Welcome Guest. Sign in or Signup

2 Answers

magneto check

Asked by: 8795 views Student Pilot

you have to cancel your flight if you find a more than 175rpm drop in magneto check or there is an alternative way to resume your flight?.i want to know is there any way to fix this error without asking a mechanic? your magneto is broken if  you find a more than 175rpm drop in magneto check?

Ace Any FAA Written Test!
Actual FAA Questions / Free Lifetime Updates
The best explanations in the business
Fast, efficient study.
Pass Your Checkride With Confidence!
FAA Practical Test prep that reflects actual checkrides.
Any checkride: Airplane, Helicopter, Glider, etc.
Written and maintained by actual pilot examiners and master CFIs.
The World's Most Trusted eLogbook
Be Organized, Current, Professional, and Safe.
Highly customizable - for student pilots through pros.
Free Transition Service for users of other eLogs.
Our sincere thanks to pilots such as yourself who support AskACFI while helping themselves by using the awesome PC, Mac, iPhone/iPad, and Android aviation apps of our sponsors.

2 Answers



  1. Sam Dawson on Dec 09, 2013

    The more common cause of a magneto “failure” during run up is a spark plug problem, usually a fouled spark plug.
    First prevention. Lycoming has a procedure that they recommend for their IO-360 series engines but it can be used for any engine without harming it- you will actually help the engine. After start set your RPM to 1200. Then lean the mixture until the engine runs rough. Enrichen just enough to stop the roughness then set 1000 RPM.

    To “cure” the problem do a high power run up. Initially I will try about 2100-2200 RPM. lean for maximum EGT, then let it set for about a minute at this setting to “burn off the plugs”. If this does not work try a full power run up and lean the mixture again. If this does not work time to get a mechanic.

    If you have an engine monitor page or an engine monitor use it during the mag check as it will give more information than just an RPM drop. If only one cylinder is cold during the mag check then it is probably a fouled mag or bad spark plug. If all the cylinders are the same when you get a large RPM drop then it is probably a mag issue.

    +1 Votes Thumb up 1 Votes Thumb down 0 Votes



  2. Sam Dawson on Dec 09, 2013

    Here is the Lycoming service instruction I referenced:
    http://www.lycoming.com/Portals/0/techpublications/serviceinstructions/SI%201497A%20(04-12-2011)/Engine%20Procedures%20for%20Flight%20Training%20Operations.pdf

    +1 Votes Thumb up 1 Votes Thumb down 0 Votes


The following terms have been auto-detected the question above and any answers or discussion provided. Click on a term to see its definition from the Dauntless Aviation JargonBuster Glossary.

Answer Question

Our sincere thanks to all who contribute constructively to this forum in answering flight training questions. If you are a flight instructor or represent a flight school / FBO offering flight instruction, you are welcome to include links to your site and related contact information as it pertains to offering local flight instruction in a specific geographic area. Additionally, direct links to FAA and related official government sources of information are welcome. However we thank you for your understanding that links to other sites or text that may be construed as explicit or implicit advertising of other business, sites, or goods/services are not permitted even if such links nominally are relevant to the question asked.