I don't know if anyone has had this happen, but today, I believe my AP74 failed in flight. It's powered from the avionics bus and the only way to remove power from it is to turn off the radio master switch. Unfortunately, when I do this, I loose radios, transponder, GPS, and my traffic alert system. During flight with my autopilot engaged in level cruise flight, I kept getting an EFIS message that said something like 'AP74 connection lost'. Don't know if that's the exact message, but it was something like that. I would acknowledge the message to make it go away and within about 15 seconds it looked like a white light inside the AP74 would flicker on for a second. I didn't see this at first, but after seeing it a couple times (the message kept coming back), I finally decided it could be arcing inside the AP74 case. I turned off the autopilot servo switch, but this had no effect. I shut everything down for a while and then powered back up. The AP74 stayed off (no lights) and I landed. I did hear audio 'pops' in my headset that went away when I turned the alert volume down to zero. I don't have the 'failover' alerts wired from the EFIS/EMS, but I'll be changing that. Tomorrow I'm going to remove the AP74 and have a look. When I do, I assume I'll have to reconfigure my system if I want to fly without the AP74. By the way, I have a FLTDEK 180, AP74, and two SV32 servos mounted in my RV-8. I'm wondering if I should have a separate power switch so I can isolate my AP74. Powering it through my avionics master doesn't allow this. This has been working fine in my airplane for 2 years, other than poor performance from my altitude servo being able to hold altitude in an acceptable way. That problem has been hashed over here on this forum, but no solution was found - yet.... in fact my airplane actually holds altitude better with the altitude servo turned off (I'm not trying to be funny - it's true). Please let me know if you think my AP74 is fried. There was no smoke, smell, or hot surfaces when this was happening. Maybe there's a little white light in there that I didn't know about......
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AP74 Failure
- Thread starter shersha
- Start date
Scott,
When the AP74 and HS34 are on but not part of the DSAB bus, the backlights will come on bright behind the buttons.
If the communication is disrupted between these expansion units and the Master, the lights all turn on bright on the expansion units.
Is this what you may have saw?
When the AP74 and HS34 are on but not part of the DSAB bus, the backlights will come on bright behind the buttons.
If the communication is disrupted between these expansion units and the Master, the lights all turn on bright on the expansion units.
Is this what you may have saw?
Brantel,
That is, no doubt, what I was seeing. Sometimes the light would stay on for a couple seconds. Now the question is, why wasn't it communicating? I'll try to re-configure the system and maybe reload 5.3 to see if that helps.
Thanks.
If you Dynon staffers have any suggestions, please let me know.
That is, no doubt, what I was seeing. Sometimes the light would stay on for a couple seconds. Now the question is, why wasn't it communicating? I'll try to re-configure the system and maybe reload 5.3 to see if that helps.
Thanks.
If you Dynon staffers have any suggestions, please let me know.
- Joined
- Mar 23, 2005
- Messages
- 13,226
If there was an intermittent DSAB wire, you would definitely see this behavior as power stays on but the data connection goes away, yielding the behavior that Brantel mentioned. Beyond that, it could be a hardware problem as well. Does it do it on the ground? Does jiggling the wires have an effect if it doesn't do it on the ground w/ the engine off?
Does it do it on the ground? By that I assume you mean does it not connect on the ground. It does not connect on the ground with the engine off or running. Jiggling the wires doesn't help. I checked all the wires and even replaced the power and ground wires to make them a little longer for ease of maintenance, but that didn't make it work. The DSAB and voice alert wires looked fine. When I tried to re-configure, the EFIS didn't recognize the AP74. It said 'AP74 not installed'. It is now configured with the FLTDEK180 and the two servos, but no AP74. When I power up on the ground, the lights in the AP74 flash on, indicating it is getting power, but it does not communicate with the bus. I got an RMA number today and the AP74 is on it's way to you.
jaba-who
Member
Scott,
How did you go with your problem? What was the problem?
My system sounds like it is the same as yours (but in a Jabiru) and I had what sounds like the same problem in the last couple of days.
I have pulled my AP74 out and am about to organize sending it back to the factory for looking at. Anything come of yours that could be a help to me before I send it halfway around the world?
John Martin
How did you go with your problem? What was the problem?
My system sounds like it is the same as yours (but in a Jabiru) and I had what sounds like the same problem in the last couple of days.
I have pulled my AP74 out and am about to organize sending it back to the factory for looking at. Anything come of yours that could be a help to me before I send it halfway around the world?
John Martin