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Wing De-Icing Question



 
 
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  #11  
Old February 15th 09, 11:23 PM posted to rec.aviation.piloting
Dudley Henriques[_2_]
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Posts: 2,546
Default Wing De-Icing Question

On Feb 15, 11:59*am, Gezellig wrote:
On Sun, 15 Feb 2009 06:00:13 -0800 (PST), Dudley Henriques wrote:
On Feb 13, 4:44*pm, "Robert11" wrote:
Hello,


I guess de-icing is going to be a popular subject.


Question, please: *On commercial jet airliners like, e.g., a 767 or 757, is
there any in-flight deicing system for the wing and tail surfaces, other
than a leading edge pneumatic boot ?


What about the "main," large upper surfaces ?


How in general is wing de-icing accomplished on these new, modern jets ?


Thanks,
Bob


There's a very good chance the Boston crash might have been tailplane
icing.
DH


To explain the erratic flight behavior?


It's just a guess, but yes. I viewed a NASA film only this morning on
this issue. The key if correct would be that whatever happened
happened immediately after they went to 15 degrees of flaps. That
would have increased the aoa on the tail surface leading edge. That
leading edge is sharper than the wing leading edge and very
susceptible to icing. Assuming the boundary layer sep point was moving
aft on the stabilizer already, when they lowered the flaps they could
have easily exceeded the CLmax for the tail.
Even if this theory is correct, I'd be looking for additional factors
related to icing coupling to cause the autorotation they seemed to
have entered prior to impact.
It's all theory anyway. The NTSB will come up with something as they
progress with the investigation.
DH
  #12  
Old February 15th 09, 11:41 PM posted to rec.aviation.piloting
Tman[_2_]
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Posts: 37
Default Wing De-Icing Question

Dudley Henriques wrote:

There's a very good chance the Boston crash might have been tailplane
icing.


Did you mean BUF or did I miss something in Boston?
T
  #13  
Old February 15th 09, 11:42 PM posted to rec.aviation.piloting
Tman[_2_]
external usenet poster
 
Posts: 37
Default Wing De-Icing Question

Bertie the Bunyip wrote:

Note that this flight started its plunge right at or after the outer
marker. The outer marker is where you normally lower gear and flaps.
Lowering flaps is the thing that causes the tailplane stall if the
tailplane is iced up.


Rubbish.


Uhh, which part of this is rubbish?
As I recall from a news account of the FDR, the loss of control was
immediately following gear / flap extension.

If it was the "outer marker is where you normally lower gear and flaps",
well yeah but I'm not sure that's the point.
T
  #14  
Old February 16th 09, 01:04 AM posted to rec.aviation.piloting
Dudley Henriques[_2_]
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Posts: 2,546
Default Wing De-Icing Question

On Feb 15, 5:41*pm, Tman wrote:
Dudley Henriques wrote:
There's a very good chance the Boston crash might have been tailplane
icing.


Did you mean BUF or did I miss something in Boston?
T


Yes. I've been dealing with a Boston issue most of the day and my
senior moment quota kicked in. It was Buffalo.
DH
  #15  
Old February 16th 09, 02:09 AM posted to rec.aviation.piloting
Bertie the Bunyip[_24_]
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Posts: 2,969
Default Wing De-Icing Question

cavedweller wrote in
:

On Feb 14, 9:12*pm, Bertie the Bunyip wrote:
K l e i n wrote
innews:2d099c70-cb73-40be-a62e-feb3015f5

:





On Feb 13, 3:36*pm, "Robert M. Gary" wrote:
On Feb 13, 1:44*pm, "Robert11" wrote:


Hello,


I guess de-icing is going to be a popular subject.


Question, please: *On commercial jet airliners like, e.g., a 767
o

r
7
57, is
there any in-flight deicing system for the wing and tail
surfaces, othe
r
than a leading edge pneumatic boot ?


What about the "main," large upper surfaces ?


How in general is wing de-icing accomplished on these new,
modern jets
?


Thanks,
Bob


Jets don't typically have boots. Most use hot air stollen from the
engines to heat the leading edges. Some use a "leak" system to
drip anti-freeze like solution on the tail surfaces to avoid
having to plumb the hot air to the rear, although this is less
common. I'm not sure that I woudl call the type of plane that
crashed less modern than a 767 considering by-pass jet engines
(the type in a 767) have been around longer than turbo prop
engines that were involed in this recent crash.


-Robert


The more I hear about this, the more it sounds like tailplane
icing. Take a look at
http://video.google.com/videoplay?do...60735779946for a
NASA
produced video on the subject.


Note that this flight started its plunge right at or after the
outer marker. *The outer marker is where you normally lower gear
and flaps. Lowering flaps is the thing that causes the tailplane
stall if the tailplane is iced up.


Rubbish.

Bertie- Hide quoted text -

- Show quoted text -


The NASA study on tail stall notwithstanding?


Well, OK not impossible, but Wing if anythng..


Bertie

  #17  
Old February 16th 09, 02:01 PM posted to rec.aviation.piloting
[email protected]
external usenet poster
 
Posts: 251
Default Wing De-Icing Question

On Feb 15, 4:23*pm, Dudley Henriques wrote:
On Feb 15, 11:59*am, Gezellig wrote:



On Sun, 15 Feb 2009 06:00:13 -0800 (PST), Dudley Henriques wrote:
On Feb 13, 4:44*pm, "Robert11" wrote:
Hello,


I guess de-icing is going to be a popular subject.


Question, please: *On commercial jet airliners like, e.g., a 767 or 757, is
there any in-flight deicing system for the wing and tail surfaces, other
than a leading edge pneumatic boot ?


What about the "main," large upper surfaces ?


How in general is wing de-icing accomplished on these new, modern jets ?


Thanks,
Bob


There's a very good chance the Boston crash might have been tailplane
icing.
DH


To explain the erratic flight behavior?


It's just a guess, but yes. I viewed a NASA film only this morning on
this issue. The key if correct would be that whatever happened
happened immediately after they went to 15 degrees of flaps. That
would have increased the aoa on the tail surface leading edge. That
leading edge is sharper than the wing leading edge and very
susceptible to icing. Assuming the boundary layer sep point was moving
aft on the stabilizer already, when they lowered the flaps they could
have easily exceeded the CLmax for the tail.
Even if this theory is correct, I'd be looking for additional factors
related to icing coupling to cause the autorotation they seemed to
have entered prior to impact.
It's all theory anyway. The NTSB will come up with something as they
progress with the investigation.
DH


Maybe a silly notion/question buuuut...if this (pitching/roll -this
from new reports as of 2/16) had occurred at a higher altitude, 7000
ft say, would the plane have entered a 'flat' spin? Was the impact
indicative of such?
  #18  
Old February 16th 09, 02:01 PM posted to rec.aviation.piloting
Robert11[_2_]
external usenet poster
 
Posts: 3
Default From OP Re Wing De-Icing Question - A Few More Questions

Hello,

Not a Physicist, so please bear with me.

The posts here seem to imply that wing icing occurs (mainly), if not
exclusively, on the leading edges, and not on the upper or lower wing
surfaces.

Why ?

If it does occur on the upper surfaces in modern jet commercial aircraft, is
there also
hot bleed air available for this large surface, as there is for the leading
edges ?

If it does occur on modern turboprops, on the upper surface, there is
nothing they can do to remove it.
Right ?

Why did they say that a 180 degree turn "may" help break off ice ?

Thanks,
Bob
---------------------------------


"VOR-DME" wrote in message
...
In article
,
says...


On Feb 15, 5:41 pm, Tman wrote:
Dudley Henriques wrote:
There's a very good chance the Boston crash might have been tailplane
icing.

Did you mean BUF or did I miss something in Boston?
T


Yes. I've been dealing with a Boston issue most of the day and my
senior moment quota kicked in. It was Buffalo.
DH



Oh thanks! Spent two hours on the NTSB database trying to figure what
Boston crash we were talking about! :-)



  #19  
Old February 16th 09, 02:56 PM posted to rec.aviation.piloting
Maxwell[_2_]
external usenet poster
 
Posts: 2,043
Default Wing De-Icing Question


wrote in message
...
On Feb 15, 4:23 pm, Dudley Henriques wrote:

Cool! Let's speculate on speculation.




  #20  
Old February 16th 09, 02:57 PM posted to rec.aviation.piloting
Dudley Henriques[_2_]
external usenet poster
 
Posts: 2,546
Default Wing De-Icing Question

On Feb 16, 8:01*am, wrote:
On Feb 15, 4:23*pm, Dudley Henriques wrote:



On Feb 15, 11:59*am, Gezellig wrote:


On Sun, 15 Feb 2009 06:00:13 -0800 (PST), Dudley Henriques wrote:
On Feb 13, 4:44*pm, "Robert11" wrote:
Hello,


I guess de-icing is going to be a popular subject.


Question, please: *On commercial jet airliners like, e.g., a 767 or 757, is
there any in-flight deicing system for the wing and tail surfaces, other
than a leading edge pneumatic boot ?


What about the "main," large upper surfaces ?


How in general is wing de-icing accomplished on these new, modern jets ?


Thanks,
Bob


There's a very good chance the Boston crash might have been tailplane
icing.
DH


To explain the erratic flight behavior?


It's just a guess, but yes. I viewed a NASA film only this morning on
this issue. The key if correct would be that whatever happened
happened immediately after they went to 15 degrees of flaps. That
would have increased the aoa on the tail surface leading edge. That
leading edge is sharper than the wing leading edge and very
susceptible to icing. Assuming the boundary layer sep point was moving
aft on the stabilizer already, when they lowered the flaps they could
have easily exceeded the CLmax for the tail.
Even if this theory is correct, I'd be looking for additional factors
related to icing coupling to cause the autorotation they seemed to
have entered prior to impact.
It's all theory anyway. The NTSB will come up with something as they
progress with the investigation.
DH


Maybe a silly notion/question buuuut...if this (pitching/roll -this
from new reports as of 2/16) had occurred at a higher altitude, 7000
ft say, would the plane have entered a 'flat' spin? *Was the impact
indicative of such?


Difficult to say. I'm far from being the expert on transport aircraft.
My understanding is that if, and that is still a big IF, tailplane
icing was involved in the Buffalo accident, it was the lowering of the
flaps and the cfg change to the wing increasing the aoa on the tail
that was the factor actually taking them into stall. If that was the
cause, the actual breaking of the stall caused by the ice on various
leading edges could very well have taken them into uncontrolled auto
rotation. For that to happen, yaw had to be present at the stall.
The scenario above assumes low altitude due to the flap extension
factor.
At this stage in any accident investigation, it's always conjecture.
Already however, the seldom discussed issue of tailplane icing is
getting a lot of attention throughout the entire aviation community
and that alone is good for flight safety. The NTSB investigation will
provide the answer I'm sure.
Dudley Henriques
 




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