SMA Diesel for RV-10

Hi all, has anybody considered the SMA diesel engine (www.smaengines.com) for an RV-10? Since they're already STC'd for Cessna 182 and are reported to have better performance for lower operating cost (downside is higher purchase price), it should make an ideal engine for the -10.

Where I operate (SE Asia), Avgas is now 3x the price of Jet A. Ouch!

Anybody want to chime in with opinions?

First I would try to get feedbacks from the Cessna 182 owner/operators that operate with it; As any piece of equipment has its pros and cons you should get honest feedbacks (avoid SMA distributors/dealers since they may be biased).

When you ask them check for at least:

- Propeller reliability (can only handle composite props due to instanteneous torque),
- Exhaust system reliability,
- Crankcase reliability,
- Corrodability (worst if you live close to the ocean).

My recollection is that the basic engine has good reliability. If you go with it pay a lot of attention to cooling (oil and cylinders). Also, you should try to operate it in the mechanical mode ONLY and, only use the data acquisition and engine map modules of the ECU (avoid the servo'd part, many issues and un-necessary complexities); Get an output from the engine map module to create a gauge showing you the actual calculated power vs the maximum authorized calculated power for the conditions say in %; Keep the MP gauge as a sanity check and back-up; Then you will truly get a "Single Lever" as opposed to the current configuration in full ECU mode that requires a mode change lever (manual reversion); You really need to get rid of all the bull **** and hazards associated with the manual reversion mode (trust me, some of the failure cases are not pretty); BELL Helicopter learned the hard way (5 accidents with casualties) that automatic reversion is the only acceptable way to do reversion on engines; Manual reversion like the one offered by the SMA engine should be avoided at all costs.

Pay close attention to oil drainage at the governor. Avoid the negative g hardware (accumulators, etc.) that are required to comply with 23.943.

Also, one of the good point of that SMA engine is that it needs no electricity (if used in the mechanical mode) to entertain the fuel injection (as opposed to Thielert); That makes the ability to use all of the fuel tanks in the event of an electrical failure a true reality and, it drammatically improves serviceability (less maintenance and no need for fancy electronic maintenance equipment and knowledge) especially when you are far away from a distributor and/or the manufacturer. Also, you get less costly parts that can fail on you !

One more thing, going full mechanical with that engine makes no change since metering is by design only made by hydro-mechanical systems; The ECU on that engine is only a fancy "throttle" servo, nothing to do with fuel metering.

The price might give you a bit of a shock.

rv6ejguy said:

The price might give you a bit of a shock.

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That as well...but if one really wants it while having considered all pros and cons, I guess that's OK.

JetA4GA, I understood very little of what you said. Guess I'll have to brush up on how diesel engines work. I'm hoping someone else more knowledgeable irons out the kinks before I adopt the engine.

contact info

I happen to know the gentleman personally who is doing the SMA conversions, please let me know if you want his phone number etc...
Best
Brian Wallis

Sonic said:

JetA4GA, I understood very little of what you said. Guess I'll have to brush up on how diesel engines work. I'm hoping someone else more knowledgeable irons out the kinks before I adopt the engine.

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In a nutshell what I said is that if you elect to use that engine use it in the mechanical mode ONLY. In that mode, ONLY, the engine is acceptable and can provide relative trouble free service (except for propeller reliability, exhaust system, crankcase cracking, corrosion and maybe a few others which you will need to consider and get confirmation if these issues are fixed). The servoed normal mode it comes with is anything but TROUBLE and contains numerous quirks (picture a swiss watch bolted to a truck engine). I have over 1000 hours experience with that engine and we had actually nicknamed the back-up (mechanical) mode the "superior mode". The fuel injection/metering system is hydro-mechanical by design and doesn't need AT ALL to be servoed to perform its intended function. The electrically servoed system this engine has (called the normal mode) just has no value added except for additional maintenance, costs, operational complexity and, failure modes some of which are pretty nasty.

Further, pay close attention to oil drainage at the governor (the governor pad on the engine has been designed up side down from the MS spec which results in the governor gravity drain to be at 12:00 instead of where it should be at 06:00 - unless your plan is to fly inverted all the time; Though it is required by the MS spec, on that engine the governor plunger at the splined drive end is not opened to the crankcase but in a dead end - check on a Lycoming how it is done which is the right way). Also, avoid the negative g hardware (accumulators, etc.) that are required to comply with 23.943.

JetA4GA, thanks very much for your insight into this engine. As an aside, I'm guessing that your experience with this engine has to be predominantly in the Cessna182SMA?
Would you then say that this aircraft is not worth the hassle? The reason I ask is a flying club here is considering purchasing one to use as a trainer/rental. What are your thoughts on that?

Sonic said:

JetA4GA, thanks very much for your insight into this engine. As an aside, I'm guessing that your experience with this engine has to be predominantly in the Cessna182SMA?
Would you then say that this aircraft is not worth the hassle? The reason I ask is a flying club here is considering purchasing one to use as a trainer/rental. What are your thoughts on that?

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Not only the 182, but more.

All engines have their issues (and I mean ALL) especially when they are of a new design and from a company where it is its first shot at an aero recip engine (Even the TCM and Lyco of this world get to suffer from time to time).

If you want to go Diesel there is only two certified options as I write these lines: SMA and TAE; The latter is not a horse I would put much money on these days; As for SMA, they seem to still be well backed by SAFRAN/SNECMA. If you need the Diesel option then you have to weigh the added acquisition and maintenance costs into the business case. A suggestion would be to assess what is the status of these issues and, beef up the warranty.

If you can wait a year, maybe a Diamond DA 40 TDi with the Austro Engine's 2 liter diesel that should be certified in 2009-Q1 could be an option; Even if that engine gets issues (and it will certainly have some as I described above), the Owner of DAI and AE is the same person and, can support both products very well.