Boeing MCP build 420 - overspeed problems

[Ray Proudfoot]

I'm using all the latest beta Boeing builds for PM but on several occasions during descent the aircraft has oversped whilst in VNav mode.

The problem appears to be that when it's in speed mode and descending at 280kts it will switch back to mach mode and the resultant higher speed target causes the engines to spool up resulting in an overspeed.

I've never experienced this before and I've also seen it happen on a friend's setup so I know it's not my system.

Before I report it to Enrico has anyone else experienced this? I'm flying the PMDG737-900 but my friend was flying the 700 variant. I'm using build 420 of the MCP.

Cheers.

[Ray Proudfoot]

Hi Thoms,

Both. FS9 on my setup and FSX on a friends. PM software is the common element. I may switch back to an earlier version of the MCP and see if it helps.

Are you experiencing this problem if you're running build 420?

[Ray Proudfoot]

I never had a problem in FS9 up to 421a.
But it is a known issue in FSX, it happens very often. The only way to get the control back is to restart FSX. The restart of MCP doesn't change anything!
It's like a connection lost of Simmconnect with this value.

This is a different problem to the one you're referring to. I'm aware of the issue in FSX where LNav and heading control doesn't work and VNav is also damaged.

This is purely an issue of speed changing back to Mach causing an overspeed with the engines spooling up when they should be at idle. I'll try the last official release and see if it helps.

[Ray Proudfoot]

I can only test this with FS9. I hope to get time for a flight tonight or tomorrow. But the problem only occurs during descent. Climb and cruise speed is fine.

Cheers.

[excalibur67]

Hi Ray, just to know , due that this problem it's happened also to me just yesterday, (mcp ver. 422) and FS9 simulator, i would like to know in what way you solved it.

Thanks,
Giuseppe Reda

[NicD]

I've had the same problem. Also seeing an underspeed problem on climb sometimes in VNAV - the bug stays at 250 kts up to cruise level

[themis]

I've had the same problem. Also seeing an underspeed problem on climb sometimes in VNAV - the bug stays at 250 kts up to cruise level

I have also an N1 increase for 3-5 secs after pressing DESCENT NOW ( 20miles from T/D ). Airspeed from 310 goes about 330 then N1 drops and the descent is starting.

[Ray Proudfoot]

Hi Ray, just to know , due that this problem it's happened also to me just yesterday, (mcp ver. 422) and FS9 simulator, i would like to know in what way you solved it.

Thanks,
Giuseppe Reda

Hi Giuseppe,

I thought this had been resolved with the Aug 19 builds but just occasionally it does reappear. I'm not sure what the cause is.

All I can suggest is that you restart the MCP and perhaps the PFD and CDU software before each fllight. I'm also going to try different Cost Index values ranging from 100 down to 50 and see if it has any untoward effect. Why change CI? It changes the descent speed/rate which may be linked to the problem.

A bit of a long shot I know but sometimes the less obvious has to be tried.

[excalibur67]

Thanks Ray for the reply, i will do also other tries and if exit something i will post here. Eventually if you have some news pls let me know.

Thanks,
Giuseppe

[Jan Pemöller]

At this time, to use the MCP software with FSX you will have to disable the AP gauge in the FSX panel.cfg of the aircraft type you are using for flight with the PM / MCP software. Generally if not using a panel at all in MSFS, then the only section you need in the panel.cfg is the section referring to [VIEWS] everything else can be deleted. Please *always* keep a back-up of your original files in case you have to revert back.

NOTAM from PM 29.9.07 !!!

Maybe it helps ...

Best regards
Jan

[Ray Proudfoot]

NOTAM from PM 29.9.07 !!!

Maybe it helps ...

Best regards
Jan

Thanks Jan but I have always flown the PMDG series in FS9 and FSX without any of their panels. I doubt anyone here has them showing since there's no need to use them. The PM software controls the aircraft.

Cheers.

[Thomas Richter]

Thanks Jan but I have always flown the PMDG series in FS9 and FSX without any of their panels. I doubt anyone here has them showing since there's no need to use them. The PM software controls the aircraft.

Cheers.

The reason of the Notam has been because we get a lot of e-mails about problems that MCP doesn't work anymore in FSX and mystic things are going on in FSX-AP.
The reason is that people run the complete FS9/FSX cockpits in the background.
Why ? Often to compare things with FS cocpits like trim display ......
The result is that they have a lot of problems and never belief that this is the problem. They try to solve the problem by using the "W" key in FS to rotate the cockpit view away, but then it is still there.
That is a never ending story we see every day.

[rob747]

HI,

I'm getting the same in the 747. Start a flight with VNAV/LNAV - all ok - speed holds as expected..... during climb I engage spd/vert spd and BAM - speed run's away..... also vspeed is ignored.. flight directors are correct but the plane just keeps on going!

Managed to get out of it by flying manual for a while and then slowly re-introduceing the autopilot one step at a time... then worked for the rest of the flight and then on decent - problem came back - again - swtich from vnav to commanded speed... Guess something not quite right in the software somewhere.....