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convair880mfan
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Joined: Fri Jun 25, 2021 12:33 am

If snubbers failed to stop wheel rotation during retraction, would this adversely affect the airplane?

Fri Oct 01, 2021 4:34 am

Or would they just continue spinning until they decelerated on their own in their wheel wells? Would the spinning wheels engendered by failed snubbers create a gyroscopic force on the aircraft. I've never read of snubbers failing. Maybe they are too simple to fail. I collect aircraft manual and have never seen a chapter on this type of failure condition.
 
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fr8mech
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Re: If snubbers failed to stop wheel rotation during retraction, would this adversely affect the airplane?

Fri Oct 01, 2021 4:58 am

The reason you want to stop the nose wheels...and the main wheels, for that matter...from spinning in the wheel wells is to prevent damage should a tire fail.

That having been said, we do replace snubbers on occasion. It's usually when the flight crew writes up that the nose wheels continued to spin after gear retraction.

And yes, they'll just keep spinning until they stop.
 
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Starlionblue
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Re: If snubbers failed to stop wheel rotation during retraction, would this adversely affect the airplane?

Fri Oct 01, 2021 5:28 am

convair880mfan wrote:
Or would they just continue spinning until they decelerated on their own in their wheel wells? Would the spinning wheels engendered by failed snubbers create a gyroscopic force on the aircraft. I've never read of snubbers failing. Maybe they are too simple to fail. I collect aircraft manual and have never seen a chapter on this type of failure condition.


The wheel(s) stop spinning after a minute or two.

Information about the A330, but should apply pretty generally.

Gyro forces aren't a problem for the nose wheels, as the nose gear retracts without putting a sidewards force on the wheels. On the mains, there are no snubbers. The brakes are applied automatically prior to retraction.

If we dispatch with a brake inoperative, the procedure is to delay gear retraction for two minutes so the affected wheel is allowed to spin down. The loads on the landing gear due to gyroscopic forces if a wheel is spinning during retraction are unideal. And there would be vibration once the wheel is in the well and spinning.

If there's an engine failure, we retract anyway and accept the vibrations.
 
Wacker1000
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Re: If snubbers failed to stop wheel rotation during retraction, would this adversely affect the airplane?

Fri Oct 01, 2021 12:30 pm

Snubbers are optional equipment on some fleets. The downside to not having them is the potential for additional noise and vibration until the tires stop spinning.
 
bradyj23
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Joined: Thu Apr 19, 2007 9:24 am

Re: If snubbers failed to stop wheel rotation during retraction, would this adversely affect the airplane?

Fri Oct 01, 2021 1:14 pm

CRJ-200 doesn’t have snubbers. Those wheels would spin and spin.
 
vikkyvik
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Re: If snubbers failed to stop wheel rotation during retraction, would this adversely affect the airplane?

Fri Oct 01, 2021 1:38 pm

fr8mech wrote:
It's usually when the flight crew writes up that the nose wheels continued to spin after gear retraction.


Is the cockpit crew able to feel it, or is there a warning of some sort?
 
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fr8mech
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Re: If snubbers failed to stop wheel rotation during retraction, would this adversely affect the airplane?

Fri Oct 01, 2021 5:37 pm

vikkyvik wrote:
Is the cockpit crew able to feel it, or is there a warning of some sort?


There is no indication on the flight deck.
 
LimaFoxTango
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Joined: Wed Jun 16, 2004 11:33 pm

Re: If snubbers failed to stop wheel rotation during retraction, would this adversely affect the airplane?

Sun Oct 03, 2021 5:15 pm

vikkyvik wrote:
fr8mech wrote:
It's usually when the flight crew writes up that the nose wheels continued to spin after gear retraction.


Is the cockpit crew able to feel it, or is there a warning of some sort?


Depending on the aircraft type, it can be heard quite clearly in the cockpit and sometimes yes, you do feel a bit of vibration.
 
gregorygoodwin
Posts: 94
Joined: Wed Jun 11, 2014 10:01 pm

Re: If snubbers failed to stop wheel rotation during retraction, would this adversely affect the airplane?

Mon Oct 04, 2021 2:55 pm

We frequently have to replace the pads on our B767s when they come in for B-checks (actually its called an L-check now). The pads are mounted on two spring arms and are of some type of abrasive composite material. The attaching bolts are counter-bored down into the material but as the wheels abrade the pads away they can begin to erode the bolts away also, have seen this on several occasions. I learned quickly, that when you drill, counter-bore, and mount the new pads you want to wear gloves and a protective suit. This abrasive will get into your skin and make you miserable for a few days until it goes away.

Gregory

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