Power fluctuations at idle

[Guest]

I have been noticing strange power fluctuations with the 757. They occur when the throttles are pulled back to idle during taxi. They happen as follows:1. Begin from a still position.2. With the brakes off, increase power to 45% or so of N1 until the plane starts moving. 3. Pull the throttles back to idle in a single smooth motion.4. The power drops off as expected, but when it reaches idle, it momentarily goes back up slightly before returning to idle and staying there. At first I thought it was something with the sound, but when I looked at the engine read-outs, I could actually see the power go back up (only slightly and only for a fraction of a second). Does anyone else experience this? Is this intentional? I admit that I have not looked in the manual for an explanation of this behavior, but I do not remember it happening with the 777.Andrew

[MELKOR 5]

Yep, I'm getting the exact same behaviour.- Bill

[Guest GrantM]

same hereGrant

[Guest]

I have the exact same problem as well. Has done this in the exterior view? When I did it the sound sounded like a grehound bus changing from 2nd to 1st gear at 40 mph. CB

[Guest]

Actually I was thinking more like a Volvo Simi with my girl friend trying to do a 3 to 2....Ditto on the Engine surge, mine is mostly with the port engine with the occasional duet from starboard.

[Guest]

Well, looks like we have a number of people (if not everyone?) with this happeneing. It's not a very serious issue, as the surging does not interfere significantly with controling the aircraft during taxi, but it is a little annoying. Hopefully, Rob, Lefteris and company will take a look at it when they get a chance.Andrew

[Guest]

bump

[Guest]

bump

[Guest]

same hereChris Catalano

[Guest]

bump.

[Ben Johnson 3]

I'm experiencing the same (whether it's interior or exterior).Bob L

[Guest]

Just bumping it up again. I would like a comment from someone with PMDG when they get a chance, just so I know it is on their list of things to look at.Regards,Andrew

[lefteris 70]

Gents-I've been waiting for Vangelis to pick this up, but he's currently really busy with other stuff, so I'll post a somewhat-generic answer:The phenomenon you're noticing is due to the Fly!2 Jet Engine model. The way it's been programmed, you will either experience those momentary fluctuations, or you would be getting idle N1 at 35% (not very realistic, right?). We (as always) went with more realism.Hope this answers (a bit) your questions...