AndyinPIT From United States of America, joined Sep 2007, 318 posts, RR: 0 Posted (4 years 6 months 3 weeks 2 days 4 hours ago) and read 4446 times:
Last night (10/28) there were icing conditions out with snow showers. At about 11pm a E170 came in and as I was parking it, I noticed a build up of ice on the slats between the engine and the body of the aircraft. I went upstarirs and told the captain and he told me that it was designed like that, and also the tail doesn't have anti-ice. The ice on the slats was probably around 1/8 inch and on the tail it was built up to about 1/4. The captain explained that when aerodynamic tests were being done, it was determined that no deteriation in performace was noted. Now that might be the case, but why wouldn't they just put the anti-ice on the whole wing and tail? Doesn't it make more sense to be safe than sorry?
TristarSteve From Sweden, joined Nov 2005, 3689 posts, RR: 34 Reply 1, posted (4 years 6 months 3 weeks 2 days 4 hours ago) and read 4410 times:
Most airliners are the same. Wing deicing on the slats outboard of the engine only. Tail deicing has been missing for years now.
B737NG is also missing deicing on the outboard slats.
AndyinPIT From United States of America, joined Sep 2007, 318 posts, RR: 0 Reply 3, posted (4 years 6 months 3 weeks 2 days 3 hours ago) and read 4387 times:
Hmm. Thanks for the responses. Just odd I've never seen it on the Boeing or Airbus. We had each in last night and didn't notice any ice build up.
OPNLguy From , joined Dec 1969, posts, RR: Reply 5, posted (4 years 6 months 3 weeks 1 day 22 hours ago) and read 4306 times:
Quoting Tdscanuck (Reply 4): That doesn't sound right...why do they bother putting extendable air ducts into the slats if they're not going to be used?
PhilSquares From , joined Dec 1969, posts, RR: Reply 6, posted (4 years 6 months 3 weeks 1 day 16 hours ago) and read 4259 times:
Quoting Tdscanuck (Reply 4): That doesn't sound right...why do they bother putting extendable air ducts into the slats if they're not going to be used?
Please re-read what I wrote. With the LE devices extended there is no heat for that area. With the LE devices retracted, the area is heated.
The simple reason is the airfoil is designed so ice if it does build up will break off. On the 727,757,A320, DC10, B747 and B744 it's all the same. In 25 years of flying those aircraft, I can count on one hand and have fingers left over the number of times I have used wing heat.
TristarSteve From Sweden, joined Nov 2005, 3689 posts, RR: 34 Reply 7, posted (4 years 6 months 3 weeks 1 day 10 hours ago) and read 4219 times:
Come on, aircraft are different.
Phil flies the B747. B747 has no wing deicing with leading edge flaps extended.
A lot of aircraft do. The B757 and A320 and B737 all have Slat heating which works whether the slats are retracted or extended. but not on all slats, and definitely not on the inboard Kruger flaps on the B737. In most aircraft MEL, wing deicing valves are only allowed inop when there are no icing conditions.
Having said that, some aircraft don't really need wing deicing. The B757 is one. Boeing proved in flight test that it wasn't required, but had to fit it anyway. Ask any B757 pilot if he uses wing antice.
Tdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 81 Reply 8, posted (4 years 6 months 3 weeks 17 hours ago) and read 4138 times:
Quoting PhilSquares (Reply 6): Please re-read what I wrote. With the LE devices extended there is no heat for that area. With the LE devices retracted, the area is heated.
I did. If you only heat the LE when the devices are retraced, there's no need for the extendable air duct...you'd just butt the air duct up against the retracted slat to provide air when the slat is retracted (like the air coupler between the frame and door in some cars). The extendable duct is a part that adds weight and only has a purpose of you're deicing an extended slat. That fact alone very strongly suggests that it can deice while extended.
Quoting PhilSquares (Reply 6):
Please re-read what I wrote. With the LE devices extended there is no heat for that area. With the LE devices retracted, the area is heated.
I did. If you only heat the LE when the devices are retraced, there's no need for the extendable air duct...you'd just butt the air duct up against the retracted slat to provide air when the slat is retracted (like the air coupler between the frame and door in some cars). The extendable duct is a part that adds weight and only has a purpose of you're deicing an extended slat. That fact alone very strongly suggests that it can deice while extended.
Tom.
Tom, I can assure you when you have the flaps extended on the 747 or 744 the bleed air is dumped overboard. I am stretching my memory but IIRC all Boeings are pretty much the same. But, I am absolutely certain about the 747 family.
HAWK21M From India, joined Jan 2001, 31201 posts, RR: 58 Reply 10, posted (4 years 6 months 3 weeks 13 hours ago) and read 4111 times:
Quoting TristarSteve (Reply 1): B737NG is also missing deicing on the outboard slats.
The B757 has a similiar situation too.
Quoting TristarSteve (Reply 7): Having said that, some aircraft don't really need wing deicing. The B757 is one. Boeing proved in flight test that it wasn't required, but had to fit it anyway
TristarSteve From Sweden, joined Nov 2005, 3689 posts, RR: 34 Reply 11, posted (4 years 6 months 3 weeks 10 hours ago) and read 4100 times:
Quoting HAWK21M (Reply 10): Quoting TristarSteve (Reply 7):
Having said that, some aircraft don't really need wing deicing. The B757 is one. Boeing proved in flight test that it wasn't required, but had to fit it anyway
Any more details available.
regds
MEL
No sorry only hearsay.
One of our B757 captains was involved with the B757 development. He once told me that they covered the leading edges with plastic bags full of gell to simulate the worst ice formations, then flew the aircraft. He said that the simulated ice was unnoticeable on the handling. we were having a problem with a wing antice valve, and he said don't waste your energy, we very rarely use it.
AndyinPIT From United States of America, joined Sep 2007, 318 posts, RR: 0 Reply 12, posted (4 years 6 months 3 weeks 5 hours ago) and read 4076 times:
Thanks for the responses guys....after working with these planes for 4+ years on the ramp I'm still learning new things every day!
Tdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 81 Reply 13, posted (4 years 6 months 2 weeks 6 days 4 hours ago) and read 4003 times:
Quoting PhilSquares (Reply 9): Tom, I can assure you when you have the flaps extended on the 747 or 744 the bleed air is dumped overboard. I am stretching my memory but IIRC all Boeings are pretty much the same. But, I am absolutely certain about the 747 family.
This appears to be a uniquely 747 phenomenon among Boeings...the 727, 737, 757, 767, and 777 all have telescoping ducts between the leading edge and the slat, allowing anti-ice of the slat whether it's extended or retracted.
HAWK21M From India, joined Jan 2001, 31201 posts, RR: 58 Reply 14, posted (4 years 6 months 2 weeks 5 days 16 hours ago) and read 3937 times:
Quoting TristarSteve (Reply 11): He once told me that they covered the leading edges with plastic bags full of gell to simulate the worst ice formations, then flew the aircraft
Still trying to visualise this.
What about Wind tunnell tests?
regds
MEL.
LongHauler From Canada, joined Mar 2004, 4275 posts, RR: 36 Reply 15, posted (4 years 6 months 2 weeks 4 days 4 hours ago) and read 3859 times:
Another unusual quirk with respect to the E170/E190 series is that the approach speeds are adjusted when using full flaps for landing if the ice detectors detected ice at any point in the flight. This is the adjust for the ice that could possibly be on the tail, and undeiced wing sections.
It always seems a bit odd to adjust for ice detected on climb out from YYZ, then land at PHX when its 105 degrees and use "ice speeds" for landing! (there is a reason for it, but I wont bore you with it here)
Never gonna grow up, never gonna slow down .... Barefoot Blue Jean Night
PGNCS From United States of America, joined Apr 2007, 2511 posts, RR: 45 Reply 16, posted (4 years 6 months 1 week 6 days ago) and read 3643 times:
Quoting PhilSquares (Reply 2): Every Boeing, McD or Airbus I've flown is the same. With the LE devices extended there is NO wing heat at all. No tail surface had heat either!!!
I don't know what all Phil has flown, but some aircraft DO have tail heat and LE heat that works with LED's extended; most common example: any DC-9 or MD-80/90 ever built.
Please re-read what I wrote. With the LE devices extended there is no heat for that area. With the LE devices retracted, the area is heated.
That IS true for the 747.
Quoting Tdscanuck (Reply 8): I did. If you only heat the LE when the devices are retraced, there's no need for the extendable air duct...you'd just butt the air duct up against the retracted slat to provide air when the slat is retracted (like the air coupler between the frame and door in some cars). The extendable duct is a part that adds weight and only has a purpose of you're deicing an extended slat. That fact alone very strongly suggests that it can deice while extended.
Again, I don't know what all Phil has flown here, but like Tom is saying, SOME aircraft DO have effective LE heat regardless of Slat (or LE Flap) position; some also have tail heat. A very few even have airfoil anti ice that works on the ground as well as in flight (some modified DC-9-10 series).
Quoting PhilSquares (Reply 9): Tom, I can assure you when you have the flaps extended on the 747 or 744 the bleed air is dumped overboard.
That is true; I understand Tom's point to be that some aircraft have this feature and some don't, though it's possible I have misinterpreted what he's saying.
Tdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 81 Reply 17, posted (4 years 6 months 1 week 5 days 23 hours ago) and read 3626 times:
Quoting PGNCS (Reply 16):
That is true; I understand Tom's point to be that some aircraft have this feature and some don't, though it's possible I have misinterpreted what he's saying.
That's exactly what I was saying.
With regard to Puget Sound-heritage Boeing's, the 747 is the odd duck out. Most of them do have anti-ice with the LE devices extended.
Sponsor Message: 
From United States of America, joined Sep 2007, 318 posts, 
From Sweden, joined Nov 2005, 3689 posts, 
From , joined Dec 1969, posts, 
From Canada, joined Jan 2006, 12709 posts, 
From India, joined Jan 2001, 31201 posts, 
Sponsor Message: 
Printer friendly format
