Unison magneto troubleshooting

Unison Magneto Troubleshooting

By Harry Fenton

February 1999

With more than one quarter million products in the field, the Unison Industries Slick Aircraft Products Customer Service Department is contacted by scores of customers on a daily basis to provide answers to a wide variety of magneto, ignition harness, LASAR® and SlickSTART™ issues. While each situation is different and no two customers are quite alike, there are many frequently asked questions that are discussed on a repetitive basis. Interestingly, it is the most basic issues that consume the bulk of the Customer Service Department time in handling customer issues.

The following article provides some insight into the most common magneto and ignition harness questions received by the Unison-Slick Customer Service Department. Even though some of the issues presented here are fairly basic, the fact that so much of the Slick Customer Service Department's time is spent discussing these topics indicates that even basic issues are not as clear cut as they may seem.

What are all of these holes for?
The Slick distributor block is common to both conventional and LASAR™ magnetos, and is aligned, or "pinned", depending upon magneto rotation. The "L" and "R" hole correspond to rotation of the magneto, not the placement of the magneto on the engine (See Figure 1). Rotation can be determined one of two ways. First the dataplate has a box labeled "ROT" with either and "L" or an "R" embossed into the box (See Figure 2). Observe the direction that the rotor shaft needs to be turned to engage the impulse coupling: Left rotation magnetos engage the impulse coupling by turning the rotor shaft counterclockwise, right rotation magnetos engage the cimpulse coupling when the rotor shaft is turned clockwise (See Figure 3).