912is back to a 912

Re: 912is back to a 912

by Glenn Martin » 9 years ago

Glenn Martin

4 291 858

I think it must be your specific installation.
we have about 7 912IS engines in my local area and so far no gearbox issues. I would also look at the Prop, inertia, balancing, and any places that are non standard that could setup a harmonic. That is things like rubber isolators of incorrect shore hardness etc.

Check that you have a battery as large as specified in the 912 IS installation manual, it is bigger than a ULS one low voltage on starting is hard on gearboxes and sprag clutches.

Good luck

Re: 912is back to a 912

by geoffrey klestadt » 9 years ago

geoffrey klestadt

27 94 94

Malcolm, what fuel are you using? I am aware of a commercial user who has done 3 gearboxes - all on 100LL. There is a suggestion that the gear backlash settings on the 912 iS might be a little tight for regular Avgas use with lead buildup.

I don't think there is a general problem with gearboxes, otherwise it would be all over the internet.

Re: 912is back to a 912

by Richard Boslaugh » 9 years ago

Richard Boslaugh

9 122 84

I have had my 912iS gear box rebuilt 3 times. Engine has 200hrs. total time. I have used 92 mogas all 200 hrs. I am inspecting oil filter every 25 hrs. as at the second rebuild enough metal was found to require the Rotax contaminated oil proceedure including new oil cooler. All rebuilds were rotax warranty.

Re: 912is back to a 912

by Glenn Martin » 9 years ago

Glenn Martin

4 291 858

I am sure you have it correct,

But can you confirm what UK 92 Mogas actually is ?

there are three common ways of measuring Octane, RON, MON and AKI (RON + MON/2).

In New Zealand the "pump gas" is displayed as RON.

92 RON is NOT high enough for a 912IS engine. The 912IS manual states a minimum of RON 95.

Therefore I need to use "95 octane" in NZ although the placards say minimum 92 as that is AKI not RON .

Re: 912is back to a 912

by Richard Boslaugh » 9 years ago

Richard Boslaugh

9 122 84

Hi Glen, Richard Boslaugh here. I am located in the US. The normal octane rating in the US is AKI. (average of RON and MON). So 90-94 AKI is equivalent to 95-99 RON. For those reading that have never heard of AKI it is the anti knock index of the particular blend. Also 92 Mogas has no ethanol added.