for... Skyking...

[Don Hickman]

Yes, Bob, I read the article on burnt valves. But I didn't find much in the way of legalese in it so most of it probably went right by me. However, taking your advice I'm changing oil tomorrow and putting in some AVblend. Will let you know what happens.

And, Skyking, I'll keep running my hightime front engine until either the compression goes south, the oil consumption goes north or the metal goes up. How's that? Now you just better hope I don't have to use that VERY expensive little rubber dinghy I am required to carry along every time I fly over the Gulf!

While I'm at it, I'm having my mags replaced on the rear engine. Hopefully that will stop the engine roughness I've started experiencing above 16,000 feet. And we're going to clean the screens in the prop governor. Maybe one of these days I'll actually get the thing running right!

[Bob Cook]

Don

What a way to get a free dinner. If you hit me up I want a receipt for that AV stuff <G>.

If you do not have pressurized mags then you better put the mod in or you are going to experience misfiring above 14k ft about 25 hrs after the plugs have been cleaned. It is not that expensive to do. You add a filter and run the upper deck air to the mags thru the filter.

I was experiencing the same thing until I added the pressurization.

Don't even think about the little yellow rubber ducky err dingy.........

How's the dog (not talking about AC)?

Bob

BTW: Southwest have relabeled the autopilot. It is now know as .......... "designated driver"

[kevin]

Just for another viewpoint, my mechanic felt that proper ignition maintenance would prevent high-altitude miss. He did not like the pressurized mag mod, I can't remember why.

Anyway, I clean and gap my plugs every 100 hours, and I have not had problems. I fly at 18 to 20K very frequently.

Now I'll probably get it on the next flight, just for opening my mouth...

I still think Bob's right, and pressurized mags are the way to go.

Kevin

[Bob Cook]

Kevin

It was highly recommended at the CPA course. These mags are smaller than the 400 series and are more prone to have ignition jump within the mag itself. I should not have stated 25 hrs, however, since I did the mod I have not had problems.

It was simple to install and you add small fitting on mag and replace one of the filter with a plug. Suggest it be done when the mag is out or when the rear inside cover is open.

Bob

[kevin]

It seems to me that he was saying that it blew "crap into the mag" (that's mechanic talk). Whatever. I wanted to install them, he balked, so far he has been right, but if I have even a hint of a problem (now that he has retired), in they will go.

Kevin

[Don Hickman]

Same with my mechanic. He took out the rear mags yesterday and one has a shot bearing and the distributor block on the other is bad so that probably accounts for the rough running at altitude. I told him to put in the pressurized ones but he doesn't want to and points out correctly that the front engine runs smoothly at altitude so it's just that these mags needed repairing. Guess we'll see what happens when he reinstalls them.

[SkyKing]

Hi Don,

Curious as to how much time you've got on your rear engine Mags... and the front Mags too.

So far, no mag probs on this end, with our rear reman at 150hrs, and while the front engine has 1250, factory reman mags were installed about 250 hours ago. One counsel tells me they should be R&R at 500 hours, and yet another says they need only to be taken off at 500 hours and sent to a mag-shop for preventive maintenance... what say GMAs?

SkyKing

[Bob Cook]

Skyking
Think there is a mandatory overhaul at 500 hrs on the mags.

the filters on the pressurized mags are clear and there is no sign of oil or dirt showing up so far after 150 hrs.

GMAS

Question. Have you ever seen engine mounts fail on the rear engine ? What is you opinion if two failed on the same side?
BTW nothing to do with my aircraft.

Very interested in hearing from you , or anyone else.

Bob

[Don Hickman]

Oh, Bob is just being nice. He's inquiring because I have two failed mounts on the right side of the rear engine. And, no, I don't bounce my landings! My mechanic said he had never seen engine mounts fail the way mine did. But then he also said he had never seen mags in such bad shape and the engine still ran, either. Just lucky, I guess. The engine mounts failed sufficiently to cause the entire engine to shift to the right such that I could no longer get the oil dipstick out without using a lot of force to push it to the left. So when I got back from Mexico this weekend I told my mechanic about it which is why he went looking to find the failed mounts.

Skyking, the mags had 1200 hours on them. I haven't yet looked through the logs to see when they were last overhauled. But they're getting overhauled now!

My mech said the screens in the prop governor were clear so he thinks the RPM variation on the rear engine that I have been experiencing at cruise may have been caused by the mags. But the interesting part about that is that when I would do the runup and the mag check, the rear was completely steady. No RPM drop on either mag. Go figure!

[Mark Hislop]

Don:

No RPM drop on either side sounds to me like broken P leads. It happened to me, with my factory reman. I think there were wire connectors that were not properly connected in my case.

Mark

[SkyKing]

Don,

I'm beginning to wonder, do you have any recourse back to the selling dealer for the problems you're experiencing, or did you sign away with a forebearance? If memory serves me, I think your plane came from Bar-"X" with new paint, panel and interior... is yours the one with the big letters on the fuselage sides, serial #190?

I've never heard of an engine mount failure... do you think maybe there was some hidden damage from an incident before you bought the plane? Hhmmm.

Mark's right... if you're not getting ANY drop, your P-leads are probably defective... WATCH OUT FOR ANYONE AROUND THE PROPS WHO MIGHT THINK TO MOVE THEM... NOT GOOD!

SkyKing

[Bob Cook]

just turn off the engine with the mag switch. if it doesn't shut down then you have a failed switch or open P lead.

and re mnts.

I have never heard of failed mounts like this / reason for asking Gmas and anyone else. This could also cause the engine WOW. That is scary to have engine mnt failures. I have only seen deteriorated rubbers.


Bob

[kevin]

For what it's worth, we found the actualy engine mount frame (or whatever you call it, i.e. *not* the rubber "mounts" that you change when changing the engine) on my '73 P337 had significant damage due to a cable that came loose and started rubbing on the *inside* of the frame, where the ongoing damage was not obvious. We had to remove the engine, have the frame repaired, and then reinstall. Fun (not).

Kevin

[GMAs]

the mag problem....

Lets see... ya it says that you should have them checked every 100 hrs at annual for points and condition... Hmmmm 1200... now thats a long time for a mag... your mechanic should have picked it up... but, how come YOU don't read your log books,maintance manual... after all you are the one.. that is responsible for your plane...right... (we have been thru this how many times...smile)

As to our recomendations...

normal asp non high flying...

We recomend that you have the mags serviced every 500 hrs... along with the alternator... smile... Now some have said .. well ya we took a look at them and they looked fine... but, my response was ... how do you know if you don't take them out of the plane/engine... which most are not.. they just look at them sitting their... no.. no.. that is not what we mean... the mags come off and go into the shop... and are opened up and and inspected and repaired... the ignition wires are tested with a meggar.. for break down.. etc...

Most of the time they ..the shop.. such as savage mag......

SAVAGE MAGNETO SERVICE PO Box 2401 Airport Station Bldg 73 Oakland Int. Airport
Oakland, CA 94614 Phn: (510) 562-2941 Fax: (510) 562-1593,

will do a tear down and inspection/overhaul... cost is minimal.. but, when done...it is then run on a mach and tested for operation and voltage... as well as crossfireing... which well get to in a min...

their are more things in the mag that can happen wrong than just it makes sparks... timing and springs get out of whack... seals and bearings get dry... so their are a bunch of reasons to have them done at that interval.... as we have found it keeps the fear factor down with the passengers...

But,....

Now for the high flyers.. them TURBO guys...

Here we recomend that you take them out and have them inspected every 250 hrs... yep.. thats not much... but, because you are up in a drier climate way up their things go bad quicker... grease which has water in it... yep it does... drys out...oil oxidies faster...etc... causing drag on the bearings... this in turn causes the impuse spring to have to work harder... etc... seals are another item that seem to dry out faster... and of course the crossfiring in the dist block seems to happen more frequently... which we will get into here in a min...

again the inspection is not just to physically look at the mag.. its to open it up and check how its doing... and replace any parts that are not within limits... or carbon tracked... (Bendix overhaul manual...TCM x42002 and "the Magneto Ignition System" by John Schwaner at Sacramento Sky Ranch... 800-433-3564... are two good books to have... and in Johns' book he has a section on High flying make sure you mention the 337Skymasters Club for the discount)

Now as to the pressurization of the mags... the reason that your mechanic is reluctant to change is becasue if the turbo has problems... and/or starts spitting oil/parts... guess where its going... right into the top of the mag... also it has been shown that the turbo air... you know the stuff that is compressed from the compresser side of the thing... is a lot hotter... yep about 250 deg F... don't believe me... start up and go for a flight.. land and then try and put your hand on the intake tube... its real hot... and its not from the engine... its called heat of compression... on turbines it gets up to about 450 deg f in cases... you can cook with that... and the hot compressor section gets up to about 600... but, that is for the turbine guys.... we are talking our little turbo compressors.. here....

Now if you have a device called a intercooler... then you take the temp of the compressed air for the intake back down to normal air temp levels... but, if not.. well... all that hot air is going inside the mag... and now while its dry air.. which has higher resistance to allowing a spark to cross (oh ya.. think spark plugs too.. and ignition wires... smile)... it does have its drawbacks... the heat.. which cooks parts like greases and seals...

So putting the pressure connection on... well just remember 250 hrs... is your max time for overhaul of the mags... I would think if you don't need them... I wouldn't put them on...

Now... a word about spark plugs and ignition wires...

As you go up... the density of the air decreases...along with mositure... so to make the spark jump the gap in the plug.. is going to require more voltage... yep it goes higher... and if you have a bad wire harness for the ignition... guess what... is going to start jumping out of the wire its in to x fire... to another one that it likes... not firing at the appointed spark plug...it should.... a lot of time it goes to another one that is on the intake side... fuel rich air takes less voltage.... and sparks that plug befor its time ... not good... as it really plays havic with the engine.. but, you don't know it because the prop and the mass motion is greater than the power generated.. but, the engine does...

So you can have a spark plug/ mag/ wire harness that appears perfict down on the ground.. but, up in the air... its a nightmare... and not doing what it should... and no the JPI/EGT doesn't seem to show it...

Ya.. Ya.. so what has this got to do with my broken motor mount... well the stress of the x firing is putting a pulse on the mount... and because it is so repitious it is causing it to flex... and like flexing a piece of bailing wire back and forth so many time... it will break eventually... not to mention what is happening inside to the crankshaft counter weights... which I would have checked too by the way... along with the crank and the prop and hub... as these will be the next things that will start cracking...up... and can actually end up breaking the crank...

so is the maintance of the mags improtant... yep ranks right up their with the fuel... and if you don't do it... well I am sure you all have heard the old saying... you can pays' me now ... or you can pays' me more later ... and here it does make a differance...

If you like we can get into the mags further... as their are several things that you and your mechanic should check for... and we came up with a neet little device to check them... both in flight as well as on the ground... because the impulse springs are another biggie... and most engines don't fire both plugs at the right time...unless you check it out... their are several AD's on the mags we use that don't seem to be complied with... you might want to check it out and make sure your is done too... again.. if their is any interest we can compile a status report that you can check against... along with the AD's and how they are supposed to be complied with... your mechanic should have access to the AD listing.. and it should be posted in the back of your log book... you remember that thing.. its what was supposed to be done to the airplane....

So in closing... this little mini siminar on mags... I suggest that who ever is replacing the motor mounts... (not the rubber stuff)... that you are being given a warning from the engine... something is not right in it... something is either not in time.. or that something was put in wrong... and yes mags can do it... along with bad ignition wires... and now bad counter weights on the crankshaft... as well as bad spark plugs... and one other thing... fuel... valves and lifters... (see that was really 3 things but... just checking...to see if you were paying attention)

checking the log book is the first order.. and using a seperate piece of paper of the computer... put the date, time and maintance or replacement item... and compair it to the current time and problem... (YOU ALL.... should be doing this with yours too... for record keeping... some of the computer gurus might want to come up with a program that others could have to keep records on the computer with.. would be nice)...

you should not be breaking motor mount frames... and if the vibration is so bad that its causing a cable to rub thru... you got a real big problem... that is ringing a really.. really ...big wake up bell... which if not answered.. could cause you to buy the farm... to keep flying it.. is not what you want... to do.. until you can fix the problem... its not normal... and should not be though of as such..... remember I said once the engine does talk to you... well... its limping around...breaking things.... think it has a problem???...

start with the simple things... and work up... but, because it has been going on... its later than you think.. and may end up costing you big bucks.. to have a safe plane... vibrations are deadly... to metal and... to you....

GMAs

[Don Hickman]

P leads were broken. So, when I thought I was turning the mags off I wasn't accomplishing anything. Lesson learned.

Logbook shows that the mags were removed and worked on about 3 years ago which would have been less than 100 hours before I bought the plane given how little it was flown. But my mech says there's no way that any significant work was done on them given the shape they were in. So we're no longer taking the logs at face value and are going to check into everything.

But given the amount of hours I'm putting on the plane (150 in the last 8 months) versus the amount it was previously flown (25 total in the 2 years prior and only about 50/yr for the previous 25 years), I should think that we'll eventually get things working right.

And thanks to GMAS and all the others who have written with info and ideas. I'm saving everything, printing it out and taking it to my mechanic. You guys have all been very helpful.

So, while I'm seeking help, how about someone telling me how to seal the darn avionics compartment? We've tried everything and still it leaks when I fly into rain. The last rain I flew into knocked out my GEM. Now I no longer know my EGTs or TITs or any other temperatures. Sometimes when I fly into rain it knocks out my Shadin fuel flow gauge -- it registers 0 pounds per hour until it dries out.

My mechanic is about at his wits end. Says he's tried everything, sealed every place he can think to seal, put in new silicone gaskets under the access plates in front of the windshield and still it leaks. Not as much as it used to (it would soak my feet!) but still the avionics are getting damp. Hard to do IFR work when you have to stay dry! Any suggestions?