Pmag life

[RV6-KPTW]

I pulled my pmag and note some play. Reading the service material led me to call Brad at EMAGAIR to see if he could quantitate “excessive” play. Makes it sound like some play is acceptable.

Now that our fleet is growing and making maintenance observations, I wonder what your experience is with the pmag? Brad notes that there are better and worse engine, prop, and ignition combos but no one does the upfront testing in experimental. We’ll have discover and report them.

For my case, I received a Thunderbolt IO390 with one Slick mag on left and one pmag ( EMAG P114L4 ), I hung the standard 72” Vans Hartzell prop (HC-C2YR-1BFP/F7497-2) and found play in the pmag at 168 hours. I am sending it off for an eval. Is the play excessive? I will report back.

Brad indicates that there are two failure modes as play increases. The generator will stop generating, and / or the unit will stop sensing where to fire. Brad said that there was nothing catastrophic that might occur. I probably should have probed further on this.

Once I receive the pmag back, I will check for play to understand the “new” condition. I am thinking I will build a fixture and use a dial indicator to check and track change over time until failure.

Brilliant or stupid?

What are your combinations and experience?

Thanks

[rv8ch]

Originally Posted by RV6-KPTW

... I am thinking I will build a fixture and use a dial indicator to check and track change over time until failure.

Brilliant or stupid?

What are your combinations and experience?

Thanks

Sounds like a great idea. I think capturing this information could be helpful. I think the kind of place to do this would be by someone like Savvy, where they also have other info about engine data.

Another option is a google sheet like this one:

https://docs.google.com/spreadsheets...it?usp=sharing

Feel free to add your info, additional columns, whatever.

[MJarreau]

Originally Posted by RV6-KPTW

Brad said that there was nothing catastrophic that might occur.

A matter of perspective, I would say....

Originally Posted by RV6-KPTW

I am thinking I will build a fixture and use a dial indicator to check and track change over time until failure.

How would one go about doing such a thing? (Please keep in mind we have close to NO mechanical skills.)

Originally Posted by RV6-KPTW

Brilliant or stupid?

HA! Seems to me the lines are too close to differentiate!

Mike

[jcarne]

Originally Posted by rv8ch

Sounds like a great idea. I think capturing this information could be helpful. I think the kind of place to do this would be by someone like Savvy, where they also have other info about engine data.

Another option is a google sheet like this one:

https://docs.google.com/spreadsheets...it?usp=sharing

Feel free to add your info, additional columns, whatever.

Should your column name change from flight hours to tach hours? That way you get consistent numbers.

[rv8ch]

Originally Posted by jcarne

Should your column name change from flight hours to tach hours? That way you get consistent numbers.

I track flight hours, but feel free to change it!

[jcarne]

Originally Posted by rv8ch

I track flight hours, but feel free to change it!

No worries, flight hours works too, just thought some people might throw in tach hours which would be different.

[bruceh]

I just pulled my P-mags at 981 hours and sent them in for new bearings. Both of them had play in the bearings. Right side was much more than the left side.

Short video of it here:
https://www.overthehills.com/RV-9A-P...se-2/i-PpKMJkB

I wasn't having any ignition issues, just checking them every 100 hours at my annual inspection time.

[jcarne]

Originally Posted by bruceh

I just pulled my P-mags at 981 hours and sent them in for new bearings. Both of them had play in the bearings. Right side was much more than the left side.

Short video of it here:
https://www.overthehills.com/RV-9A-P...se-2/i-PpKMJkB

I wasn't having any ignition issues, just checking them every 100 hours at my annual inspection time.

Thanks for posting Bruce, I always wondered what the play they are talking about in the manual would look like.

[erich weaver]

I’m having a hard time believing that there is some noticeable amount of play in the bearing that would ever be acceptable for continued use. If it can be rattled back and forth it’s time to send it in for repair.

[RViator60]

Originally Posted by bruceh

I just pulled my P-mags at 981 hours and sent them in for new bearings. Both of them had play in the bearings. Right side was much more than the left side.

Short video of it here:
https://www.overthehills.com/RV-9A-P...se-2/i-PpKMJkB

I wasn't having any ignition issues, just checking them every 100 hours at my annual inspection time.

Hi Bruce, thanks for posting. I have dual pMags and 100 hrs on the engine so far, and will definitely check for play. I'd be interested in talking with you about what you include in your 100 hr condition inspection. My email is cogolfman@yahoo.com.