Team,
My Robin Dr253 is equipped with a 1960’s Badin-Crouzet 1-axis, vacuum-driven autopilot.
As 1) it is showing its age, 2) it is the only remaining device in the aircraft using vacuum, and 3) my vacuum system is developing issues, I am thinking of getting rid of the vacuum system altogether (instead of fixing it) and replacing the autopilot by something modern, electric, and 2-axis.
But before going into the details of which model to choose and the technicalities of the installation, I would like to get the administrative points out of the way first. Pardon my silly question, but I am a bit lost with what requires an STC, a Minor Change, or anything else.
Obviously no autopilot manufacturer created an autopilot retrofit STC for any Robin. Therefore what are the options here?
Is an STC necessary? If yes how much does one cost?
Would a minor change be sufficient?
Any other points to consider?
Any tips?
Thanks,
Etienne
Some Robins do have autopilots so can I suggest that you call Robin and.see if they can answer your question. Next week or the week after might be a good time as most are returning to work after the holidays.
etn wrote:
Obviously no autopilot manufacturer created an autopilot retrofit STC for any Robin. Therefore what are the options here?
Is an STC necessary? If yes how much does one cost?
Would a minor change be sufficient?
There are no existing STCs for US-manufactured autopilots. Robin do have TC-approved installations of the STec 55X and possibly the System 30.
A new STC from Garmin or S-Tec isn’t possible as the majority of Robin aircraft do not have a US Type Certificate and can’t therefore be listed on an FAA STC.
Certainly Garmin won’t support a GFC500 EASA STC being produced by a third-party – I tried that several years ago when I ran a Part 21J.
Your only current option will be an STec installation by the Robin factory.
Why could this route not be used?
If Robin approved it on their TC then a 3rd party can install it. The debate (as that thread shows) is around how much installation data is justifiably required. But this route is widely used for retrofit installing factory-TC-approved avionics. The wiring diagrams are obviously available and the rest is “obvious” mechanical stuff.
Of course it would not be cheap and would cost a lot more than the whole plane is worth. Last time somebody spent that much on a 253… well we all know what happened and EuroGA is still getting silly “legal” threats from that guy 
Peter wrote:
Why could this route not be used
We’ve asked in the past and they wouldn’t allow us access to the installation data or specific airframe parts (servo mounts etc). All we could do was buy the servos and computer directly from S-Tec but then had no legal basis or data to install them. There’s more to an autopilot installation than just a wiring diagram! You need all of the clutch settings for the servos, mechanical drawings for installation of servo mounts and flying control cables, rigging instructions etc. Lots of this doesn’t normally appear in the aircraft maintenance manuals and is often supported by a separate Instruction for Continued Airworthiness which is also supplied by the design approval holder. You also need a controlled copy of the Flight Manual Supplement. Robin wanted to do it in-house and I’m not aware of anyone who has got around this and done a field installation.
All we could do was buy the servos and computer directly from S-Tec but then had no legal basis or data to install them
How do people install a DFC90, given STEC’s openly poison letters about it? Obviously there is more to an AP that just wiring (obviously I knew that) but the servos and mounts can be purchased.
With N-reg it’s a lot easier to get stuff done pragmatically but lots of DFC90 installations are not N-reg.
controlled copy
Is there an unambiguous legal reference for that?
I would not expect Robin to co-operate of course. But it seems the rest is just an installer’s interpretation of a collection of rules. Like whether 4 or 6 screws to screw down my TAS605 needs a DER8110 design package for £2000; it doesn’t but you will remember that job
People were regularly retrofitting GNS boxes into TBs based on Socata TC and Socata both never co-operated and were never asked.
The bottom line is that this job is completely pointless financially.
Peter wrote:
How do people install a DFC90, given STEC’s openly poison letters about it?
They use an STC from Avidyne. Approved data package with ICA and AFMS available to the installer.
SA00310BO_DFC90_pdf
Peter wrote:
but the servos and mounts can be purchased.
In the case of the Robin, the servo mounts are proprietary parts produced by Robin, not STec.
Peter wrote:
Right… and a 253 is from around 1970, I think? Did Robin ever make servo mounts for those?
Probably not! Doing a new autopilot installation requires a STC as the potential effect on primary flying controls and handling makes it automatically a Major Change. Flight testing is extensive including looking at the effects of un-commanded runaway conditions. Not something to undertake lightly and doubtless very expensive. Without the support of the autopilot equipment OEM it’s a non-starter.
Thank you for your answers. It looks indeed that the options are pretty much limited to keeping the existing autopilot, buying a new airframe (no thank you), or fly without an AP. Paying a PPL training for my partner seems the cheapest option here :D
I will still make a few calls to Robin, maybe Avionik Straubing and a few others, and hear what they have to say. Will keep you posted.
