REFLECTOR: Overheated Brakes Causes Landing Gear to Bow

[Lou Stedman]

Something that you should be concerned about in this situation is epoxy 
wicking. When the gear leg is heated up by the rotor enough to deform, the 
epoxy is being changed back into a liquid. Gravity will then cause it to run 
down inside the leg. After repeated heating you can leave the hot spot in 
the leg void of epoxy and your leg will fracture at that point. That is what 
happened to me. I have picture for anyone who wishes to see the results. The 
bootie is the answer. It is all aluminum and replaces the portion of the leg 
which has been damaged.

Lou Stedman
Velocity N7044Q
Olean, NY
stedmanlou at adelphia.net
----- Original Message ----- 
From: "Dave Philipsen" <velocity at davebiz.com>
To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
Sent: Wednesday, August 27, 2008 12:25 AM
Subject: Re: REFLECTOR: Overheated Brakes Causes Landing Gear to Bow


> Kirk,
>
> It sounds like your warping may have been a little more pronounced than
> mine.  Do you have heat shields?  I recently noticed one of my gear legs
> was ever so slightly splayed outward at the bottom.  It may have been a
> degree or two off from perpendicular.  Here's the solution that worked
> for me.  Your mileage may vary:
>
> I completely removed and disassembled the wheel and brakes and axle.  I
> then mounted the axle on the gear leg in reverse (axle pointing inward
> toward the middle of the plane).  Then I rested the weight of the
> airplane via the end of that axle on a wooden block (the wooden block
> was only supporting the *end* of the axle).  The force acting upon the
> gear leg was exactly opposite as when the wheel is mounted normally.
> Then I used a 250-watt IR reflector heat lamp and heated the leg up at
> about the same place where the rotor would have heated it (on the
> outside edge of the gear leg).  The lamp was about 8-10 inches from the
> leg.  Then, I used a ruler to measure the distance from the floor to the
> bottom of my gear leg.  As the leg heated up and started to bend back,
> the bottom of the gear leg would get closer and closer to the floor.  I
> only let it go maybe 1/16 - 3/32 of an inch and then I took the heat
> lamp off.  This procedure allowed the gear leg to bend back maybe one
> degree or so.  After the leg cooled down I assembled the axle back on
> the correct side of the leg, put the wheel back on (without the brake
> caliper) and moved the airplane forward and back a few times and then I
> checked the camber of the wheel.
>
> To make a long story a bit shorter, I had to do it again and let the leg
> bend a little bit more.  Total time under the heat lamp was probably in
> the neighborhood of 40-45 minutes. Just for good measure I wrapped that
> area of the gear leg with some 2-inch-wide fiberglass BID tape and
> wetted it down with epoxy.  I've probably performed 15 takeoffs and
> landings since the gear leg "re-formation" and everything is just fine.
> I fashioned a heat shield out of aluminum sheet metal with some glued on
> backing made of exhaust pipe insulating cloth tape and installed it
> while I had the axle off.
>
> This procedure *may* work for you if the leg is not badly disfigured and
> if it has not been heated so badly as to cause the epoxy to actually run
> out of the leg.
>
>
>
> Kirk Aragon wrote:
>>
>> Hi all,
>>
>> Recently, I overheated my brakes and have noticed that my gear legs
>> have warped inward towards the rotors (in addition to small bubbling).
>> There is currently a very small gap between the rotor and the leg on
>> each side. I remember that someone else had this issue and
>> Reflectorites discussed the procedures to fix this issue. Can anyone
>> point me to that discussion as I can't seem to find it manually in the
>> archives?
>>
>> Thanks
>>
>> Kirk
>>
>> N360TV
>> SE RG
>> TO-360-E1A6D
>> ------------------------------------------------------------------------
>>
>>
>
> -- 
> Dave Philipsen
> Velocity STD-FG
> N83DP
>
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