Piper Seneca I right hand engine harder to start?

[tommywcom]

Did you have both mags serviced on the right engine? Usually only one has the impulse coupler, that one could still be bad...

The one with the impulse was serviced.

[Strega]

Any idea what was done to it?

[tommywcom]

Any idea what was done to it?

When I bought the plane, it had been sitting for 3 years. There was no impulse from the mag when the prop rotated - so the mag on RH engine that is supposed to generate the impulse was sent out to get serviced.

[Strega]

Id take a look at the service that was done. might have just fixed the impulse coupler, and not touched any internals.

[tommywcom]

Id take a look at the service that was done. might have just fixed the impulse coupler, and not touched any internals.

I looked at the invoice. It said:

"Repaired; Completed 500hr Inspection and tested serviceable in accordance with CMM: L-1363F/REV F/05Jan2011:

[tommywcom]

Also, it seems to be a Slick 4330.

[Strega]

I would ask your mechanic to swap that mag, with the one in the left engine- see if the problem follows the "repaired" magneto. only takes about 15 mins to swap.. Mags that have weak magnets, are sometimes hard to diagnose when cold.

[Big Pistons Forever]

Saw a similar problem on a Piper twin. Mag was repaired but internal timing was mis-set during repair. After that was rectified the starting problems went away.

[tommywcom]

I would ask your mechanic to swap that mag, with the one in the left engine- see if the problem follows the "repaired" magneto. only takes about 15 mins to swap.. Mags that have weak magnets, are sometimes hard to diagnose when cold.

Thanks. Great idea.

[5x5]

Just a caution to confirm the 15 minutes with your AME prior to asking for the swap. Not saying it will take longer (and cost accordingly) but the Seneca 1 doesn't have the most user-friendly cowls as I recall and it may well take a bunch longer from start to finish unless he's already inside for some other work.

[GyvAir]

"15 minutes"

I was thinking the same thing, and we've had the same conversation on this forum before. Although I'm sure it's not a big job to swap mags, there are virtually no such maintenance tasks that can be accomplished in 15 minutes. The cowls on and off alone taking that much time for one. Depending on the shop set up, it could take 15 minutes to gather the required timing tools. Who knows how much time working it into a space on the hangar floor. Aquiring gaskets, lock washers if you need them. Making a log entry afterwards. If the mechanic isn't familiar and current on that particular engine, magneto, airframe set up, simply finding the timing procedure and marks will burn up some time.
We all do it to each other: telling an owner that their mechanic can look after some snag or perform some test in just a few minutes.. it just sucks being the mechanic on the other end of that well intended, but unrealistic estimate!
Thanks for the explanation of the hot engine/old, weak magnets scenario, Strega.

[tommywcom]

Actually I have a dumb question - can the RH engine impulse mag be switched to the LH engine given the props are counter-rotate? I recalled at the time my AME saying something about the mag on the RH has a different part number than the LH because of counter-rotate. Different timing and points before / after TDC ...

[GyvAir]

Not a dumb question at all! Probably one that more than one mechanic forgot to ask themselves before actually doing the swap and finding out they'd just made things worse..

LIO-360-C1E6 (20°,200HP) LH Magneto: 4330 RH Magneto: 4302
IO-360-C1E6 (20°,200HP) LH Magneto: 4372 RH Magneto: 4370; 4372

I once saw someone rob the LH starter off of a parked Navajo to service the RH engine of another Navajo that had a trip to do, post haste... didn't work out so well for him.

Never be afraid to verify what's going on with your airplane when you hand the keys over to your mechanic!

[tommywcom]

[quote="GyvAir"]Not a dumb question at all! Probably one that more than one mechanic forgot to ask themselves before actually doing the swap and finding out they'd just made things worse..

LIO-360-C1E6 (20°,200HP) LH Magneto: 4330 RH Magneto: 4302
IO-360-C1E6 (20°,200HP) LH Magneto: 4372 RH Magneto: 4370; 4372

So is the answer no then? It cannot be swapped since the part numbers for the mag across the LIO-360 and IO-360 are different?

[GyvAir]

Correct. The magnetos on your aircraft can't be swapped for troubleshooting.
4330 is RH rotation
4372 is LH rotation

[Strega]

Ok my bad.
I forgot the seneca 1 had cr engines..


Anyway, I would take the "repaired" mag off, and check to make sure the e-gap is set correctly, and it is assembled correct (the timing of the distributor gear)

Also, Make sure the mechanic that installs it in the plane is using the correct "pin hole" when installing it. ie you can insert the timing pin in the "LH" hole. of a RH mag, time everything, and the plane will run- just not very well.

[tommywcom]

This has been very informative. Thank you all for your response!

[GyvAir]

Best of luck with it. Hopefully the problem gets cornered without too much chasing. I'll try to refrain from anymore 1000 mile troubleshooting on this one. I'm pretty sure some of the other people here are more experienced and current on type than I am.
There is a nice little troubleshooting guide in the Slick L-1363F M&O manual (several pdf copies available with a google search). Worthwhile read, whether you're flying or fixing.

[tommywcom]

So finally just last week I had the answer. Apparently the issue was with the mag - and the same shop which looked at it said it was producing an impulse every 4 turns. And they fixed it - they might even have done it under warranty too. It was getting to the point where not even my AME could start the RE engine at all.

Now I could reliably start the RE engine every time. It's still slightly harder than the LH engine to start, but it's not a problem.

[Strega]

Glad you have it fixed!

I guess opens your eyes to the quality of work that comes out of some overhaul shops

[Strega]

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