Magneto overhaul

[Jeremy Liber]

Can anyone recommend a good magneto overhauler/fixer? I have a pair of Slick 4301s on the O-200 in my Jodel that could do with a coat of looking at. They've done about 700hours since new and starting is getting difficult.

Thanks

Jeremy

[JohnMead]

Jeremy,
email me re mags.

[Dave Evans]

I had mine done at Norvic Aero Engines, very quick and reasonable.

http://www.norvic.com

[Jeremy Liber]

Thanks Dave and John

I've just had them looked at by Tim at Oaksey Park but heven't run them yet. He was also quick and reasonable so I'm hoping to be able to report a successful outcome.

Jeremy

[Rob Swain]

700 hours?
My inspector insists mags are overhauled at 500 or soon after. He's very good and checks them at the permit renewal / annual inspection and lets us know that they will need doing before next time.

And yes, he did refuse to sign off permit renewal on an RV that he had advised a year ahead and hadn't got them done.

[mike newall]

The 500 hour is an SB, not an AD.

It is not a requirement, it is a recommendation.

That said - if the mags are running fine, don't fiddle and if your Inspector 'insists' on an overhaul at 500 hours......... change your Inspector

[Terry Lee]

The 500 hour is an SB, not an AD.

It is not a requirement, it is a recommendation.

That said - if the mags are running fine, don't fiddle and if your Inspector 'insists' on an overhaul at 500 hours......... change your Inspector

How very true!! Slight drift here but I wonder if anyone has come across this before. A friend of mine has just had a BTH impulse mag overhauled, armature rewound and new condenser etc, its off a Cirrus powered Auster, on the bench the newly overhauled mag produces a big spark, but when bolted to the engine it will not

We have so far proved 100% it has nothing to do with points, ignition harness including plugs, mag switch P lead or points cover. It is so bizarre, this happens, the mag is sat on the floor next to the Auster with a jump lead connecting its casing to one of the mounting studs on the engine, so it is effectively earthed at the same potential as the engine. With a single wire connected to one of the HT outputs on the distributor cap and held a few mm from its casing or the engine and it will spark when turned,
bolt it to the engine and carry out the same test by turning the prop and it will not spark

It is going back to the overhaulers, but if anyone has any ideas or similar experiences we would be very interested to hear!

[Clive Richards]

I do not know this make but is it set up for the correct rotation of the engine so when you turn the prop the magneto turns in the correct direction to release the impulse.

Clive

[Terry Lee]

Clive, yes it is!

Terry

[dangerous pete]

Terry,
If your mags work ok off the engine then they are ok. There must be something wrong on the engine. At a guess it could be the earth return gone high resistance. Refit the mags and run a temporary wire from the mag case to the cylinder head near the plugs. This will eliminate any dodgy contacts through nuts/bolts/washers etc.
Jeremy,
Have just had the mags off our A65, done after 500 hrs. Oil had got inside through the oil seals, and there were various things iffy inside. The cost by Swiftair at Leicester was over £800. Our mags are Bendix, and they have a lot of single use parts, which all have to be replaced. There was also mandatory replacement for some of the parts. The cost is worth it just for peace of mind. Slick mags apparently do not have single use parts on them and are consequently cheaper to overhaul.
Dont go down the 'dont disturb if ok' route, things wear out, oil gets in, I have a friend who was dropped out of the sky by oily mags, ok when cold, stop working on climbout.
Pete.

[Terry Lee]

The fault has now been identified, it is the impulse. whilst on the bench if you turn the impulse and let go immediately after the click it sparks every time, but, if you keep hold of the impulse coupling after the click, as though simulating it being on the engine with the drag of the gear etc
it will not spark, so there is some unwanted friction somewhere which is proving very difficult to eliminate. I should add we have replaced the main spring but still its being obstinate.

[Rob Swain]

The cost [of overhaul] by Swiftair at Leicester was over £800.

Isn't a brand new pair of Slicks about that, after the core return discount?

Probably the route I'd go.

[Jeremy Liber]

Magnetos overhauled by Tim at Oaksey Park. Quick turnaround at a reasonable cost and they now work fine.

We also had a problem with a tired and sha**ed out carburettor (probably done 2200 hours plus) which was making starting very iffy and, at the last attempt, we were 200rpm down on the (attempted) take-off roll.

Carburettor removed and sent to Nicholson Mclaren for complete overhaul. Again it was turned around in less than a week, £560 plus VAT. It has transformed the engine. Starts easily, runs smoothly throughout the rev range and ticks over better at about 600rpm. Looks nice too.

[Rob Swain]

Carburettor removed and sent to Nicholson Mclaren for complete overhaul. Again it was turned around in less than a week, £560 plus VAT.

Assuming it is a Marvel Schebler carb, you can get a brand new new one for not much more than that. (Adams Aviation)

[dmcnicholl]

The 500 hour is an SB, not an AD.
It is not a requirement, it is a recommendation.

How very interesting. Is there an 'official' statement of that somewhere? I'm not doubting you but it would be nice to have in the locker at my next annual.