Dual mag future

[KSMooniac]

I concur that the D3000 is nothing to fear... Just maintain it, check mounting security at every oil change, etc. and keep flying. I'd rather have it vs a pair of slicks.

Having said that, I plan to move to the Electroair at some point. Would've been this summer-ish but I'm dealing with hail repairs and a repaint first, with some more airframe mods in between. I still have vacuum instruments so I'll need to do something else in conjunction with that upgrade, but I was going to do that anyway.

Never forget that most J models were delivered with the Dual Mag... So if you exclude it you might be searching a very long time.

Sent from my LM-V405 using Tapatalk

[OR75]

The factory overhauled A3B6D is about 3k more than an A3B6 (they take the D as a core) 

need a few brackets and change a few hoses . Probably 1k worth of. 

so net net about 2k cheaper. 

From what I heard , the non D does not make the accessories ( governor, oil filter, oil screen) easier to access 

agree that if torqued and installed properly, the Dual mag is great. 

[201Steve]

I just got my airplane back from overhaul and they installed my D Mag with 8 lbs of the 17 lbs torque required. I was pissed. 

[Guest]

6 hours ago, 201Steve said:

I just got my airplane back from overhaul and they installed my D Mag with 8 lbs of the 17 lbs torque required. I was pissed. 

Did they install new style clamps with it?

Clarence

[tpavlusik]

I did not see any information on their website. Are booth magnetos electronic?

[201Steve]

1 hour ago, M20Doc said:

Did they install new style clamps with it?

Clarence

I already had the new style clamps added last year so they were used for new install. Thx for the nudge, though. 
 

My alternator almost fell off, too. Pirep of a beloved MS staple coming soon. 

[toto]

44 minutes ago, tpavlusik said:

I did not see any information on their website. Are booth magnetos electronic?

Yep, it replaces both mags, and requires a second source of power (either a second alternator or a second battery). There’s nothing on their website yet. They announced at S&F. 

[mooniac15u]

14 hours ago, A64Pilot said:

You could make that statement about most anything...

You said you weren't aware of any failures of the dual magneto.  I pointed out a known failure mode that was common enough for the the FAA to issue an SAIB and you decided to belittle my choice of words.  Nice!

[A64Pilot]

1 hour ago, mooniac15u said:

You said you weren't aware of any failures of the dual magneto.  I pointed out a known failure mode that was common enough for the the FAA to issue an SAIB and you decided to belittle my choice of words.  Nice!

No, I didn’t say that I was unaware of any failures of the dual mag, I said I was unaware of failures of the drive shaft, that being the only common item of the dual mag that I knew of, but if there are enough of anything, there will be failures. 

But I woud say it’s safe to say that pretty much any item that falls off of the aircraft will cease to function, but being incorrectly torqued or even if the mounting stud broke its not a mag failure, it’s an engine failure, or a human failure. There are innumerable single items on the engine and aircraft that the failure will bring it down. 

So if a wheel falls off on landing because the mechanic left the cotter pin out, is it a wheel failure?

You can’t make something idiot proof, there will always be a better idiot, and we all can on occasion be that idiot.

Edited May 11, 2021 by A64Pilot

[mooniac15u]

 

16 minutes ago, A64Pilot said:

No, I didn’t say that I was unaware of any failures of the dual mag, I said I was unaware of failures of the drive shaft, that being the only common item of the dual mag that I knew of, but if there are enough of anything, there will be failures. 

But I woud say it’s safe to say that pretty much any item that falls off of the aircraft will cease to function, but being incorrectly torqued or even if the mounting stud broke its not a mag failure, it’s an engine failure, or a human failure. There are innumerable single items on the engine and aircraft that the failure will bring it down. 

So if a wheel falls off on landing because the mechanic left the cotter pin out, is it a wheel failure?

You can’t make something idiot proof, there will always be a better idiot, and we all can on occasion be that idiot.

Here's where you said you believed that the only failure that could take out the dual mag that didn't take out independent ones is the failure of the driveshaft..

23 hours ago, A64Pilot said:

I believe the only failure that could take out the dual mag that didn't take out independent ones is the failure of the driveshaft, and I have never heard of that occurring.

I pointed out a specific, known failure mode.  A failure mode that you were unaware of that could affect your aircraft.

Of course anything falling off an aircraft could affect it but not everything has a history of causing accidents to the extent that there is an SAIB about it.  To argue otherwise is just being disingenuous.

You now know about the SAIB.  You're welcome.

 

[WaynePierce]

On 5/10/2021 at 10:41 AM, A64Pilot said:

I know your talking about modifying the engine to accept separate magnetos.

However, why do that? I believe the only failure that could take out the dual mag that didn't take out independent ones is the failure of the driveshaft, and I have never heard of that occurring.

I don’t believe there is a failure mode of the accy gearbox that doesn’t take the whole thing down.

‘I believe there may be an electronic alternative for the dual mag, I don’t know anything about it, but I had rather have dual electronic ignitions in one box than dual independent magnetos myself, mostly to get away from the 500 hour maintenance requirement, and if done correctly a much hotter spark, although a higher amp ignition does increase wear on the spark plugs, it out to enable smoother LOP.

Maybe one day we will have dual electronic ignitions triggered off of a crankshaft sensor? Shouldn’t be hard to do, but can you make money with it?

I have the dual mag system in my "J" and had one fail two years ago. In addition to the gearbox in the accessory box if you have a plastic gear disintegrate inside the magneto could take both of them out. I actually think this is more plausible for a failure scenario as well.  

[Guest]

I’d be curious to know how many of these failed magnetos had had 500 hour inspections completed?

Clarence

[chriscalandro]

2 hours ago, A64Pilot said:

No, I didn’t say that I was unaware of any failures of the dual mag, I said I was unaware of failures of the drive shaft, that being the only common item of the dual mag that I knew of, but if there are enough of anything, there will be failures. 

But I woud say it’s safe to say that pretty much any item that falls off of the aircraft will cease to function, but being incorrectly torqued or even if the mounting stud broke its not a mag failure, it’s an engine failure, or a human failure. There are innumerable single items on the engine and aircraft that the failure will bring it down. 

So if a wheel falls off on landing because the mechanic left the cotter pin out, is it a wheel failure?

You can’t make something idiot proof, there will always be a better idiot, and we all can on occasion be that idiot.

You must have missed that time that guy here had to have his airplane helicoptered out of the mountains because of exactly this failure.

[tpavlusik]

I guess one can have an issue in accessory box gears that can potentially take out two magnetos. All I wanted to know if they are prone to failure since they both have a single coupling and single shaft. From what I can see they are pretty dependable if serviced correctly. 

[A64Pilot]

38 minutes ago, chriscalandro said:

You must have missed that time that guy here had to have his airplane helicoptered out of the mountains because of exactly this failure.

I did miss that.

‘Just from a glance of the electronic replacement, it appears as if something is going to be driven from the single mag drive pad, which if I understand it will still have many of the same failure modes.

‘I woud have hoped it would have used a crankshaft sensor and nothing be driven from the drive pad.

‘But back to there are many items that if they fail, your going down, from a crankshaft, cam shaft and has been said I don’t believe there are any gears in the accy gear box that if one breaks that anything will continue to function if nothing else the chunks will break what remains.

‘I’m 100 or so hours away from a 500 hr inspection myself, when I get there, I’ll evaluate the electronic ignition, but I’m comfortable with my one big ole mag as long as it’s professionally serviced.

‘My belief is that for whatever reason many are overly concerned about the (D) magneto, and I believe it’s risk is easily managed, have it serviced, don’t re-use the lock washer and don’t put the wrong gasket under it.

Personally I think the problem came from being tough to access, so it was often undertorqued and no one ever looked at the thing

‘While I’m legal to service it, it’s one of those things that i’m my opinion is best left to people that specialize in that area, so I send one off.

It’s usually actually cheaper to have one (D) mag serviced as opposed to two single mags

‘I believe years ago I used Maxwell’s magneto’s, I’d assume he’s no longer in business as it was awhile ago.

By the way, I’ve known about the SAIB for quite some time. It’s been revised by the way to suggest that at overhaul the Mag flange be dye penetrated.

But it’s not an AD, I can’t explain why because it wouldn’t be a tough AD

Edited May 11, 2021 by A64Pilot

[PT20J]

1 hour ago, chriscalandro said:

You must have missed that time that guy here had to have his airplane helicoptered out of the mountains because of exactly this failure.

Maybe you can find the thread. I remember it had a video of the extraction. As I recall, the mag didn't break, it fell off the engine.

[OR75]

18 hours ago, 201Steve said:

I just got my airplane back from overhaul and they installed my D Mag with 8 lbs of the 17 lbs torque required. I was pissed. 

I am curious to know how you found out 

[EricJ]

4 hours ago, chriscalandro said:

You must have missed that time that guy here had to have his airplane helicoptered out of the mountains because of exactly this failure.

That looked like it was due to installation error as well, if I remember correctly.   Last I heard it was going to litigation with the outfit that had done the annual.

4 hours ago, tpavlusik said:

I guess one can have an issue in accessory box gears that can potentially take out two magnetos. All I wanted to know if they are prone to failure since they both have a single coupling and single shaft. From what I can see they are pretty dependable if serviced correctly. 

As mentioned, the main input shaft and magnet, and its bearings, are common to both sides.   It'd be quite a stretch to imagine how the main shaft/gear/magnet would fail, as it is quite stout to carry the mass/inertia forces of the magnet.   There are probably failure modes that can take out both sides, but they seem to be very rare, rarer than failures due to other single-thread systems in the airplane, like the carb or fuel servo, exhaust valves, etc.

It seems to be worthwhile to do 500 hour inspections on any magneto, but these seem to be particular candidates for getting that done.  

 

[jaylw314]

7 minutes ago, EricJ said:

That looked like it was due to installation error as well, if I remember correctly.   Last I heard it was going to litigation with the outfit that had done the annual.

As mentioned, the main input shaft and magnet, and its bearings, are common to both sides.   It'd be quite a stretch to imagine how the main shaft/gear/magnet would fail, as it is quite stout to carry the mass/inertia forces of the magnet.   There are probably failure modes that can take out both sides, but they seem to be very rare, rarer than failures due to other single-thread systems in the airplane, like the carb or fuel servo, exhaust valves, etc.

It seems to be worthwhile to do 500 hour inspections on any magneto, but these seem to be particular candidates for getting that done.  

 

Now that you mention it, I realized the D magneto, when an 500 hour IRAN is done, I assume almost always will be done on BOTH magnetos at the same time.  I've heard suggested and have planned on doing my IRAN's at different times so that I don't have a maintenance-related failure on both, but nobody is going to do it that way with a D mag, right?

[Guest]

4 hours ago, PT20J said:

Maybe you can find the thread. I remember it had a video of the extraction. As I recall, the mag didn't break, it fell off the engine.

That what I recall as well, improper installation technique led to the mag falling off the engine.

Clarence

[Guest]

5 hours ago, tpavlusik said:

I guess one can have an issue in accessory box gears that can potentially take out two magnetos. All I wanted to know if they are prone to failure since they both have a single coupling and single shaft. From what I can see they are pretty dependable if serviced correctly. 

The loose nut in the left seat still causes more accidents than the magneto failing.

Clarence

[A64Pilot]

1 hour ago, jaylw314 said:

Now that you mention it, I realized the D magneto, when an 500 hour IRAN is done, I assume almost always will be done on BOTH magnetos at the same time.  I've heard suggested and have planned on doing my IRAN's at different times so that I don't have a maintenance-related failure on both, but nobody is going to do it that way with a D mag, right?

Yes they will certainly be serviced at the same time. The 500 hours comes from not a time of likely failure, it’s a time interval that ensures that a failure due to time is very remotely possible. The likely hood of both mags failing in one flight are so remote as to be statistically insignificant.

The reason many people will try to split overhaul times on twins isn’t to reduce likelihood of a failure, it’s to spread costs so your not hit with both engines being overhauled at the same time.

[201Steve]

2 hours ago, OR75 said:

I am curious to know how you found out 

There wasn’t much of the stud protruding past the nut, not a sure fire way, but I was suspicious from other finds. I threw a torque wrench on it to confirm. Wasn’t even close. 

[PT20J]

Torque seal is a great thing. Sometimes we get interrupted. It's easy sometimes to lose track of which bolts got torqued and which didn't. Having a rule that torque seal is immediately applied after proper torqueing is a great way to be sure.

A  friend that worked at United's maintenance depot at SFO told me years ago that they had found so may tools inside airframes that they made a rule that you could not set a tool down on an airframe. It sounds great. Try it -- it's really hard. But if you do it you won't wonder where that missing wrench got to.

Skip

[carusoam]

Yes...  Mags and vac pumps wear...

yes...  Some people pro-actively OH these devices at or around 500hrs...

yes... Some people avoid OHing both mags at the same time...

Mags and vac pumps have a history of infant failure modes...

So... it makes statistical sense to OH them separately on different schedules...

The nylon gear inside each mag is sensitive to O3 (ozone)... exposure to ozone makes it brittle and allows it to lose teeth...

Losing teeth causes challenges with the mag’s timing...

 

If the guy OHing your mags asks you if you would like to re-use the nylon gear... a simple no thank you will work... 

PP summary only, all stuff written about around here...

Best regards,

-a-