abnormal
Topic Author
Posts: 73
Joined: Tue Aug 21, 2007 12:14 pm

How To Deice Inside The Nacelle?

Sun Mar 03, 2013 6:32 pm

Does anybody have experience deicing the inside/intake of a engine nacelle between the heated engine lip and the fan blades.

During the extensive ground delays associated with heavy snowfalls we've observed some rather excessive ice buildups inside the nacelle and it has damaged the fan blades on occasion. 2" thick accumulations were noted several times (reported as 3" but lets keep it real)

The ground heaters are too slow in melting the ice so now we're thinking of using glycol applied with a low pressure sprayer. There are obvious engine and cabin air contamination concerns so we'd rather not go the glycol route but I can't think of any other reasonable solution.

Anybody have any suggestions or cautions with respect to using glycol?
 
tb727
Posts: 1729
Joined: Thu Jun 30, 2005 1:40 pm

RE: How To Deice Inside The Nacelle?

Sun Mar 03, 2013 6:40 pm

Wow, I think I'd invest in some engine covers!

Our mechs go out and try and scoop the snow out before it freezes into blocks of ice.

[Edited 2013-03-03 10:41:07]
Too lazy to work, too scared to steal!
 
B777LRF
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Joined: Sun Nov 02, 2008 4:23 am

RE: How To Deice Inside The Nacelle?

Sun Mar 03, 2013 6:51 pm

Clear away snow with soft brushes, do not attempt to scrape off ice. Only approved method of removing ice from the engine intake and fan blades is to direct hot air at it, and wait until it melts. Might take a while, during which it is common to have a thought about how clever engine covers really are. General bitching about inaccurate weather forecasting and the folly of trying to run the circus in a blizzard, are usually also vital components of engine de-icing.
From receips and radials over straight pipes to big fans - been there, done that, got the hearing defects to prove
 
fr8mech
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Joined: Mon Sep 26, 2005 9:00 am

RE: How To Deice Inside The Nacelle?

Sun Mar 03, 2013 7:05 pm

Our cold weather manual allows the copious use of isopropyl alcohol to melt any ice after mechanically removing snow and loose ice.
When seconds count...the police are minutes away.
 
MD11Engineer
Posts: 13916
Joined: Sun Oct 26, 2003 5:25 am

RE: How To Deice Inside The Nacelle?

Sun Mar 03, 2013 7:09 pm

Hot air (don´t use an airstarter, they are much to strong and hot and you can cause damage or injury if the hose slips out of your hands). Use a cabin heater instead. CFM also approves a certain type of de-icing fluid for the fanblades on the engines of the 737NG, but i forgot the spec and don´t have the manuals available here at home. It is applied hot. Also make sure that the drain hole in the intake is open, so that the water will be able to run out.

Jan
Je Suis Charlie et je suis Ahmet aussi
 
abnormal
Topic Author
Posts: 73
Joined: Tue Aug 21, 2007 12:14 pm

RE: How To Deice Inside The Nacelle?

Sun Mar 03, 2013 11:29 pm

Jut to fill in some blanks

We do clean out the nacelles and check the blades prior to pushback but when your motoring around in 11/2 sm vis due to snow while waiting 45 mins to 2 hrs to deice, the snow and ice accumulate. We've had so much blade damage, the deicing folks are now checking the nacelle for us to see if we need to return to gate and have it cleaned out.

Our thinking is that the ice is formed by 2 means:
1) from water and slush being sucked up off the ground (if the plane is stationary for a period you can see the dry
empty spot on the ground getting bigger and bigger), or
2) snow that hits the lip and melts runs back only to refreeze before the fan.

At this point I'm even contemplating finding a wax or non toxic oil (olive oil?) that could be used to coat/polish the inside of the nacelle inlet before pushback which would let the water flow back easier and make it less likely for ice to form?
 
VC-10
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RE: How To Deice Inside The Nacelle?

Mon Mar 04, 2013 2:28 am

If the suction is great enough to suck snow/slush off the ground it in not going to hang around in the intake, it will keep going and pass through the fan. Likewise if the lip is warm enough to melt snow it must mean the anti-ice in selected on which in turn means the engine must be running creating the suction that will draw any water through the fan.

You can't go round thinking of any old fluids/compounds to eliminate the problem, what ever you use has to be approved by the airframe/engine or nacelle manfacturer
 
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crj900lr
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RE: How To Deice Inside The Nacelle?

Mon Mar 04, 2013 3:28 am

Quoting VC-10 (Reply 6):
You can't go round thinking of any old fluids/compounds to eliminate the problem, what ever you use has to be approved by the airframe/engine or nacelle manfacturer

And it must also be approved in the de-icing/winter opertions manual. if it is not an approved method it can't be used.
 
MD11Engineer
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Joined: Sun Oct 26, 2003 5:25 am

RE: How To Deice Inside The Nacelle?

Mon Mar 04, 2013 11:53 am

Quoting crj900lr (Reply 7):
And it must also be approved in the de-icing/winter opertions manual. if it is not an approved method it can't be used.

The de-icing manual is just a compilation of data from the maintenance manual. Everything written in the de-icing manual for the aircraft (minus the actual operation of the de-icing vehicle and the quality checks of the de-icing fluid) is also listed in the AMM.

Jan
Je Suis Charlie et je suis Ahmet aussi

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