Jump to content

Mag Stranded me again


nfonville

Recommended Posts

4 hours ago, nfonville said:

So I removed the p-leads from both mags and tested the wiring.    All appears to be correct and work as expected.  I guess in the end it will be 100 hour failure of the left mag.

Thanks for the input from everyone.

 

If your engine is starting normally, it’s likely that your left Mag is operational. When you hit the starter, the Right mag is grounded (no spark) and the impulse coupling fires the left mag at TDC to facilitate starting. SkyKrawler maybe on to something regarding the reversal of your P leads.  However, give that it starts easily, I think the left mag is functioning. I don’t think you should fly it at this time. The problem is still undiagnosed. It’s risky and illegal (and not bright) to fly with a known defect it’s even worse to fly with an unknown defect.

  • Like 1
Link to comment
Share on other sites

My understanding is the left mag is the one closest to the left side of the airplane (looking at the engine from the rear). The left mag should have a spacer to accommodate the extra length with the impulse coupling.

Total mag failure can be due to a primary or secondary coil failure,  coil/points wire coming loose, points coming loose, rotor gear failure, ....something that causes all four ignition leads to not operate.  You said  "the plane shook and begin to vibrate",   but if a single mag drops out all you typically will see is a small drop in RPM and EGT rise.  So that's strange.

If it were me I would have to take off the bad magneto to see what the failure is before I order another.  Could be a simple fix.  Of course you should coordinate with your A&P.  The data plate on the magneto has the part number.

https://www.youtube.com/watch?v=nzkykFRlBgw

https://www.youtube.com/watch?v=PdM2KVBf_ts

https://www.youtube.com/watch?v=XhHBoyGVvjQ

 

Link to comment
Share on other sites

51 minutes ago, Guitarmaster said:

Here's an ugly, shorted P-Lead



IMG_20190106_172235_1.thumb.jpg.d53466d339d1b2c9677707c1e7ac7aa8.jpg.  

Had a guy tell me long ago; mags don't fail, P-Leads do.  

Clearly this is a blanket statement, but I wonder how many mags take the blame for the P=Lead. 
 

That expression was coined with “hot mags” in mind. Most hot mag incidents are P lead problems. That said, mags fail. Fly long enough and it will happen to you. I’m curious how a set of P-leads get so beat up?

Link to comment
Share on other sites

That expression was coined with “hot mags” in mind. Most hot mag incidents are P lead problems. That said, mags fail. Fly long enough and it will happen to you. I’m curious how a set of P-leads get so beat up?
I think just years of heat, oil and vibration. There's a good chance they are the age of the airplane. In this case, 63 years.

Sent from my Pixel 2 XL using Tapatalk

  • Like 1
Link to comment
Share on other sites

If you can only remember three wires...

A ) The pair of P-Leads is good for two...

B ) The field wire would be the other...

The first can goof up the mags, the other keeps the alternator from working...

Not knowing about a break in the field wire becomes obvious after a while...

Not knowing about a break in a P-lead can be pretty hazardous...

One mag is worse then the other... it has the starting timing, and is really ready to fire...

PP thoughts only...

Best regards,

-a-

Link to comment
Share on other sites

8 minutes ago, Guitarmaster said:

I think just years of heat, oil and vibration. There's a good chance they are the age of the airplane. In this case, 63 years.

Sent from my Pixel 2 XL using Tapatalk
 

I know that mine are 51 years old.  I’m sure the landscape will change but it’s weird to think that in 20 years many of the brids at my drome will be over 70 years old. We have quite a few that are pushing 80 now.

Link to comment
Share on other sites

On 1/26/2019 at 8:23 AM, skykrawler said:

When the switch is in the L position the right mag is grounded and the engine is running on the left mag only.  Vise-versa for the R switch position.  From your last post it seems like your p-leads may be reversed.   From your last post is sounds like both mags are operating.   Disconnect p-leads and use an ohm meter to test between each p-lead and ground.   Both p-leads should show OPEN in the both position  and CONTINUITY for the opposite p-lead for the R and L switch position.

It's important to have the p-leads attached to the correct mag for diagnosing cylinder/ignition problems with the engine monitor.

P lead reversal is unusual if no change from factory wiring...there simply isn’t enough wire length to reach mags if rerouted left to right

Link to comment
Share on other sites

I wish emags STC were ready - this is the way to go.  Meanwhile my now 400 hr mags will need to be overhauled at some point this year, eh.  I emags were available I would use that opportunity to go with that right now.  I am just not that excited by electro air. 

Link to comment
Share on other sites

46 minutes ago, aviatoreb said:

I wish emags STC were ready - this is the way to go.  Meanwhile my now 400 hr mags will need to be overhauled at some point this year, eh.  I emags were available I would use that opportunity to go with that right now.  I am just not that excited by electro air. 

Magnetos are on condition items. However every 500 hours it is a very good idea to do a 500hr inspection. 

Link to comment
Share on other sites

On 1/28/2019 at 5:30 AM, thinwing said:

P lead reversal is unusual if no change from factory wiring...there simply isn’t enough wire length to reach mags if rerouted left to right

I don’t know about your machine,but the mags on the back of an IO360 are around 12” apart, maybe less. They could certainly be swapped. Hard mistake to make with an SOS ignition given the left mag has two P-leads but wire length is not a limiting factor

Edited by Shadrach
  • Like 1
Link to comment
Share on other sites

This mag has 113.2 hours and was new in Jan 2018. This kind of failure is really unacceptable. This will cost me $1500 before it's all done after paying the shop and return trip for the plane. $15 per hour times 2 for mag reserve seems kinda high....

Link to comment
Share on other sites

18 hours ago, thinwing said:

P lead reversal is unusual if no change from factory wiring...there simply isn’t enough wire length to reach mags if rerouted left to right

On the 172 that had the leads reversed it was at the switch not the mags. 

Link to comment
Share on other sites

19 hours ago, nfonville said:

This mag has 113.2 hours and was new in Jan 2018. This kind of failure is really unacceptable. This will cost me $1500 before it's all done after paying the shop and return trip for the plane. $15 per hour times 2 for mag reserve seems kinda high....

Get a refund or exchange for the slick mag, and swap them both for Bendix units, and sell the Slicks to an RV builder.

Link to comment
Share on other sites

22 hours ago, aviatoreb said:

I wish emags STC were ready - this is the way to go.  Meanwhile my now 400 hr mags will need to be overhauled at some point this year, eh.  I emags were available I would use that opportunity to go with that right now.  I am just not that excited by electro air. 

Whats the advantage of Emag over Electroair? Every person nearly all the people that installed Electroair seem to love it. I'm quite liking the idea of it myself.

Link to comment
Share on other sites

5 minutes ago, Niko182 said:

Whats the advantage of Emag over Electroair? Every person nearly all the people that installed Electroair seem to love it. I'm quite liking the idea of it myself.

electro air seems really nice - but it is more complicated to install and wire and depends on ships power so the failure mode after an alternator failure is annoying.  The e mag is a more elegant unit the fits onto the mag slot - similarly sized - less extra wiring and it has a built in mini alternator so it does not rely on ships power.  So over all cheaper to acquire, cheaper to install and a nicer concept I think.

Link to comment
Share on other sites

Just now, aviatoreb said:

electro air seems really nice - but it is more complicated to install and wire and depends on ships power so the failure mode after an alternator failure is annoying.  The e mag is a more elegant unit the fits onto the mag slot - similarly sized - less extra wiring and it has a built in mini alternator so it does not rely on ships power.  So over all cheaper to acquire, cheaper to install and a nicer concept I think.

EIS is still a ways out for me, but does the Emag offer the same performance gains the Electro air does. Most people who install it claim about a 4 to 8 knot increase on less fuel.

Link to comment
Share on other sites

2 minutes ago, Niko182 said:

EIS is still a ways out for me, but does the Emag offer the same performance gains the Electro air does. Most people who install it claim about a 4 to 8 knot increase on less fuel.

I don't know.  I have heard that the performance enhancements is by advancing timing which is relevant for a normally aspirated engine but not relevant for a turbo airplane.  So I have heard that performance enhancement is minor for my turbo machine.  I have heard a tad more fuel efficient.  Much better starting and more reliable and also more modern being the three reasons why I would spring for an e mag when it comes.

Link to comment
Share on other sites

Whats the advantage of Emag over Electroair? Every person nearly all the people that installed Electroair seem to love it. I'm quite liking the idea of it myself.

I don’t have any data but I would think mounting a electronic device to a engine with all that heat and vibration will cause more failures, where a device mounted to the firewall would be more reliable.


Tom
Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.