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AX-3 Brakes

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  • AX-3 Brakes

    I need some help with my fathers AX-3 G-MZDS. Ever since we have had to aircraft (since 2009) their has always been a problem with the brakes sticking on. I know that the AX-3 doesnt really need them as everything is 50mph and thus you stop fairly well just by the planes weight. We have changed all the bungys as we thought this was the cause but it hasnt seemed to resolve anything at all. I was wondering if anyone else has had this problem or can help as it will be getting permetted after 2 years out of action due to skin stiching deteriorating.



  • #2
    AX-3 Brakes

    Hi Ed, see my attached pic. When I did MYRO's brakes I found that on one side, the spindle that passes through the backplate and connects the operating arm to the cams that work the brake shoes was almost seized (see no 1 in the attachment). I had to carefully work it for a long time with WD40 to free it and get it to move smoothly but if you have the same problem (and I bet you do) be very careful NOT to work it by yanking up and down on the operating arm. The arm is quite thin and is only connected to the spindle by having a square cut-out sitting on a short square section on the spindle and if it is tight you will soon knacker the arm. Take the arm off and use some kind of tool to grip or hold the spindle and work it without marking it up.

    Then assuming that your brake cables are running free, that the springs 2 and 3 are in good condition and are good and tight and also that spring 4 on the cable is in good nick and not just a rusty chunk of wire, I can't see how your brakes can stick on. I've made sure than when I'd finished I left a bit of high temp grease around the spindle 1 and also on the brake shoe pivot point at 5 just so I knew everything would stay nice and free and I've had no problems since. And don't forget that under the panel you have a thin bungee that's pulling the heel brake upwards ie towards the 'on' position, and even with that I find that my brakes operate absolutely fine.

    You must have some sticking somewhere and if the aircraft has been operated without the brakes being inspected and serviced now and again, I'd say it's almost bound to be that spindle that I've marked as 1 in the pic.

    Hope that helps


    PS I'm assuming that the little clamps holding down and attaching the heel brake lever to the pedal base plate that I've marked with arrows in the second pic haven't been over-tightened? Also, they need a bit of lubricant too I think even though they're plastic, just as do the rudder pedal clamps IMO. I use moly grease so you will still have lubicant there even if/when the grease disappears.

    Attached files


    • #3
      AX-3 Brakes

      I suspect that Roger's first shot is the right one, although our AX3 has not had the problem I have encountered it on the very similar Thruster drum brakes. When you remove the spindle you'll probably find it encrusted with aged, hardened lubricant of some sort. When this is cleaned off I use Copperslip or similar and it seems to work well. When we had a brake problem when we first bought the AX it was the cables, long neglected and with the outers damaged which had allowed water ingress and the cable was solid, but that was fairly obvious when you looked at it.

      While you may never need brakes on a grass strip wait till you visit an airfield with tarmac taxiways, it is amazing how quickly you build up speed on a slight downhill :freaked: .