engine lip ice in flight - Page 2

leadmx · 07-03-2008, 10:57 PM

Not sure if this helps the discussion but, the ice detectors will detect .020" thickness of ice or about the thickness of a index card. It my not be a problem because the amount of ice build up on the lip versus any aerodynamic changes is nill. FYI, the most reliable deicing system on the aircraft is the little rubber tit on the end of the engine spinner. I have never had it fail a single ops check!

Yariv · 07-03-2008, 11:09 PM

ah yes, the vibrating nipple! no, it's not heated...

the amount of ice is impressive, but irrelevant. no ice will form on the ice detector unless it's exposed to a temp (TAT) of 0*c or less, which happens at a none-wing temp of about 0.5*c (TAT) in flight. so at 1*c or more, no ice will form on the detector, but ice will form in the engine all the way up to 10*c tat. at least that's the theory.

no mention in the book, so you're not required to do it! you're also not required to turn on the wipers when it's raining. it's not mentioned in the book either.

the original question was is there an automatic system that does it, since IT NEEDS TO BE DONE regardless of what the book says. the answer is there is no such automatic system.

is the discussion about whether or not it's required (it's not) or whether or not it needs to be done? can you explain to me why it doesn't need to be done? (not the same thing as 'not required')

some of the previous posts show an alarming misunderstanding of what sat and tat are and when ice can form...

kidicarus5897 · 07-04-2008, 01:03 AM

Quote:

Originally Posted by Yariv

ah yes, the vibrating nipple! no, it's not heated...

the amount of ice is impressive, but irrelevant. no ice will form on the ice detector unless it's exposed to a temp (TAT) of 0*c or less, which happens at a none-wing temp of about 0.5*c (TAT) in flight. so at 1*c or more, no ice will form on the detector, but ice will form in the engine all the way up to 10*c tat. at least that's the theory.

no mention in the book, so you're not required to do it! you're also not required to turn on the wipers when it's raining. it's not mentioned in the book either.

the original question was is there an automatic system that does it, since IT NEEDS TO BE DONE regardless of what the book says. the answer is there is no such automatic system.

is the discussion about whether or not it's required (it's not) or whether or not it needs to be done? can you explain to me why it doesn't need to be done? (not the same thing as 'not required')

some of the previous posts show an alarming misunderstanding of what sat and tat are and when ice can form...

Yariv, I am assuming that because you are in the training department, and if you thought this was an important issue that everyone should be familiar with, you would suggest it be in the CFM. Everyone has seen the vapor that froms in the egine intake on jets rolling down the runway for takeoff on a humid day. Surely a cold/humid day would produce a little ice on said engine intake before any fomed, if at all, on an ice detector. And if the first thing Yariv does on lift-off is throw on some lip air, you are my hero. You obviously know something that the enigneers/authors of the manuals don't and it might be wise to spread the word. It is amazing that we have diverted disaster all this time!!!!!!!!!!!!!!!!! (and the wiper analogy was poor at best)

Yariv · 07-04-2008, 08:04 AM

not right after takeoff, but at 1701' AGL!

if you do it right after takeoff and lose an engine you won't clear obstacles!

now I'm just being annoying. and I was, and am not, in the training department.

you haven't explained what's wrong with what I said, or what's wrong with the analogy...

kidicarus5897 · 07-04-2008, 03:06 PM

Quote:

Originally Posted by Yariv

not right after takeoff, but at 1701' AGL!

if you do it right after takeoff and lose an engine you won't clear obstacles!

now I'm just being annoying. and I was, and am not, in the training department.

you haven't explained what's wrong with what I said, or what's wrong with the analogy...

the wipers are common sense............and I guess you could argue that engine lip air is common sense too and that everybody should be doing it. But I want to know how many people actually do this every time the conditions warrent vs how many people turn on the wipers in the rain. I never use ENG air in flight, and curiosity is the only reason I brought this up. Maybe you are a better pilot than the rest of us, who knows. Hell, not flying into a mountain in mexico is common sense, having engough fuel is common sense, taking off on the correct runway is common sense, and everyone is aware that many people died in the face of common sense. This is the exact reason that laws and procedures are designed. If common sense were enough, CFIT wouldn't exist. Lexington would never have happened and one of our crews wouldn't have missed a mountain in mexico by 200ft. Point is, if you think that avoiding engine lip ice is a pilot responsibility, maybe it should be alluded to in a manual or some training somewhere. And if it is NOT an issue, my origional question is why?

mszluka · 07-18-2008, 10:00 AM

I can see what Yariv is saying, because I've flown airplanes with manual engine anti-ice before. In most "normal" airplanes (such as Boeing products), you always turn on the engine anti-ice when the TAT is less than 10 degrees C and you are in visible moisture. Trust me, it is hard to be flying in rain at +4C and not reach up and go to ENG on the icing panel. It just doesn't make sense.

I'm not a big fan of this "automatic" icing system. From what I've read in the CFM, I don't see anything that precludes the pilot from turning on the ENG or WING/STAB anti-ice if he or she so chooses. We just have temperature limitations on manual use, not a limitation on when we can use it. Is there a page in the CFM that says we cannot use the OVRD function?

kidicarus5897 · 07-18-2008, 01:26 PM

Quote:

Originally Posted by mszluka

I can see what Yariv is saying, because I've flown airplanes with manual engine anti-ice before. In most "normal" airplanes (such as Boeing products), you always turn on the engine anti-ice when the TAT is less than 10 degrees C and you are in visible moisture. Trust me, it is hard to be flying in rain at +4C and not reach up and go to ENG on the icing panel. It just doesn't make sense.

I'm not a big fan of this "automatic" icing system. From what I've read in the CFM, I don't see anything that precludes the pilot from turning on the ENG or WING/STAB anti-ice if he or she so chooses. We just have temperature limitations on manual use, not a limitation on when we can use it. Is there a page in the CFM that says we cannot use the OVRD function?

There isn't anyting that says we can't use it, and nothing that says we should under the above mentioned circumstances. There is also nothing that says we can't use the manual gear extension lever every time. The book says that if we see ice acreet on the wipers and the ice system hasn't kicked on to use the over ride knob. However, physics would lead me to believe that we would get engine lip ice before any ice forms on the windscreen. I have yet to hear one aircraft have a problem with engine ice, so I am guessing the engineers either found a way to ensure lip ice wouldn't be a problem, or found a way to detect it and triger the anti-ice system. I'll bet that if we took a poll of our pilots to see how many people actually turn on the eng ice during those circumstances, 99% would say they have never thought about it. 3 years here on this aircraft and not once has somone turned it on manually in flight, of course I have not flown with Yariv...............
Someone mentioned above that the shape of the ice detector might cool the air faster than the engine inlet and that might triger the ice system before engine ice occurs. Sounds plausable; I say we get the myth busters on it.

Ryan J. More · 07-18-2008, 01:40 PM

On my current aircraft we have varieants with manual ENG Anti Ice and some have an auto feature. The only guidance on the issue for us is, if you have no auto then you must turn it on anytime in visible moisture below 10* but above -40* (yes, even if it is that warm up at FL270). On our aircraft with an auto feature, it is up to us. We may leave it in auto or turn it on manually. Someone smarter than me has made it official that I can leave it in auto and be protected.

Yariv · 07-22-2008, 01:54 PM

767 has automatic ice detectors very similar to the EMB. CFM sepecifically says, however, to turn engine ice protection on with visibile moisture and temp betweeen 10 and -40. so having an auto system means nothing.

again, I'm not saying this is required, merely asking why you're not doing it, even though it's not required. you're perfectly within your right NOT to do this, since the book doesn't require it. but you should be able to explain your thought process.

there are things not in the book that you do (wipers when it rains) and there are things not in the book that should be in the book... and yes there haven't been any incidents... the same was true with our windshields, until they started cracking so we changed what the book says.

lonestarwings · 07-26-2008, 04:52 AM

I guess the argument for not manually selecting engine anti ice when flying through icing conditions in this airplane is that the ice detectors should be adequate to turn it on automatically if needed.

I realize there is a temperature drop due to the venturi effect of the engine's intake/inlet, and on the ground this needs to be compensated for due to a lack of airflow over the ice detector.

However, the ice detector has an airfoil-esque shape, that when airborne, probably cools the air to a similair degree as the air flowing through the engines' inlets.