Questions Asked By The Pilots or Mechanics About Textron Lycoming Geared And Mechanically Supercharged Engines

QUESTION - I hear the term "Shower of Sparks" relative to ignition systems. What does this term mean to pilots?

ANSWER - It means that while the engine is cranking during a start, that a prolonged series of sparks is jumping the spark plug gap as compared to one single spark. This results in improved cold weather starting.

QUESTION - During starts with the shower of sparks ignition system, I get some pretty severe kickbacks. Why?

ANSWER - The common cause here is the retard breaker doesn't close, resulting in a start attempt on the advance points. A simple check is to run the engine at about 700 RPM and for a fraction of a second hold the starter switch to the start position. The tachometer will indicate an immediate drop in RPM if the retard points are operating. There will be no drop in RPM with a malfunctioning retard breaker.

CAUTION - This check not recommended on our direct drive engines using automotive type starters.

QUESTION - At what RPM should I check my mags?

ANSWER - Where the airplane manual says. For example, checking at a lower than indicated RPM may give a higher than normal mag drop.

QUESTION - Is the actual mag drop in RPM very important?

ANSWER - No. We are more concerned that the mag drop is less than 50 RPM between the two mags and smooth, rather than whether it's 50-75 or 150. Again, it should be within the limits as indicated in the manual.

QUESTION - I noticed some of your engines show practically no mag drop. Is this normal?

ANSWER - Yes, but give it a little more time and I think you'll note some mag drop. However, if in doubt about any mag drop, be suspicious of a hot mag. Reduce engine RPM to idle and turn switch to off and see if engine dies out. If it keeps running, beware of hot mag. It's sad but true that we will still have people getting hurt due to hot mags.

QUESTION - Can I save the engine any by using less than take-off power?

ANSWER - Indeed not. In fact, harm to the engine can be caused by using less than take-off power.