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How Is This Ice Build Up Not Dangerous?  
User currently offlineB727fan From United States of America, joined Apr 2004, 298 posts, RR: 0
Posted (4 years 3 months 1 week 6 days 23 hours ago) and read 18894 times:

Hello,
Just saw this pic:
http://www.airliners.net/photo/Jet-A...rways/Boeing-777-35R/ER/1635373/M/

Is this common, and wouldn't this type of build up be dangerous?

Thank You in advance.

23 replies: All unread, jump to last
 
User currently offlineVoar From Canada, joined Jul 2008, 95 posts, RR: 0
Reply 1, posted (4 years 3 months 1 week 6 days 23 hours ago) and read 18864 times:

Hmm... looks like a bit of hoar frost on the tail section. Would be dangerous if it was on the wings also. On the tail like this the effects should be minimal. It looks like its only on the side that was in the shade also, the dark paint and the speed of the airplane should make the frost sublimate quickly.

User currently offlineLowrider From United States of America, joined Jun 2004, 3220 posts, RR: 10
Reply 2, posted (4 years 3 months 1 week 6 days 23 hours ago) and read 18818 times:

It does not appear to be on any lift prodicing surfaces and looks to be far enough aft on the tail and fuselage so that flow seperation would negate any concerns over increased drag. If I saw it on preflight, I would get it cleaned off, but judging by the lack of coverage on CNN, it does not appear to have been critical.


Proud OOTSK member
User currently offlineAA737-823 From United States of America, joined Mar 2000, 5637 posts, RR: 11
Reply 3, posted (4 years 3 months 1 week 6 days 22 hours ago) and read 18548 times:

Harmless, most likely.

You can have 1/8 inch buildup in certain areas, even parts of the wing.
I'd get on it.


User currently offlineTristarSteve From Sweden, joined Nov 2005, 3930 posts, RR: 34
Reply 4, posted (4 years 3 months 1 week 6 days 19 hours ago) and read 18270 times:



Quoting B727fan (Thread starter):
Is this common, and wouldn't this type of build up be dangerous?

Yes it is very common. The whole fuselage can be covered in hoar frost, to a depth of about 3mm as long as you can see the paint and markings underneath.

No it is not dangerous.


User currently offlineBartonsayswhat From Canada, joined Oct 2007, 434 posts, RR: 0
Reply 5, posted (4 years 3 months 1 week 6 days 19 hours ago) and read 18215 times:

I'm not spraying the fuselage if I can see the letters. Time consuming and not required for safe flight.

User currently offlineNZ107 From New Zealand, joined Jul 2005, 6335 posts, RR: 39
Reply 6, posted (4 years 3 months 1 week 6 days 19 hours ago) and read 18187 times:

The atmosphere is so dry and the sun can warm up the metal (or at least give it enough energy to break free) so my feeling is that it'd end up evaporating at higher altitudes anyway. Just my opinion.


It's all about the destination AND the journey.
User currently offlineB727fan From United States of America, joined Apr 2004, 298 posts, RR: 0
Reply 7, posted (4 years 3 months 1 week 6 days 14 hours ago) and read 17763 times:

Thanks everyone for the insight, learned something new, appreciate it.

User currently offlineSolarflyer22 From US Minor Outlying Islands, joined Nov 2009, 814 posts, RR: 2
Reply 8, posted (4 years 3 months 1 week 6 days 13 hours ago) and read 17645 times:



Quoting TristarSteve (Reply 4):
Yes it is very common. The whole fuselage can be covered in hoar frost, to a depth of about 3mm as long as you can see the paint and markings underneath.

No it is not dangerous.

Ditto. It is not a danger. There is no where near enough ice to impede movement of the rudder at the rear. Even if it did, you would know it right away. I don't know what the regulations say though. I would be curious to find out.


User currently offlineDonnieCS From United States of America, joined Jan 2007, 75 posts, RR: 0
Reply 9, posted (4 years 3 months 1 week 6 days 12 hours ago) and read 17344 times:

They way it built up also appears that it accumulated after takeoff. Also ice usually built up at low altitudes will shed as you climb higher due to the higher pressure of the oxygen in the ice crystals which formed at lower altitudes. Theres a name for this effect but it escapes me right now, NASA has some excellent material on icing that explained this situation really well.


Charlie - Gulfstream flight mechanic
User currently offlineTtailfan From United States of America, joined Sep 2009, 69 posts, RR: 0
Reply 10, posted (4 years 3 months 1 week 6 days 11 hours ago) and read 15100 times:

The flight crew has the final say on whether to de/anti-ice or not. And since its their lives on the line, I trust their judgement.

I agree that it isn't that big of an issue because it is "within limits", but if I was on the de/anti-crew, I'd have been confirming with the Captain that he was ok with it. Err on the side of caution.


User currently offlineGr8Circle From Canada, joined Dec 2005, 3069 posts, RR: 4
Reply 11, posted (4 years 3 months 1 week 6 days 11 hours ago) and read 14808 times:



Quoting Lowrider (Reply 2):
but judging by the lack of coverage on CNN, it does not appear to have been critical.

Good one..... rotfl 


User currently offlineJayeshrulz From India, joined Apr 2007, 1027 posts, RR: 2
Reply 12, posted (4 years 3 months 1 week 6 days 10 hours ago) and read 14328 times:



Quoting Gr8Circle (Reply 11):
Quoting Lowrider (Reply 2):
but judging by the lack of coverage on CNN, it does not appear to have been critical.

Good one..... rotfl

lol....
But seriously, can it freeze/jam the rudder the way it used to happen to 737 classics?



Keep flying, because the sky is no limit!
User currently offlineMD80fanatic From United States of America, joined Apr 2004, 2659 posts, RR: 10
Reply 13, posted (4 years 3 months 1 week 6 days 9 hours ago) and read 11992 times:

Trailing edge icing is not critical, it the leading edge that when iced over prevents laminar flow over the airfoil shape, reducing lift / control authority.

Frost typically forms mid-chord on the maddogs, over the fuel tanks. The addition of anti-ice panels on top of the wing (over the tanks) was to eliminate the chance of ice being ingested into the engines, I believe, and was not really to improve flight characteristics (I can only presume ice/frost "south" of the leading edge is not that critical aerodynamically).


User currently offlineTrnswrld From United States of America, joined May 1999, 891 posts, RR: 0
Reply 14, posted (4 years 3 months 1 week 6 days 8 hours ago) and read 11385 times:



Quoting Jayeshrulz (Reply 12):
But seriously, can it freeze/jam the rudder the way it used to happen to 737 classics?

No, there is no way light "frost" could jam a rudder powered by powerful hydraulic actuators.


User currently offlineSEPilot From United States of America, joined Dec 2006, 6676 posts, RR: 46
Reply 15, posted (4 years 3 months 1 week 6 days 8 hours ago) and read 11385 times:

It is only the leading edges and 1st 1/3 of the wings and horizontal/vertical stabilizers that are critical. Ice anywhere else can increase drag but is not dangerous as long as it is not excessively thick. As Tristarsteve says if you can read the lettering underneath, ignore it.


The problem with making things foolproof is that fools are so doggone ingenious...Dan Keebler
User currently offlineTheCol From Canada, joined Jan 2007, 2032 posts, RR: 6
Reply 16, posted (4 years 3 months 1 week 6 days 5 hours ago) and read 8395 times:



Quoting NZ107 (Reply 6):

 checkmark 

That pretty much sums it up. In some cases, the ice on non-critical surfaces is left to melt on it's own. Usually the rule of thumb is: absence of moisture, along with a temperature of 4c and rising.



No matter how random things may appear, there's always a plan.
User currently offlineMatheus From Brazil, joined Nov 2003, 135 posts, RR: 7
Reply 17, posted (4 years 3 months 1 week 6 days 5 hours ago) and read 7643 times:

Over the winter here in CWB, its quite common to see airplanes taking off with this amount of frost over it, or even more, as here we dont have any de-ice equipament.

User currently offlineVoar From Canada, joined Jul 2008, 95 posts, RR: 0
Reply 18, posted (4 years 3 months 1 week 6 days 5 hours ago) and read 7568 times:

In Canada, the clean aircraft concept is used and Transport Canada uses the following definitions (CAR 622.11, definitions):

"contamination" - means any frost, ice or snow that adheres to the critical surfaces of an aircraft.

"critical surfaces" - means the wings, control surfaces, rotors, propellers, upper surface of the fuselage on aircraft that have rear-mounted engines, horizontal stabilizers, vertical stabilizers or any other stabilizing surface of an aircraft.

So by their definition the take-off would not have been legal since there is frost on the vertical stabilizer. The JARs may have slightly different interpretations so it is possible that it was ok.

In practice though, things are somewhat different. I don't see an issue at all.


User currently offlineYycramprat From Canada, joined Apr 2007, 36 posts, RR: 0
Reply 19, posted (4 years 3 months 1 week 6 days 2 hours ago) and read 5163 times:

It's Hoar frost like mentioned before. Not a huge deal.

If the rest of the aircraft was de-iced, they ,may of avoided this area in an effort to avoid snuffing out the APU. Can happen easily on the 777 and 767 as the APU intake is in this area. Happens much more on the CRJ though.


User currently offlineTdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 20, posted (4 years 3 months 1 week 6 days 1 hour ago) and read 5010 times:



Quoting Jayeshrulz (Reply 12):
But seriously, can it freeze/jam the rudder the way it used to happen to 737 classics?

No. The 737-classic problem was an internal issue within the rudder PCU's. It was caused by temperature swings, but the presence/absence of ice or frost had nothing to do with it.

Quoting MD80fanatic (Reply 13):
Trailing edge icing is not critical, it the leading edge that when iced over prevents laminar flow over the airfoil shape, reducing lift / control authority.

Preventing laminar flow isn't a big deal...unless you designed for it on purpose (and I'm not aware of any commercial airliner with a natural laminar flow wing) you're going to have turbulent flow anyway. Preventing *separated* flow is very important, however...that's where you get major lift problems.

Tom.


User currently offlineCALTECH From Poland, joined May 2007, 2004 posts, RR: 27
Reply 21, posted (4 years 3 months 1 week 4 days 3 hours ago) and read 3524 times:



Quoting B727fan (Thread starter):
Hello,
Just saw this pic:

Would have deiced the tail. F.A.R. 121.629 does state

"(i) A pretakeoff contamination check, as defined in paragraph (c)(4) of this section, determines that the wings, control surfaces, and other critical surfaces, as defined in the certificate holder's program, are free of frost, ice, or snow."

http://ecfr.gpoaccess.gov/cgi/t/text...&node=14:3.0.1.1.4.21.3.22&idno=14

Illegal in the U.S.A. Trouble if a F.A.A. inspector saw this in the states. A rudder is a critical primary flight control.



UNITED We Stand
User currently offlinePITrules From United States of America, joined Jun 2000, 3032 posts, RR: 4
Reply 22, posted (4 years 3 months 1 week 4 days 2 hours ago) and read 3436 times:



Quoting SEPilot (Reply 15):
It is only the leading edges and 1st 1/3 of the wings and horizontal/vertical stabilizers that are critical. Ice anywhere else can increase drag but is not dangerous as long as it is not excessively thick.

The ATR that crashed in IN had icing behind the leading edge which caused the aileron snap-back, leading to its fatal plunge.

Quoting Voar (Reply 18):
In Canada, the clean aircraft concept is used and Transport Canada uses the following definitions (CAR 622.11, definitions):

"contamination" - means any frost, ice or snow that adheres to the critical surfaces of an aircraft.

"critical surfaces" - means the wings, control surfaces, rotors, propellers, upper surface of the fuselage on aircraft that have rear-mounted engines, horizontal stabilizers, vertical stabilizers or any other stabilizing surface of an aircraft.

So by their definition the take-off would not have been legal since there is frost on the vertical stabilizer. The JARs may have slightly different interpretations so it is possible that it was ok.

 checkmark 

Quoting CALTECH (Reply 21):
Would have deiced the tail. F.A.R. 121.629 does state

"(i) A pretakeoff contamination check, as defined in paragraph (c)(4) of this section, determines that the wings, control surfaces, and other critical surfaces, as defined in the certificate holder's program, are free of frost, ice, or snow."

http://ecfr.gpoaccess.gov/cgi/t/text...&node=14:3.0.1.1.4.21.3.22&idno=14

Illegal in the U.S.A. Trouble if a F.A.A. inspector saw this in the states. A rudder is a critical primary flight control.

 checkmark 

A vertical stabilizer can stall just like a wing if airflow is disrupted or separates from the surface. This may happen when large rudder applications are made in conjunction with a contaminated surface at low airspeeds.

Usually there is no reason to make such a large rudder application; however I would not have liked to be on board that airplane if an engine failed at a low airspeed (at or immediately after V1), which would have necessitated a large rudder input and resultant large angle of attack on the vertical stab.



FLYi
User currently offlineHotelDJRomeo From Canada, joined Dec 2009, 159 posts, RR: 0
Reply 23, posted (4 years 3 months 1 week 4 days 1 hour ago) and read 3411 times:

While the following video isn't 100% connected to the picture in the OP, it is most definitely right along the lines of it.

It is the NASA tailplane icing video (about 23mins run time). I'm sure many people have seen it, or parts of it, during initial or recurrent flight training. It's certainly a must-watch in terms of icing safety:

http://video.google.com/videoplay?docid=2238323060735779946#



Roger, Roger. What's our vector, Victor?
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