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Thunderbolt44

Next MU-2 Update & Comment on AP Problems with the Lear

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Yesterday, I reinstalled the latest version of the MU-2 and took it on an IFR cross country.  The airplane flies pretty well.  My main concern was that in cruise climb using IAS, it would not level smoothly at the selected altitude.  I'm assuming  this may be because the the ALT hold on the APCP is not working.  On departure, I was happy to see that when the first step climb was entered and the ALTS was armed, the FD assumed the take off pitch.  I was pleased to see this as the Lear 35A FD only arms for Heading.  Regardless, the MU-2 departure went fine when arming the desired step climb altitude and arming the VS with the desired feet/min rate of climb.  It also leveled off at that altitude properly.  However, the ALTS and VS buttons do not switch over to the ALT button. You have to keep the ALTS and VS buttons lit.  These do not work manually either.  Also, if you click the VS off, the AP does not hold the selected Altitude.  Otherwise, the MU-2 seems to fly fine.  On decent, you have the same procedure.  You have to just control the Altitude with the ALTS & VS buttons.  They do go off after intercepting the LOC and arming the APP button when the GS is active.  

 

As long as I'm doing this let me make a comment on the Lear 35A too.  It's nice to be able now to arm the FD before engaging the AP.  However, I am unable to arm the FD to indicate the take off pitch.  This should happen when you dial in your first step climb or by arming the TOGA on the Throttle.  If someone can tell me how to arm the FD for pitch, I would appreciate it. 

 

Mike Nicholson

 

 

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Don't know about the MU-2, but as for your question about the Lear, here's some information:

 

From "Flying the classic Learjet" by Peter D. Condon:

On aircraft 35-068 to 35-249 and 36-018 to 36-044, the G/A attitude indication starts when the G/A button is depressed and the flaps are lowered beyond 13°.
On aircraft 35-250 and subsequent and 36-045 and subsequent, the G/A attitude indication starts when the G/A button is depressed.

When using the G/A mode the flight director V Bar should only be used as an initial pitch reference with airspeed being the primary pitch reference.
Initial pitch is about 9°.

 

So, not all aircraft will show a takeoff pitch through the FD with the typical flaps 8° takeoff setting.

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