737 csd gauge

[rr892igw]

The csd gauge in my 737-400 has a IN temp
amble band starts at 135c but boeing books says 157c whereas RISE was concurrent at 20c.
Anyone has an answer to this? :confused:

[Le Pen]

Hi...

Not too clear what the Question is...

Can you clarify?

LP

[BmPilot21]

Hi, I know what you mean. The amber range starts at 135c for generator IN temperature (T), whereas the limit is 157c. The RISE amber range starts at 20c and the limit is 20c. Doesn't make sense, unless you are allowed a caution range with the IN, but not the RISE. RISE is more important as it tells you the condition of the generator drive / excessive load.

[Carnage Matey!]

The amber range starts at 135C and rises steadily to the red at >500C should you tell the CSD that she really isn't worth more pay than the FO, especially as you've only got 25 pax on board. The gauge can actually fly off the scale and even rupture if the CSD is asked to leave her office at any point during the 13 hour flight to help with the cabin service. Oh, sorry, wrong sort of CSD! :p

[Gypsy]

BMpilot - sorry but your a bit off course.

Inlet temp is more important in one way as the figure of 157 is a LIMIT and will cause a little amber light to appear leading to QRH checklist for Generator High Oil temp.

The figure of 20 for the RISE is as you suggest for monitoring the health of the Generator and if exceeded does not prompt any crew action other than to record the event in the Tech Log.

[rr892igw]

I SHOULD MAKE THE QUESTION CLEARER:
WHY THE LIMIT FOR MAX CSD IN TEMP AT 157C
IN THE BOOK WHERE THE AMBER BAND ON THE GAUGE
STARTS AT 135C?I DON'T THINK THERE IS A RED LINE LIMIT.SOMEONE TOLD ME THAT A PIVATE AVIATION PUBLISHER PUT THE LIMIT AT 140C INSTEAD OF 157C BY BOEING.
ANOTHER POSSIBILITY IS THAT MAY BE SOMEWAY
DOWN THE LINE OF 737 EVOLUTION,BOEING PUT IN
A BETTER CSD BUT STILL USING THE 1ST GENERATION CSD GAUGE.ANYONE HAS A VIEW ON THIS ? :D

[avmech]

Doesn't the 737-400 use IDG'S ? That might account for the difference

[CT737]

Just a thought. My 737-300 manual states that the "MAX" CSD oil temp is 157 degrees C. The 'IN' scale give the inlet temp and the 'RISE' scale gives the rise in temp as the oil passes through the CSD. Adding these two together would give you the oil temp as it leaves the CSD. Looking at the gauge closely, you could say that the begining of the amber band on the 'IN' scale is at 137 degrees C. Adding the max 'RISE' of 20 degrees gives you a total of 157 degrees C as it leaves the CSD. I beleive that the reason for the amber band on the 'IN' scale is that it warns to check the 'RISE' if the 'IN' temp is over 137 degrees C. If the 'RISE' is at the max of 20 degrees and the 'IN' temp is over 137 degrees the CSD oil temp will exceed 157 degrees C. This is only one example . The other extreme is with a 'IN' temp of 157 degrees and a 'RISE' of 1 degree. I have been unable to get any confirmation of this as the boss won't bother Boeing for such a 'trivial' matter!

[stator vane]

my two current volumes (which have greatly reduced information compared to the older versions) state the following;

max gen drive oil temp 157 C.
it also states that it is not AFM limitation.

in the electrical section it says;

higher than normal rise indicates excessive gen load or poor condition of drive.

lack of adequate cooling will generally cause the rise to decrease.

readings above 20 ARE USED BY MX IN TROUBLESHOOTING DRIVE PROBLEMS.

the only limit i see as valid is the 157 C. i understand that will cause the light to come on. then use the QRH and only then. i think it will apply to the impending break down of the lubricant close to the engine oil temp of 160-165.

i would not add the rise to the in and go for the disconnect myself.

if things are getting warm, i was told to consider turning an electric hydraulic pump off to help cool it if all else is okay. (that was an unofficial suggestion from United instructors in Denver)

[ 23 October 2001: Message edited by: stator vane ]