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MD80 In Cold Weather

Sun May 22, 2005 11:28 am

I've heard that the MD80 does not do too well in cold climates such as Interior Alaska. I understand that the wings are more prone to icing due to the lack of wing mounted engines. Is this the only reason for their problems in the cold, or is there more to it?
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RE: MD80 In Cold Weather

Sun May 22, 2005 2:02 pm

It has nothing to do with the wing mounted engines and everything to do with the fact that the wing is very thin due to MDD making it as efficient as possible and also stretching it as well.

The problem is that during cruise the wing cools and can "cold soak" the fuel to temperatures below freezing. During decent into more humid air this causes moisture to sublimate (I think that's the one) water vapor to a solid. Causing ice buildup on the top of the wing. There is an optional tank heating blanket that AA has, and some airlines have come up with other ways of finding ice accumulation such as strings and "rumble strips" that are smoothed out by ice accumulation. This isn't just possible in cold climates, it's actually more common on days where it's humid and above freezing. I've seen MD-80s at STL getting deiced when it was 70 on the ground. A professor I had was an MD-80 captain and taught systems for a now defunct airline before coming to my school said that he once had to deice at PHX when it was nearly 90 on the ramp.

The strakes on the front fuselage, however, are heated with bleed air because they found that if ice accumulated on those the airflow would sent it directly into the intake when it broke off.
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RE: MD80 In Cold Weather

Sun May 22, 2005 3:34 pm

Quoting FlyingNanook (Thread starter):
I've heard that the MD80 does not do too well in cold climates such as Interior Alaska

Actually in Fairbanks it wouldn't be as big of an issue, since cold air holds less moisture. However taking one into Southeast in January is a whole different issue, because you have cold air and moisture.

Pilotpip stated the issue, cold soaked fuel causing water contacting the wing to freeze. But there have been issues with engines FOD'ing out as ice breaks off the upper surface of the wing and gets ingested.

If you watch before a flight on an MD-80 you often will see a mechanic or pilot type head out to the trailing edge of the wing with a stepladder and a wand. What they are going to do is test the upper surface for ice.
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RE: MD80 In Cold Weather

Sun May 22, 2005 8:19 pm

Pilotpip got it all right.As ice forms on thee critical areas and the wing flexes as it does during take-off,the ice will break off and get sucked into the engines.We (SAS) had an MD-80 crash after take-off at ARN some years ago.No fatalities but the plane was a write-off.Several new anti- and de-icing procedures were adopted by McDonnell-Douglas and MD-80 operators after this episode.

The MD-80 works very well in cold climates.The engines are a lot more resistant to ice forming on the fan blades during freezing drizzle conditions than engines with higher by-pass ratios like the 737NG and A320 series.We have these conditions at OSL several times during the winter,and the MD's continue operating when everything else is grounded.We used to operate the MD-80 far into the Arctic (LYR) in the Spitzbergen Islands with no problems whatsoever.The nearest alternate was 1:45 hours away,though!
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RE: MD80 In Cold Weather

Tue May 24, 2005 5:11 pm

The SAS 1991 Gottöra accident would have been avoided if SAS had paid the due attention to de-icing. Finnair had already done the detective work finding out why there had been mysterious MD engine fan blade damages after the 1981 MD introduction along with the DC-9s. It turned out to have been from minor ingestions of ice forming in-flight near the wingroot where a strengthening of the airframe had been made during the ugrade from the DC-9 to the MD-series. That same area can also be very resistant to de- and anti-icing. The reason was found out years ago before the SAS accident, and the SAS people were duly informed, as were all MD operators.

I'd say any modern passenger transport can take-off safely when properly de-iced in winter and when the de/anti-icing is in use. I believe it's a certification requirement.

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RE: MD80 In Cold Weather

Wed May 25, 2005 1:05 pm

MD-80's in my experience did fine flying in cold weather but when they sat overnight in cold weather (say below -20F) then they seemed to have more cold related problems in the morning than Boeing products.
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RE: MD80 In Cold Weather

Thu May 26, 2005 1:33 am

Quoting Bjones (Reply 5):
when they sat overnight in cold weather

One of the problems I've run into is, after sitting overnight the forward grey water drains on planes modified by Flight Structures would occasional plug due to freezing inside the drain line routed near the wheelwell structure. The problem was amplified because when it plugged at that location, everything poured down the galley sink drain would come out the floor drain under the carts and either run into the flightdeck during descent or leak past the floor panels onto the ebay below.
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RE: MD80 In Cold Weather

Thu May 26, 2005 8:42 am

As has been said, it's all about wing icing. If the Mad Dog didn't do well in cold weather, I would wonder why both SAS and Finnair have had it as the mainstay of their fleets for decades.
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RE: MD80 In Cold Weather

Fri Jun 10, 2005 5:03 pm

MD-80s and DC9s don't do all that bad in the cold. The aircraft that doesn't like the cold in the DC9 family is the 717. The computers seem to take exception to not being kept warm on cold winter nights in the upper midwest.

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