MGL Avionics User Forum

I have to admit I am getting pretty fed up with the lacklustre performance of the MGL autopilot but would genuinely like to do something to get it sorted out.

Why does my autopilot think it's perfectly acceptable to climb 300 ft before it realises it needs to descend? Today I had a 450 ft descent before it realised it was doing a bad job and had to climb to return to where I'd told it to stay put. Headings wander by +/- 10 degrees.

I've tried all sorts of combinations of magnitude and reaction to errors but nothing makes it function any better.

Flying the same aircraft type (Eurofox) with the Dynon or Garmin autopilots shows how it can be done. They don't wander all over the place like my MGL system does. The same frame is used for holding the servos and the mountings are rock solid. There is no excuse on the installations.

I don't think it's the servos; they seem to do what they're told. I think it's the shoddy signals that are being produced in the iEFIS (I have an Explorer Lite) and the information is not being fed sufficiently quickly to the servos. Is this just the difference between an AHARS chip that seems to 'wander', as opposed to the likes of Dynon and Garmin, whose chips don't wander?

I'm not going to spend more money fitting an external AHARS (SP7) because everyone I've spoken to, who has done this, said it made no difference at all to the performance of their EFIS. That would just be throwing good money after bad.

I would be happy if the poxy thing just held an altitude and a track. Don't even get me started on trying to use it in LNAV.....that is a complete and utter joke.

I suspect that the issues such as this are generally related to the Lite version, and can be traced back to inbuilt AHRS being affected by vibration.

I suspect you are correct in that this seems to be the standard response for anything that suggests the AHARS does not perform well. It's funny how 'vibration' causes the kit to suddenly do a bit of a dance, when a second before it was behaving itself and nothing has changed inside or outside the aircraft. It's also funny how 'vibration' causes issues, even though the EFIS is mounted exactly as it should be. Why fitting an SP7 doesn't solve the same 'vibration' issues in a bit of kit remote to it is also a real head-scratcher. Same aircraft, with Dynon and Garmin equipment, don't seem to have the same vibration.

If the SP7 was guaranteed to sort out the lacklustre performance of the Lite's internal AHARS chip I'd be prepared to give it a go. The fact that everyone I've spoken to or read about says it made no difference does not make me want to go and waste the money.

So just a question, PaulSS or Tasmag, what servo's are you using with your autopilot?

I have just started sorting out my autopilot. Up until now, I have not been able to keep my autopilot engaged, thanks to David 8 on this forum, Jake and Chuck from Trio Australia and the USA whom all advised about the clutch in the Trio Gold servo, hopefully it's sorted now.

With my autopilot now staying engaged so I can fly to a waypoint. My autopilot flying envelope for alt hold is not flying so nicely, but I am hoping my Voyager EFIS setting will sorted this out to make some improvements.

If anyone on the forum is using a Voyager EFIS with Trio Gold servos in a Jabiru 230/430 and would like to share their Voyager EFIS setting, I would be grateful to see them.

Cheers
JimJab

Hi Jim, I have the MGL servos. No capstan, just the normal arm. As I said, I reckon the servos should be okay but they probably just get bad commands from the EFIS (or no commands……either way it wanders too much).

Mine is all mgl components commanded by an explorer lite.

My AP works fine when using straight ahead level mode, the only issue I have found is turbulence knocks it about a bit and heading to a waypoint doesn't follow the HITS properly, always seems to be off to the left side of track.

I am thinking about getting an sp7 to try and fix that issue.

Mike

I have an SP-7 and a Challenger system.
The autopilot is not as good as the GFC500 coupled with a G3x/G5 in the same aircraft.

It may well be an AHARS problem - or maybe not.
Wondering if anyone has stumped up for the SP-9 AHARS and if that improves the situation? It feels like the AP is the weak link in what is otherwise a fantastic EFIS system.

(Disclaimer - I don’t think that I have spent enough time adjusting the sensitivity of the servos which may be the real issue).
The AHARS in my Sling is mounted well and on a damped surface so it’s not that.

Of note is that I also have the left of track issue that other people mention - it simply will not fly through the highway in the sky boxes…..

I have the same problems as everyone else when using the ap. I have an explorer with mgl servos and the sp7. I have to keep my hand on the stick to make sure I don’t ascend/decend at 500 fpm. Sometimes it works better but cannot fgure out what conditions create that. I thought for a while it was vibration in the stick but that doesn’t affect the servo movement. Would be nice is there was concrete/absolute answer.

I never have an issue with the altitude, only ever wanders in the 50 feet range, never 500 feet.

I do tend to add a bit of trim up so that servo had some force to work against.

Mike

I’ve attempted similar ‘work arounds’ but to no avail. If the same aircraft type wandered around the same as mine does, equipped with Garmin or Dynon kit, I could accept it was something to do with the low wing loading. The fact they don’t (and I’ve tested quite a few now) points to trouble at the MGL end of things.

The silence from the maker is stunning but I suppose it is inconvenient to point out failures of systems and it doesn’t involve selling new types of radio or transponder. The only reason I’m not as vocal as I might be about how bad things are is only because the UK rep is such a nice and helpful bloke and I know it has nothing to do with him but could negatively affect him.