Brake caliper aluminium plate shear

[Shaunus]

Morning Chaps

I had an incidence of sheering both my tyre and the aluminum plate holding the brake calipers on my J430 (bigger tyres)

I was at MAUW and the tyre blew just after I landed. The brake caliper had cut into the tyre causing it to shred. Initially I thought that since the clearance between the tyre and the 2 brake calipers is so little, that maybe my tyre was a little under-inflated, and hence caught the caliper, causing it to shred. As the tyre shredded, the soft aluminum plate holding the calipers also sheered somewhat off its bolts.

I put it down to having an older tyre that got quite close to the caliper as it aged, and then touched possibly due to being heavy and possibly under inflated a tad (though I do check regulatory).

Then when flying yesterday, I noticed that I inadvertently landed with a brake on. I always do a brake test on downward leg and thus guess that sometime during the flight, I must have hit some turbulence that caused the handbrake mechanism to flop over. Thus when checking the brakes, that handbrake engaged without me noticing. (I will double check that in the future!). Am thinking that that may have caused the aluminum plate to sheer due to the forces, which would have sent the calipers into the tyre?

Anyone have any similar experiences or thoughts?
Thanks
Shaun

[weeds]

Hi,
I did a conversion onto a Jabi recently and part of the down wind checks is to ensure that the brake ratchet( park brake) has not flipped over.

[J430]

I broke one of the aluminium plates recently on my 400 hour J430. I have no idea why it broke other than fatigue. It was still mostly in place, just rotated somewhat so the brakes were seemingly working, just not very well. When I pushed it back in the hanger there was a bit of a scrape, scrape, scrape noise which is how I realised it was destriyed. Naturally of course, I would have picked up the issue on my detailed pre-flight inspection before my next flight

It was a bit of a surprise as I have a 1,000 metre runway and really don't use the braked that much. These pads are 200 hours old and are as good as new... which probably explains how come they don't work that well.

[ZuluBen]

Hi.

How about posting a few pics, I am unsure to which component exactly you are referring to ..

[J430]

Your wish is my command...

As much as it may look corroded, it's just dirt. I'd been operating on a wet white gravel runway and the scum built up quite quickly. You can tell it's a fairly new tyre, so not long since this was all apart, cleaned and checked. As I don't take the spats off very often, I'm usually quite thorough when I do. The factory said that this isn't an uncommon occurrence. They should possibly be a little thicker for a longer life or perhaps steel, however it's the first one I've broken in 1,000 hours across two aircraft.

[Tricky Dicky]

Many moons ago I was the first owner of CMZ the first J430 Jabiru Len assembled in the country. The plane suffered a number of gear leg failure due to the fibreglass gear leg seeing the radiant heat from the brake disc. The had been plane originally, as was then standard ,were with with a single caliper which gave inadequate braking and had no heat shield. To cure both these problems I designed and fitted twin calipers and a central heat shield similar to that shown in the (J430) photos. This design cured both problems and was subsequently submitted to Len and adopted by Jabiru Australia. However my design was a solid plate and as can be seen from the photo, Jabiru then decided to produce it with the cut out in lower section of the central heat shield section as per J430's pic. (maybe to save weight) If one looks at the failure in that pic it appears that the thin section on the LHS of the cut out has buckled under compression and led to the failure. Trust that is of assiatance.

[ZuluBen]

WOW!

Never seen that before ....

Very interesting. Question: How powerfull are your brakes? For example, can you lock your tyres on a tar runway?

I see you are using the "wave" disc rotor. Are the brake pistons the new generation "free floaters" or the older "plate benders"?

[J430]

I assume they are free floaters based on your use of plate bending terminology.

How good are my brakes? Terrible! They *may* lock up on gravel but not bitumen or concrete.

They fade under moderate usage. I feel as though
the pads are too hard as they simply dont wear out. My estimated brake pad life on the dual callipers would be 400 hours but my old singles on previous would be half that.