If, during the process of developing an STC, a certified aircraft is put into experimental for the testing phase of development, then is there going to be a big problem in returning to certified as originally manufactured?

Jack,

I anxious to the response. I have asked this question before and never gotten a good answer.

Two years ago garmin was talking to me about doing this with my S. they indicated it , going experimental back to certified, was not an issue, but I didn't do it, however i had no reason to doubt it.

When my previous airplane went in for an engine conversion (GO-435 to a Helio Courier GO-480 and 3-blade) it went into the experimental category while testing was done. It flew that way for six months, and when the applicant collected all the required data (weight and balance, limitations, new flight supplement), it went back to normal category with the issuing of the STC. That was in the 1980's. Everything might be different now, and if it is, it sure won't be easier.
Robin White

We did this more than a few times with our corporate aircraft for diff. reasons. It all depends on your local FISDO's attitude. If they understand what you need to get done and WANT to help it is easy, if they don't it can be a nightmare. Our Chief of Maint. was really good at keeping a good relationship with those folks.

If your shop folks have connections with their FISDO folks it should not be hard to do.

Good luck,

Joe

Wouldn't it automatically go back to normal once it re-complies with the type certificate?

You have to have a C of A showing the correct airworthness and the FISDO issues that.

We do this all the time in the flight test world.

Need to prove (inspection & documentation) that the configuration was returned to type design, if that's what's happening. Most often the aircraft stays in the new (recently approved by STC, for example) configuration.

Will all be part of the cert plan negotiated with the certifying agency.

Yep, it depends on what you are doing.

Jack was talking about taking a certified aircraft from Certified to Experimental and back to Certified.

If you do something that could change the loads on the airplane you will have to demonstrate you did not over stress the airplane.
Something like a wing tip, changes the loads on the main spar.
If you can't prove you did not overload the spar you may not be able to get the plane back out of experimental.
To properly change something like a wing tip you should have stress measurement equipment on the plane as you flight test.
I was asked to test some wingtips on my Baron, so checked this out with a very well known test pilot friend.
For wing tips that hold fuel, the worse case scenario is when the tips are empty.

I recently sold an airplane that was accidently left in the experimental category in the FAA records even though it had a normal FAA Certificate of Airworthiness. They fixed the database pretty quickly once I got in touch with them with the proper paperwork. But yes, airplanes are taken out of the normal category and put back in all the time for various research and testing reasons. This particular Bonanza was in the research/experimental category for avionics test work.

-Neal

My KA B200 was the test bed for several of the Raisbeck mods, it was back and forth experimental-certified several times. They are still using my 200 in their advertising, if you see a Raisbeck ad, with N1850X, like in the recent King Air magazine, thats my Baby!!

So yes an airplane can go back and forth experimental - certified and I have the logbooks to prove it.

Rick

The question is whether this has any effect on future sellability. In this world of google and outdated databases, someone may shy away from your plane if it comes up as experimental in 'myplane' or any of these other secondary databases. Aircraft buyers are irrational, finding that label may cause someone to pass on to the next one.

I would document what was done during the time as experimental/flight test. For a future buyer it may make a difference whether your plane was used to get a STC for a different color of the baffles vs. having gone through testing to establish the flutter behaviour of a 3ft tall winglet approaching Vne at the gust limit in inverted flight .

Thanks, fellas. Considering something non-structural along the lines of the "baffle color" example posted. Seems like the biggest challenge might be, as always, the FAA and their desire to work with the customer.

My other consideration was how receptive the insurance guys will be to insuring an experimental Beech.

Jack-
If it is an otherwise TC'd airplane that changes to an Experimental for equipment testing purposes/certification insurance is less of an issue than if the airplane was an Experimental aircraft to begin with. Normally underwriters will accomodate a temporary change such as this for testing but you might want to inquire with whatever carrier insures it now. For reference the experimental underwriting market is a lot tighter (ie fewer carriers) than what you can expect for a TC'd airplane.