Dual Mag Timing Issue?

[201Steve]

200 on a Kelly, no issues

[jetdriven]

they are thrown together with old parts by uncertifed individuals working under a repair station license. I sent a 1200 mag to Montana for a 500hr, and they called me.  It had a distributor block from 1976 in it. That was supposed to be replaced in 1980.  But Kelly has their own manuals, which say you dont have to throw anything away, even if superceeded.

Yes plenty of people here are doing fine so far. But thats not an indicator of quality control.

[A64Pilot]

On 8/13/2023 at 8:00 AM, jetdriven said:

they are thrown together with old parts by uncertifed individuals working under a repair station license. 

Not to belabor it, but that’s sort of the point of being a repair station, not having to have people that can work under their own certificate.

Standing up a Repair Station is a major pain, you would be foolish to have one and staff it with A&P’s.

I stood one up and staffed it with people from the manufacturing side, as they didn’t have their A&P’s they weren’t qualified to fix the aircraft they manufactured, so we had to have a Repair Station.

Thats how aircraft are built too, by certainly uncertified individuals, and sometimes unqualified ones. I was hiring “Sandwich Artists” to work on the floor for awhile, most didn’t last long unfortunately.

A sandwich artist is what you’re called when you work at Subway.

Sometimes or actually very often for components like a Mag it can be better to go to a one man or small shop with a good reputation, but not a Certified Repair Station. That way maybe a Sandwich Artist won’t be who overhauls your Mag or Starter / Alternator etc.

[KSMooniac]

3 hours ago, A64Pilot said:

 

Thats how aircraft are built too, by certainly uncertified individuals, and sometimes unqualified ones. I was hiring “Sandwich Artists” to work on the floor for awhile, most didn’t last long unfortunately.

 

Unfortunately correct.  Modern aircraft production plants share more in common with a sausage factory than most would like to know.

Avoiding any Kelly products is good advice IMO.  They've not shown a great track record for quality, and for something as singularly important as a dual mag I think choosing a smaller expert shop is a better choice unless you're stranded somewhere AOG and need one off the shelf quickly.  If you have a dual mag and a long ownership horizon, it would be wise to acquire a spare, get it overhauled/IRAN'd by a competent shop, and have it ready to go.  That would also protect you in the future from supply chain issues, somewhat.

[Adverseyaw0317]

.... Still waiting for that list of shops that everyone endorses that isn't Kelly

[kortopates]

.... Still waiting for that list of shops that everyone endorses that isn't Kelly

See the thread “MAG 500 hrs shops”.
I prefer Aero Accessories in Van Nuys.


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[toto]

7 minutes ago, Adverseyaw0317 said:

.... Still waiting for that list of shops that everyone endorses that isn't Kelly

Next time I do this, I think I’m going to send my mag to Don Downs. 

 

[Scott Ashton]

More trouble today - four hours after replacing the mag with another exchange unit the left mag points were failing again.   Pre takeoff mag check was perfect, and flight test yesterday was perfect.    By the time I got to altitude and set up cruise flight, I couldn’t get it run LOP and then tried the In flight mag check and the left side was super rough with a big RPM drop.  Got back to base and did another mag check on the ground and it was super rough on the left mag and the tach was bouncing around - same symptoms as before.   Third failure of points in 12 hours since replacing the original mag with 750 hours on it that worked fine.    So the saga continues.   

[EricJ]

Might be worth taking a close look at the left side P-lead, all the way through the ignition switch.   Something to try might be to disconnect the left side at the mag and see if it makes a difference.

Sounds like there may be more than coincidence happening. 

[LANCECASPER]

53 minutes ago, Scott Ashton said:

More trouble today - four hours after replacing the mag with another exchange unit the left mag points were failing again.   Pre takeoff mag check was perfect, and flight test yesterday was perfect.    By the time I got to altitude and set up cruise flight, I couldn’t get it run LOP and then tried the In flight mag check and the left side was super rough with a big RPM drop.  Got back to base and did another mag check on the ground and it was super rough on the left mag and the tach was bouncing around - same symptoms as before.   Third failure of points in 12 hours since replacing the original mag with 750 hours on it that worked fine.    So the saga continues.   

This sounds like more than just the mags. Maybe ignition harness? Check the resistance on all of the plugs?

[KSMooniac]

I agree with Lance and would check the p leads, plug resistance, and harness in that order.

There is a decent chance you got another piece of crap from Kelly, though, in which case you should ask for a refund and send it to a good shop to get fixed properly. Check the rest of the system first, though, before going to battle with Kelly.

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[N201MKTurbo]

I’ve never seen points make it run rough. They seem to make it completely quit. Unless your cam was so unequal that two cylinders quit and two were still working. Did you notice which cylinder EGTs went up or down when it was running rough? 
 

Have you replaced your condensers? When you sent the mags back, did you send the condensers too? A bad condenser will make it run very weak and eat points.

[OR75]

7 hours ago, Scott Ashton said:

More trouble today - four hours after replacing the mag with another exchange unit the left mag points were failing again.   Pre takeoff mag check was perfect, and flight test yesterday was perfect.    By the time I got to altitude and set up cruise flight, I couldn’t get it run LOP and then tried the In flight mag check and the left side was super rough with a big RPM drop.  Got back to base and did another mag check on the ground and it was super rough on the left mag and the tach was bouncing around - same symptoms as before.   Third failure of points in 12 hours since replacing the original mag with 750 hours on it that worked fine.    So the saga continues.   

reading your older post when you removed the mag . Did you actually look at it ? what was wrong with points ? Just curious what "bad" meant ? burnt ? not closing ? 

[Scott Ashton]

Just put a new cap and harness on order and we are starting over with new points and condenser and harness.      Hopefully we will know more next week….the harness looks like original ‘85 vintage so if that’s not it we are out of ideas.  After three sets of points failing after five hours each, we’re thinking an issue somewhere else in the system…

[EricJ]

26 minutes ago, Scott Ashton said:

Just put a new cap and harness on order and we are starting over with new points and condenser and harness.      Hopefully we will know more next week….the harness looks like original ‘85 vintage so if that’s not it we are out of ideas.  After three sets of points failing after five hours each, we’re thinking an issue somewhere else in the system…

I suspect with those updates you'll make good progress.

[dominikos]

Any update on the findings? Found myself in the same exact situation with L mag droping to 600 rpms during mag check. The harness and plugs were checked. The mag was a replacement unit less than 100 hrs ago. 

The EGTs are dropping on Cyl 1&2.

[N201MKTurbo]

40 minutes ago, dominikos said:

Any update on the findings? Found myself in the same exact situation with L mag droping to 600 rpms during mag check. The harness and plugs were checked. The mag was a replacement unit less than 100 hrs ago. 

The EGTs are dropping on Cyl 1&2.

There is no easy way around this. If you have a mag timer and know how to use it, there is a lot you can do. The first thing is to check the timing on #1, and #3. That will check both sides of the cam. Check both sides of the mag. At this point you will know almost everything that can go wrong, except the distributor gear slipping and a condenser or coil failing. You need a spark gap tester to figure these out.

[Scott Ashton]

I ended up replacing the cap and harness too so I basically had a new ignition system, including an exchange mag, condensers, etc.   Never figured out the issue unfortunately.   

[OR75]

must be contagious ... having the exact same issue 

Mag recently overhauled.  

Checked harness leads and the are all OK. 

Spark plugs look visually OK and gapped correctly but need to check resistance . Any thought on what the resistance range needs to be ?

If that checks, next step is to remove the mag and check the points 

[Fly Boomer]

2 hours ago, OR75 said:

Spark plugs look visually OK and gapped correctly but need to check resistance . Any thought on what the resistance range needs to be ?

I have read between 1,000 and 5,000 ohms.

[jetdriven]

On 7/22/2023 at 8:48 PM, KSMooniac said:

There is a non-trivial chance your Kelly mag is junk out of the box. If your mechanic confirms it, I'd return it for a full refund and get a good one from a better vendor that specializes in the dual mag.

Sent from my LM-V600 using Tapatalk
 

Likely, actually.  Or it could be the capacitor.  Kelley changed their OH manual to say that anything that looks good can be reused.  So they do.

[EricJ]

3 hours ago, OR75 said:

must be contagious ... having the exact same issue 

Mag recently overhauled.  

Checked harness leads and the are all OK. 

Spark plugs look visually OK and gapped correctly but need to check resistance . Any thought on what the resistance range needs to be ?

If that checks, next step is to remove the mag and check the points 

<5k Ohms.   The Tempest Maintenance Manual indicates it's good if it is less than 5000 Ohms.   The Champion manual doesn't mention anything, at least the manual that I have.

 

[dominikos]

A good outcome, taking the mag off, checking the timings solved the problem. the plane is happy to fly again and ready for the check ride tomorrow

[OR75]

3 hours ago, dominikos said:

A good outcome, taking the mag off, checking the timings solved the problem. the plane is happy to fly again and ready for the check ride tomorrow

what happened to the timing ?

internal timing of the mag ? or timing of the mag to the engine ?

don't forget to use the right new teeth washers and torque both nuts correctly (the bottom is a pain to torque) 

[skykrawler]

On 12/22/2024 at 1:10 AM, OR75 said:

don't forget to use the right new teeth washers and torque both nuts correctly (the bottom is a pain to torque) 

Those would be internal lock washers.    As apposed to external lock washers.

internal

external

Teeth washer

Edited December 23, 2024 by skykrawler