B744 Oil Quantity

[Durango]

From the FCOM - "The oil quantity indication changes color to magenta if low oil quantity is detected or if the oil quantity differential is exceeded."

Can any engineers shed any light on what this differential is?

Thanks
Durango

[Old Fella]

Don't know about -400, but it sounds like a differential between engine oil quantities for individual engines.

[Spanner Turner]

Your answer in Magenta has "popped-up" from the -400 manual below;

Difference Quantity

Oil Quantity Difference Monitoring begins when;

•At least 2 Engines are running within 2% N1 RPM, and
•The change in altitude of the Airplane is less than 200 feet/min or the aircraft is on the ground motionless.
An automatic pop-up of all oil parameters occurs when the difference in oil quantity between the high and low quantity Engine is 7 Litres
for greater than 180 seconds;
•The indication, which represents the low quantity Engine, will turn magenta in colour at the differential limit.

:ok:
.

[Durango]

Great stuff Spanner Turner!
Thank you...
Durango:ok:

[bigduke6]

"During cruise, oil quantity displays on EICAS whenever oil quantity on one
engine differs from any other engine by a predetermined amount. When this
occurs, the lowest oil quantity is shown in magenta. If there is an increase in oil
quantity during cruise (indicator malfunction or leaking fuel/oil heat exchanger),
the EICAS oil partial engine indications display may appear. However, for this
condition the low quantity displays in magenta, even though that oil quantity may
be normal."

I thought the quantity difference was 5 quarts, but they have removed the number from the FHB. Perhaps a customer specific option?