Thorp Air Command - T18.net

Feisty has two Bendix mags, the right one having the impulse coupler. During the condition inspection, the right mag timing was observed to be 18.5 degrees TDC. So I set it to 25 degrees TDC and read the engine log and Sac Sky Ranch's book The Magneto Ignition System.
This mag has had the timing slip before, which was caused by wear to the points rubbing block. The E timing of the permanent magnet alternator is no long phased correctly to the opening of the points; now the spark is weak at start up. It almost didn't start when we were at an 'away' airport. In flight mag check was fine.
The points cam is supposed to be immersed in special heated Bendix oil for a half hour, something I can't do as a field repair.
So a new electronic ignition is cheaper than a new mag & harness, but more than a mag 500 hour service & repair. What is the appropriate time to ditch the old mag and update?

_________________
Scott Emery
EAA Chapter 326
T-18 N18TE

When one of my mags poops out Scott, I am going electronic, if they both poop, I am going electronic on both sides.........Dan

I'm never going both electronic, except of course with the S18R. But that one has an auto set up which is way more reliable than any of the aircraft ones out now
Cubes

Scott

I'm running a Mag & Elec. Ign. (EFII product)
Very clean and simple - considering E.I. harness etc.
The ECU is mounted @ the pass. side between Instrument
panel and tank.
Coil is mounted on the firewall (engine side)
The trigger or pick-up is billet mount, very clean, mounts behind flywheel.
Kit comes with harness, plugs, adapters also.
Only about 40 hrs now, so far I like it.
I'm hangered at KAWO if you ever get up there.

Mark

Thanks for reinforcing what I was thinking, and Mark for your offer to show me the EFII system, the very one I'm considering.
I'll probably go one mag and one EFII. Later I think I would remove the vacuum pump and install an SD-8 vacuum pad mounted back up alternator, If I'd go with dual electronic ignition. I like the Pmag self powered idea, I like other features of the EFII and the SD-8 brings the EFII a dedicated back up power supply.

_________________
Scott Emery
EAA Chapter 326
T-18 N18TE

Off subject but the impulse mag should be on the left if you are using a typical bendix style start switch, the start position disables the right mag, impulse is better in the start process.

_________________
Lee Walton
Houston, TX
N51863,N118LW
KEFD

I've been reading about the 500 hr limit on magnetos. Is that true for all mags? I have bendix mags manufactured for a lycoming 0320 E2A in the late 60's. I've rebuilt them several times but really never paid a lot of attention to the hrs. Just did it when I thought they were ready. I'm quite sure I am around the 700 hrs since rebuild. Mags are running good. Any comments?

Jim Borg

I have the Slick Mags...came with the new Aero Sport Power 0-360 . Not sure about the Bendix mags at 500 hours , but from what I have read about my Slick's , it is better to just trade them in at 500 hours as a core for new as the parts/labor/rebuild = a "new" unit ? BOOM ?
RB

Slicks used to be throw away mags, but they have changed models so maybe that policy is a little different.
Aircraft Magneto Services web page has some helpful info on Magneto troubles and services.
http://www.aircraftmagnetoservice.net/
Sac Sky Ranch has a very good booklet on mags.
http://www.amazon.com/Magneto-Ignition- ... pd_sim_b_1
It's possible that any of us could maintain our own mags, after all, they are pretty simple. But some of the problems they have don't seem intuitive, so the SacSky book is helpful. also, you can download an old copy of the Bendix overhaul manual.
http://hhh.gavilan.edu/hspenner/Main/Ma ... agneto.pdf
This in more intimidating, shows the special tools used, and describes processes we can't do at home. Still, you can service your mag to a point.
Lee, as for 'Feisty', yes the impulse mag is on the right side, but also, the key switch turns off the left mag while starting. Strange, I know, but that's the way Fred Ferguson built it.
Also, there is a 1975 Lycoming service bulletin that redirects the routing of the plug leads to: Right mag to bottom plugs on right side, Left mag to bottom plugs on left side. The shorter the plug lead, the hotter the plug spark. Those lower plugs need all the help they can get! 'Feisty" has not been so modified. The Left mag still sparks the lower plugs on the right side.

_________________
Scott Emery
EAA Chapter 326
T-18 N18TE

Stirring up a can of worms here, but so be it. I went with a PMag from EMag a few months ago. Happy with it and the simplicity of the installation. Like the self contained alternator backup power, too. Yeah, I fouled a plug during the flight to OSH, but pretty dang sure that was completely unrelated to the electronic ignition. I just have an old motor and it's starting to use a bit of oil. My fuel economy on the flight to and from OSH was amazing. Flying in formation with Fraser and Cubes I burned about a gallon an hour LESS than they did. Every leg. And they have O-320's, mine is an O-360. Some of that is because of the electronics (some because Lee built such a slick airplane)... It also starts much more easily than it did before.
I'm sold on it, and on the customer service I've gotten from Brad at EMag...

To do a "complete " overhaul of the Slick Mag requires "special tools" to remove the more expensive parts . As I found out doing my research . The "Over Haul Tool Kit" is about $500.00 . The parts that need to be R & R with the "Tool Kit" add up to more than a new Slick Mag . From what I have read , Slick does not accept cores as it is more cost effective to buy new . No BOOM here ! Just $$$$ .

RB

As many of you know, I have had trouble starting my fuel injected 180 HP IO-360 when it was hot. This has gone on for for couple of years. I finally chased the problem down to the magnetos. This after overhauling the servo and the spider on my FI system. I did what many red blooded American men find it hard to do -- I read the directions. With the encouragement of a couple of great airplane mechanics on the field, I tore into the mags, cleaned the guts, set the points to the proper gap (.008-.010) and regapped the plugs to the minimum setting (.015) and reinstalled everything. Cold starts are now on the second blade and hot starts occur after three blades! As for special tools, you need Torques Bits for your screw driver and should you need to remove and replace the coil, you could use the special cam pry bar to remove the locks. My mech buddy has one of those and is willing to lend it to me.

_________________
Bob Highley
N711SH
SN 835
KLAL

More info on the Slick Mags...

RB

After all the discussion about upgrading, I went the passive route and sent the mag in to Aircraft Magneto Services.
I wanted to go with the EFII system, but I'm in the middle of so many other projects. I can't catch up if I increase the scope of every job to make things Mo' Betta'. I decided to go with the unbolt, send out, receive, and bolt back in 'plan'. I should have it back in a few days. I'd like to get it back in the air before winter ends the extended flying season..
I did open the mag points cover and have a look. The points were adjusted all the way to the end of the adjuster slot. The points rubbing block was worn down that much. This generally agrees with what I read in the log book, (mag points reset after noticing timing had slipped) so there is some reason for rapid wear. The mag only has about 340 hours since overhaul, although the engine was assembled in the 1970's and the first flight was 1984. Maybe the points grease dried out or the points condenser might be bad, supposedly the plastic rubbing block gets hot and wears faster, also I have intermittant radio problems which might be the radio auto squelch dealing with this mag's noise. Unfortunatly that does not co-incide with the points contact surface being OK.
Cliff sent me a note explaining the problem on the last set of mags I sent him. I hope he does so again.

_________________
Scott Emery
EAA Chapter 326
T-18 N18TE

Another dream shattered!
The mag requires 'rebuild' instead of 'service'.
$700 or $800 if I want to ugrade the impulse coupler.
The mag was rebuilt in the early 1970s, so the coil and the distributor gear (?) have AD notes for replacement. Plus other wear issues. I was thinking $350 or $500.
So I'm willing to upgrade for the difference. The P Mag looks attractive, although it has a lower spark energy than the EFII unit.
It sure is easy to install in replacement of a mag...

_________________
Scott Emery
EAA Chapter 326
T-18 N18TE