Vibrations on B777-300ER during Roll

[leonard17F]

Dear fellow PPruners,

Have you ever experienced vibrations while rolling a B777-300ER ?
No exact correlation with speed, nor weight, nor altitude...
If yes, is it a known phenomenon ?

Thanks a lot,
Leo

[Commander Taco]

About 4,000 hours on it, never experienced unusual vibrations during the T/O roll.

[ACMS]

Bit of an open ended question subject to personal interpretation isn’t it?

most Aircraft I’ve ever flown ( A and B ) can shake vibrate rattle and roll on T/O…….especially on a crap runway….

Most of the unusual vibrations experienced tend to come from the nose wheel, either Tyres ( flat spots after overnight sitting ) or the scrubbers after retraction.

[maui]

In 15,000 hours never rolled one so can't offer advice, and haven't heard comments from colleagues expressing such concerns.

[Amadis of Gaul]

Originally Posted by leonard17F

Dear fellow PPruners,

Have you ever experienced vibrations while rolling a B777-300ER ?

Leo

I have not.

[leonard17F]

Thanks a lot ! I was talking ailerons roll maneuver, not "take-off roll"

[HOVIS]

Originally Posted by leonard17F

Thanks a lot ! I was talking ailerons roll maneuver, not "take-off roll"

Has maintenance been informed? Could be aileron or spoiler bearing wear or even a PCU attachment point worn/failed.

[leonard17F]

Originally Posted by HOVIS

Has maintenance been informed? Could be aileron or spoiler bearing wear or even a PCU attachment point worn/failed.

Good question ! Yes, we have informed maintenance and they are also checking of course !

[Chesty Morgan]

Originally Posted by maui

In 15,000 hours never rolled one so can't offer advice, and haven't heard comments from colleagues expressing such concerns.

That's a hell of a straight line you've done there.

[fdr]

Originally Posted by leonard17F

Thanks a lot ! I was talking ailerons roll maneuver, not "take-off roll"

Normally the roll is smooth, rapid alieron input will give a slight kick from inertial rates developing, the wing is a flexible beam. Hovis is probably pointing intnhe right direction, I would be checking spoiner float for excessive bearing float. If it is low speed, outboard and inboard PCU leak rates and rod end float. High speed, just inboard but putting an observer aft of the TE of the wing will give a good idea of what is happening.

[FullWings]

Yes, I have experienced vibrations while someone else is rolling the aircraft. As FDR points out, the wing is long and flexible, so abrupt aileron inputs (often from those recently converted from a side stick type) send a ripple up and down the wing which feels like vibration but is actually closer to a PIO.

The acid test is to engage the autopilot and see if the “vibrations” or “turbulence” continue; often they mysteriously go away at that point...

[ACMS]

I used to feel aileron buffet quite a bit when guys would roll too too quickly. If you did it smoothly ( like the A/P would ) it didn’t happen. Generally after T/O when clean around 230 knots.

[student88]

I've noticed the ailerons kicking when making small deflections back to neutral when close to neutral on both -200/-300s i.e. when quickly removing smaller applied roll inputs. I don't recall similar inputs on other FBW a/c types causing a similar reaction so I just put it down to the behaviour of 777 PFCs.

[leonard17F]

Thanks a lot for your inputs, Everybody !