Chief CaptainChief Captain
Joined: Jun 26, 2004 Posts: 4112 Location: UK
Answered

The minimum N1 setting is 55% / 70% so anything above that will mean that ice has the potential to be present, but won't be unless the weather conditions are sufficient. Basically engine anti-ice will be used when the OAT is below 8C (46F), and either moisture is visible or the OAT and dewpoint are within 3C (5F) of each other. with N1 above 55%, so in essense, it is just the weather conditions that determine whether you use engine anti-ice in flight because N1 is always likely to be more than 55% in flight.

I think the minima of 55 / 70% are there to show that engine anti-ice isn't needed on the ground.

Thats my understanding of it anyway 😉

Matthew Shope (mypilot)
Matthew Shope (mypilot)
Chief CaptainChief Captain
Joined: Nov 26, 2004 Posts: 1695 Location: Long Beach, California KLGB/KTOA
Answered

Is there any ice in Flight simulator anyways, I never encountered any. 😕

violentviolet
violentviolet
First OfficerFirst Officer
Joined: May 26, 2006 Posts: 392 Location: Kilmarnock
Answered

mypilot wrote:

Is there any ice in Flight simulator anyways, I never encountered any. 😕

Download the Tupolev TU 114 from AVSIM, fly it , and watch the icing take effect. 😉

Bartholomew
Bartholomew
First OfficerFirst Officer
Joined: Dec 15, 2004 Posts: 172 Location: LYBE
Answered

I think the minima of 55 / 70% are there to show that engine anti-ice isn't needed on the ground.

Yes, that’s the bit I didn’t mention. It says to increase power on each engine to 50%N1 minimum , every five minutes, to prevent surging during prolonged periods of ground operation.

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