Be sure to look for the part number and name-plate on the magneto. This will tell you the type of magneto you have.
Bendix S1200 is the largest and heaviest but is less prone to cracking. This magneto has TMC casted into the housing.
Bendix S4LN-xxx, S4RN-xxx, S6LN-xxx, S6LN-xxx are the most common types of magnetos.
The Bendix magneto, also known as an ignition magneto, was developed by Andre Boudeville but perfected by Robert Bosch and Frederick Richard Simms. The magneto is a permanent electrical generator that produces high voltage for spark plugs. The magneto is used in aviation because it is more reliable than a battery coil system.
This specific Magneto’s responsibility is to ignite the fuel in the engine of the helicopter. It is an electrical generator that creates impulses of high voltage that are needed in order for the helicopter to become airborne.