New gremlin and I'm stumped! No trim??

[lancair360]

This one is new and I can't figure it out yet. Putting it on here before I email support, see what comes loose if I shake the tree.

Install done 5 years ago (before my time with the plane). Lancair 360 (dingo_360 on instagram) It's a new intermittent problem. Dual SkyView SE 7" screens, skyview comms, autopilot control panel, PMA4000 intercom. Electric elevator and aileron trim on the coolie hat on the sticks, trims have a TRIM circuit breaker. The only trim indication on the skyview is for the elevator trim.

Last couple times I flip the master switch as it all boots up I get a caution message "AP Panel Offline". Fine, don't need it, controls on the screen still work, AP still works fine. But I also have NO trims!! Cycling the AP breaker/switch does nothing (and the switch is OFF during all this anyway, it's just the panel offline).

Flew yesterday and on first master swtich flip it happened. A couple power cycles didn't sort it. So I started up and taxiied to the end to give it time, cycled the master switch there, and it came online and trims now worked. Any subsequent OFF/ON the rest of the day and there were NO problems.

The screens themselves will illuminate the AP panel, so I have yet to try just powering down the screens (or rebooting) instead of using the master switch. A cycle of the TRIM circuit breaker didn't fix anything either. I haven't put the AP back in simplified mode to remove the panel from the loop but then if everything works I can't be sure it's THAT that fixed it or that it's just working and didn't fail. intermittent problems are the worst.

The servos are connected to controls, not trims. And AP off or on the problem persists until I cycle the master. Happens before start up so no weird voltage drops during start scrambling anything. Battery is good. Master solenoid just replaced. Elevator servo just overhauled, but since been reinstalled and all calibration and tests complete. This is isolated to just the AP panel and trims. Totally has me stumped. Thoughts?

 

[Raymo]

Sounds like a loose connection at the AP Panel. Check for a recessed pin or weak wire.

 

[lancair360]

Sounds like a loose connection at the AP Panel. Check for a recessed pin or weak wire.

but how would this disable the trim? If I pull the CBs for the dynon stuff and power up the plane the trim still works.

 

[Raymo]

The trim relays are inside the AP Panel. If that power is removed, you'll have no trim. Your trim CB supplies the power to the AP Panel for trim and allows pass-through functionality regardless of EFIS/AP power.

 

[lancair360]

Son of a .........

 

[lancair360]

No loose wires in the back of the autopilot control head.
Also powered up twice today doing other things and no failures. Any other tips before I get hold of Dynon? May just send it in to bench test and IRAN. Thanks everyone.

 

[kellym]

No loose wires in the back of the autopilot control head.
Also powered up twice today doing other things and no failures. Any other tips before I get hold of Dynon? May just send it in to bench test and IRAN. Thanks everyone.

Check your network configuration and make sure the network is seeing the AP Panel. If not, reconfig and make sure the AP panel is found. If not it is a network cable problem.

 

[lancair360]

It’s an intermittent problem. So I can’t do that until it fails again. Works fine the other 99 times. Though I’m certain it’ll show offline since I am getting a caution message AP panel offline when / if it fails again.

 

[jakej]

No loose wires in the back of the autopilot control head.
Also powered up twice today doing other things and no failures. Any other tips before I get hold of Dynon? May just send it in to bench test and IRAN. Thanks everyone.

It’s not necessarily that simple, there are ’tracks’ & solder joints to consider as well. Maybe you could borrow another panel just for testing?

 

[lancair360]

Problem is the failure rate is so minuscule it’s hard to run any kind of differential diagnosis.

not finding any loose wires is a good step. Bench testing the unit would be another big piece. If it’s fine then it really narrows down what to look at.

I appreciate the help. I’ll look again with fresh eyes tomorrow.

 

[lancair360]

UPDATE - Spoke with Dynon, they recommend sending the unit in. Airplane down for inspection anyway so, no big deal. Thanks again for the help everyone.

 

[lancair360]

AP panel is back and installed. They replaced some hardware according to the RMI and waived the repair fee. Class act Dynon! Ops check good. Return to service.

 

[lancair360]

2 years on from this repair and it’s failing again in the same matter. Calling Dynon now.

 

[lancair360]

Uploaded screen diagnostics for Dynon last week. Waiting to hear back. Exact same failure mode as 2 years ago except not intermittent it’s 100% of the time. Only fails after the second screen is fully booted. Until the , from master in to screens booted the trim works normal. Had the aircraft powered up for database update and no problem. After database update I cycled the power to check both screen had sync’d and that’s when the failure started. After two days of 100% failure rate and talking to Dynon I pulled the diagnostics. The whole time I was powered up and pulling files…..no failure. Every single subsequent power up showed no failure. While up and running I wiggled ever wire connection I could and couldn’t induce a failure.

Waiting to hear back, get back from work tomorrow and first thing in the hangar I’ll power it up and see what happens. No clue what it’ll do next.

 

[lancair360]

Dynon shows no hardware or network faults. Apparently software guys still digging through code to find answers. The failure doesn't occur until after the second screen has booted which is super weird. Handful of subsequent boots since this have had 100% zero failures. Bit flip? Chinese spy balloons? I dunno

 

[lancair360]

Constant back and forth with Dynon trying to get them the best information. As usual Dynon customer support is fantastic.

Turns out the previous repair two years ago was all the solder joints on the main board were broken and causing the intermittent failure. I suspect the same thing has happened here. Dynon is sending me a new unit to install.

Grasping at straws the only piece of info that seems to affect whether it fails or not is the temperature. the over/under is about 43ºF it seems. it's a stretch, who knows. Happy to be getting a new unit to install and get back up and running.

 

[Rhino]

Temperature very often affects bad solder joints, so I'd say you're on the right track.

 

[lancair360]

Temperature very often affects bad solder joints, so I'd say you're on the right track.

You know I wasn't sure but if the shoe fits. So weird!

 

[lancair360]

Update for everyone. Dynon has been the absolute best to deal with on troubleshooting and getting me a new AP panel, couldn't be happier with them.

Installed the new AP panel and halfway to the runup pad, AP Panel offline master caution. wtf Power cycle the plane and it's fine for the rest of the day. Did 3 flights, never came back. Speaking with Dynon I'm also getting new network cables to replace mine two on the AP Panel, just to rule out bad wire somewhere.

Here's where it gets weird. And Dynon has all this info, waiting to hear back from them. Nice warm day today, power up the plane, AP Panel offline. Now like I said earlier the failure only occurs after the right hand screen boots up. Also, as an aside, anyone tell me why one screen boots before the other?

Power cycle, fixes it. This is the NEW Ap panel installed. Go flying, no trouble. Land and turn off the runway, AP Panel offline. Back to the hangar and I do several power cycles on the plane, no failures at all. I start wiggling and twisting the two network cables, no failures at all.

Looking at the back of the AP panel. The D9 on the left goes to the right hand screen. The D9 on the right goes to the network hub, then left screen.

Pull the hub one and I lose ARINC429, other display offline, ADAHRS fail, pitch servo offline, roll servo offline, xpndr fail.

Now for the cool part, plug that back in and then pull the other one that goes to the right hand screen and I get all of that plus AP panel offline. The AP panel offline is only tied to the right hand screen. And that’s the screen that has to boot before the failure happens. That’s gotta mean something right?

Regardless I'm replacing those two network cables because that's cheap and easy. But come one, there's gotta be something weird with that right hand screen. Both screens are 7" Skyview. Both serial number 4xxx Left one went back for an SSD replace two years ago, no faults thrown on the other screen yet but I can't help but wonder.......hmmm.

 

[Rhino]

Probably the reason why one screen boots before the other in a dual screen system is because one must be the master on the network. It doesn't really matter which screen that is, but one is always automatically chosen.