Posted for Theo Mulder <mulder@tlm-designs.com>:

The speed brake design as implemented by Maddox is a not airworthy by any
standard.
When the brakes were first installed in 1999 the complexity of the
electronics
was questioned. As a electronics engineer I could see the design was done
by someone with little background in this type of work.
The brakes operated good on the ground but would either not extend or retract
or only one would work in flight. The controller was returned once to the
engineer
Maddox used for the electronics, but when that corrected nothing I designed
my own
controller.
The attached schematic is the the new controller retrofitted in the existing
enclosure.
The pictures show the replacement controller on the left and the Maddox
controller
on the right.
The new setup uses the LNC4 nose gear micro switch to sense the brake
positions and will NOT retract if extended and the power is removed.
This was decided after flight tests involving go-a-rounds with the brakes
extended.
The brakes were found to retract with a estimated 1/2 inch of ice covering
them by simply
braking the ice as it retracts. These brakes will easily remove fingers if
operated on
the ground and fingers are in the way.
In summary the mechanical part of the brakes are good but the electronics
were a bad
design. My brakes have now seen 550 hours service with no problems and are
used
on virtually every flight.