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RMC
30th Sep 2008, 14:38
Hi all,

Looking for confirmation of my understanding.

If you fly with the lower screen blank and a secondary engine parameter exceeds the "normal operating limit" then this will result in a pop up screen activation to attract your attention to the problem.

Does this then mean that oil temp would have to reach around 135 degrees c before you got to see it?

Or that engine vibration of 3.9 would not be displayed on the screen?

Oil pressure drops to 13 PSI before you get to see it?

Any other pop up triggers.

Surely it is better to fly with this screen displayed watch the trend and (in most cases) pick it up early

BOAC
30th Sep 2008, 21:53
That indeed is my understanding, and why I scan it at intervals in flight as I would 'normal' instruments - and the HYD page when taxying.

speedbird37
30th Sep 2008, 22:30
i think during take off roll it' s easier to see a malfunction if the screen pops up!

Screen pops up -> rejecte the take off

barit1
30th Sep 2008, 23:51
In periods where your attention should be focussed outside the cockpit, the "idiot light" mode is preferred - short-term decision-making is in order. Don't be distracted by vibes bouncing between 3.6 to 3.8.

In cruise you have time to analyze the fine points!

BOAC
1st Oct 2008, 18:07
According to BA, on the 737 the vibration 'idiot light' is NOT calibrated unless you are airborne - it is an AVM system they teach.

I don't think RMC is talking about the take-off roll anyway, is he/she?:confused:

RMC
4th Oct 2008, 11:40
BOAC correct...it is for monitoring of trends I was refering to (not instantaneous T/O reject decision making).

BOAC
4th Oct 2008, 12:30
I would sincerely hope that our Pr pilots here are well attuned to casting regular glances at engine and other parameters in 'round dial' cockpits?

RMC - I prefer to 'select' the screens on the same basis as above rather than have them constantly displayed, that way retaining the 'surprise' popup notification option.

RMC
6th Oct 2008, 07:55
BOAC - Our understanding of the logic is the same ..just the way we prefer to use that design option differs.

There are pros and cons to both preferences. Having an engineering background I like to know as soon as the oil temp starts to move that 40 or 50 degrees towards the normal operating limit/or as soon as the pressure starts to drop.

I guess if you scan it often enough you get the best of both worlds. Its just all that execise having to lean over and press the button so many times :)

Lightning5
6th Oct 2008, 09:23
normally the "pop up" will occur when the temp/pressure hits the yellow band on the display, very much similar to the 57/67 models. Mr Boeing once told me the reason for this blank screen senario was to remove "clutter" on the screens, (dark flight deck) but still have the ability to inform if all goes wrong!

BOAC
6th Oct 2008, 13:40
As I posted earlier, having once had an NG B system dump itself through a LE slat actuator while taxying in, I taxy with the HYD page displayed, to the consternation of some F/Os who find it 'non-standard'.

Todders
6th Oct 2008, 13:57
Interesting thread. I'm of the opinion that it should be blanked, but checked (for me I do it during fuel checks).

The other point i have is i have had a "pop" up with out any of the the yellow or red bands being reached. Was an eng failure (bearing failure) with symptoms similar to a serge. No ENG FAIL etc just a bang, drop in both N1 and N2 then a vibration (vib still reading 0.0). The EGT was then rising and looked like it would red line but we accomp. the recalls before it had the chance.

RMC
6th Oct 2008, 21:55
Todders...interested in what parameter caused your pop up. The only (unofficial) info I have is that pop ups occur when the "normal operating limits are reached".

If the system is smarter than this then I may have to adopt the regular scan proceedure:confused:.

BOAC
6th Oct 2008, 23:34
I cannot lay my hands on it, but I suspect the 'pop up' display has the same sensing as the 'abnormal start' with which you are accustomed - ie any EGT rise which is heading for an exceedance will trigger.

Todders
7th Oct 2008, 10:50
Not sure myself hadn't really given it too much thought until this thread.

I like the idea of the same logic as the abnormal start but to be honest the egt rise wasn't really until after the pop up and we were having a damn good look at the inst.

The vibration i personally think is the key, now i do have two possibilities even in this:

The vibration was cause by abnormal airflow over the rear of the aircraft, the chance of this to be honest i think is slim as there was no real sign of movement of the cc.
The vibration was indeed an eng vibration. But as i said the VIB was reading 0.0. This suggests it had been knocked/ripped off. This lack of reading may have been the reason for the pop up. Still only a theory though.