Last week I purchased  PA31 Chieftain. I made  some flights with A/P. No incident.

If I fly by hand. There is no way I can hold the plane's altitude. It is up or down. No time even put proper trim to avoid this kind flying.

Some thing is wrong, if you memebers having no problem by hand flying, then problem must be from my side. 

What causing this problem ? How can I correct the proper inputs to plane's  controls.

Are your controls calibrated?  It takes a light hand on a fast turboprop and that can be difficult if the controls aren't right.

1 hour ago, asanal said:

What causing this problem ? 

1. Are you using the correct technique? First establish the desired attitude with the yoke/stick, then trim away the force you need to push/pull the yoke/stick.

2. Is your plane properly loaded? The more nose heavy, the more stable in pitch the plane is. Many sim pilots are loading the aft baggage compartment first instead of using the forward one first.

3. Have you tried setting the repeat slider for the elevator trim in the controls menu to the mid position? This slows down the trim motion by 50% and makes fine adjustments much easier.

 

@Gregg_Seipp  The Chieftain isn't a turboprop and the highest IAS at max crz is only 180kts, so this shouldn't be a problem

To test, I follow the Rhin in Orbx Germany South with this addon, flying by hand from Dusseldorf to Heildeberg. The trim is a little more difficult than some others because this fine aircraft, well powered, have a tendance to climb.

Before, I don't have a hardware for trims, With buttons this is more difficult to make a fine trim...

1 hour ago, ms2 said:

1.The trim is a little more difficult than some others because this fine aircraft, well powered, have a tendance to climb.

2.With buttons this is more difficult to make a fine trim...

1. If the plane has a 'tendency to climb' you simply have to trim nose down. That's what the trim is for ;)

2. If you reduce the repeat rate by 50%  you can make very small adjustments.

Sure ;-) the sens of mine comment to asanal is: some aircrafts are a little more difficult to trim well, this a question of feeling for the machine you fly.

The method of Gregg above is the right one to do, as learned by real pilots.

With the Da42 or 40, the finesse near a planner of those aircrafts make that you more often correct your trims following lift acting arround the aircraft... ;-)) 

1 hour ago, ms2 said:

The method of Gregg above is the right one to do, as learned by real pilots.

I don't think that real pilots have to calibrate their controls ;)

A miss of person this your method I spoke :))

Thanks for your responses.

My problem:

During level flight, as soon as  I disconnect the  A/P. Plane goes up/down rapidly no way you can  trim the plane.

I have various airplanes, none of them has this problem

Is it possible some  AXIS in puts causing these  problems. I have CH Eclipse yoke and CH pro pedals.I calibrated it recently. 

I will make  test flight with various payload and calculate the take-off trim  accordingly.

 

 

I followed Gregg and J35OE advise.  Reduced  the Elevator Trim repeat rate by 50% from 64%. It gave me control back.

Thanks all.

1 hour ago, asanal said:

I followed Gregg and J35OE advise.  Reduced  the Elevator Trim repeat rate by 50% from 64%. It gave me control back.

Thanks all.

Good news.  I love flying a good turboprop. 

4 hours ago, asanal said:

During level flight, as soon as  I disconnect the  A/P. Plane goes up/down rapidly no way you can  trim the plane.

Glad that it works now. Nevertheless there seems to be a problem with your joystick setup as the plane shouldn't pitch up or down when disengaging the AP.