Anyone having issues with Flightsimware's C414 not being able to hold a consistent altitude with the autopilot?

 I'll see it level off at the selected altitude and then two minutes later, begin a wild excursion, climbing 1500 feet per minute for no apparent reason.

Btw, I'm using the latest version of the plane, combined with the payware PMS GTN750.

Only the C414?....Have you installed Blackbox trislander? It causes problems with kap140 autopilot in all planes

To capture altitude you must first hit the ALT button then either IAS or VS.  That is the only way I was able to capture the altitude set in the preset selector.

Yes occasionally the autopilot is acting up in ways that you mentioned. It seems infrequent though - it doesn't happen every flight. But sometimes it's really bad with the plane suddenly going into a climb or descent for no apparent reason. 

I also have the (infrequent) issue that in some flights I cannot control climb/descent with IAS or VS. I've mentioned it on the Flysimware and TDS (I use the GTNXi) Discords, but it seemed nobody had experienced the issue. 

Edited August 7, 20223 yr by Cpt_Piett

2 minutes ago, Cpt_Piett said:

I also have the (infrequent) issue that in some flights I cannot control climb/descent with IAS or VS. I've mentioned it on the Flysimware and TDS (I use the GTNXi) Discords, but it seemed nobody had experienced the issue. 

I have also experienced this, not sure what is causing it, though..

1 minute ago, Bert Pieke said:

I have also experienced this, not sure what is causing it, though..

Well it's not just me then 🙂 Are you on SU10 beta?

5 minutes ago, Cpt_Piett said:

Well it's not just me then 🙂 Are you on SU10 beta?

Nope, SU9.

Might be due to weather injection quirks ( ? )

If for some reason and all of a sudden a pressure rise or decay is injected from real world weather, the result will be that depending on the code that is used for the ALT channel of the A/P...  Just and hypotesis because IO do not own either the C414 or the TDS /PMS GTN units.

I haven't had this happen yet.  I use the TDS unit with the C414.  

I have noticed MSFS doing little wind shifts here and there on final but that's, to me, not unrealistic (they're not drastic changes) and I was flying in the mountains  (Missoula, Montana).

It is possible that a pressure rise or decay injected in short order could throw it off as jcomm mentions.

One thing I have noticed is that sometimes the AP will take a while to reach the target altitude, in that let's say my target altitude is 12,000 feet, let's say I'm in IAS mode at 140 kts.  It will climb to 11,700 and then the last 300 feet it will settle in for several minutes to get that last 300 feet.  It'll get it, right on the money, but it doesn't do it quickly.  I don't know if that's real-world behavior or not.

I'll keep an eye out for any sort of wild oscillation (1500 ft as described) though.

I just had the plane suddenly go into a ~1500ft/min descent over the mountains of Macedonia. I'm only a few thousand feet over the hills, so there's a bit of turbulence. Other than that, nothing seems unusual about the weather. 

The plane seems to be behaving itself today (just finished four pretty normal flights), however, I've discovered another strange quirk; above about 13,000 feet, the manifold gauges start twitching, showing a variance about 1.5". At the same time, the EGT needles also twitch. This behaviour seems to dampen as you descend and it disappears altogether below 13,000'.

SU9, using the PMS + WTT, I've seen the autopilot do wacky things like blow through FL190 and automatically select a new altitude on its own. Brought it up in the discord, no one else seemed to have the issue, so whatever. 

2 hours ago, sgreen91 said:

To capture altitude you must first hit the ALT button then either IAS or VS.  That is the only way I was able to capture the altitude set in the preset selector.

See that's wrong. If they have it coded that way it's broken.  It was working previously.  I haven't flown in a while or used the latest version.  In the real GFC 605 the only time you press ALT is to hold current altitude.

Unless you're speaking of the default GNS old school autopilot.

 

 

 

39 minutes ago, ryanbatc said:

See that's wrong. If they have it coded that way it's broken.  It was working previously.  I haven't flown in a while or used the latest version.  In the real GFC 605 the only time you press ALT is to hold current altitude.

 

Agree... actually, the only time I press ALT is to discontinue Altitude Hold..

Capturing target altitude works reliably for me, just the odd time when the vertical speed hold (VS) seems to get undone and then wanders..

I've had erratic AP behaviour (enter steep dive or climb) twice in recent weeks (SU9).

Neither was with the C414 (one with SR22 and I seem to recall the other with Carenado's C182). In both cases the departure from level flight was abrupt and I needed a LOT of elevator trim to regain level flight. I searched the topic and someone suggested removing all flight-surface commands from keyboard settings. I did so and all was fine for a fortnight (until yesterday with SR22 when the same occurred again). Run away trim?

I do frequent multi-hour flights, spend lots of time on AP and this has not occurred until about 2/3 weeks ago. Don't have the Trislander installed, no changes to settings (apart from removing flight-surface commands from keyboard). Who knows about add-ons ... I add and remove (Addon Linker) scenery, mods and planes all the time.