Mags

O

OldNewbie

Filing Flight Plan
Joined
Jan 27, 2015
Messages
1
Display Name
Display name:
OldNewbie
Is it legal for a Private Pilot to replace mags?
 
Or if you do it under the supervision of a AP
 
Tom-D said:
Do you know how?
Click to expand...
Doesn't really matter to the FAA -- unless it's an E-AB or there's an A&P supervising/signing, it's not legal no matter how much the pilot knows about doing the work.

Now, that's not to say that it wouldn't be a good exercise to get with your licensed mechanic and do the work under his/her supervision, including learning how to do it if you don't know how already. I think the more you know about your aircraft, the better. But for Standard category aircraft, just knowing how isn't enough to satisfy the FAA.
 
Last edited:
Ron Levy said:
Doesn't really matter to the FAA -- unless it's an E-AB or there's an A&P supervising/signing, it's not legal no matter how much the pilot knows about doing the work.
Click to expand...

Point is, if he doesn't know how he won't get it done anyway.

who would sign him off under the supervision, when the engine won't run?

Square 1, step 1, does he know how?

The rest of your edit is well taken.
 
Last edited:
Tom-D said:
Point is, if he doesn't know how he won't get it done anyway.
Click to expand...
That assumes lack of the legally-required supervision.

who would sign him off under the supervision, when the engine won't run?
Click to expand...
If the engine doesn't run after the mechanic "personally observes the work being done to the extent necessary to ensure that it is being done properly and ... is readily available, in person, for consultation" as required by 14 CFR 43.3(d)), there is a larger problem with which to deal, namely, the supervising mechanic's competence.

Square 1, step 1, does he know how?
Click to expand...
If done legally with a competent mechanic's supervision as required by 43.3(d), that takes care of itself -- just might take a bit longer. :wink2:

Like the old mechanic's shop sign:

LABOR RATES
I do the work -- $50/hour
You watch while I do the work -- $75/hour
You work while I supervise -- $100/hour
 
Experimental yes, certified no.

I pulled the magnetos on my experimental last year, completely tore them down,rebuilt them (using parts I pulled from magnetos I bought from a pawn shop), and reinstalled them, and put it all in the log book. I had no idea how to do it before I started but that has never stopped me with anything else in life.

Believe it or not - tractor forums were the best reference for how to properly rebuild them.

They're working great, BTW.
 
When you go to a quality auto show you immed. Realize that to these types, the ones that rebuild these beauty's, an aircraft engine like a cessna, Piper, etc would be child's play. I would venture to say that the majority of these rebuilders are as good or better than the average aircraft mechanic. A magneto would not bother them a bit. Many good aircraft mechanics either came from cars or do both.( many replacement parts on the cessna 195 were obtained at a car parts store)
 
Last edited:
jesse said:
Experimental yes, certified no.

I pulled the magnetos on my experimental last year, completely tore them down,rebuilt them (using parts I pulled from magnetos I bought from a pawn shop), and reinstalled them, and put it all in the log book. I had no idea how to do it before I started but that has never stopped me with anything else in life.

Believe it or not - tractor forums were the best reference for how to properly rebuild them.

They're working great, BTW.
Click to expand...

Did you, or did you not, time them 180 degrees out?
 
Ron Levy said:
If the engine doesn't run after the mechanic "personally observes the work being done to the extent necessary to ensure that it is being done properly and ... is readily available, in person, for consultation" as required by 14 CFR 43.3(d)), there is a larger problem with which to deal, namely, the supervising mechanic's competence.
Click to expand...

You forget, the supervisor must make the decision on how much supervision they must apply, with out knowing the workers knowledge they can't do that.

step 1, square 1, do you know how to do this? No/Yes directs what you do next.

I don't understand how a CFI doesn't know the thought process of understanding what a student knows and what they must teach and what they simply can verify and go from there.
 
Tom-D said:
Did you, or did you not, time them 180 degrees out?
Click to expand...

lmfao, ok Tom... Did I or did I not sort that out? Everything you work on works the first time and you never do something incorrectly that you fix when your quality checks don't make sense?

If so, please...move to Nebraska. I'd love to give you a job building technology...because I've never met someone that does so without mistakes, professionals or not.

Let'see....

Looks like in this thread you wired an intercom incorrectly and were lucky you didn't fry it:
http://www.pilotsofamerica.com/forum/showthread.php?t=66591

It took me 30 seconds to find that. I'm sure I could find a lot more mistakes you've made. But I don't care to because I recognize everyone makes mistakes regardless of whether or not they hold a certificate. Plenty of NTSB reports to back that up.

As to my particular mistake, big deal? I knew it wouldn't matter if I had it wrong because I would know it was wrong as soon as I pulled the prop through. So the plugs sparked on the exhaust stroke. That hurts absolutely nothing and you won't be flying anywhere like that. I fixed it. I posted here for some advice because there are plenty of people who are willing to give advice without being a dick.

I don't expect to fix something on my airplane faster than an A&P can. I enjoy working on it and would rather spend my time than pay for someone elses. I ask A&Ps when I have questions and have plenty that give advice nicely. I do know that when it's done, I'll have it done right, because I'm detailed as hell with such things.
 
Last edited:
jesse said:
lmfao, ok Tom... Did I or did I not sort that out? Everything you work on works the first time and you never do something incorrectly that you fix when your quality checks don't make sense?
Click to expand...

You bet, what doesn't kill ya, should make you smarter :)

Try timing an engine that turns the other way.
 
Tom-D said:
Try timing an engine that turns the other way.
Click to expand...
Send me one that's better than my A75 and I'll bolt it up and give it a run. I can find the right BTDC position now in a minute or so. I've done it like 50 times now. lol...

Speaking of which, any idea why the service manual for the A75 calls for one mag to be at 32 degrees and the other at 29 degrees (i think those are the values, either way they're different). When I bought it they were both at the same position and it was less likely to kickback like that...but I set it to what the manual called for when I rebuilt the mags..it's just way easier to have it kickback when propping now.
 
jesse said:
Send me one that's better than my A75 and I'll bolt it up and give it a run. I can find the right BTDC position now in a minute or so. I've done it like 50 times now. lol...

Speaking of which, any idea why the service manual for the A75 calls for one mag to be at 32 degrees and the other at 29 degrees (i think those are the values, either way they're different). When I bought it they were both at the same position and it was less likely to kickback like that...but I set it to what the manual called for when I rebuilt the mags..it's just way easier to have it kickback when propping now.
Click to expand...

Wouldn't the 32 degree mag be carrying the load? it would fire first. the 29 degree mag would be firing into a burning mass.

TCM back in the day wanted a bigger split between the two positions. we now set them at 30+- 1 If I remember right that was a way old SB.
 
Last edited:
jesse said:
Send me one that's better than my A75 and I'll bolt it up and give it a run. I can find the right BTDC position now in a minute or so. I've done it like 50 times now. lol...
Click to expand...

Find the proper TDC, mark it on the prop flange, back it up 30 degrees and mark that. then all you need to do the next time is, leave the #1 plugs in, remove 1 from the other three cylinders, then find the compression stroke of #1, by feel. then go to your marks.
 
Tom-D said:
Find the proper TDC, mark it on the prop flange, back it up 30 degrees and mark that. then all you need to do the next time is, leave the #1 plugs in, remove 1 from the other three cylinders, then find the compression stroke of #1, by feel. then go to your marks.
Click to expand...

That would work but I bought a fancy digital setup that I need to use to justify the cost :). I'll try to find that service bulletin.
 
Tom-D said:
Wouldn't the 32 degree mag be carrying the load? it would fire first. the 29 degree mag would be firing into a burning mass.

TCM back in the day wanted a bigger split between the two positions. we now set them at 30+- 1 If I remember right that was a way old SB.
Click to expand...

Hmm..This SB was published in 2010 and calls for the 29/32. I'm not a big fan of its kickback tendency like that thought.

http://www.tcmlink.com/pdf2/msb94-8d.pdf
 
jesse said:
That would work but I bought a fancy digital setup that I need to use to justify the cost :). I'll try to find that service bulletin.
Click to expand...

lmao, that engine was build using the hammer and file techno, and you are using a digital angle finder on it.

Funny
 
jesse said:
Hmm..This SB was published in 2010 and calls for the 29/32. I'm not a big fan of its kickback tendency like that thought.

http://www.tcmlink.com/pdf2/msb94-8d.pdf
Click to expand...

That is a new SB. that doesn't make much sense. time it like a C-65 in table 2. you will like it a lot more when it doesn't kick back.

The wording in the para telling how to find TDC is weird too. It simply means to turn the engine in the direction of rotation until it touches the piston stop, mark that spot. then opposite rotation until it touches the piston stop. Mark that position. remove the piston stop, rotate the engine in direction of rotation until a point half way between those two marks is reached, that is TDC.
 
Tom-D said:
That is a new SB. that doesn't make much sense. time it like a C-65 in table 2. you will like it a lot more when it doesn't kick back.

The wording in the para telling how to find TDC is weird too. It simply means to turn the engine in the direction of rotation until it touches the piston stop, mark that spot. then opposite rotation until it touches the piston stop. Mark that position. remove the piston stop, rotate the engine in direction of rotation until a point half way between those two marks is reached, that is TDC.
Click to expand...
That's basically what I did the first time. Problem is I didn't check to make sure I was on the compression stroke to begin with and was actually on the exhaust stroke. That is how I ended up perfectly 180 degrees off.
 
jesse said:
That's basically what I did the first time. Problem is I didn't check to make sure I was on the compression stroke to begin with and was actually on the exhaust stroke. That is how I ended up perfectly 180 degrees off.
Click to expand...

That is important. Forget a step, be messed up.
 
Tom-D said:
That is important. Forget a step, be messed up.
Click to expand...

Yeah. It's a step that wasn't mentioned in the directions of my over-priced fancy digital TDC finder deal.
 
Tom-D said:
You forget, the supervisor must make the decision on how much supervision they must apply, with out knowing the workers knowledge they can't do that.
Click to expand...
If that were true, nobody could supervise anything. As I said, if the mechanic is competent, s/he will supervise properly based on his/her knowledge of the person doing the work. Absent any knowledge, a competent supervisor supervises very, very closely. And if the mechanic is not competent, it doesn't matter who's doing the work -- it won't get done right.

I don't understand how a CFI doesn't know the thought process of understanding what a student knows and what they must teach and what they simply can verify and go from there.
Click to expand...
Oy. So what, you think when someone comes to me for training, I just let them go fly and then see if they crash? :nonod:
 
Clark1961 said:
methheads who haven't stolen anything else...
Click to expand...

My guess is this pawn shop bought them at an estate sale or something. Not sure. They have a ton of them although they're mostly junk, and missing parts. Order enough junk magnetos and you'll get enough spare parts to build a few good ones.
 
jesse said:
Believe it or not - tractor forums were the best reference for how to properly rebuild them.
Click to expand...


I can believe it.

I'll bet you also found that the posters there are generally nicer and more humble than in a pilot's forum, and their posts are shorter.
 
Just as much nonsense about turnips though.
 
Ron Levy said:
If that were true, nobody could supervise anything. As I said, if the mechanic is competent, s/he will supervise properly based on his/her knowledge of the person doing the work. Absent any knowledge, a competent supervisor supervises very, very closely. And if the mechanic is not competent, it doesn't matter who's doing the work -- it won't get done right.

Oy. So what, you think when someone comes to me for training, I just let them go fly and then see if they crash? :nonod:
Click to expand...

Done confuse reality and common sense with what is legal.

I wouldn't allow you to open the box prior to knowing your back ground and how to proceed.

Do you treat you instrument students the same way as your primary students? Have you ever taken over training of a student of another instructor? did you treat them as a primary student and start over?

When mentoring any owner doing their own maintenance I treat each as an individual, what they know provides me with a means of judging what I can allow them to do.
 
You must log in or register to reply here.
Back
Top