If this is your first visit, be sure to
check out the FAQ by clicking the
link above. You may have to register
before you can post: click the register link above to proceed. To start viewing messages,
select the forum that you want to visit from the selection below.
I think that some airplanes have a limit on how much time continuous ignition can be used continuously. For example, I think that the MD-80 has a 10 minutes limit.
Run it all day on the 747-400.
As a note: The 747-8 does NOT have a continuous ignition switch, it is all done automatically.
1) With design of robust engines that can survive the event, and 2) installing more engines per plane than required to sustain flight, in case one fails to survive the event.
All in all, it seems to have work in this case. It didn't even go to the second line of defense.
1) I'm not aware of any engine design currently out there that has a unique ability to reliably withstand the effects of ice crystal ingestion. I believe one of those effects (compressor stall) is aerodynamic anyway. Perhaps future designs can incorporate bleed air into the compressor blades or use surface coatings that resist moisture.
2) Any environmental condition should similarly effect all engines exposed to it, be it two or four or eight. True, more is probably better in this phenomena, but as we are moving to twinjets for reasons of efficiency I think this is not a viable defense strategy.
It seems at this point that the only viable defense is to avoid convective weather systems (both towers and low cloud formations) that have the potential to updraft ice crystals. As SOP, I expect this would lead to longer and more frequent weather deviations and result in higher fuel burn expense. I would expect the industry to push back on that.
1) I'm not aware of any engine design currently out there that has a unique ability to reliably withstand the effects of ice crystal ingestion. I believe one of those effects (compressor stall) is aerodynamic anyway. Perhaps future designs can incorporate bleed air into the compressor blades or use surface coatings that resist moisture.
2) Any environmental condition should similarly effect all engines exposed to it, be it two or four or eight. True, more is probably better in this phenomena, but as we are moving to twinjets for reasons of efficiency I think this is not a viable defense strategy.
It seems at this point that the only viable defense is to avoid convective weather systems (both towers and low cloud formations) that have the potential to updraft ice crystals. As SOP, I expect this would lead to longer and more frequent weather deviations and result in higher fuel burn expense. I would expect the industry to push back on that.
Like flying around tall thunderstorms in the Intertropical Convergence Zone?
Like flying around tall thunderstorms in the Intertropical Convergence Zone?
Chicken!
The "keep my tail out of trouble" disclaimer: Though I work in the airline industry, anything I post on here is my own speculation or opinion. Nothing I post is to be construed as "official" information from any air carrier or any other entity.
Like flying around tall thunderstorms in the Intertropical Convergence Zone?
Like flying around lower altitude convective systems that won't even appear on the radar if the tilt is not right. I think that's not going to happen. Did you read Snyder's link?
The good news is that thus far all the affected engines have been restored in flight. And all the pilots have handled the upset without making it worse.
Strange that AF447 did not register any such engine anomalies. The engines were at a reduced power setting at the time that the pitots were evidently overcome by ice crystal ingestion.
Don't really want to drag this into one of the liveliest long running discussions I've followed here. When everybody dies, you lose the most essential info, that in the minds of those whose decisions wrote the end of the story.
It seems at this point that the only viable defense is to avoid convective weather systems (both towers and low cloud formations) that have the potential to updraft ice crystals. As SOP, I expect this would lead to longer and more frequent weather deviations.
That's foresight!
Originally posted by The Aviation Herald
On Nov 25th 2013 Boeing confirmed that a Multi-Operator-Message (MOM) has been sent to B747-8 and B787-800 customers, "who operate some GE-powered engines after instances of ice crystal icing that resulted in temporary diminished engine performance. To reduce chances of ice crystal conditions, Boeing also updated its Airplane Flight Manual (AFM) to prohibit flight within 50 nautical miles of large convective weather systems that may contain ice crystals. Boeing is working with its customers and GE to address the icing issue. Only a small number of GEnx engines have experienced the ice crystal icing issue in flight. GE will introduce the improvements necessary to return the engine to expected performance levels. Boeing is disappointed in any impact this situation may have on our customers, as is the GE team. We, like our customers, expect the delivered product to meet all expectations and will work closely with GE to address the subject condition. We regret the business disruption this will cause for our customer and remain ready to provide whatever assistance we can to Japan Airlines."
Aviation Herald - News, Incidents and Accidents in Aviation
--- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
--- Defend what you say with arguments, not by imposing your credentials ---
The achilles heel of redundancy is the environment. Pitots, engines... Maybe they should run a mix of RR's and Genx on each plane, eh?
The question roaming in the back of my mind is: in making these engines more efficient, are they making them less robust? How does that affect ETOPS? I guess it doesn't really help to have a couple extra vulnerable engines either...
Thanks, that's all very interesting. It seems that once ice crystals adhere to interior surfaces warm enough to melt rather than deflect them the game is lost because they then become the film for additional ice accumulation. Therefore I wonder if current surface technologies are capable of producing a coating that would not allow this moisture film to adhere in the first place. Perhaps something based on nanoscience. If melting ice crystals cannot adhere to compressor blades it would seem to solve the issue.
Thanks, that's all very interesting. It seems that once ice crystals adhere to interior surfaces warm enough to melt rather than deflect them the game is lost because they then become the film for additional ice accumulation. Therefore I wonder if current surface technologies are capable of producing a coating that would not allow this moisture film to adhere in the first place. Perhaps something based on nanoscience. If melting ice crystals cannot adhere to compressor blades it would seem to solve the issue.
There is a technology in development called "passive anti-icing" that is exactly that: a highly hydrophobic coating that prevents water drops, ice crystals and even super-cooled water to stick to the surface. However, it failed the "frost" test. Frost is made of very small droplets that are too small for inertia or drag to displace them from the surface, and form a surface on which ice can build up.
The investigators believe that they can fix it applying to the surface a very fine roughness or texture (don't know how it works), which is small enough to prevent any aerodynamic implication like added drag, early turbulent transition or flow separation.
While I've read about this technology linked with airframe ice (the hydrophobic additives could be added to the paint so the process to "equip" airplanes with this technology would be very simple), I think that it could also apply to engines.
--- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
--- Defend what you say with arguments, not by imposing your credentials ---
Can I borrow your disclaimer? I mean, nobody pays me any attention anyway because I am stupid around here (learned, but nowhere near as smart I guess) but it would be nice to have.
I do work for a domestic US airline, and it should be noted that I do not represent such airline, or any airline. My opinions are mine alone, and aren't reflective of anything but my own knowledge, or what I am trying to learn. At no time will I discuss my specific airline, internal policies, or any such info.
We process personal data about users of our site, through the use of cookies and other technologies, to deliver our services, personalize advertising, and to analyze site activity. We may share certain information about our users with our advertising and analytics partners. For additional details, refer to our Privacy Policy.
By clicking "I AGREE" below, you agree to our Privacy Policy and our personal data processing and cookie practices as described therein. You also acknowledge that this forum may be hosted outside your country and you consent to the collection, storage, and processing of your data in the country where this forum is hosted.
Comment