Using brakes to stop tire rotation

[Guest]

It was common practice on Lear35 unless operating from contaminated runways. It was almost second nature, “Positive Rate”- tap the brakes, “gear up”. Almost impossible to shear a valve with tubeless tires and 210psi.... really hard to break the bead seat when changing tires.

[Liquid_Charlie]

It wasn't that common - I didn't do it --

[Slick Goodlin]

The rice rockets I flew had balance weights on all wheels

And probably the most normal thing about those aircraft, which
I always suspected were designed by a team of engineers that had never seen
an aircraft before.

The team had plenty of experience, it’s just that their most recent prior projects were designed to be flown full bore into the side of a US Navy ship.

[Colonel]

They got pretty good at that, if memory serves.

[FourBars]

I seem to recall that some airliners that I flew (Boeing’s?) automatically applied the parking brake when the gear was selected up.
The school that I instruct at has a Duchess and a Seneca, the one POH recommends tapping the brakes before selecting gear up, the other makes no mention either way.
I initially thought that there was two reasons for stopping wheel rotation before retraction. The one was for reducing the chances of debris, contamination or freezing of the many components exposed in some wheel wells, including aileron cables going through sheaves. This would also reduce the chances of damage should a tyre burst or throw a re-treaded cap as it adjusts to not having to support any weight at its highest rotational speed.
And the other reason was that the spinning wheel and tyre represent-after the turbine engine or propellers- the largest gyroscopes on the airframe and asking this considerable force to turn its axis of rotation during retraction must exert quite the force on the scissors. However, upon further reflection, I now realize this must be much less than the forces generated during a landing with drift...

[Colonel]

You can either use up a tiny bit of brake pad to stop the tires, or a tiny bit
of tire rubber with the snubbers in the gear well. Not sure either matters.

They all get consumed and replaced over time.

[Nark]

I was told earlier on gas is cheap, brake pads are expensive.
I have done thousands of landings in my 180 and have yet to wear through them.

Same goes for tire tread for that matter. I have 8.50’s, put them on the same day I brought it home.

[Colonel]

Whoever told you brake pads were expensive were full of #fakenews

https://www.aircraftspruce.com/catalog/ ... gIIBfD_BwE

You can get a pair of pads for under $15

Just be sure to get rid of your chicken strips, ok?



You'll have to excuse me now, I'm going out to the garage to Armor-All my motorcycle tire sidewalls.

Remember, Black Dogs Look Better In The Shade!

[Nark]

I have 2 or 3 sets of linings in the hangar somewhere. I was excited to buy the rivet pop tool thingy. Haven’t used it yet though...

[Eric Janson]

Some interesting discussion.

Interesting that some POH have this as a procedure.

Probably a difference between tubeless tires and tires with an inner tube - I'm not an expert.

The fact that the tire is in contact with the runway probably makes a difference.

Some more details in this paper:-

https://commons.erau.edu/cgi/viewconten ... text=ijaaa

A tire exploding in the wheel well is not something you want - a lot of steel belts are incorporated into large aircraft tires. This becomes shrapnel and there are a lot of critical components very close to the tire. Earlier models of the 737-300 had zero protection in the wheel well - later models had a cage to protect components.

As for balancing - I can think of several reasons why this isn't done.

- You don't want the weights coming off at high rotational speeds - more shrapnel that can do a lot of damage. If you see footage of tires coming off they always go ahead of the aircraft.

- Every landing strips a patch of rubber off the wheels altering the balance of the tire. Becomes impossible to balance.

We can have nose wheel shimmy on the A340 - usually between 80-100 knots. Fixes include equalising tire pressure between the two tires and replacing one tire if it is more worn than the other one. Never noticed much in the way of shimmy on the main gear.

Brake units on the A340 cost $250,000 each and there are 8 of them.