$12k here and that is a new one. You can get Sandel-refurbished as-new ones for half that. Probably I would avoid this kind of thing because that shop has no specific SN3500 expertise.
There is no comparison between the build quality and reliability of Aspen and Sandel, but the Sandel is just an EHSI.
GI275 probably the best bet. If you are only doing one and potentially think about adding others later ensure you read the STC’s and then question your shop on their knowledge of them.
GI275 is not massively more expensive than the G5, has a much nicer display and arguably looks better in the panel. Each can be a certified source for display of 3 or 4 pieces of information.
Thanks for all the info. I actually wasn’t aware the G5 HSI could be used to drive a legacy AP, as I was confusing it with the AI version which cannot. I’m going to make one fail-fast attempt to diagnose and fix the current setup first, but I may end up going down the EHSI route if that looks like a can of worms. I’d rather spend the money on an engine monitor, because the King HSI gives me everything I care about.
. I actually wasn’t aware the G5 HSI could be used to drive a legacy AP
It can’t emulate a KI256, unless this is very recent.
Peter wrote:
It can’t emulate a KI256.
I would need it to work with a Century autopilot. My understanding is that dual GI-275s could replace both my AI and HSI and drive the AP, but dual G5’s would require retaining the existing AI. There’s also the uAvionix AV-30, which I actually prefer from a display perspective for the AI, and there are plans to support Century autopilots. But at the moment it’s just the HSI function I need.
My C41 works perfect with the SN3500 I love this unit. A bit of thread drift maybe, but I am looking into replacing my gyro ATT with a GI275 + magnetometer maybe even two. Required for driving the AP. The open question if the GI275 ARINC label output for magnetic can be used for the SN3500 magnetic heading data. From the SN3500 install manual: ARINC 429 Heading Input from AHRS. Sandel monitors for Label 320, Magnetic Heading Data and Label 270 System Status (SN3500 unslaved). See section 7.1.3 for Label 270 options available in software version A4.08 and above. Label 270 seems to be a discrete input crucial for the mode selection….HDG, DG, ATT,…
Question: Can you dump the KG102 as input for the SN3500 when installing two GI275? The second GI275 can be CDI 2 ,MFD, back up, etc..this would unload a lot of weight. One heavy ADI, remove the vacuum pump, remove NAV2 indicator, remove Altimeter 2, remove back up ATT, remove KG102. remove T/C, plumbing. good for 15+ pounds
From Terry Markovich (avionics guru on BT) I got this info: ARINC 705 (AHRS) defines the bits as:
Align Mode/Not Ready
Reversionary Attitude Mode
Normal Mode
Magnetic Heading/DG Mode
Attitude Invalid
On Battery
TAS Invalid
AHRU Fault
IRS Use
I assume the Sandel only uses a few of those.
Garmin does list 270 as being part of the AHRS output bus, I assume they follow ARINC 705
dutch_flyer wrote:
I actually wasn’t aware the G5 HSI could be used to drive a legacy AP, as I was confusing it with the AI version which cannot.
My club has a PA28 with the Piper Autocontrol IIIB AP (rebranded Century IIB AP) driven by a G5 EHSI. It works very well! We kept the mechanical AI to provide attitude information to the AP.
You need some discrete components to interface this AP to the G5. We used this box, which has all the components built-in: https://www.aircraftspruce.com/catalog/avpages/delkin_11-17574.php
dutch_flyer wrote:
Of course I know the Aspen is also a possibility, but that’s pretty major surgery.
The Aspen E5 works with your AP and all your other stuff perfectly and it is at around just below $6k. It would interface easily with your 530W and provide GPSS as well as heading e.t.c. to your legacy AP all in one box.
I don’t think it is significantly more surgery than a G5 or similar which needs adapters to work with your AP and it imho gives a lot more functionality. It is still one instrument (like a single G5) which covers 2 holes however. You could move the existing horizon to where your ADF used to reside.
Personally I love the Aspen’s functionality and it’s readability. It works really well with my S-TEC AP and I know people who use it with your AP type and are quite happy with it.
