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MAIN GEAR LEG OVERHEATINGFrom CP57, Page 10 (Octrober, 1988)
Suddenly, we are receiving
a number of reports of softening main gear problems. This subject has been covered before,
but there is now a new factor so it bears mentioning again.
The new factor is, of course, the very popular "big"
brakes, particularly for the Long-EZ. We believe the big brakes are aggravating this
problem and we feel that it may be appropriate to install an aluminum heat shield between
the brake disc and the main gear strut. We have done this quite easily by cutting a
piece of 1/8 " thick 2024-T3 aluminum that fits between the axle flange and the
strut, and is clamped in place when the four AN-4 bolts holding the axles on are
tightened. The 1/8" thick plate will probably require the use of one size longer AN-4
bolts. This heat shield should be tall enough to protect the strut to about one inch above
the brake disc, and should be wide enough to prevent the heat radiating out of the disc to
"see" any of the main gear strut. (see Doug Shane's article: EZ LIFE.)
Several Long-EZ's are flying now with these heat shields with no
further problems reported. Don't let it happen to you. Never do taxi tests, low speed or
high speed, with wheel pants installed. Be aware that your brake discs can, and will, get
red hot. This heat can radiate directly into the "S" glass and epoxy strut. Once
the epoxy in the strut reaches its heat distortion point, the strut will fold up, an
extremely frustrating experience at best, requiring extensive repair or replacement of the
strut. If this happens away from home, it can be even more frustrating. Take care of your
main gear strut and it will take care of you with years of trouble-free service.
1) Wrap the strut with fiberfrax covered with Reynolds wrap or
aluminum tape. Use RTV silicone to glue the fiberfrax to the strut.
2) Install the 1/8" aluminum plate heat shields.
3) Cut vent holes in the TOP of your wheel pants to vent
the hot air inside, after a panic stop.
4) Plan your taxiing and landings so as to use minimum braking -
better to roll to the end using little or no braking, than to brake violently in order to
make the first turn off.