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Fokker F27 - Climbing while cruising

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Bruce R View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Bruce R Quote  Post ReplyReply Direct Link To This Post Topic: Fokker F27 - Climbing while cruising
    Posted: 04 May 2015 at 5:15am
I've noticed during the cruise phase of flights the F27 still climbs slowly.  I'm talking about a 1000' every 10 or so minutes.  The autopilot power is on, as is the engage switch.  Altitude hold, and speed hold are both on, and tracking inbound on a VOR.  This occurs in every flight.  The vertical speed indicator shows ever so slightly above the '0'.

I've done some shortish flights around New Zealand, cruising at 16000', but end up 18 to 19000'.   

Does anyone else have this problem? 


Bruce Ross 
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Adamski_NZ View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Adamski_NZ Quote  Post ReplyReply Direct Link To This Post Posted: 04 May 2015 at 6:44am
Yep - same here.

Adam.

EDIT: Weird. Just tried another test - with speed on and off - altitude remained rock steady in both cases. What sort of speed where you cruising at? My spoeed was 190kt.
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Bruce R View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Bruce R Quote  Post ReplyReply Direct Link To This Post Posted: 05 May 2015 at 12:48am
Thanks for your reply Adam.  In some ways I'm pleased to hear someone else has the same problem, so it's not just me.  I did a short flight from NZGS to NZNR this morning and with power/autopilot on together with altitude and speed hold on it still climbed another 950' in the short 75 mile distance.

I usually have my cruise speed set at 220kts as per the tutorial flight.  This morning I flew at 180kts at 6000' but it made no difference. 

I've submitted a ticket to Support so will update this thread in due course.

Bruce Ross
   
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freaknout View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote freaknout Quote  Post ReplyReply Direct Link To This Post Posted: 05 May 2015 at 4:38pm
I've got the same problem, funnilly enough flying in NZ! Perhaps that's the BIG market for Fokkers?!

Anyway, have the same issue with altitude hold except I lose altitude and not gain it. This is my third, fourth flight and I hadn't noticed it before and I was using the switches on the main panel. I hadn't done that before so I wonder of that could be an issue.

I also notice that the HDG and AUX/NAV modes are switched. Or is that just me and I'm doing something wrong as I definitely had to switch into HDG to obtain the ILS at NZDN.

Many thanks
Jay
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Bruce R View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Bruce R Quote  Post ReplyReply Direct Link To This Post Posted: 05 May 2015 at 9:26pm
Sure is a coincidence.  NZDN is my home town.  Aircraft virtually fly overhead on the glide slope to R 21.  I live in the Mosgiel area which is about 11 - 12 miles northerly from NZDN.  If you have ORBX South Island, it's obvious.


Bruce Ross
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Adamski_NZ View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Adamski_NZ Quote  Post ReplyReply Direct Link To This Post Posted: 06 May 2015 at 2:40am
Being the "land of the long white cloud", I reckon we have particularly strong thermals here in NZ - enough to give any autopilot a headache :lol:.

@freakout - I also had it descend on me as well.

Adam.
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Adamski_NZ View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Adamski_NZ Quote  Post ReplyReply Direct Link To This Post Posted: 06 May 2015 at 6:23am
OK - I have some further thoughts on this issue.

Whilst playing around with the autopilot in general, I found that even with altitude hold de-selected, elevator trim keep creeping up or down. It turns out that the pitch rocker wasn't properly zeroed, so the aircraft kept trimming to that value after any manual pitch trim input. I've no idea whether this is correct behaviour.

It's possible that you had that rocker set to some non-zero value when you had altitude hold enabled - and that (maybe) was enough to introduce small errors.

I've just tried a couple of flights (NZAA-NZWN), keeping an eye on that rocker and the altitude remained rock steady - even climbing/descending to the preset altitude when resetting the barometer (I had OPUS live weather updates enabled).

If you had live weather enabled, where you re-setting the altimeter baro as you went?

FINALLY: What's the procedure here? I get the impression JF don't monitor these topics much - preferring to use the support ticket system. I've created a ticket for the self-shadow problem, but issues like this altitude creep may or may not be a bug. It could be perfectly accurate and we're just using the A/P wrong. So ... what to do? Keep discussing here and get no input from the developers - or keep bothering their support desk with what could be just user error?

Adam.
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freaknout View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote freaknout Quote  Post ReplyReply Direct Link To This Post Posted: 06 May 2015 at 9:25am
Originally posted by Bruce R Bruce R wrote:

Sure is a coincidence.  NZDN is my home town.  Aircraft virtually fly overhead on the glide slope to R 21.  I live in the Mosgiel area which is about 11 - 12 miles northerly from NZDN.  If you have ORBX South Island, it's obvious.


Bruce Ross


Hi Bruce

I'm ex-Wellington myself but have lived in the UK now for over 10 years.

My NZ geography has rapidly degraded but I'll take off over your place rather than land. Final approach is far too stressful for me without having to lean out the window and wave ;-)

I'm using Orbx NI and SI in P3d. Just great stuff, makes me homesick or wonder why I never went to Wanaka more!

Kind regards
Jay
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freaknout View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote freaknout Quote  Post ReplyReply Direct Link To This Post Posted: 06 May 2015 at 9:35am
Originally posted by Adamski_NZ Adamski_NZ wrote:

OK - I have some further thoughts on this issue.

Whilst playing around with the autopilot in general, I found that even with altitude hold de-selected, elevator trim keep creeping up or down. It turns out that the pitch rocker wasn't properly zeroed, so the aircraft kept trimming to that value after any manual pitch trim input. I've no idea whether this is correct behaviour.

It's possible that you had that rocker set to some non-zero value when you had altitude hold enabled - and that (maybe) was enough to introduce small errors.

I've just tried a couple of flights (NZAA-NZWN), keeping an eye on that rocker and the altitude remained rock steady - even climbing/descending to the preset altitude when resetting the barometer (I had OPUS live weather updates enabled).

If you had live weather enabled, where you re-setting the altimeter baro as you went?

FINALLY: What's the procedure here? I get the impression JF don't monitor these topics much - preferring to use the support ticket system. I've created a ticket for the self-shadow problem, but issues like this altitude creep may or may not be a bug. It could be perfectly accurate and we're just using the A/P wrong. So ... what to do? Keep discussing here and get no input from the developers - or keep bothering their support desk with what could be just user error?

Adam.


Hi Adam

I think you might be right as I hadn't noticed it my first few flights. I will give it a try.

Jay
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Bruce R View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Bruce R Quote  Post ReplyReply Direct Link To This Post Posted: 07 May 2015 at 12:14am
Adam, I think I have to agree with you - to a certain extent.  I have noticed the rocker value was not zeroed during cruise and I was climbing.  This morning with a short 168ml flight NZAA to NZNP, I leveled off at 14000' using the rocker, gradually getting down to zero, then altitude hold, and it stayed exactly 14000'.  But to put a spanner in the works, I descended to 2500' on approach and leveled out at that altitude using the same method.  I cruised for a few miles and noticed it climbing a few hundred feet.  I checked the rocker and it was "-3".

In regard to your comment about JF support, I have to come to their defence on that one.  Here's a quote from an e-mail I received from a support team member when I reported this issue;  

We do check the forums and this is one of the items the developer is looking at.  With any fresh release there are always things that come up and we assess all feedback so we can work out if an update is needed.

Will wait to see what happens.


Bruce Ross





       
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Adamski_NZ View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Adamski_NZ Quote  Post ReplyReply Direct Link To This Post Posted: 07 May 2015 at 1:24am
Drat! I thought I'd got the answer!

About support: yes, that sounds reasonable enough!

Adam.
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Bart Reurts View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Bart Reurts Quote  Post ReplyReply Direct Link To This Post Posted: 14 May 2015 at 2:03pm
Yes i have .,also the problem of climbing or decending , but not when i use the alt. hold on the autopilot itself .

Only when i use the alt hold on the flight director controls on the main panel .
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Cowpatz Quote  Post ReplyReply Direct Link To This Post Posted: 14 May 2015 at 11:09pm
Does the aircraft still climb with just ALT HOLD engaged?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote yankeeromeo Quote  Post ReplyReply Direct Link To This Post Posted: 15 May 2015 at 1:38pm
yes, still cimbing with eveythings on hold at around 100 Fpm...
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Bart Reurts Quote  Post ReplyReply Direct Link To This Post Posted: 15 May 2015 at 3:02pm
100 Fpm , that is a lot , i have a slight climb around 10 or 20 Fpm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote yankeeromeo Quote  Post ReplyReply Direct Link To This Post Posted: 17 May 2015 at 2:32pm
yeah, 100 fpm is way too much, i got this for behavior either up & down Exclamation
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Bart Reurts Quote  Post ReplyReply Direct Link To This Post Posted: 17 May 2015 at 5:52pm
Is this also happening when you use the auto pilot on the peddestal ?
I got this problem when  i use the alt hold on the flight director controls on the main panel .

Also it is importand that you fly level ( by trim and not force on the controls ) before you lock the alt hold . 

And switching of and on while in level flight , wil also help sometimes .

But using the alt lock on the autopilot , gives me the best response .

Gr Bart
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Post Options Post Options   Thanks (0) Thanks(0)   Quote yankeeromeo Quote  Post ReplyReply Direct Link To This Post Posted: 18 May 2015 at 8:06am
Hello Bart,
Well, i tried to be "perfectly" level off before applying the "peddestal" AP, i have the same behavior.
I tried also without the speed hold and i have better result, smaller values, from - 37 till +80 but
still flying like Russian moutains !
Cheers.

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Scotty View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Scotty Quote  Post ReplyReply Direct Link To This Post Posted: 18 May 2015 at 8:18am
Just a quick note that we are aiming for this issue to be addressed in the upcoming service pack.
Scotty



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