Certificated to Experimental Exhibition conversion?

HomeBuiltAirplanes.com

Help Support HomeBuiltAirplanes.com:

rv7charlie

Well-Known Member
Joined
Nov 17, 2014
Messages
671
Location
Jackson
Hey skydawg, what you describe aligns perfectly with the info I've received from my FAA neighbor, and with what I've read about others doing. But you're the 1st I've encountered with 'been there; done that' experience. Have you considered putting together a web site detailing your experiences? Or writing a series for a mag like Kitplanes? There's so much misinformation floating around about relatively obscure practices, I'd think that Kitplanes would welcome it. (I know I would.) I'd enjoy seeing both your experiences on the 'paperwork' front (FAA inspections, documents, etc), and your actual hardware processes for your particular application, including engine choice, power transmission method (gearbox, or direct drive/extra main bearing, etc), cooling techniques, engine mount design/adaptation, etc etc. And PICTURES. :)

Thanks,

Charlie
 

Toobuilder

Well-Known Member
Log Member
Joined
Jan 19, 2010
Messages
4,771
Location
Mojave, Ca
One problem that might come into play is the long known history of the non standard FSDO response to a given situation. That V8 Seabee on the cover of SA some years ago being a prime example. It was issued an E-AB (not exhibition) AWC despite being very clearly a "restoration" of a Seabee with an engine conversion. I think the stuff hit the fan right after and the FAA tried to reel in the rougue FSDO's, but as we know all too well the individual offices have very different ways of "interpreting" the regs.
 

BBerson

Light Plane Philosopher
HBA Supporter
Joined
Dec 16, 2007
Messages
13,237
Location
Port Townsend WA
Some changes are promised in the next few years. Maybe owner maintenance will happen with the new LSA rules.
 

JohnB

Well-Known Member
HBA Supporter
Joined
Aug 18, 2019
Messages
64
(my C172 has a V8 engine) so I want to exhibit its unique features, performance and advantages of using modern car engines.
I'm not sure moving a TC'd plane to EXP is for everyone, but for me it made sense when I bought an over TBO C172 cheap and sold the engine off. It used to cost over $60/hr with original Lycoming, now its about $18/hr and is a way better engine.



Can you give a short discription of what engine, gearbox you have? Performance numbers? Thanks John B
 

skydawg

Active Member
Joined
Jul 26, 2016
Messages
34
Location
Denver, Colorado
my EXP C172 has about 100 trouble free hours so far....Its a GM engine block but a lot of mods to make it work safely for aircraft, especially in the internal oil system. AS far as man hours it took, don't really know but it was over a 3 year period of working on it part time pus another year of research and design figuring/head scratching. Weight increase was about 150 lbs but I added additional items as well. I would not recommend trying to duplicate such an undertaking unless you have a lot of free time, aero structural & electrical engineering background, as well as handy with welder, CNC machines and are a car engine guru..... even then it will cost you a fortune and would be cheaper just to rebuild the original motor and upgrade the avionics...with lots left over for new paint, upholstery and another C172. I get a lot of pilots asking about the V8 conversion and think its as easy as making a mount and bolting on a junk yard engine, its not if done right. Problem is there are not any such complete engines designed to meet normal cert standards, most just put together from automotive parts. And with electrical motors the new rage, not sure the expense of designing, manufacturing and testing/certification one would be prudent.

There are many auto conversions out there, and lots of accidents in them. Some because of the actual engine, but most due to the PSRU, or the car engine electronic controller / EFI system which is a poor choice for a plane even with "re-tuning" using commercial software. I tried this method but found car controllers are designed to prevent people from changing anti theft & emissions features and often open up other issues when you do. I've seen a number of auto conversions reverted back to carb and distributor set-up, but then there is no room for any meaningful redundancy. There are also some simple EFI systems marketed to exp aircraft, with mixed reviews but I have no first hand knowledge of them.

There is a company actually currently flight testing C172/182's V6 and/or V8's for STC certification designed to meet FAA cert standards. I only got a glance at engine about 6 months ago while they were putting the top cowl on, but it looked like a real production aircraft engine.... I think it was a V8 or V6. It had a neat LED engine display that monitored the engine and would alert if something was out of whack. It was extremely quiet when it taxied out and took off. They didn't really want to answer any questions about it, but stated the engine would not likely be available in US due to liability issue. Maybe they will make an experimental version for the US which may keep the price in check... but this usually isn't the case when it comes to aviation engines.

The cost of converting a C172 to the Continental Diesel is about $100k and it still cost about the same or more to operate as the original engine. It's no wonder why the experimental category is growing so much faster than the certified. A neighbor asked what kind of plane to buy, a C172 or PA28 (as if there was no other practical option)....I suggested finding a used experimental.
 

proppastie

Well-Known Member
Log Member
Joined
Feb 19, 2012
Messages
4,562
Location
NJ
nice sound

I think what that said was it was approved for install and testing....no stc has been issued

"QA will begin immediately in defining the details, documenting, implementing, and testing"
 

skydawg

Active Member
Joined
Jul 26, 2016
Messages
34
Location
Denver, Colorado
Actually, an STC would work to install an engine not originally certified for the air frame listed on the TCDS. problem is, such an STC for certifying a car engine would be way more expensive than the small GA market would likely be worth. That's why Lycoming and Continental have not improved or introduced any meaningful new designs.... they have a monopoly so why bother; they just continue to buyout companies that make approved aftermarket parts. The certification is the barrier to entry for new companies, keeping not just aircraft piston engines in the dark ages, but avionics as well.

the company I mentioned prior post that's now flying V8 engine conversions in C172's for a STC, said they won't sell a certified version in the US. Some companies do this to take advantage of the FAA cert and use it to quickly certify in other countries (the FAA has private party DER's that work a lot faster than civil servants). If the V8 C172 actually get the FAA STC, it's likely the cost of product liability insurance which will be the issue in the US. Even with the aviation Revitalization Act & its 18 year limit to sue the aircraft manufacturer, such protection resets the clock if such a change/mod is made to older aircraft.

So, new technologies really has 2 considerable barriers before the certified market sees it... this is why there are mostly large, resourceful, legacy companies supplying major components.

But, again, a STC would allow installation of another engine, prop, wing, ect.. to replace the original component.... just not easy or cheap to get.
 

skydawg

Active Member
Joined
Jul 26, 2016
Messages
34
Location
Denver, Colorado
Bberson
I'm not sure your question was actually answered, and there was a lot of incorrect info given along the way to this part of the thread. ... but if still interested: yes, you can convert to experimental-exhibition if you have a reason that meets one of those listed in FAR 21.1919 d....or maybe an easier mod for air racing 21.191(e), like a larger exhaust system (the exhaust won't be certified and you increase performance for racing). Just stating you are swapping to EXP for cost savings won't do it.

However, I am not sure this will get you out of needing an A&P to do maintenance because FAR 43 which outlines what qualifications someone must have to work on aircraft, basically states anyone can work one an experimental aircraft, UNLESS the aircraft was previously certified in another category. So, like my experimental C172, I need an A&P. However, an A&P can do the condition reports. Unlike other experimental categories, the exhibition does not expire (same as standard), others like R&D category expire in 12 months and must be reinspected each year with a FAA DAR at your cost....expect to pay $500-1000 for this. The conversion process is not all that complex but you would be better off finding the DAR you want to use and ask him to draft program letter.
You will also need to send in annual letter to FSDO listing how many hours you intend to fly and events you INTEND to exhibit....you are not required to go to any. New exhibition op limits are about the same for home builds after phase 1 testing.

Someone mentioned swapping to primary category. This is way expensive as you will have to go thru a certification process with the FAA certification office, and they will require a lot of stuff and likely require hiring a DER. The FAA just does not wants old certified aircraft to go away, regardless of the impact on the industry or how they are pricing our most aviators. They will not make it easy on you and fight you every inch of the way going for primary.

I am not familiar with your aircraft type, but if its a LSA, there are some additional freedoms compared to standard category. For me it works great in my C172 with a V8 engine.... I fly for for $18/hr compared to $65 with original engine and its flex fuel rated so can burn most cheap fuel types and even get an off road tax rebate per gallon. I would not likely be able to afford to fly otherwise. Good Luck, hope this helps.
 

BBerson

Light Plane Philosopher
HBA Supporter
Joined
Dec 16, 2007
Messages
13,237
Location
Port Townsend WA
skydawg,
The Grob is a motorglider and is not a LSA. I think compliance with Part 21.191(d) is difficult or unlikely.
The cost of operation is low in the current standard category. So, I think I will wait and see if the FAA adopts the owner/maintenance option in a few years.
Thanks for your interest and information.
 
Top