RB211 spool times

[FLCH]

This may seem a little off the beaten track, but does anyone have any info regarding spool times for the RB211 on the 757? I had flown a ship that had one engine lagging behind the other on spool up and down (about 40 % and beyond they synced up). So much so that during the flare using normal retardation process, the plane yawed at about 10 feet, it was easily countered, but my question is what about during a CAT3 Autoland ? Obviously the rudder will compensate, but would it put it out of the "normal" parameters for a CAT3 and hence initiate a Go-Around ? If there are specific limits for times for the engines I would appreciate some insight, so I will have some ammunition the next time this happens. I asked the maintenance people at my airline and was met by mostly blank looks and shrugged shoulders.(No offence to MX people in general though).

[WenWe]

You need to ask for an accel test to be performed (AMM 71-00-00 test 11 IIRC).

The engine should spool up from flight idle to 95% of rated epr for the day in around 5 seconds (again IIRC).

[FLCH]

Thanks for the quick reply !!

[barit1]

But does that check pertain to decels (retards)?

[Fargoo]

That check does indeed pertain to decell also.
The problem you are suffering from is generally a fault with the FFG.
Not much to test 11, it either passes or it doesn't.
Take the engines from Flight idle (approach idle) to 95% and time how long itg takes - compare this with the graph supplied.
Decell is even more simple - from 95% to flight idle must be no more than 10 seconds.
Checks are pretty similar for the 535C and the E4 engines.

WAIVER - this is not the entire contents of the check, just an idiots guide.