B737 Nosewheel Vibration

[ROGER Co-J]

I'm fairly new on the 737-300, but in the past couple of months I've noticed that most tend to have a noisy and sometimes uncomfortable nosewheel vibration on the T/O and landing roll.

Put it on the tech log and the engineers say it's "flat spots" on the tyres,uneven inflation of the wheels, worn bushes.It just seems to ocur more often then on any other a/c I've flown.

Might anyone know if this is an inherent problemm on the 733? Does it occur in others? Have there been any write ups on it?

Any response appreciated.

[G.Khan]

I remember 'nose wheel shimmy' on the -200 series way back in the mid seventies and guess what, the engineers then were saying exactly the same as they are now so it is probably true!

[Gspot]

I fly for Southwest Airlines with 350ish 737's in the fleet -200, -300, -500 and -700.

Can't say I've noticed a nosewheel problem except on a couple of occassions. When it has been in the log mx have simply changed the wheel / tyre assy.


[ 11 November 2001: Message edited by: Les Couilles de Chien ]

[Track]

Our 737-300's tend to shimmy occasionally as well, got exactly the same reply from the tech dept. NG is far better.

A little bit of forward pressure on the controls usually takes care of this shimmy during rollout or t/o.
---------------------
Track

[cirrus01]

Lots of problems on the 737-300 Nose gear ....some point to a difference in specification of parts by Boeing .... Just had a -400 with severe reported shimmy ...which after changing numerous bits without improvement , so Engineers were put on board and aircraft Hi speed taxyed....turns out the problem was in the main gears, namely the drag struts were shot to pieces ( a overhaul company problem, buts that is another story )

[JetMender]

This is a known problem on 733 which is temporarily fixed by replacing nosewheels or lubricating nosegear linkage (as per above postings). If problem continues, then linkage re-bushed at next suitable opportunity. Defect more apparent if nosewheels are un-evenly worn (ie. 1 well worn & 1 new tire fitted) so replacing nosewheels as a matched pair helps reduce problem.

[topman]

B737's can suffer from NLG vibration but it is important to acknowledge the difference between vibration and shimmy. Vibration can be caused by uneven tyre wear or worn torque links for example. Shimmy is a different problem and the aircraft has shimmy dampers installed on both main gears. If one of these is defective then the problem can be the main gear and not the nose.

[ROGER Co-J]

Thanks a lot for your posts guys.Thought I was getting pranoid.

Did a quick turnaround the other day with a "707 era" skipper and he insisted on motoring the engine till the EGT was 120 degrees before " fuelling" insisting that the engine was still hot after the 20 min turnaround and he didn't want a hot start.

Does boeing give any guidelines ( certainly not in the manual!) on engine handling on quick turnarounds or did my skipper think he was stating the 707's Pratt & Whitney JT-Ds?

[rr892igw]

Roger,
Motoring is a norm for me operating 5
sectors a day with oatup to 34c.the egt before eng start is nomally 200c.My rule of thumb is to motor till egt 140c or below before fuelling then the peak will hardlly
touch 680c,thus it's a lot more comfortable
then egt reaching 710c-720c.typically fueling
is about 35-40secs after starter engagement.

(This is for -400 with 22k engines)
[img]null[/img]

[ROGER Co-J]

Thanks rr.It makes sense to do it ,but is there some sort of manufacturer guideline.Are there detrimental effects on the starter life ? Or is this countered by the saving on turbine blade wear due to high EGT.

[Bearcat]

You may find the nose wheek shimmeys on taxi at any thing over 15 kts. Our engineers tell me it is worn bushes on the linkages that need replacement at the next available opportunity and it is very common on the 737s. Any one have probs with the 737 pulling to the left or right on taxi?

[ 17 November 2001: Message edited by: Bearcat ]

[Hew Jampton]

When I started my flying career, on Cessna 150s/152s, a big problem was nosewheel shimmy. Now, having reached the dizzy heights of B737s, a big problem is - nosewheel shimmy! Strangely, the cause seems to be the same.

[DoctorA300]

Roger,
The B737 Classic have a Service bulletin, and I canīt remember the number, introducing a new Nose wheel steering bracket, to cure nose wheel shimmy at high ground speeds.
Brgds
Doc

[vmo]

Apparently, main cause of nose whl vibration on the 737 is holding on exactly to the centerline, hitting the centerline lights during t/o and landing.
Happy trails.

[ROGER Co-J]

Thanks guys.

Bearcat,

Haven't nany "pulling" tendancies, but will lookout .

TCS'
N2 peaked at about 27%.

Cheers all!