The 912UL

[Emory Bored 61]

I checked all of the topics open so far and we haven't talked about the 80hp Rotax 912. So, tell me about it. I'm looking at one with a little over 300 hours since new but I don't know yet the date of manufacture. The airplane it's in was signed off in '96. It's been sitting idle since 2008.

What do I have to do before running that thing. Does it need to be torn down and seals replaced like the two strokes or can we just change the oil and give it hell?

Thanks for the ideas

EB

[Av8r3400 1178]

The 912 is a very "tight" motor. The manufacturing tolerances are very close. This is a good thing. The are not very susceptible to storage corrosion and problems sitting like many other motors. They do not have " seals" like the two strokes so that is not a major concern. Oil, oil filter and maybe carb cleaning might be all you need. .

But, here are some questions that need answers:

Has the engine run at all in the last 5 years?

What were the storage conditions? Inside/outside/weather conditions...

What fuel (auto or av) was in it during this period?

What type of oil was in it?

This information will help determine what, if anything, needs to be done before running.

[C5Engineer 1170]

You looking at an Avid that's for sale?

[dholly 718]

I checked all of the topics open so far and we haven't talked about the 80hp Rotax 912. So, tell me about it. I'm looking at one with a little over 300 hours since new but I don't know yet the date of manufacture. The airplane it's in was signed off in '96. It's been sitting idle since 2008.

What do I have to do before running that thing. Does it need to be torn down and seals replaced like the two strokes or can we just change the oil and give it hell?

Thanks for the ideas

EB

'morning EB-

A couple of thoughts come to mind. I bought a KF4 w/912ul that had a similar history: engine circa and signoff both 1996, 170hrs TT, sat in a barn for a few years with only a few prop pull-throughs per year after the builder passed. I removed plugs and exhaust to check for internal corrosion and found none. Zero.

When I got it home I did the mandatory carb dis-assembly and cleaning, fuel system flush and hose replacement etc.. The log showed new plugs and an oil/filter change when put into storage so all I did after the foregoing maintenance was give it fresh fuel and coolant before hitting the starter. Fired right up, ran great, came to temp with all gauges in the green. No probs to date and I can tell you if you are used to 2-strokes in an Avid or KF platform, you will be shocked at the power and smoothness of the 912. Uses the same or less gas than a 582. Cost aside, I think it is the single best engine for our little planes.

As to costs: they can be -very- large if your 912ul is of early vintage and certain Service Bulletins remain undone. There were quite a few costly Mandatory SBs issued, not all of them are *normally* undertaken by owners. The SBs seem to come hot and heavy from Rotax on this engine, in large part I believe, because the 'certified' 912 platform is used for military applications where they have to err waaay on the side of caution (good example is the Stator Replacement SB, which almost no one chooses to perform). You can get an idea what Rotax 'recommends' to bring an older 912 up to snuff by reading the email attached regarding the 912 in a plane for sale I looked at a few years back.

You may already be aware of this: you can plug in the serial number of your engine HERE to see all applicable SBs and Letters, etc. You can also download all the owner's and maintenance manuals. You will find the 912 schedule maintenance items in the manual by run hours or years (some rubbers have a 5 year replacement, something to consider in you case). I found it helpful as a pre-start checklist and, of course, you will want to familiarize yourself with the engine somewhat before doing something stupid. RTFM(s), eh? One note: the 912 manuals and SBs etc. are all translated into English by Rotax, which makes for some funny or odd-sounding wording at times, but no different than the 2-stroke manuals and you will still understand easy enough. You can also check their Blog for info and, if you pay the price, have access to a ton of very instructional videos. If you register (free), they will email you any pertinent info and keep you abreast of any SBs etc. applicable to your engine s/n. It's a very good resource website IMHO, although I got miffed when Rotax started charging for certain content a couple years ago.

Do let us know how you make out.

912.pdf

[Emory Bored 61]

You looking at an Avid that's for sale?

Yup.

[Emory Bored 61]

'morning EB-

A couple of thoughts come to mind. I bought a KF4 w/912ul that had a similar history: engine circa and signoff both 1996, 170hrs TT, sat in a barn for a few years with only a few prop pull-throughs per year after the builder passed. I removed plugs and exhaust to check for internal corrosion and found none. Zero.

When I got it home I did the mandatory carb dis-assembly and cleaning, fuel system flush and hose replacement etc.. The log showed new plugs and an oil/filter change when put into storage so all I did after the foregoing maintenance was give it fresh fuel and coolant before hitting the starter. Fired right up, ran great, came to temp with all gauges in the green. No probs to date and I can tell you if you are used to 2-strokes in an Avid or KF platform, you will be shocked at the power and smoothness of the 912. Uses the same or less gas than a 582. Cost aside, I think it is the single best engine for our little planes.

As to costs: they can be -very- large if your 912ul is of early vintage and certain Service Bulletins remain undone. There were quite a few costly Mandatory SBs issued, not all of them are *normally* undertaken by owners. The SBs seem to come hot and heavy from Rotax on this engine, in large part I believe, because the 'certified' 912 platform is used for military applications where they have to err waaay on the side of caution (good example is the Stator Replacement SB, which almost no one chooses to perform). You can get an idea what Rotax 'recommends' to bring an older 912 up to snuff by reading the email attached regarding the 912 in a plane for sale I looked at a few years back.

You may already be aware of this: you can plug in the serial number of your engine HERE to see all applicable SBs and Letters, etc. You can also download all the owner's and maintenance manuals. You will find the 912 schedule maintenance items in the manual by run hours or years (some rubbers have a 5 year replacement, something to consider in you case). I found it helpful as a pre-start checklist and, of course, you will want to familiarize yourself with the engine somewhat before doing something stupid. RTFM(s), eh? One note: the 912 manuals and SBs etc. are all translated into English by Rotax, which makes for some funny or odd-sounding wording at times, but no different than the 2-stroke manuals and you will still understand easy enough. You can also check their Blog for info and, if you pay the price, have access to a ton of very instructional videos. If you register (free), they will email you any pertinent info and keep you abreast of any SBs etc. applicable to your engine s/n. It's a very good resource website IMHO, although I got miffed when Rotax started charging for certain content a couple years ago.

Do let us know how you make out.

This is all really good info sir. Thanks. The airplane has been indoors in air-conditioned comfort in a super dry state since the death of the owner. I will get the serial # of the engine and submit that for a SB readout. The airplane is a speedwing with extensions. I'm going to measure the spar thickness (if I can get at it with the wings folded) and make some other measurements soon. There are many lookers.

EB

[Av8r3400 1178]

What have you found out?

[Guest]

I have yet to start, run and fly behind the 912 in the plane I recently bought. However, I've been around a lot of them for a while and helped significantly with two conversions of Avids to 912's from other power. One a 582 and the other a Subaru. The 912 is a tight install in the Avid. While a fantastic incredibly reliable engine, it is very difficult to inspect within the engine compartment for the everyday things you want to look at in a pre-flight or "routine" lookover. For instanse, the plane I just bought had a broken (sheared) motor mount bolt still saftied in place between the block and mount only recognizable by putting a hex wrench on it, and an impossible to see break in the mount itself hidden behind the muffler.....and the plane was being flown! I almost crapped when I found these things once I got it home. I almost flew it home too, but weather didn't cooperate si I trailered it...Thank goodness.

There is quite a pile of hoses both coolant and oil as well as an oil resivoir, especially if you have the oil thermostat. It's more like looking into a modern small car's engine compartment than looking at the straight 6 in a 56 chevy....So very easy to overlook potential problems unless you are very diciplined. I am learning that I am going to have to get a mirrior and be very vigilant looking around in the engine compartment regularly. Also all those hoses I mentioned tend to rub on motor mount parts and wear thin fast even with protection.

That said I have seen nothing but wonderful performance and reliability from the 912 WHEN PROPERLY MAINTAINED and I expect to have much the same sense of confidence when I get done with this plane, if that is the word for it, that I had when I switched from flying 1250 hours behind my trustworthy 582's, to the Lycoming 0-320 in my Magnum.

The thing you will like the most is that at 150 or 300 hours you don't have to take the engine apart to inspect and decarbon. You just change the oil, cut the filter open and look for particles and have the oil analyzed regualrly, change the plugs and check compression at intervals and fly to TBO!

Thats the experience most everyone I know flying 912's has had.

[Emory Bored 61]

What have you found out?

Nothing yet. I spent the day over at the airport getting the Luscombe settled down in a hangar. Tomorrow SWMBO has a couple of must dos that I can't bet out of. I'll try like heck to get over there Saturday evening or sometime Sunday.

Dan

[Emory Bored 61]

I still haven't made it over there. My mother had a stroke, the owner is incredibly busy building engines for Ferrari Challenge cars and I just bought a new to me pickup because mine took a shit. Good news is I may have a possible looker at the Luscombe. I'm outa cash otherwise so we'll see. In a couple of the photos the bottom of the wing looks to have some camber in others it looks pretty flat. Joey thinks the speedwings are permanent dogs but Leni thinks with extensions they can work out just fine. Leni's world is one I used to live in; density altitudes in winter are below zero. Joey flys where I fly.

Can a guy get ahold of a Stol Heavy Hauler wing out there??

Dan

[C5Engineer 1170]

Dan I only know what I've read about them. From what I've heard with the extensions they work well. Leni has real world experience with the speeding I do not.

[Av8r3400 1178]

There was a speed wing Mk 4 on my field with a 582 in it.  I don't know if it had the long or short wing, but it would barely climb with 12 gallons of fuel and two 180 pound guys in it.  Total, total dog.  The owner bought it to fly off floats.  He quickly found out that was not going to happen.

 

The owner sold it and bought a Challenger II with a 503.  A much better performer, I'm sad to say.

 

 

IMO - An Avid Speedwing is not worth buying, unless it comes with another set of wings or is cheap enough you can build/buy another set of wings.

Edited 15 May 2013 by Av8r3400

[dholly 718]

Old thread, but I'm an old fart with a few minutes so I'll toss in another .02 cents.

 

Make no mistake, with all other variables equal, there will be a BIG performance difference in performance between aircraft using Avid's longer undercambered wings (Heavy Hauler or STOL) or short flat bottom wings (Aerobat or Speedwing). And with all due respect, anyone thinking that an Avid Speedwing or Aerobat is appropriate for water or STOL ops (particularly on a heavier Mk-IV vs, lighter A,B,C model) simply has not done much homework. My personal observations include a local buddy who must weigh all of 160lbs. soaking wet and drove many hours up into Canada to buy a relatively bare-bones, manual start 582-powered C model speedwing on AquaFloats, He couldn't even break suction and get the bird off the water solo. Had I known, I would have discouraged or advised him that he would need to purchase or build longer STOL wings. BTW, he just sold it. Compare that to another local 200+lb. buddy who regularly flies his 582 KF3 with an avg size spouse on the same floats. Obviously a short flat bottom Avid wing vs. a long undercambered Kitfox wing, but the early KF 1-3 and Avid undercamber ribs are almost identical and the rest of the planes so similar it makes the point.

 

That is not to say all Avid Aerobats or Speedwings are useless if enjoyed as Dean Wilson envisioned ie., light and fast. Safe to say he didn't expect or intend to design STOL characteristics in the Speedwing airfoil. Never the less, with a few simple tweeks I think they might appeal to a larger audience than many give them credit for. Leni has repeatedly recounted his personal experience with an Avid extended speedwing (IIRC, a 582 C model with wing extension kit) and swears performance was not far behind the Avid STOL or HH wings which he has plenty of experience with (and he ain't exactly on the Atkins Diet, no offense brother!). I am not a fan of the extensions, IMO excessive wing twist results from adding an extension kit to already spec-built speed/aerobat wings and creates negative implications to both STOL and top end performance.

 

That said, I had absolutely no hesitation building hybrid wings for my Avid+, using single long spars with less twist and substituting speed ribs for undercambered. I know it will offer less STOL performance than the HH wing. But with a 26% increase in both wing area and aspect vs. a Speedwing, it will also offer a hell of a lot more STOL performance than a short spar Aerobat or Speed wing ever could. In fact, comments from others flying a hybrid long wing like mine, I fully expect my Avid+ will offer performance much, much closer to a standard Avid HH than a standard Avid Speedwing. For this plane, I'll gladly give up a little short field performance for the ability to break through that 100mph aerodynamic wall and cruise consistently at 120+mph while sipping fuel.

 

Whether they get a fair shot or not, I think blanket statements and over expectations have caused a generally negative inference to the Avid Speedwing, as well as lower resale prices compared to STOL or HH wing equipped Avids. That could make for some terrific bargains for knowledgeable buyers. Heck, find a cheap B or C model Speedwing then buy or build a new set of HH or long (not extended) hybrid Aerobat/Speed wings and you got a winner at what likely would be less than a complete, used Avid with HH wings. Plus you got an extra set of wings to futz around with or sell. Or bolt a 912ul on an Avid Mk-IV Speedwing for what I suspect would be a very nice plane.

[1avidflyer 1983]

My first ride in an Avid was a B model with long wings, but speedwing  ribs.  It took off and climbed just fine.  Cruise speed was a good deal faster than the undercambered wing however.  Maybe if a guy was to build the wings with 2 extra feet length, speedwing ribs, and a more pointed front on the front spar, it would end up better than either one.  But then that is nearly what the Kitfox 4 and later wing is.... Jim

[Av8r3400 1178]

Why not just build a set of Kitfox wings and be done with it.

[Emory Bored 61]

It's kinda spendy to be building new wings for.  I'm all over the place on it and a couple other airplanes right now anyway.

Why not just build a set of Kitfox wings and be done with it.