i was wondering if you could use two of the great planes gas engine ignition kill switch,part# LXJ776 . they sell for $7.99 ea, from tower hobbies. the wiring harness has a hand off/on switch and a micro switch,you could install the two micro switches,one on each side of the servo you would use for a engine shutoff . you would shap the servo round arm with flat sides so that when the servo is activated the arm would pivit,contact the two micro switch arms compressing them to activate the switch and ground out the mags,shutting the engine down,i hope this is understood.yours truly,arnie..