The Magneto Ignition System

Engine Topics Accessories

The Magneto Ignition System
By John Schwaner, Sacramento Sky Ranch
98 pages         $10.95

The magneto and ignition system as used on Lycoming and Continental engines. A clear and concise description with lots of photos and drawings of how your mags work, what maintenance they require, and typical failure modes to watch for. This is the first book I've found that actually made me comfortable and confident working with my airplane's "mysterious" ignition system. I guarantee, that's saying a lot.

From the introduction:
     Magnetos are reliable and provide a redundant safety factor, but they have the potential of causing engine failure if they are not inspected and serviced. When the Magneto bearings fail on one magneto, the rotor seizes causing the gear teeth inside the engine to break. The broken gear uncouples both mags causing instant engine shutdown. worn inpulse coupling rivets can cause engine failure when the impulse coupling engages in flight. The adage "if it's not broke - don't fix it" translates to "operate it until it fails and hope it doesn't take the engine when it does".
     These are tough words to start a book. When we open up magnetos for overhaul we see that many are not receiving proper preventative maintenance. With an understanding of the magneto's mechanical and energy design you have the knowledge to make the correct maintenance decisions so that your magnetos operate safely and reliably.

Table of Contents

Introduction                                3
the magneto                                 6
the magneto coil                           7
the magneto rotor                          14
the magneto capacitor                     16
the ignition lead                         20
testing the ignition lead                  22
"E" gap                                    23
the "P" lead                               25
how much voltage is required               27
how much energy is required                29
how altitude affects magnetos              32
how temperature affects magnetos           36
the impulse coupling                       37
inspecting the Bendix impulse coupling    42
installation tip for Bendix impulse coupl. 44
the retard breaker magneto                45
retard breaker circuit design              48
the magneto check                         51
magneto induced engine roughness           52
magneto wave form interpretation          56
bumping magneto timing                     57
Bendix S-20/S-200 rotor bearings           59
Bendix S-20/S-200 bearing grease           61
moisture drains on Bendix s-1200 magnetos 63
Bendix breaker cam lubrication             64
Bendix distributor block lubrication       65
replacing distributor felt Bendix magnetos 66
coating the s-20/200 distributor block     66
magneto oil contamination                  67
checking the ignition filter              69
the D-2000/3000 dual magneto              71
timing the magneto to the engine           72
ignition system EMI                      74
electrical bonding                         83
storing magneto rotors                     85
Slick magneto supersedure listing          85
data plate information                     86
Bendix service bulletins                   87
Slick service bulletins                    91
which magneto is best                      92