Solid-State Magneto Start Booster
By Harry Fenton
The techniques and opinions on how to start aircraft engines are as varied as the airplanes, engines, and operators that encompass this topic. Starting problems can be caused by poor operator technique, cold weather, hot restarts, poor priming, or problems inherent with some engine designs (in that some are just harder to start than others). Whatever the reason, starting problems are time-consuming, frustrating, and costly.
Unison Industries, an ignition system manufacturer, has developed a device to specifically address the dilemma of hard starting aircraft engines. SlickSTART™ is a magneto starting booster which uses solid-state electronics with capacitive discharge technology to improve the performance of engines with poor starting characteristics.
SlickSTART improves aircraft engine starting by delivering 340 percent more spark energy to an aircraft’s spark plugs than conventional impulse coupled or retard breaker magneto systems. By increasing spark energy and the number of spark events each second, SlickSTART boosts the magneto’s electrical output to overcome hard starting issues caused by fouled spark plugs, poor priming, hot engine restarts, and extreme cold weather
conditions. Other direct benefits for the aircraft operator include reduced electrical stress on starter motors and batteries and improved dispatch capability of the aircraft under conditions likely to result in hard starting.
SlickSTART is STC-approved to be installed on airframes and engines equipped with most models of Slick and TCM/Bendix magnetos. SlickSTART P/N SS1001 is used with the Slick 4200/6200 and the latest model Slick 4300/6300 series magnetos, but is not approved for use with obsolete 4000/4100 or 400/600 series magnetos. SlickSTART P/N SS1002 is approved for all TCM/Bendix 20/200 and 1200 series magnetos, but is not approved for the Bendix D2000/D3000 dual magnetos series. For most aircraft equipped with an existing starting vibrator, the SlickSTART can be bolted right in place of existing equipment. For new installations, the SlickSTART can easily be mounted to the aircraft firewall. Both SlickSTART part numbers can be used with either 12- or 24-volt aircraft electrical systems.
As SlickSTART is designed to boost only one impulse coupled or retard breaker magneto, a second SlickSTART can be installed on engines configured with two impulse coupled or retard breaker magnetos. Some helicopter applications, notably the Schweizer 269 series, use two vibrators so two SlickSTARTs would be required to accomplish a complete retrofit.
How it works
SlickSTART is energized when the ignition switch is in the "start" position, and provides high electrical output only when needed – during engine start. SlickSTART stores electrical energy in a series of capacitors and increases the voltage prior to delivery to the magneto circuit. When triggered, the high energy capacitive voltage of the SlickSTART is discharged into the coil via the magneto primary circuit. When the contact points open, the electrical charge in the secondary field collapses and discharges through the distributor block circuit. The resulting capacitive/inductive spark arcs across the distributor electrode and distributor tower air gap with peak voltages as high as 23kV (depending upon the spark demand requirements at the spark plug).
At first glance, the SlickSTART may appear to be functionally similar to the TCM/Bendix vibrator, but aside from a couple of common wiring connections, the SlickSTART has little in common with electro-mechanical starting vibrators. The solid-state electronic components of SlickSTART are hermetically sealed, do not wear, and do not require cleaning or adjustment.