That is what I heard i.e. the old gyro needs to be retained – but what are they?
It may be something to do with stepper motor drive, and could be needed if you wanted to move your old KI525 HSI to the RHS for example.
As I understand things the Aspin has yet to get the software to drive an RMI so some sort of drive would be required for this function.
I don’t have the IM to hand… does it only output ARINC429 heading and no X/Y/400Hz (XYZ)?
A KI229 RMI can take composite pointer bearing, but it needs XYZ for the compass card.
You can buy ARINC429 to XYZ converters, too.
Loads of older avionics need XYZ heading but can’t take ARINC429 heading e.g. WX500 etc stormscope, KMD550 MFD (unless you fit an interface card in there which costs what a KG102 costs), radars, etc. The Avidyne TAS boxes fortunately can take ARINC429 heading.
That is what I heard i.e. the old gyro needs to be retained
Your mixing up two different systems…
- Stepper function, which is not being support
- XYZ synchro mode, which is supported. One analog load can be supported.
Loads of older avionics need XYZ heading but can’t take ARINC429 heading e.g. WX500 etc stormscope
The WX-500 can use choose to use no heading input, or use stepper, XYZ sychro, RS-232/RS-422 serial heading input. With the EFD1000 PRO the heading will be available trough RS-232.
OK… so the people who told me they had to retain the KG102A must have been those who installed the EFD1000 on the LHS and wanted to move their old KI525 to the RHS.
The KI525 installation on the RHS is an EASA Minor mod so long as there is no autopilot connection apparently – same as the FAA position.
That could be the case, it does not support the stepper motor drive.
I doubt any approval is needed if the system is allready installed, as it is only relocated. Unless that mounting location is described in the approval I wouldn’t know why you couldn’t move it from right to left.
An autopilot capability on the RHS HSI/EHSI needs the autopilot AFMS updated, hence the Major mod issue. That is certainly the case under FAA. Is it not so under EASA?
Technically it is trivial – a couple of RS08 relays to switch the good number of deviation signals and the HSI OBS signals going back the other way 
I have a simple altimeter on the RHS, but I have a spare KEA130A encoding altimeter on the shelf (one already is on the LHS), and wonder what would be involved in having either altimeter as the pressure altitude source – for the autopilot, transponder, TAS605… three AFMSs to change (in theory)! It would be a great redundancy feature though.
Sorry for miscommunication. I was refering to moving it to the RH panel without autopilot. I think it would be better too use the Aspen to drive the A/P in that case, and don’t have two sources for autopilot. It would require quite some switching, which can be done, but is also prone to failures. I would suggest to keep it simple.
The same for your altitude encoder. I would keep it as a spare for the LH side. These are quite good, and don’t fail to often from my experiance. Your autopilot is likely to use a separate altitude transducer instead of the altitude encoder.
Some newer equipment can have multiple altitude sources, such as Garmin GTN. When source 1 fails (no data), it will transfer to source 2 etc. This newer equipment does no longer accept the commonly used parallel gray code, only serial formats.
All the sources I listed work from the single KEA130A. I had one go faulty – it was discussed here, maybe 6 months ago. One of the Gray code lines got stuck and there was an intermittend very high altitude reading – something like FL410. I had the altimeter overhauled. One could have bodged it by grounding that line; it was the highest of the ten and would never go to a 1 (in a TB20).
One can also get altimeters (or encoders) which output ARINC429 altitude, which is just 2 wires to switch instead of 10. But that breaks the KFC225 autopilot STC.
This newer equipment does no longer accept the commonly used parallel gray code, only serial formats.
What do GTN installations normally do? Do people fit a Gray code to ARINC429 converter? The GTX330 can take in Gray code and output ARINC429 altitude, but there is a mysterious incompatibility between this and Avidyne, which neither company wants to talk about… My TAS605 box had to have the 10 wires brought to it.
On SEP aircraft the D lines are often omitted as they are only active above 30700 Ft.
I have had only once that one line of this KEA-130 was stuck. For a new installation (or when the altitude encoder goes bad) I always recommend to install a new stand altitude encoder. In most case this is more affordable including labour than to have a new or overhauled unit installed.
An encoding altimeter is more expensive than a regular altimeter and altitude encoder, while it offers the advantage to only exchange one unit if one fails.
For the GTN it is often possible as you suggest to use the altitude conversion option from the transponder. This has a disadvantage as well, if the transponder fails, you will also loose GPS accuracy. With the GNS I therefor always connected both the GNS and transponder to the gray output. A transponder failure would not degrade GPS in that case, it is only a little more in labour to install it like that. With the GTN it is no longer possible.
If the altitude encoder doesn’t have a serial altitude output capability or if that function is unwanted that a serial altitude encoder is to be used.
In combination with an Aspen EFD1000 both the Garmin and GTN benefit from their interconnection, for wind calculations for example. In this combination the GTN receives air data from the EFD1000, and in some case also serial from the transponder. In which case the EFD1000 would be the primary source. If unavailable the GTN would switch to the secondary source from the transponder.
For the TAS I always used parallel gray input. Do note that some manufacturers say that their equipment works with equipment from another manufacturer, only they don’t tell you how to set it up correctly. This can be very frustrating for the installer.
