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electricdeathjet
8th Feb 2008, 21:32
In the limitations section of the FCOM, the minimum air temperature indicated in the environmental envelope is SAT -70 C.
What exactly is the limitation for?? Is it structural? Fuel cold soak? Airconditioning? Hydraulics?
Recently we have encountered temperatures below this, -73C at flight level 380, there were no ECAM warnings and the wings didnt fall off... Now what are we to do?? Descend? Speed up?
Loads of other airbuses at the same and at higher levels with their wings still attached.
Is it safe to assume that Airbus could not find air cold enough to test in for certification? Or are we all about to have a nasty shock one day soon?:\

Wingswinger
8th Feb 2008, 21:37
Write to Airbus in Toulouse and tell them you have just expanded the aircraft's environmental envelope. We can all then look forward to an FCOM update.

DFC
8th Feb 2008, 21:43
Not being type specific but the minimum temp can be for things like seals in undercarriage system. Brake seals being one good exmple.

Having the brake seals damaged will not make the wings fall off but they can cause a minimum of smoking brakes on landing when the fluid leaks.

Aircraft above could be in warmer air.

Perhaps someone can give the Airbus specifics.

Regards,

DFC

electricdeathjet
8th Feb 2008, 21:46
Wingswinger...

Dammm thats a great idea.... any commission in it?? :ok:

edj (self appointed test pilot)

Right Way Up
8th Feb 2008, 21:50
I think the term "limitation" gives it away!
Its an uncomfortable enough position to be in when you have had an incident whilst following procedures. Imagine if you operate outside the manufacturers limitations, and any incident occurs.

electricdeathjet
8th Feb 2008, 22:16
The question then is, why are there other aircraft flying at the same level? Are bus drivers aware of this limitation? About 80 percent of my collegues are unaware of this limitation (trainers included)....

Wingswinger
9th Feb 2008, 07:54
In my experience, limitations are often there simply because the manufacturer's test pilots have not had the time or resources allocated to take the aircraft beyond the limitation in question. On a military type I used to fly it was common to get expansions to the flight envelope as test pilots continued to completed flight test schedules for various fits and configurations. I doubt that -70C is a structural limitation. I suspect it is simply the coldest SAT experienced on any test flights.

EDJ, why don't you pop this one onto the Test Pilot forum? Somebody there might be able to give you a more informed opinion.

Right Way Up
9th Feb 2008, 08:06
EDJ,
I think you are right. There are a lot of bus drivers that are unaware of the limitation, although it has been in the FCOM for quite a long time. The fact that -70 deg C is very rare in Europe probably has something to do with it.

Chris Scott
9th Feb 2008, 09:53
Temperatures (SATs) of less than -70C are, as you imply, a bit unusual at temperate latitudes. They are common in the tropics, where the tropopause is so much higher. You have to climb high to find them, though, well above the certificated ceiling of the A320 (F/L 391?). That ceiling is, I think, based on restricting the cabin altitude to a max of 8000 ft at max-diff pressure.

But I see know reason why Airbus could not have flown high enough during certification in 1987.

Max Angle
9th Feb 2008, 10:22
Now what are we to do?? Descend? Speed up? You descend to find warmer air, speeding up won't change the SAT only the TAT. Had to do it once in the winter with a northerly airflow whilst flying over Scotland. We weren't the only ones, several long haul aircraft off the Atlantic on the same frequency were asking for the same.

electricdeathjet
9th Feb 2008, 13:54
It happened twice this year, both times over the North Sea one time -73C at FL380, we descended and the other time -71C FL390 and stayed at level as the fuel was still warm in tanks.
I shall repost in Test Forum and keep you all posted...

Bruce Waddington
10th Feb 2008, 22:15
All,

The A320 family minimum temperature limitations vary according to altitude.

The -70c limit mentioned above is at the maximum certified altitude. The minimum allowable outside air temperature increases (gets warmer) with a decrease in altitude. For example, an early model A320 at 20000 feet has a minimum outside air temperature limitation of -55c. An A321 at 20000 feet has a limit of -60c. A look in the environmental section of your limitations chapter will show you the appropriate graph for your aircraft model.

I am not sure why the limitation is in effect, but the fact that the aircraft manufacturer states it as a limit is good enough for me. :-))

best regards,

Bruce Waddington

electricdeathjet
11th Feb 2008, 10:32
Would that suggest that you would need the graph to hand at all times?
Surley the ECAM could be programmed to give a warning and alert the crew?

Thunderbug
11th Feb 2008, 14:31
Would that suggest that you would need the graph to hand at all times?

Or a very switched on First Officer.....!

Had this just recently. I pointed out that the temp was -72 at FL380 and he replied that it put us outside of the aircraft's envelope. After a brief "Yeh, right", we descended to FL360 and a tropical -68 . A dig through the books revealed -70 as the limit. Beers on me then........:ok:

T'bug