EFWD Build

[Frontier Fox]

Eddie, you should consider yourself lucky to get 600 hours out of your gearbox. I run a Rotax 912iS and during a routine oil change found a piece of metal on the magnetic plug. It was recommended that it be torn down for inspection, 368 hours. It cost $2250 in parts to rebuilt it. I bought a shop press and did the work myself, pretty straightforward. I was also very careful to keep the RPM’s no lower than 2000, always brought the RPM’s up to 2000 as soon as possible on roll out. I sent pictures and filled out a report for Rotax, no reply so far.

Frontier Fox

[Shadowrider]

Yeah this stinks. Does the 912is share a gearbox with any other engines?

[efwd]

notice the little spray nozzle.

[Frontier Fox]

Eddie,
The early model gearboxes on the 912iS did not have oilers as shown. They were added later when early failures were occurring. My gearbox is a later model so it has the oilers. Another change that was made was in the dog gears. The 912uls has 60 degree lash on the dog gears, but was changed to zero degree on the later iS gearboxes, if memory serves me correctly. If you want more info I recommend talking to a tech at Leading Edge Airfoils.
At this point in the “Space Time Continuum” Rotax has a monopoly on LSA engines. They are excellent engines but do have faults. They charge a premium amount for parts but remember it’s just numbers.

Joe

[Eric Page]

...but remember it’s just numbers.

Funny story... My mom worked in banking for many years. At one point she was supervising a couple of tellers, one of whom wasn't terribly bright. The teller had made a significant (as in, order-of-magnitude) error in tallying her cash drawer and when questioned about it, shrugged it off and said, "Zeroes are just placeholders!"

[efwd]

Well in the end I am so pleased it was found before it trashed the engine. I picked it up today and I notice a huge difference. It has been thrashing around up front for some time I suppose, given how noticeable the improvement. Man, I can't ever recall it being this smooth, even after Dynavibe prior to first flight. Maybe Im crazy and it was once this smooth but Im grateful its fixed and the fact I notice is a plus. I have my paperweight too.

[Cherrybark]

Hi Eddie,

With the same Kitfox / Avionics / Engine configuration, I've always appreciated your posts for advice and "gulp" potential problems. You'll certainly be on my mind while unscrewing the magnetic plug on the next oil change! Thanks for the report and photos. Hopefully the "smoother" gear box will last.

Carl

[efwd]

Hi Carl
here's the rub. All that I ever found on the mag plug was the black iron looking stuff with a bit of glitter mixed in. I have torn open the engine oil filters at oil changes. I never found any chunks or anything, very little glitter too. Sometimes I thought there might be a bit more black fuzz than I figured was normal but....
I even had an engine oil analysis done but all it told me is what everyone said was a normal finding for Rotax. I was told that the corrosion product that was used back in the day has since been replaced with something improved. That detail came about when I asked about why it appeared so dry when we opened it up. I also noticed the rust color crap all over the shaft. It was as if this stuff never washed out. I don't know how thick this stuff was when applied but I can't figure out how the cog gear got bound up in one spot along the splines. I will have to wait another 600hr to see if anything changes. If it is anything like it is now I will have to drop another $1200 for a newer style case I suppose. Now I know the symptom to watch for so I should catch it long before the damage becomes this bad.

[Cherrybark]

Maybe it's time to start the build on that Factory Five Cobra. Your two sons should be reaching the age where a spin in Dad's Cobra sounds perfectly reasonably when he's not around to ask!

[Delta Whisky]

I was going to sand it out and re-do; but, decided it was good to look at when checking the oil before flying so a person always stays humble...

Take care & keep on Kitfoxing

I like the quote - after a close look at my plane you might come away thinking: "What a humble guy!"