Time for a new Mag

[RLCarter]

1 hour ago, Yetti said:

Ya which boat did you pull that off

It looks like it came off the Titanic........ Sorry Paul, had to say it

[gsxrpilot]

1 minute ago, RLCarter said:

It looks like it came off the Titanic........ Sorry Paul, had to say it

I know! I couldn't agree more. There were several people by the shop today and all of them said it looked like we dredged it up off the bottom of the ocean somewhere.

 

[jetdriven]

If you can fix Bendix 1200s they don’t need to be pressurized. 

[RLCarter]

2 hours ago, gsxrpilot said:

I know! I couldn't agree more. There were several people by the shop today and all of them said it looked like we dredged it up off the bottom of the ocean somewhere.

Make or buy a shadow box and hang it up in your man cave or hangar.......I'm impressed it worked at all

[Greg_D]

Another example of why a ROP static run-up on the ground is of little value.  I do mine LOP, at altitude, just before beginning descent.  And then I'll do a quick continuity check while rolling to the run-up area, prior to the next flight.

[DXB]

I wonder if this was an instance where a failing mag also produced erratically timed sparks, thus interfering with function of the good side and causing the roughness during climbout.

[Marauder]

New left Mag installed, timed and test flown. During the test flight I took it to 4500 ft. leaned it out to 1550 TIT on 65% power and did a long, 60 sec mag check on each mag. Using the normalized display on the EDM900, the EGT's rose in perfect unison on each mag. The engine also runs very smooth on each. Satisfied that everything is working normally, I did a lean find test to see how lean it would go. Previously, with a GAMI spread of only .2 I couldn't go below 9.5 gph without roughness, today I was able to lean to 8.0 gph without any roughness. 
I'm gonna fly to North Carolina tomorrow and then back on Saturday. Over Christmas while I'm away, they'll pull the right mag and take a look at it. 
This 252 will certainly get annual IRAN on both mags going forward.

Glad you took care of the left mag, bit surprised that the right one wasn’t pulled just for nothing more than a look see. That is a LOT of crap inside a sealed mag.


Sent from my iPad using Tapatalk Pro

[mooniac15u]

8 hours ago, Greg_D said:

Another example of why a ROP static run-up on the ground is of little value.

I find significant value in knowing that both of my mags and all my plugs are functioning right before a takeoff, under conditions similar to what I'm about to depend on during that takeoff and climb.  LOP checks are more of a long-term diagnostic tool.

[kortopates]

13 hours ago, jetdriven said:

If you can fix Bendix 1200s they don’t need to be pressurized. 

Bendix makes a pressurized version of big tractor style S-1200 called the S-1250. Its used on some turbo's that like the 252 are certified to FL280, and RAM for example uses it on their Cessna 421 engine. As you bring it up, those larger tractor style mags are far more durable and reliable.  But the problem is the vast majority if not all Turbo engine where the mags are installed on the back on the accessory case  along with the TCM starter adapter that you couldn't possibly fit a pair of the larger footprint mags there. The space is just too tight. You are are left with small footprint mags by either Slick or Bendix. And really size seems to be everything, once you get into the smaller footprint sizes, the mags need a lot more maintenance regardless of whom makes them. But pressurized turbo mags flown IMC really need to be opened annually (or every 100 hrs) since the mag filter isn't at all 100% effective in keeping the mag dry.    

[Greg_D]

6 hours ago, mooniac15u said:

I find significant value in knowing that both of my mags and all my plugs are functioning right before a takeoff, under conditions similar to what I'm about to depend on during that takeoff and climb.  LOP checks are more of a long-term diagnostic tool.

As shown in this thread, the ROP static run-up does not prove that the mags or ignition system are functioning properly.  The only real value it provides can be accomplished by a quick continuity check while rolling.  If nobody touches the plane after performing a satisfactory LOP check at altitude before descending, it should be good to go on the next takeoff.  The LOP check puts much more stress on the ignition system.  If it passes that, it will almost certainly function properly on the next takeoff at full rich.

[mooniac15u]

31 minutes ago, Greg_D said:

As shown in this thread, the ROP static run-up does not prove that the mags or ignition system are functioning properly.  The only real value it provides can be accomplished by a quick continuity check while rolling.  If nobody touches the plane after performing a satisfactory LOP check at altitude before descending, it should be good to go on the next takeoff.  The LOP check puts much more stress on the ignition system.  If it passes that, it will almost certainly function properly on the next takeoff at full rich.

I prefer to focus on taxiing when I'm taxiing.  Are you doing a runup?  If so, why not do a quick mag check then?  It adds about 15 seconds to the runup process and you aren't needlessly distracted while taxiing.  I understand the value of the LOP mag check I am just not so quick to dismiss a pre-takeoff checklist item.

[kortopates]

1 hour ago, mooniac15u said:

I prefer to focus on taxiing when I'm taxiing.  Are you doing a runup?  If so, why not do a quick mag check then?  It adds about 15 seconds to the runup process and you aren't needlessly distracted while taxiing.  I understand the value of the LOP mag check I am just not so quick to dismiss a pre-takeoff checklist item.

Exactly! When Mag teeth break off the ozoned  out wheel (as opposed from maintenance) they seem to break most often right at startup and shutdown. So I prefer to check after every shutdown/startup, regardless if I just did a LOP Mag check before landing. Although in this scenario you'll most likely have a dead mag and should be real obvious. many things can happen including fouling a single plug from a rich descent which won't be quite so obvious.

[mike_elliott]

On 12/12/2017 at 10:08 AM, gsxrpilot said:

I jumped in the 252 yesterday to go get the O2 bottle filled for a long cross country planned for tomorrow. The run up was smooth and the take off roll uneventful. During the climb out, I noticed one hiccup and thought it might just be my imagination. But then the roughness started. I immediately was looking at distance to the runway and also at possible off field landing areas. Some quick troubleshooting while returning to the field seemed to indicate it wasn't a fuel issue.

I landed and noticed the engine smoothed out at low power. I did some high speed taxi and couldn't reproduce it. But and even a mag check again seemed normal. I took off again just for one lap around the pattern and immediately got the roughness again. On landing I went for another Mag check, but this time held 1600 rpm while I leaned to raise the engine temp. I normalized the EDM900 display and did the mag check again. This time on the left mag numbers 2,4,6 EGT temps dropped out while 1,3,5 climbed as usual. On the right mag all EGT's climbed as expected. I would have expected all 6 cylinders to fall or the engine to actually quit with a completely failed Left mag, but three cylinders were certainly not firing. We pulled the plugs and swapped positions and did another runup. Same result. We checked the wires to those plugs and everything checked out. So finally we pulled the mag. Here are the pictures.

That ought to buff right out

[Greg_D]

On 12/13/2017 at 3:41 PM, mooniac15u said:

I prefer to focus on taxiing when I'm taxiing.  Are you doing a runup?  If so, why not do a quick mag check then?  It adds about 15 seconds to the runup process and you aren't needlessly distracted while taxiing.  I understand the value of the LOP mag check I am just not so quick to dismiss a pre-takeoff checklist item.

I don’t have a problem doing a continuity check with the key switch while on a wide and straight taxiway.  If there’s going to be an issue, I’ll do it before taxiing or at some place before the runway when stopped.  No, I don’t normally do the full blown run ups on the ground unless work has been done on the plane.  They are of very little value.  I’ve had two mag failures in the 34 years I’ve been flying and both were preceded by successfully completed run ups the way I was taught years ago.  After attending the APS class in Ada, I adopted their conclusion that doing run ups the way most of us were taught potentially causes more harm to the engine/prop than they’re worth.

[mooniac15u]

24 minutes ago, Greg_D said:

I don’t have a problem doing a continuity check with the key switch while on a wide and straight taxiway.  If there’s going to be an issue, I’ll do it before taxiing or at some place before the runway when stopped.  No, I don’t normally do the full blown run ups on the ground unless work has been done on the plane.  They are of very little value.  I’ve had two mag failures in the 34 years I’ve been flying and both were preceded by successfully completed run ups the way I was taught years ago.  After attending the APS class in Ada, I adopted their conclusion that doing run ups the way most of us were taught potentially causes more harm to the engine/prop than they’re worth.

Your definition of little value and mine must be very different.  All kinds of problems can be identified during a runup.  You might also consider that the OP's runup and mag check did exactly what was needed.  It verified that the mags were functioning during takeoff conditions.  It did not identify the ultimate problem which was revealed while leaning at a safe altitude.  It might help to think of the value of a runup with respect to what it is intended to accomplish rather than trying to compare it to some other test.  Will it substitute for an in-flight LOP mag check? Nope.  Does it provide valuable information?  Yep. Is it better than not doing one? Yep.

[Greg_D]

2 hours ago, mooniac15u said:

Your definition of little value and mine must be very different.  All kinds of problems can be identified during a runup.  You might also consider that the OP's runup and mag check did exactly what was needed.  It verified that the mags were functioning during takeoff conditions.  It did not identify the ultimate problem which was revealed while leaning at a safe altitude.  It might help to think of the value of a runup with respect to what it is intended to accomplish rather than trying to compare it to some other test.  Will it substitute for an in-flight LOP mag check? Nope.  Does it provide valuable information?  Yep. Is it better than not doing one? Yep.

No, the OP’s run up did NOT verify that the mags were functioning during takeoff conditions.  By the book run ups are done under static conditions and the engine is developing nowhere near takeoff power and is substantially below takeoff RPM.  It is only a marginally better test than a simple magneto continuity check.  The trade off one gets for that is prop dings and creating hot spots on the cylinders (very little air flows through the cowl while sitting still).  And no, the prop blast contributes little to the air flow.

If you read the OP’s post again, you will see that the problem first occurred right after takeoff, BEFORE he leaned, but while at full power.  That’s not what a run up replicates.  In fact, the real issue wasn’t apparent until after he leaned on the ground.

Full rich static run ups prove very little.  Take the time and attend the course in Ada one weekend and they will show you why, real time, on both a Continental and Lycoming test engine.

[Guest]

On 2017-12-13 at 8:26 AM, Marauder said:

 

Glad you took care of the left mag, bit surprised that the right one wasn’t pulled just for nothing more than a look see. That is a LOT of crap inside a sealed mag.


Sent from my iPad using Tapatalk Pro

 

With AoA and a modern engine monitor what could go wrong?

Clarence

[gsxrpilot]

On 12/13/2017 at 7:26 AM, Marauder said:

Glad you took care of the left mag, bit surprised that the right one wasn’t pulled just for nothing more than a look see. That is a LOT of crap inside a sealed mag.

 

I agree that the right mag should be pulled. But the combination of a good running engine after solving the left mag problem AND after a phone conversation between JD at SWTA and one of the technical guys at Slick, I didn't feel it was a big enough issue to cancel my trip. The information from Slick was that this is not uncommon on the left mag but much more rare on the right mag.  After replacing the left mag and timing both mags, I took it out and flew it a bit. It frankly ran better than it ever has. 

On the flight the next day... which is detailed over in the Today's Flight post, it ran smooth LOP at 9.5 gph for almost five hours. It's never been really smooth LOP. 

Once I get back this weekend, we'll pull the right mag and take a look at it.

[gsxrpilot]

23 minutes ago, M20Doc said:

With AoA and a modern engine monitor what could go wrong?

Clarence

I've got both so I'll be fine 

[Guest]

Just now, gsxrpilot said:

I've got both so I'll be fine 

With that equipment on board, I’d toss the other mag and safe the weight and rotational drag on the engine.  You might pick up a knot or two.

Clarence

[LANCECASPER]

For what it's worth I've had worse luck with brand new slick mags than anything.

[mooniac15u]

2 hours ago, Greg_D said:

No, the OP’s run up did NOT verify that the mags were functioning during takeoff conditions.  By the book run ups are done under static conditions and the engine is developing nowhere near takeoff power and is substantially below takeoff RPM.  It is only a marginally better test than a simple magneto continuity check.  The trade off one gets for that is prop dings and creating hot spots on the cylinders (very little air flows through the cowl while sitting still).  And no, the prop blast contributes little to the air flow.

If you read the OP’s post again, you will see that the problem first occurred right after takeoff, BEFORE he leaned, but while at full power.  That’s not what a run up replicates.  In fact, the real issue wasn’t apparent until after he leaned on the ground.

Full rich static run ups prove very little.  Take the time and attend the course in Ada one weekend and they will show you why, real time, on both a Continental and Lycoming test engine.

Again, I think we have different definitions of marginally better.  There are things that an LOP mag check will find that a regular runup check won't.  There's a big gap between that and marginal value.  You seem to be convinced otherwise so I won't waste anymore time debating it with you.

[Guest]

8 hours ago, mooniac15u said:

Again, I think we have different definitions of marginally better.  There are things that an LOP mag check will find that a regular runup check won't.  There's a big gap between that and marginal value.  You seem to be convinced otherwise so I won't waste anymore time debating it with you.

With a modern engine monitor system the retrieved data after an accident could prove problematic if one crashed with an engine failure and no run up was recorded. 

Clarence

Edited December 15, 2017 by M20Doc

[carusoam]

Did Slick give a reason that the level of oxidation in one mag is expected to be greater than in the other mag?

Just wondering...

Best regards,

-a-

[gsxrpilot]

1 hour ago, carusoam said:

Did Slick give a reason that the level of oxidation in one mag is expected to be greater than in the other mag?

Just wondering...

Best regards,

-a-

It was something about the RPM gauge being connected to the left mag and blocking the vent hole.