My aircraft is undergoing avionics upgrade. Scope of work includes glass PFD, MFD, Garmin GTN and GTX plus some other widgets. As Robin is not on Garmin AML installer suggested that a minor change request would be filed to EASA in order to approve installation for use in IFR environment. Each of the boxes comes with it’s own antenna and placement of all those can be a challenge on a small aircraft due to limited space and separation requirements. As the whole project is way behind schedule I asked the installer for a list of major tasks, what needs to be done and who is responsible for what in order to get the airplane back in the air. To my surprise I found out that the installer will only “suggest” position or placement of GTN antenna.
I quote: "You are responsible for approving my suggestion, I am responsible for the work performed. "
Q: is it an industry standard to make aircraft owner responsible for placement of antennas ? For the record, I’m not an aircraft mechanic know, little about antennas and can hardly operate the GTN. Your opinions would be appreciated.
I suspect he’s trying to absolve himself of any liability if the thing doesn’t work very well. Antenna placement can have quite big effects on how well a radio system works, and the subject of antennas is surprisingly deep (and the installer might not know much about how antennas work – it all might be some kind of voodoo to him).
I wonder if @wigglyamp has any input on this?
The more basic Q is whether one can install this equipment (in a Robin or anything else) as an EASA Minor Mod.
It’s not right for an installer to say “You are responsible for approving my suggestion, I am responsible for the work performed” because he (not the customer, usually) is the expert in the relevant field. It also obviously means he can walk away from an installation which doesn’t work for various reasons.
It’s acceptable to install the GTN in a Robin under a Minor change. However, the approval will be limited to BRNav and LNav approach. We have done exactly this under our DOA privileges including raising the necessary AFM supplement. However, PRNav and LPV require approval via an STC which will be much more hassle.
As to the antenna installation question. From a personal perspective, I believe the installer is responsible for determining the antenna location. The approved installation data, in this case most likely the GTN installation manual, will require establishing the correct separation from other systems and the appropriate interference testing must be performed before the installation can be certified. I would never expect the owner to make the decision.
Would the GTN Minor change route also be available if there was an autopilot connected to the GPS?
Isn’t antenna placement voodoo to everyone. True there are high priests, but still voodoo.
Thanks @wigglyamp It’s a relief to hear that someone has done this before. However, I’m struggling to understand rationale behind operational limitations imposed on units installed via the minor change route vs STC. After all those are the same instruments installed with the same antennas placed in locations described in the same installation manual?
Following my last post, the installer has been in touch with me to discuss the issues and has consented to me providing some clarification.
For the antennas, the installer is not asking you to determine or approve the locations. He’s asking you to sign box 12 of the CS-STAN form (EASA Form 123 which is an obligation he has to comply with if he’s to sign-off the aircraft. The precise wording is here:
12. Signature of the aircraft owner. This signature attests that all relevant documentation is handed over from the issuer of this form to the aircraft owner, and, therefore, the latter becomes aware of any impact or limitations on operations or additional continuing airworthiness requirements which may apply to the aircraft due to the embodiment of the change/repair.
If the installer had applied for an EASA Minor change, then EASA would have investigated the antenna installation and issued the approval but you would have faced additional fees and time delays.
For the limitations. CS-STAN allows installation of separate VFR GPS, VHF Comm and Nav systems, which can all be combined in the case of a GTN or GNS. The installer is not required to demonstrate compliance with AMC20-4/5 for BRNav, JAA TGL 10 for PRNav or AMC20-28 for LPV, so can’t approve the installation for any of these IFR functions. EASA have determined that PRNav and LPV require approval via an STC which is very costly and time-consuming (easily over €15K) and normally requires flight testing under permit conditions. The approach by the installer to use CS-STAN is the most pragmatic solution to get the installation complete and initially certified for VFR. If Garmin at some point get an EASA STC for the GTN in the Robin (as they’ve recently done for the G5), then you could apply that STC (probably just by inspection and test) and remove the VFR limitations. For now, you could get just BRNav approval via an EASA Minor change as this requires an approved flight manual supplement.
I think there has just been a mis-understanding which is unfortunate. I would trust your installer – he has a good reputation and knows what he’s doing.
Just to clarify. I don’t work for the installer and have no involvement in this project.
Hope that helps.
I did whatever I could not to disclose the identity of the installer. I can’t comment on your post publicly at this time due to sensitivity of this matter and possible legal implications. Will PM you