A321 - vibration on rotation
 

I recently travelled to Tenerife on an A321-211.

Both outbound and inbound the aircraft on rotation proceeded to vibrate severely prior to the main gear leaving the runway. I've never experienced this before on this type of a/c (I've flown on the actual plane twice before). Can anybody explain the likely cause of the vibration (it was shaking the whole plane including the overhead lockers).

MTIA.

The nose wheels being out of balance I would think. Certainly I can feel it quite often on the A320 when the nose wheel is at speed (not severe vibration though certainly!)

Regards, Tom.

Nose Wheel Shimmy!
Caused by:
Uneven tyre wear. Uneven tyre pressures. High groundspeed due to heavy weight take-off, incorrect pressure in the nose wheel oleo!
Feels and sounds awful, but is not uncommon!

Thanks Tom & Captain,

Perhaps severe would be overstating it, but it was enough to cause a stir and make folks look a tad worried.

Cheers.

A320 engine vibration levels
 

A bit off-topic...

Just curious, what are the acceptable engine vibration levels on the ground, prior to take-off, and in the air?

My guess is, it is something like 5.1 in the air and in the vicinity of 6 on ground.

Thanks

According to my QRH (CFM-56s).

There is an ECAM advisory when N1 vibration is equal or greater than 6 units, or N2 is equal to or greater than 4.3 units.

It states: the (advisory) is mainly a guide to induce the crew to monitor engine parameters more closely.

The procedure states if there is a rapid increase in vibration above the advisory, retard the affected engine's thrust lever.

On ground I would suspect icing, and a run up to 70% N1 should shed the ice. In flight if there is icing induced vibration, the engine can run up to shed ice, in idle descent for example.

Sorry I don't have FCOM 3 to hand to elaborate further.

I've noticed 737's always seem to have a little shake just as they get airborne...is it the same effect? (l/gear induced as opposed to engine vibration)

Well you would shake a little bit if your oleos suddenly violently extended to their stops, and your main wheels were rotating at a circumferal speed of about 160 kts and slightly out of balance before the brakes were applied!

Flew one two days ago that had this written in the tech log, I thought it was surely a mistake, had to be the nose gear, NOT. Most definitely a MLG problem. :eek: