Aspen/KFC150 AP AHRS Fail Light

[Scottknoll]

I've been trying to understand why I inconsistently get an AP AHRS light on startup. After powering up Aspen and Avionics, the AP AHRS Fail light stays illuminated. This inhibits the Flight Director on the Aspen. I've tried waiting until the Aspen is fully aligned before pressing the KFC150 test button. The only thing that has worked has been pulling the AP AHRS and AP circuit breakers. But even then it sometimes takes a few cycles to get the light to go out and the flight director to display. I'm open to ideas. Of course I took it to the local avionics shop and it would not replicate for them.

[LANCECASPER]

7 hours ago, Scottknoll said:

I've been trying to understand why I inconsistently get an AP AHRS light on startup. After powering up Aspen and Avionics, the AP AHRS Fail light stays illuminated. This inhibits the Flight Director on the Aspen. I've tried waiting until the Aspen is fully aligned before pressing the KFC150 test button. The only thing that has worked has been pulling the AP AHRS and AP circuit breakers. But even then it sometimes takes a few cycles to get the light to go out and the flight director to display. I'm open to ideas. Of course I took it to the local avionics shop and it would not replicate for them.

Part of my checklist when I had two Aspens and a KFC225 was to pull the A/P circuit breaker on shutdown, since the next time the KFC225 goes into self test mode automatically on startup and would go through the test before the Aspen was up fully and the self test would fail. So what I finally figured out to do was on startup, after the Aspen had started and was showing horizon and the amber light was off, then I put the circuit breaker in on the autopilot. Then it would pass the self-test with the right amount of beeps.

Later in another airplane, I had three Aspens and a KFC150. The KFC150 waited for me to do the self-test. If I waited until after the horizon came up on the Aspen and then did the self test I got the right amount of beeps. 

[Scottknoll]

Thanks. Will try that today. I figured it must be something in the startup sequence, since it is resettable by pulling CBs. The autopilot does pass the self-test, and will actually engage and track heading bug on the ground. But the AP AHRS FAIL light remains illuminated, and no flight director is displayed. I didn't think the autopilot would engage with the AP AHRS Fail light illuminated.

[Jake@BevanAviation]

@Scottknoll  If it was wired correctly it should not engage with the amber cats eye illuminated, indicating a EA100 failure.  If the EA100 goes down in flight and it is the source of the attitude information to the KFC150 with no disconnect you will have a very interesting ride.  See print for details.

Aspen EA100 to KFC150.pdf

[LANCECASPER]

Sad to say . . . it is not unusual for an EA100 to fail.  Aspen blamed my EA100 not working on the shop not using Aspen's specially shielded ethernet cable.

I will say Aspen was excellent to deal with though. A few months after my initial install I had an EA-100 fail on the way to Sun N Fun, rendering the A/P inop. I stopped by the Aspen booth and they walked me over to Sarasota Avionics who got me into their Tampa shop before my return trip to have the EA-100 replaced under warranty (I paid labor). 

[Scottknoll]

Thanks guys. That all makes sense. I tried turning EFIS (Aspen) switch on after start and leaving the radio master off (To keep KFC150 off). Waited until Aspen was fully aligned, then turned the KFC150 on. That worked much better. The light will actually go out prior to pressing the KFC150 self test. I think the problem was just powering everything up at the same time.

Makes sense that the autopilot should not engage with the light on. I’m not 100% sure that is what it was doing. I was focused on resetting breakers.

Now that I’ve nailed down the required power up sequence, I’ll try a few scenarios engaging the autopilot before the light goes out.

We bought the airplane equipped this way, and have been thinking about a G500Txi/GI275/GFC500. Maybe I’m looking for reasons to pull the trigger

[PhateX1337]

I have a similar, but slightly different issue ... have 3x Aspens and a KFC150. I was told by the previous owner to turn the master on first, let the three Aspens fully boot up, and then turn on the radio switch to send power to the KFC150, GNS430Ws, and the rest of the lot. When I turn on the radio, the "A/P AHRS Fail" cat eye light will illuminate and then ~10-15seconds later will turn off only about 25% of the time. If it doesn't, I have to turn everything off (radio & master - leave engine idling usually), and try again, master first, let the Aspens boot, then radio. It usually goes out on the 2nd try, but I've had to do it 3 times more frequently recently.

Any idea what could be causing this? Is there a breaker I could pull to reset this without having to do the whole master & radio off process? I've pulled the "Autopilot" and "A/P Alert" breakers but when I push them back in the AHRS Fail light comes on and stays on (though maybe I'm not waiting long enough? Doubting myself now...)

Appreciate any help @Jake@BevanAviation or anyone else!

[Ryan ORL]

It is normal for the A/P AHRS Fail light to turn on when you turn on the avionics bus.  As you note, it should extinguish after 10-15 seconds when the EA100 boots up.

If the EA100 has failed, the light never extinguishes.  When my last EA100 failed, it first did so intermittently as you describe, and then more frequently, and then always.  You can shortcut your troubleshooting steps above by simply pulling the EA100 breaker and recycling it.  Rebooting everything else is not necessary.  (Could be labeled "AHRS" in your setup maybe?)

I can echo the above statements about failed EA100 units not being particularly unusual.  Everything else in the Aspen/KAP150 system worked fine, but the EA100 is a junk piece of hardware.  I had three EA100 units fail in my plane in only 18 months before I threw in the towel and ripped it all out for a GFC500.

[PhateX1337]

Just now, Ryan ORL said:

It is normal for the A/P AHRS Fail light to turn on when you turn on the avionics bus.  As you note, it should extinguish after 10-15 seconds when the EA100 boots up.

If the EA100 has failed, the light never extinguishes.  When my last EA100 failed, it first did so intermittently as you describe, and then more frequently, and then always.  You can shortcut your troubleshooting steps above by simply pulling the EA100 breaker and recycling it.  Rebooting everything else is not necessary.  (Could be labeled "AHRS" in your setup maybe?)

I can echo the above statements about failed EA100 units not being particularly unusual.  Everything else in the Aspen/KAP150 system worked fine, but the EA100 is a junk piece of hardware.  I had three EA100 units fail in my plane in only 18 months before I threw in the towel and ripped it all out for a GFC500.

Thanks Ryan, helpful. I do have a "EA100" breaker so I'll pull just that next time this happens and give it a minute or two to boot up and see if that fixes the issue without a full reset. 

Sounds like my EA100 may be slowly dying as well ... ugh.

[Jake@BevanAviation]

@PhateX1337My initial thought is some communication problem with the EA100, see print below.  Ideally if the PFD has fully booted, then you turn on the radio master, the EA100 should communicate with the EFD, if the information is correct the ACU should tell the EA100 to extinguish the A/P AHRS fail annunciation.  It's not uncommon to hear about EA100 failures.  When they do fail you will have the A/P AHRS fail annunciation constantly and the A/P will not be able to engage.

Aspen requires that their Ethernet cable be used for communication between the EA100 and the EFD and terminated correctly, if the required cable is not terminated correctly it can cause interference issues with the EA100 per the IM.

Edited January 16, 2023 by Jake@BevanAviation

[PhateX1337]

6 minutes ago, Jake@BevanAviation said:

@PhateX1337My initial thought is some communication problem with the EA100, see print below.  Ideally if the PFD has fully booted, then you turn on the radio master, the EA100 should communicate with the ACU, if the information is correct it should extinguish the A/P AHRS fail annunciation.  It's not uncommon to hear about EA100 failures.  When they do fail you will have the A/P AHRS fail annunciation constantly and the A/P will not be able to engage.

Aspen requires that their Ethernet cable be used for communication between the EA100 and the EFD and terminated correctly, if the required cable is not terminated correctly it can cause interference issues with the EA100 per the IM.

Thanks Jake - I'll ask the avionics shop to confirm it has the correct Aspen ethernet cable as well.