High altitude ice crystals
Thread Starter
Joined: Mar 2005
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From: My house
High altitude ice crystals
Hello all,
The air France accident has sparked some investigation into high altitude ice crystals. I'm in the process of finding out as much as I can around this subject, in particular their effect on the pitot static system.
Does anyone know of any good resources I could get my hands in relation to this?
The air France accident has sparked some investigation into high altitude ice crystals. I'm in the process of finding out as much as I can around this subject, in particular their effect on the pitot static system.
Does anyone know of any good resources I could get my hands in relation to this?
Joined: Dec 2002
Posts: 2,769
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From: UK
http://icingalliance.org/meetings/RI...ersion_nss.pdf
http://www.boeing.com/commercial/aer..._article05.pdf
http://www.ukfsc.co.uk/files/Safety%...Oct%202009.pdf
http://www.specinc.com/publications/...craft_1998.pdf
http://www.sae.org/events/icing/pres...sopenmason.pdf
http://icingalliance.org/collaborati...oject_2007.pdf
IASCC - International Air Safety & Climate Change conference
Workshop 1. day 2. Eric Duvivier, EASA - "High Altitude Icing Environment"
http://www.boeing.com/commercial/aer..._article05.pdf
http://www.ukfsc.co.uk/files/Safety%...Oct%202009.pdf
http://www.specinc.com/publications/...craft_1998.pdf
http://www.sae.org/events/icing/pres...sopenmason.pdf
http://icingalliance.org/collaborati...oject_2007.pdf
IASCC - International Air Safety & Climate Change conference
Workshop 1. day 2. Eric Duvivier, EASA - "High Altitude Icing Environment"
Last edited by safetypee; 23rd July 2012 at 22:23.
Joined: Aug 2011
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From: Grassy Valley
Do not ignore the discussion of Water Ice in fuel. See BA038.
Microcrystalline water ice was held to blame, as the theory had to do with "hitherto unknown characteristics of water ice..."
No new research to see, meanwhile Rolls Royce fit new Heat exchangers to its
Trent 700.
Ice has been a punching bag of late..... Welcome to the devil you don't know, ignore the devil you do...
Jet aircraft have been flying up to 60,000 feet everywhere on the globe for sixty years....funny how we need to know more about water ice at 35,000. Are pitot tubes on ETOPS a/c especially susceptible to ice? So one would think...
Microcrystalline water ice was held to blame, as the theory had to do with "hitherto unknown characteristics of water ice..."
No new research to see, meanwhile Rolls Royce fit new Heat exchangers to its
Trent 700.
Ice has been a punching bag of late..... Welcome to the devil you don't know, ignore the devil you do...
Jet aircraft have been flying up to 60,000 feet everywhere on the globe for sixty years....funny how we need to know more about water ice at 35,000. Are pitot tubes on ETOPS a/c especially susceptible to ice? So one would think...
Usual disclaimers apply!
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From: EGGW
Not only pitot probes. The GE90 is very susceptible to ice damage to the HP compressor stage 1 blades. Flight through high level 'ice clouds' builds up a deposit on the p25 probe this then breaks free and bends a blade. They are big blades as well approx 9ins x 5ins. At best its a borescope inspection for area 'blockage' that has to be calculated and at worst it's an engine change.
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From: Grassy Valley
The knock on the pitot tube Thales that AF 447 was sporting was that the drains were susceptible to corrosion. Whether or not this came up for the AD I cannot find...
Not only does crystalline ice need to melt to drain, any corrosion on the drain would nucleate new formation of ice crystals...
So gas path, what is the nature of this deposit, 'blockage'?
Not only does crystalline ice need to melt to drain, any corrosion on the drain would nucleate new formation of ice crystals...
So gas path, what is the nature of this deposit, 'blockage'?
Last edited by Lyman; 26th July 2012 at 23:00.
Usual disclaimers apply!
Joined: Nov 1999
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From: EGGW
The ice forms on the P25 probe and eventually breaks free clouting one of the blades putting a bend/curl on the tip of the blade this reduces the area between the blades (blockage) therefore upsetting the airflow. Usually picked up by a decrease in compressor efficiency..read higher N2. Another sign is the engine makes a hell of a 'howl' during crz upsetting the pax sitting near the front end.
Joined: Dec 2003
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From: Tring, UK
I had one of those "howling" engines the other day and was glad the tech. log entry said it might be noisier than usual. I think one of the HPC blades had been damaged, like you say.
It WAS noisy! We looked at each other across the cockpit just after setting power and if I hadn't been pre-warned I might have been tempted into a low-speed RTO...
It WAS noisy! We looked at each other across the cockpit just after setting power and if I hadn't been pre-warned I might have been tempted into a low-speed RTO...
