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Dodgy Magneto Overhaul ?

Blimey 4250’s have been obsolete for well over 10 years, I’d be doing some serious looking at my own maintenance regime if I still had one of those fitted with that timescale between overhauls.
Pics look like a bearing has failed for some reason and roasted the internals, it certainly won’t be repairable.
Donate it to a museum and move on.

United Kingdom

I’d say that one doesn’t look overhauled, maybe not even IRAN, but only INSPECTED. Last time zero’ed reads 35 years ago, so what number of flight hours have been done on this max life time limit incl extension 2,000 flight hours part? Btw, I haven’t had an issue with my Slick in decades, just got two new one – knock on wood.

Germany

I have received the following photos from the OP. He was unable to post them (some IT reason)

Administrator
Shoreham EGKA, United Kingdom

Out of interest what model of magneto was it and what was the nature of the failure? Slick magnetos have been notorious for impulse coupling problems for a while now.

United Kingdom

Slick Magneto performance is and always has been less than stellar in terms of reliability and starting performance, when I was running a small fleet of aircraft I always had a spare Mag in the shelf.

It was this unreliability that enabled me to stagger the mag changes so two Mags never got changed at the same time.

The poor starting performance was addressed by fitting a Slick Start to the aircraft , this saved a fortune in battery’s and starter motors as the engines always started at the first attempt even in the hands of the most inept student pilot.

Bendix mags are far more reliable so much so that I can’t remember when the last one I owned failed.

Magneto maintenance is little understood as it seems that a 500 hr check as in the case of this thread been presented as an overhaul, the 8130 states the work done was a 500 hr inspection. So in the case of a slick mag this would be done IAW the SB covering the work and NOT a full overhaul to zero time the Mag.

This discussion about mag failures is a bit pointless when no detailed info is posted about what exactly was wrong. Basically the instrument is not rocket science so I´d like to know what exactly is checked resp. what gets replaced at an overhaul ? Points renewed, likely ? Capacitor new – coil new ?? Nobody can check coils or capacitors and assess their life from that. So it is not right to have a war with the company – unless an overhaul requires new cap and coil – and even so, you can have coil defect in short time as well. So my procedure with new coils is to have the mag run in an oven for 5 hours at 70 degrees for a kind of check at least. And I would not blame the maintenance on this when you get that sort of defect. You´d have to go for the manufacturer of the coil instead. Vic

vic
EDME

The quailty or the replacement parts is pretty shocking to.

But as Peter says comes from an approved company with an approved piece of paperwork.

Yes; an OH involves a replacement of specified parts, paint stripping, NDT, etc. Same as with an engine.

It will be interesting what the outcome of this one is.

Administrator
Shoreham EGKA, United Kingdom

Peter wrote:

Mag overhauls/IRAN is a simple enough task

Overhaul and IRAN are not the same – two different procedures. IRAN is easy, indeed, and can in principle be done by everybody but does not count to zero hours used, for a good reason. Overhaul needs special equipment and quite some expertise – the prices North a thousand are justified, imho, but only if the work was really done. IRAN beyond life time limit is stupid and yes, I missed that myself.

Germany

The “form” means nothing.

This is just really bad workmanship / quality control.

But this is not unusual. Mag overhauls/IRAN is a simple enough task, yet there is so much bad work. All nicely protected by the European Form 1 system.

Administrator
Shoreham EGKA, United Kingdom
15 Posts
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