Mag drop

alindsay

alindsay

Pre-Flight
Joined
May 24, 2007
Messages
93
Location
Omaha area
Display Name
Display name:
Allan
My mag drop at run-up has always been great - 50 to 75 on the right mag and 25 to 50 on the left. Last few times I've flown, the drop for the right mag is now 100 and the left is 75.

Timing is the obvious thought but is this an indication the mags are getting worn? Condenser problem? Should I be worried?

On my last plane, I had 2 occasions where I was stranded because of Mag problems. I have a x-cntry planned in August and would rather prevent a problem vs react to a problem.

Any thoughts?

Thanks,

Allan Lindsay
 
alindsay said:
My mag drop at run-up has always been great - 50 to 75 on the right mag and 25 to 50 on the left. Last few times I've flown, the drop for the right mag is now 100 and the left is 75.

Timing is the obvious thought but is this an indication the mags are getting worn? Condenser problem? Should I be worried?

On my last plane, I had 2 occasions where I was stranded because of Mag problems. I have a x-cntry planned in August and would rather prevent a problem vs react to a problem.

Any thoughts?

Thanks,

Allan Lindsay
Click to expand...

I'd suggest AT LEAST getting an A&P to look into that. Certainly what I'd do. :yes:
 
coup'la things...

It really makes it a lot easier for us to help diagnose or suggest things to look at if we know the make/model of aircraft and if something like this magneto related problem the make of the mags and what the logbook says was the last time somebody replaced internal parts ... points being high on the list.

In the order of probability ... spark plug lead (as in tetraethyl lead, not the wires) buildup and gap...loose plug wire...timing(*)...internal mag parts, points most probably. (*)timing can't "wander" as the mag is held down fairly tightly by a 9/16 nut; timing off indicates that the internal mag timing has drifted due to wearing parts. If the internal parts have worn to the point where timing is affected, it is time to open that sucker up and start to find the worn parts.
 
Just an afterthought...

Ask your local fixit shop if they would save you sparking plugs that they've removed from service that still have some life left in them. Mostly when you do an engine swap and/or a top overhaul, it is normal to just replace plugs with new plugs "just because".

There is a place that specializes in plug cleaning and gapping. Last time I looked they were doing it for a little under $5 a plug. The place is down in Van Nuys CA and it is called Aircraft Spark Plug Service. They do an absolutely pristine job and return your plugs in sealed plastic tubes. The shelf life of those plugs in sealed tubes is nearly limitless. They also send you a fresh set of annealed copper plug washers.

Keep a full set of plugs on the shelf so that when you have a problem of this sort, you simply pull the known good plugs off the shelf and send the old plugs in to ASPS for service. Putting known good plugs in a 4-banger can be done for less than $50, and your time is worth something.
 
Thanks for the replies - I have a 1979 Warrior II and there are ~675 hrs SMOH and I don't think the mags have had any work since 0 SMOH.

At first I thought it was lead so I leaned for 1 min at runup. Not much difference. But I did a couple of tests today and I saw the drop go back to 75 for the right mag and 50 for the left mag. the next time I tested it went back to 100 & 75.

Looks like it's time to get this looked at. Sucky part is I'm scheduled to fly a lot this next week since I'm working on my IR and it's OSH week so nobody is around.

thanks again,

Allan
 
Oy. You solved the problem temporarily by burning off the first layer of lead and you wondered why it came back? That's PROBABLY because you only burned off enough to make that one test valid.

Please, don't guess. And your logs should show when the mags were serviced. Don't assume that they were done at MOH. And if the plugs haven't been cleaned since MOH, good gravy, you are about 500 hours late.

Pull the plugs. Have somebody that knows what lead balls look like have a gander at them.

Dont'cha be guessing at what is causing the problem without twisting a screwdriver and bending wrenches. You CAN perform "preventive maintenance" including plug removal and replacement as the owner, you know?

As with all my students and owner-assisted maintenance folks, I suggest you find a copy of Richard Bach's "Found at Pharisee" and "School for Perfection", both in a collection of his short stories called "A Gift Of Wings".

Jim

Jim
 
school for perfection is classic. i dont recall found at pharisee. Ken still has my copy of "A Gift of Wings" (nudge nudge ;))
 
weirdjim said:
Please, don't guess. And your logs should show when the mags were serviced. Don't assume that they were done at MOH. And if the plugs haven't been cleaned since MOH, good gravy, you are about 500 hours late.

Pull the plugs. Have somebody that knows what lead balls look like have a gander at them.

Dont'cha be guessing at what is causing the problem without twisting a screwdriver and bending wrenches. You CAN perform "preventive maintenance" including plug removal and replacement as the owner, you know?
Click to expand...

Ok, nothing personal, Allen, because I don't know if this applies to you, but there are people who just shouldn't ever be allowed access to a screwdriver.

A couple examples from my years in the auto industry:

Engineer: I need to borrow a hammer, pliers and a file
Tech: Why?
Engineer: I put a new battery in a car and the terminals don't fit - one is too big and the other is too small.

Engineer: Do you know how to get the cylinder head of a 19xx blah blah?
Me: Why?
Engineer: I was trying to do a compression test and the thing that screws into the spark plug hole got stuck and I can't get it out.

Spark plugs can be cross-threaded, torqued improperly, etc. If you are handy with tools and have some mechanical background, great! Go for it.

If, on the other hand, you don't know which end of a screwdriver to pound with... well, perhaps your aircraft engine is not the best place to learn.

Again, nothing personal. And I'm not suggesting that many owners shouldn't do things like change plugs, change the oil, pull the engine to get a major overhaul, or do the overhaul yourself (with a mechanics signoff), or stuff like that. But there are some...
 
weirdjim said:
Oy. You solved the problem temporarily by burning off the first layer of lead and you wondered why it came back? That's PROBABLY because you only burned off enough to make that one test valid.

Please, don't guess. And your logs should show when the mags were serviced. Don't assume that they were done at MOH. And if the plugs haven't been cleaned since MOH, good gravy, you are about 500 hours late.

Pull the plugs. Have somebody that knows what lead balls look like have a gander at them.

Jim
Click to expand...

Large mag drops, for us, are mostly caused by lead fouling. We get fouling on the trainers at as little as 25 hours, especially on cool-running engines like the O-235. At 50 the bottom plugs are pretty much full unless the airplane has done a pile of cross-country flying. 100LL has four times the lead content that 80 has, and a lot of engines were designed for 80.
For the worst engines we use REM37BY Champions rather than the REM40E or 38E. These have an extended electrode setup that doesn't get shorted out by lead deposits.
A photo comparison of the two types is shown here, but the caption has it backwards; the REM37BY is on the left:
http://www.sacskyranch.com/combustionClean.htm
Make sure your engine is listed by Champion as OK for the 37s.

Dan
 
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Capt. Geoffrey Thorpe said:
Ok, nothing personal, Allen, because I don't know if this applies to you, but there are people who just shouldn't ever be allowed access to a screwdriver.

A couple examples from my years in the auto industry:

Engineer: I need to borrow a hammer, pliers and a file
Tech: Why?
Engineer: I put a new battery in a car and the terminals don't fit - one is too big and the other is too small.

Engineer: Do you know how to get the cylinder head of a 19xx blah blah?
Me: Why?
Engineer: I was trying to do a compression test and the thing that screws into the spark plug hole got stuck and I can't get it out.

Spark plugs can be cross-threaded, torqued improperly, etc. If you are handy with tools and have some mechanical background, great! Go for it.

If, on the other hand, you don't know which end of a screwdriver to pound with... well, perhaps your aircraft engine is not the best place to learn.

Again, nothing personal. And I'm not suggesting that many owners shouldn't do things like change plugs, change the oil, pull the engine to get a major overhaul, or do the overhaul yourself (with a mechanics signoff), or stuff like that. But there are some...
Click to expand...

Ha - I know what you mean. I can change plugs and am pretty good at the allowed maint items a pilot can do but since I haven't had the time to get an A&P involved, I thought I would throw the problem I was having up on the board for ideas.

I agree the logs should tell all but they are at the hangar and I haven't dug thru them yet for the mag hrs. I do know I assisted with my annual last May and cleaned the plugs. I do have all of the tools to do this and it's my next check when I get to the plane.

As I said before, I have been stranded twice before with mag problems. It's one of those things that really get me nervous now. Since I bought the plane in Jan of 2007, the mag drop has been great except for a couple of times last winter when I needed to lean for roughness.

I do appreciate the feedback and will let you know what I find.

Allan
 
alindsay said:
Ha - I know what you mean. I can change plugs and am pretty good at the allowed maint items a pilot can do but since I haven't had the time to get an A&P involved, I thought I would throw the problem I was having up on the board for ideas.

I agree the logs should tell all but they are at the hangar and I haven't dug thru them yet for the mag hrs. I do know I assisted with my annual last May and cleaned the plugs. I do have all of the tools to do this and it's my next check when I get to the plane.

God Dammit, you haven't "had the time to get an A&P involved" and "haven't dug through the logs for the mag hrs" you come on here and waste our time with wild ass guessing as to your problem?

Sonny, when you do YOUR work, we'll do ours. Until then, go away.

Jim
Click to expand...
 
jeez jim, i think that if Al had already know all the answers he wouldnt have had to ask us.
 
weirdjim said:
God Dammit, you haven't "had the time to get an A&P involved" and "haven't dug through the logs for the mag hrs" you come on here and waste our time with wild ass guessing as to your problem?

Sonny, when you do YOUR work, we'll do ours. Until then, go away.

Jim
Click to expand...

My goodness, Jim. Was all that necessary? :rolleyes:
 
weirdjim said:
alindsay said:
Ha - I know what you mean. I can change plugs and am pretty good at the allowed maint items a pilot can do but since I haven't had the time to get an A&P involved, I thought I would throw the problem I was having up on the board for ideas.

I agree the logs should tell all but they are at the hangar and I haven't dug thru them yet for the mag hrs. I do know I assisted with my annual last May and cleaned the plugs. I do have all of the tools to do this and it's my next check when I get to the plane.

God Dammit, you haven't "had the time to get an A&P involved" and "haven't dug through the logs for the mag hrs" you come on here and waste our time with wild ass guessing as to your problem?

Sonny, when you do YOUR work, we'll do ours. Until then, go away.

Jim
Click to expand...

First, this isn't wasting anyone's time, at least no more than any other thread in this totally optional read-at-your-leisure forum.

Second (and I hope a mod will chime in), we try not to yell at each other except in the spin zone, and we try very very hard not to curse at each other.

So, if you feel this thread is somehow an affront to your work ethic, value system, or beliefs, perhaps you could go away and ignore the thread.
Click to expand...
 
Yeah. I get $150 an hour as a diagnostic engineer in a lot of fields, aviation maintenance being one of them. If you'd simply like me to bypass this group, I'll be happy to do so and let a lot of ignorant folks help a lot of other ignorant folks, so be it. No problem. I'm certainly not earning my salt giving advice for free, am I?

I've been analyzed multiple times for personality defects and the one that stands out the most is that "he doesn't suffer fools graciously". I'll cop to that.

Jim
 
jim,

none of us are requiring that you be on here to offer technical advise. we all basically volunteer our time here providing advice to people who ask something that we know about. if its that big of a deal to you then maybe you just shouldnt worry about it.
 
tonycondon said:
jim,

none

That would be "None"

of us are requiring that you be on here to offer technical advise.

That would be "advice".

we all basically volunteer our time here providing advice to people who ask something that we know about.

That would be "We".


if its that big of a deal to you then maybe you just shouldnt worry about it.
Click to expand...

That would be shouldn't.

Not a big deal. Just don't waste my time asking questions that are still in the logbook in the hangar because you haven't had the gumption to go over and look them up. Both you and I have better things to do with our time than wild-ass guess answers to things that are well-documented in the logbooks that the op didn't have the time to go look up.

Jim
 
weirdjim said:
Yeah. I get $150 an hour as a diagnostic engineer in a lot of fields, aviation maintenance being one of them. If you'd simply like me to bypass this group, I'll be happy to do so and let a lot of ignorant folks help a lot of other ignorant folks, so be it. No problem. I'm certainly not earning my salt giving advice for free, am I?

I've been analyzed multiple times for personality defects and the one that stands out the most is that "he doesn't suffer fools graciously". I'll cop to that.

Jim
Click to expand...

And I used to get $350 an hour just to sit down in the left seat and turn props. So what? Ignorant folks? Pardner, there are some full-blown rocket scientists on this forum. I think it's somewhat presumptuous of you to think you're the only one here with two brain cells to rub together. Neither is this site commercial in nature. We come on here to talk to other pilots, not make money. "Suffer fools graciously"? So far, I've only run onto one fool on this forum, and it ain't Tony Condon.
 
Could one be simply seeking out common areas to cause a given symptom? They may not feel confident in handling the task entirely on their own but may want to know what a mechanic should be looking for on first review as a way to keep from being hosed on time. I've posed such questions on different areas.
 
Jim -
Take a deep breath my friend. We are all here to "talk" and offer opinions on a variety of topics.
 
Pardner, there are some full-blown rocket scientists on this forum
**************

Yeah, and I've got my initials on hardware on the moon and Mars. your rocket scientists notwithstanding. BFD. I don't make a big deal of it until I get into a ****ing match like this.

Now, let's back this on down unless you want to keep the argument going.

I asked for the make and model of the aircraft and was told it was an "Arrow II". That means snot to looking up the TCDS. It is a PA***. I'm not about to do the homework to look up what the transformation is between the two. I don't have the time. If you "rocket scientists" want to do the homework, help yourself.

Jim
 
weirdjim said:
Yeah. I get $150 an hour as a diagnostic engineer in a lot of fields, aviation maintenance being one of them. If you'd simply like me to bypass this group, I'll be happy to do so and let a lot of ignorant folks help a lot of other ignorant folks, so be it. No problem. I'm certainly not earning my salt giving advice for free, am I?
Click to expand...
And there are plenty of us that can make plenty of money in our fields but this place isn't about money--NOR is anyone demanding you answer the question.

I use this rule on forums: "If you don't have something nice to say, don't say anything". I've found the more I stick to that--the more fun this place can be. Not only that you can gain the respect of some great people.

weirdjim said:
I asked for the make and model of the aircraft and was told it was an "Arrow II". That means snot to looking up the TCDS. It is a PA***. I'm not about to do the homework to look up what the transformation is between the two. I don't have the time. If you "rocket scientists" want to do the homework, help yourself.
Click to expand...
If you don't want to do the work--don't. I've done my fair share of work to answer questions on forums and often it has paid off. If it becomes too much work--I just don't answer. The great thing about forums and the nature of a public thread is that no one is expecting you to do anything.
 
I use this rule on forums: "If you don't have something nice to say, don't say anything". I've found the more I stick to that--the more fun this place can be. Not only that you can gain the respect of some great people.


If you don't want hard questions about maintenance answered and the idiotic posting from people who don't have a clue about the answers, then stick to your "fun" answers.

As to the "respect" from the great people, I've got enough in my file to last for several lifetimes. You could start with Yeager and work through Rutan (both of them), but I suspect that would be somewhat outside your realm of reality.
 
weirdjim said:
I use this rule on forums: "If you don't have something nice to say, don't say anything". I've found the more I stick to that--the more fun this place can be. Not only that you can gain the respect of some great people.


If you don't want hard questions about maintenance answered and the idiotic posting from people who don't have a clue about the answers, then stick to your "fun" answers.

As to the "respect" from the great people, I've got enough in my file to last for several lifetimes. You could start with Yeager and work through Rutan (both of them), but I suspect that would be somewhat outside your realm of reality.
Click to expand...

Man. You crack me up. That is all I have to say...Thanks for the laugh.
 
sheesh, let's try this approach:
plop, plop, fizz, fizz!

xm4oy0.jpg
 
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jesse said:
Man. You crack me up. That is all I have to say...Thanks for the laugh.
Click to expand...


Laugh your ass off...would you like me to post my wedding certificate from Oshkosh '07 listing the best man and wedding party? And signed and formalized by the Great State of Wisconsin?

Jim
 
weirdjim said:
Laugh your ass off...would you like me to post my wedding certificate from Oshkosh '07 listing the best man and wedding party? And signed and formalized by the Great State of Wisconsin?

Jim
Click to expand...

I'm not sure you get it. I really don't care? Being rude and acting with complete disregard to the original poster doesn't earn my respect. I really don't want to fuel this thread any further.

So--with that--This is my last post in this thread.
 
jesse said:
I'm not sure you get it.

I got it 5x5. I'm not altogether sure you got it.

I really don't care? Being rude and acting with complete disregard to the original poster doesn't earn my respect.

I asked the OP for some hard data. You got a problem with that?

I really don't want to fuel this thread any further.

So go away\

Jim
Click to expand...
 
jesse said:
Man. You crack me up. That is all I have to say...Thanks for the laugh.
Click to expand...

You know, Jesse, I was never sure what one of those 'trolls' was that I see people writing about - until now. Pretty sad, huh.
 
Let'sgoflying! said:
A place I pledge never to buy from:

Can you just imagine the "customer service" from this place!

http://www.rst-engr.com/
Click to expand...


You betcha. We cater to people who know what the hell they are doing. We spend HOURS on the phone helping folks who want to help themselves.

I consider it a violation of this ng standards to post a URL without any other considerations.

NG moderators, what say you?

Jim
 
I'm not an A&P, just a pilot and owner. The OP has a cherokee (IIRC) and the
mag drops are well within limits albeit not nominal. So why is the mag drop
something to worry about? sure, monitor it, but worry?
 
Bob Noel said:
and the mag drops are well within limits albeit not nominal. So why is the mag drop something to worry about?
Click to expand...
Anytime there is an abrupt change in the readings you see on the gauges you should find out what is happening.

-Skip
 
The only statement I had problem with in this whole thread was ,

"God Dammit, you haven't "had the time to get an A&P involved" and "haven't dug through the logs for the mag hrs" you come on here and waste our time with wild ass guessing as to your problem?

Sonny, when you do YOUR work, we'll do ours. Until then, go away.

Jim""

And maybe trying to rationalize it. by telling who good he was.

Jim, I bought 4 of your head set kits way back in the 90's they are still working but they ain't nothing special.
 
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OK, everybody -- knock it off. If someone acts inappropriately, bring it to the MC's attention, and let us handle it privately. Let's all go back to talking about the mag drop problem and leave the ticking offs to the MC.

Thanks,
Ron Levy
PoA MC
 
Ron,

An "I got it, thanks" from an MC member would help those of us who DID alert the MC that the problem is being addressed. As it is, the silence is deafening. I sent in a notification yesterday.

Thanks!
 
So sorta back on topic...

I agree that not every pilot should be turning wrenches on his/her airplane.

Why?

Lack of expertise, lack of tools, and (probably most often) lack of time.

For most GA pilots, aviation is an avocation -- in other words, money spent exceeds money earned.

While we'd all want every pilot to know as much as possible about every rivet in his/her bird, the reality is that is simply not going to happen.

Expecting such or requiring such from a population not made up of the mechanically-inclined is foolish.

I've had to walk airplane owners (not only new owners) through their own airplane logbooks and show how various inspections are logged and how to derive the next due date.

This does not shock me, and neither am I all that put off. Quite frankly the standard training systems/programs/syllabi are woefully inadequate regarding ownership.

The overall intent of vehicle design over the past 50 years has been towards insulating the owner from the realities of the mechanics. You can see this in cowling covers -- you'd better have time and help to remove some of the Cessna and Piper cowlings to really get a good look at the powerplants.

(Beech did good on the Bonanza models -- the A36 has a couple of latches per side -- in 10 seconds the entire engine compartment is accessible).

Anyway, mechanics will always bemoan the lack of knowledge on the part of the owners and pilots.

But -- start telling the average A&P your troubleshooting method and your conclusions and see how highly appreciated your "mechanical knowledge" is.

This is a never-ending divide with the anomalies being temporary truces and alliances forged from time to time.
 
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