Start Your Engines: Solid-State Magneto Start Booster

The techniques and opinions on how to start aircraft engines are as varied as the airplanes, engines, and operators that encompass this topic.

Terminal 1, VIN, and ground terminals are all connected in this same manner. Terminal 2 connects to the right magneto capacitor terminal stud and terminal 3 connects to the magneto retard breaker terminal. To install a SlickSTART as a replacement for the Bendix "Shower of Sparks" vibrator that does not include a relay, the instructions are the same, except terminal 2 is left unconnected.


Once SlickSTART is installed, there is little maintenance required. However, the L-1492 SlickSTART installation, operation, maintenance, and troubleshooting manual does provide some continuing maintenance information. At 500 hours, inspect all wires and terminals for corrosion, contamination, arcing, and proper alignment. Also check the security of the mounting. Cleaning may be done using a mild detergent and water solution and dried with a soft cloth. Operation of the SlickSTART can be confirmed by removing the top spark plugs from the engine, disconnecting the power lead to the starter, and then engaging the ignition switch in the start position. As an assistant rotates the engine crankshaft to the TDC position, the impulse coupling or retard breaker points should trigger. The boosted spark generated by the SlickSTART will be clearly obvious at the spark plugs. The sparks will be bright white and continuous if the crankshaft is dwelled at the point where the magneto fires.

SlickSTART is a completely sealed solid-state device that requires no internal maintenance. In fact, should the unit be opened, it is not considered airworthy, as it no longer conforms to FAA approval.

Wiring connections at SlickSTART for impulse coupled magneto installation.


No changes are necessary to the current Pilot Operating Handbook, as SlickSTART is only activated when the ignition switch is in the "start" position. To start the engine, follow the procedures detailed in the Pilot’s Operating Handbook for the particular aircraft and engine involved. Most operators report car-like starting as the engine fires up after as few as two turns of the crankshaft. SlickSTART, however, is not a cure-all for other engine ailments. It cannot overcome faulty priming, fuel delivery, ignition problems, or bad starting techniques. Prior to installing SlickSTART, ensure that systems related to engine starting are in good mechanical order. Operators should be advised that SlickSTART has a maximum duty time of one minute on and five minutes off.

This article has touched on some system operation and installation tips for the SlickSTART magneto starting booster. It is now being offered by several general aviation companies as a standard item including Schweizer, Grob, Diamond, and Superior. To see if the system is available for installation on your aircraft, you can contact Unison Industries to speak with a customer service professional. AMT

Harry Fenton, Unison’s manager of customer services, has worked for Unison for more than 17 years. A lifetime EAA member, Harry is an active pilot, A&P/IA, and owns several homebuilt and production aircraft. He writes the popular "Ask Harry" GA advice column published in Keep 'em Flying.

Additional ReSource

UNISON Industries

530 Blackhawk Park Avenue

Rockford, IL 61104

(815) 965-4700

(815) 965-2457 FAX

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