There are a
number of ways to build the engine starter switches with
automatic jump back. Martin van Liempt is a colleague
cockpit builder who lives not far from me which makes contact
very convenient. He probably has built the nicest 737NG
cockpit in the Netherlands, it's quite amazing.
devised a simple mechanism that slips over the switch axis, so
there is no need to take the switch apart.
can be obtained from Conrad, part number ITS-LZ 1949.
If you turn
the switch to the left (GND) it moves the plunger into the
solenoid. A small spring moves the switch back in the OFF
Position. As soon as the switch contact is closed, the
software energizes the solenoid via a Phidgets Relay board and
the solenoid stays energized until the starter valve closes.
If you move the switch to the CONT or FLT positions, the lever
that is fixed to the switch axis will move freely through the
plate that is connected to the solenoid.
of this is that when there is no power or sufficient bleed air, the
software will not energize the solenoid and the switch will jump
back to the OFF position.
program provides two digital outputs for the solenoids.
It checks the value of FSUIPC offsets "fstarter1" and
"fstarter2" to be 1 and then makes the output high.
|Digital Output 0
||Engine Start 1
|Digital Output 1
||Engine Start 2