FAA certification in auto conversion aircraft

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Boomer

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Hi, I want to share with you an idea about getting FAA certification in auto conversion aircraft. My first language is spanish and I still have to learn a lot of english so excuse any mistake. Thank you.

As we all know the main expense of the aircraft is the engine: purchase , maintenance and consumption. Current aircraft have designs and costs of the last century, not having benefited of the same improvements than automotive engines. I mean car and motorcycle engines that are mass produced. But everybody in this forum knows that, let's go on.

I had the idea because the Tecnam P2006T has managed to be FAA certified using two Rotax 912 engines that are often used in ultralight, not certified aircraft.


General aviation requires engines safer that automobile ones, the idea is to achieve equivalent levels of security through redundancy of automotive engines and this is where I need expert opinions to see if giving equivalent power and security I can get FAA certification. I'll put a very simplified example to understand the concept:

Suppose a Lycoming engine O-360 with 160 hp from a Cessna 172 fails once every 10,000 hours. It could be replaced by 2 car engines with 80 hp that fail once every... say 100 hours. Whether it would be best to connect both engines to the same propeller or put a propeller on each engine, we would have an equivalent system.

Joint power of the two engines would be the same, 80 hp + 80 hp = 160 hp.
Safety will also be the same since both engines fail at the same time each 100x100 = 10.000 hours.

You can criticize that a double engine would be heavier than the engine it replaced, or that it can't maintain consistently high revs. Both problems can be solved with more power, if we use two engines of 160 hp or even more hp, we could use them at half power, as often used in cars. You could even use motorcycle engines that have better power/weight ratio.

Can also be criticized that safety is not enough, we could add more engines. Perhaps motorcycle engines are better, we could add a third central engine, even two engines on each wing. Four 500cc motorcycle engines can give 46 HP each, 184 combined horsepower. Even more creative solutions, such as several diesel engines with a generator connected to an electric motor on the propeller.

I'm talking about using it in FAA certificated aircraft. That would be a revolution because the cost would be significantly reduced. Several automotive engines are cheater than one aviation engine: purchase, maintenance and consumption. More people could buy and maintain FAA certificated aircraft.

I look forward to your comments.
 

TFF

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My company's aircraft fly 100hrs a month; I would have to change 2 engines every month with that. There are versions of the 912 that are certified. A certified airplane engine propellor turns about 2400-2700 rpm because that is where design works; your motorcycle engine spins at 10,000 rpm so you have to have a transmission that can reduce the rpm to under 3000 rpm while moving a 50-70 lb propellor. A certified engine runs an average of 2000 hrs not 10,000. 1500hrs per crankshaft revolution is equal to 100,000 miles in a car. Certification also costs millions of dollars for the FAA to believe the information.
 

rv6ejguy

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As someone who has been involved in auto conversions for almost 20 years and flown one myself for 10 years I have some knowledge of this basic topic.

The FAA requirements are far below what the auto OEMs require before they begin production these days. We actually see very few core failures of auto engines- most problems have historically been fuel related, cooling and #1 has been PSRUs. The basic certification requirements are available on the FAA website. The problem is not that the average auto engine could not pass the endurance testing involved, it is tracability of the parts and process control assurances that go into making the engine. That would be the very expensive part and no auto OEM would want to be involved in that.

Passing the endurance testing would mainly involve a few hundred hours on a dyno or test stand and a few thousand gallons of fuel. The PSRU part would be far more expensive to design and validate I believe.

The only way around the parts problem would be to use an engine which has all the parts available from aftermarket sources who would be willing to work with you and that is a slim shot. Even the LSA requirements through the ASTM are pretty difficult to meet. For true certification you need a complete layout of the process control to make each part, lot numbers and QC procedures. This kills most new engine designs seeking certification.

If only the FAA would accept the QC standards of the OEM (which are better than those of Continental, Rotax or Lycoming) AND the auto OEM would be cooperative (unlikely due to liability exposure) then you could be on the short track to lower costs on engines a lot. I don't realistically see either of these things happening.

When one of the big three have an AD issued on their engines, the FAA does not close them down even though in most cases, these are caused by defects or changes in process control or QC- in other words, the manufacturer was not following things as laid down in the type certificate documents. There have been dozens or hundreds of cases of this over the years.

Seems you'd have to build your own engine even if was a copy of a good automotive design from years past to be able to have adequate control over the whole process to gain certification without tremendous troubles. Auto process control and QC are internal and self administered, aviation requires a written disclosure and easy tracability of part lots so suspect parts can be traced and replaced if something goes wrong.
 

rv6ejguy

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Thank you for your answers. So, It was just a nice dream. The FAA is killing General Aviation.
Does the FAA Care about the Little Guy? | Flying Magazine
Well, there is LSA and Experimentals where the FAA and the US are very open with what people can do. This is probably why LSA and Experimental numbers are up and GA certified stuff is way down. In many countries, you either have to jump through a lot of hoops to build an Experimental or you are simply not allowed to.

In Canada, our rules are perhaps even more open than the US. A friend from Japan was visiting me (he was an ex aircraft mechanic) and he was simply blown away that we can build and fly our own aircraft so easily here. Not allowed in Japan at all he said. His comment in broken English: Canada is excellent! He really enjoyed looking over my aircraft and having his photo taken so he could show his parents and friends back in Japan.

The FAA has to uphold the expectation and standards people expect in certified aircraft and the process does ensure for the most part that someone coming in with new designs proves their safety and repeatability in manufacturing as much as humanly possible. It simply would not be acceptable to have someone produce aircraft or engines without proper engineering, testing and validation in place.
 

autoreply

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The more you dig into certification, the easier the actual certification is, you could probably pull that off for only a few man-years in engineering, building and certifying. Proving a product meets the FAA/EASA criteria is easy. Documenting production/quality control is the VAST majority of the expense/effort.
 

rv6ejguy

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The PMA is the hard part as mentioned but many small manufacturers have this approval from the FAA for various airframe and engine parts. The trick with the whole engine is doing it for every part inside. The paperwork is staggering for an entire engine.
 

Boomer

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Thank you again, lot of useful information here. I'm not interested in LSA because my "dream" is to fly IFR, and LSA planes aren't allowed to. Is it possible to fly IFR using an experimental plane with an auto conversion?
 

Boomer

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Even auto conversion aircraft? Then I don't need FAA certification! :shock: In example, can I fly IFR this plane?
 
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stol

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Boomer

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Thank you. Now I can tell you that my location is Spain and here homebuilt airplanes without a certified engine are forbidden to fly IFR. Ah, North America, the land of freedom.
 

Boomer

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You bet..... We can explore stuff in our experimentals that will eventually show up in certified planes in 20 years..
Absolutely true. The creator of X-Plane simulator built an experimental airplane because the main limit wasn't money, was regulations of the federal government:

Evo

 

autoreply

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Thank you. Now I can tell you that my location is Spain and here homebuilt airplanes without a certified engine are forbidden to fly IFR. Ah, North America, the land of freedom.
Be happy with that. Here IFR, even NVFR for experimentals is banned, even when flying PH-reg abroad...
 
E

ekimneirbo

Hmmm.........I just read over on the Bearhawk site that apparently Toyota is going to certify one of their V8 auto engines for airplanes.
 

karoliina.t.salminen

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Thank you. Now I can tell you that my location is Spain and here homebuilt airplanes without a certified engine are forbidden to fly IFR. Ah, North America, the land of freedom.

This to my understanding unfortunately applies to the whole EASA (europe). To my understanding there was one historical exception,
Sweden, but with the EU in place, that might be already reversed.

IFR in my opinion should be allowed for homebuilt aircraft and people should be campaigning for it or it will never happen. Many certified Cessna 152s that are legal to fly IFR, are very dangerous to fly IFR due to
poor situational awareness due to poor oldfashioned instruments which are also very unreliable compared to
today's solid state technology. And then someone could have e.g. Lancair Evolution with turbine engine and
Garmin G900x and would be prohibited to fly even on night because G900x is uncertified model of G1000 and certified
instrument panel is required for even night flying. It could be possible to fly night flying with the Evolution,
if the G900x would be marked inoperable with a sticker and the pilot would be officially relying only on
round backup gauges. The EASA rules are a farce. Or worse.
 

karoliina.t.salminen

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Be happy with that. Here IFR, even NVFR for experimentals is banned, even when flying PH-reg abroad...
This is the biggest reason why my concept for crossing big oceans and flying around the world is unfeasible. Not a technical problem but a regulatory problem - crossing oceans requires IFR flight even on VMC and that requires IFR approved aircraft and that rules out any experimental in any EU country register.

Interesting question is that would it be possible to certify a european experimental to N-register.
Because I happen to be 1/5 owner of an certified aircraft that resides in Europe but is in N-register and stays in N-register (because there is a method for that) and all maintenance is done under FAA rules including FAA annuals, and we have a mechanic for that already (comes from Germany with (reasonable) cost and it is doable). Would a similar pattern work for an experimental?

Even if it would mean shipping it to USA and (flying it) back for doing the certification, it would be better than no IFR because that can make go-nogo difference for anything further than 100 dollar (or 200 euro in EU due to gas price) hamburger trips, which unfortunately pretty much takes away any point to make a serious cruising machine as a homebuilt airplane (other than that it would be cooler to fly with own designed plane than Diamond for the 200 euro hamburger (to notice that the airport cafe has went to bankrupt and serves nothing, haha)).
 
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