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MAYDAY! FMC / AP malfunctioning in 747

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I have just finished reading the manual and prepared the FX version of PMDG 747 for takeoff following the checklist exactly. All panels are correctly configured with Trim set, proper fuel distribution, and FMC properly programmed. Flaps set, Brakes=RTO, MFD values inputed correctly, FD = On and no cautions showing. When cleared for takeoff, I put AutoThrottle to ARM and accelerated to 70%, Pressed TH button and released brakes. I had programmed a derate since GW was light, long runway, and low density altitude. The first anomally was that the speed tape was indicating "No V-speeds", and yet the FMC had correctly calculated them in the Tkof page and I had set the AS window to V2+10. Nevertheless, I rotated at Vr to 8^ as indicated by the FD and retracted Gear on 500 fpm positive climb and the plane maintained pitch and heading and I followed the FD to maintain TKOF speed V2+10 til past 800 AGL. I then selected VNAV and fully expected the pitch to reduce @ 1000 ft for acceleration and flap retraction. It did not. I attempted to active the A/P but at first it did not respond, I manually pitched for acceleration and expected the throttle to adjust to climb power once I set Flaps to 5. Again, no response. At 1500 ft, I was able to get the A/P to activate, but even though it was on, it would not respond to pitch control or heading control settings, even though the anunciator correctly displayed them as active when I selected them. After several futile attempts, I abanded the a/p and activated Vnav and Vlat again. The aircraft began rapidly pitching toward an 8000 fpm climb with rapidly decreasing airspeed. I manually forced the pitch back down to prevent a stall. I tried to find a similar problem on this forum but I did not so I am hoping that somebody will recognize what I must be doing wrong and give me a nudge in the right direction.I thought that it might have been because I had not installed FSUIP, since it had not been needed on either of my other downloads (Level D 767, and CSL DC10 ). After installing FSUIPC4, however, I experienced exactly the same responses to my attempts to activate the FMC or the autopilot. I have no problem with either of the other commercial products and with most sliders all the way to the right, I stay within 2 fps of my target 32 fps even in congested high traffic areas. My equipment is 2.66 MHZ Quad Core 8400 with Nvidia 9500 GT (1G video ram) and 4G DDR2 Ram with VISTA 64.Craig Udseth


Craig Williams

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As far as the V speeds did you press the lsk keys to confirm the v speeds?How did you activate the auto pilot? A screen shot would also be helpful.


George Morris

 

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As far as the V speeds did you press the lsk keys to confirm the v speeds?How did you activate the auto pilot? A screen shot would also be helpful.
Thanks for the reply, George. I don't understand what you mean by confirming the Vspeeds in FMC. Once I completed the Thrust Lim page and went back to Takeoff page, I entered my flap setting and the Vspeeds populated on the screen. In answer to your second question, I pressed the center CMD button to activate the AP. After doing so, I selected HDG Select and it confirmed on the Anunciation panel but the plane would not respond to heading changes. (Vlat was off) The other more obvious problem is that it will not maintain altitude under FMC or AP control, it will just suddenly put itself in an 8000 fpm climb! NOTE: But it does fly well manually!!

Craig Williams

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Thanks for the reply, George. I don't understand what you mean by confirming the Vspeeds in FMC. Once I completed the Thrust Lim page and went back to Takeoff page, I entered my flap setting and the Vspeeds populated on the screen. In answer to your second question, I pressed the center CMD button to activate the AP. After doing so, I selected HDG Select and it confirmed on the Anunciation panel but the plane would not respond to heading changes. (Vlat was off) The other more obvious problem is that it will not maintain altitude under FMC or AP control, it will just suddenly put itself in an 8000 fpm climb! NOTE: But it does fly well manually!!
Concerning the v-speeds, you need to confirm the speeds by pressing the lsk buttons for each v-speed. You will know the speeds are confirmed by the font going from smaller to bigger. For the autopilot, is the light on under the left cmd button lit? If not the autopilot is not engaged. Also what are the annunciations in the PFD for the AFD? To change heading you need to press the sel button.

George Morris

 

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Concerning the v-speeds, you need to confirm the speeds by pressing the lsk buttons for each v-speed. You will know the speeds are confirmed by the font going from smaller to bigger. For the autopilot, is the light on under the left cmd button lit? If not the autopilot is not engaged. Also what are the annunciations in the PFD for the AFD? To change heading you need to press the sel button.
Concerning the v-speeds, you need to confirm the speeds by pressing the lsk buttons for each v-speed. You will know the speeds are confirmed by the font going from smaller to bigger. For the autopilot, is the light on under the left cmd button lit? If not the autopilot is not engaged. Also what are the annunciations in the PFD for the AFD? To change heading you need to press the sel button.

Craig Williams

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Thanks again George. I did confirm the V-speeds this time as you suggested and the now APPEAR on the speed tape. Same problem as before with alt or heading hold. I did not know that it is only the left CMD that toggles the AP. I thought it was any of them as it is in the real plane. I have been using the middle one. I shall try your suggestion. It still doesnot explain why the FMC is not controlling the plane with Vnav and Vlat active. One other possibility: I only have SP1 installed for FX Deluxe. I have not installed SP2 since the description seemed to imply that it was more of an inhancement for multi-player operations. I also did not want it to install DX10. If there is an option NOT TO INSTALL DX10 then I can install it if you think that has any bearing on my problems. Please advise and thank you again for helping me.Craig Udseth


Craig Williams

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Thanks again George. I did confirm the V-speeds this time as you suggested and the now APPEAR on the speed tape. Same problem as before with alt or heading hold. I did not know that it is only the left CMD that toggles the AP. I thought it was any of them as it is in the real plane. I have been using the middle one. I shall try your suggestion. It still doesnot explain why the FMC is not controlling the plane with Vnav and Vlat active. One other possibility: I only have SP1 installed for FX Deluxe. I have not installed SP2 since the description seemed to imply that it was more of an inhancement for multi-player operations. I also did not want it to install DX10. If there is an option NOT TO INSTALL DX10 then I can install it if you think that has any bearing on my problems. Please advise and thank you again for helping me.Craig Udseth
If the CMD light is not on, the autopilot is not engaged so VNav and LNav won't work. A screen shot would also be really helpful at this point. :(

George Morris

 

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The 747X does not require SP2 (their JS41 does however), and not using DX10 mode is not relevant either.I think you are still learning the buttonology, the FMA (mode annunciator top part of PFD) is the source for automatic flight control status. The manual provides a pretty good description of the FMA indications.Also, the FMS controls the airplane through the autopilot. If FMS is not "happy" such as no ref speeds, route discontinuities, etc., then it won't talk to the autopilot.


Dan Downs KCRP

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The 747X does not require SP2 (their JS41 does however), and not using DX10 mode is not relevant either.I think you are still learning the buttonology, the FMA (mode annunciator top part of PFD) is the source for automatic flight control status. The manual provides a pretty good description of the FMA indications.Also, the FMS controls the airplane through the autopilot. If FMS is not "happy" such as no ref speeds, route discontinuities, etc., then it won't talk to the autopilot.
The 747X does not require SP2 (their JS41 does however), and not using DX10 mode is not relevant either.I think you are still learning the buttonology, the FMA (mode annunciator top part of PFD) is the source for automatic flight control status. The manual provides a pretty good description of the FMA indications.Also, the FMS controls the airplane through the autopilot. If FMS is not "happy" such as no ref speeds, route discontinuities, etc., then it won't talk to the autopilot.

Craig Williams

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Thanks, Dan. I don't use a joystick but instead use the mouse so I do not have a TOGA button! I created a keyboard shortcut key and used that. This time I activated N1 with the key press and the power increased to my derate EPR and when I reached 1000 agl and selected CMD 1 and Vnav it seemed to respond correctly. I tried Heading Select and it responded. But.... ...as I retracted flaps on schedule, it began to pitch up rapidly into a steep climb past the altitude set on the AP. The warning sounded and FMC sent me a message, but the plane did not respond until the airspeed reached the stall warning. I changed to VSI mode after manually pitching it level to gain airspeed. It then descended losing about 3000 ft (even though AP was on and VSI was set AT +1500 fpm) as it gained airspeed almost to the Vmo and then began a gradual pitch up. It seemed as if this time it was going to level off at the selected altitude, but when it was 100 ft from it, the plane pitched up to 5000 fpm and again began to decelerate to just above stall speed. I decided to turn the entire control over to FMC. I set target altitude to FL360 and selected Vnav and Lnav. It correctly followed the course but the climb was eratic. The FMC Vnav climb page was set to 320K/M.82 above FL100 but the plane either accelerated to 370Kias or decelerated by over pitching in the climb to about 190Kias. This porpoising scenario continued until I reached FL360 and then again as it reduced climb rate within 100 feet of target altitude (which is the cruise altitude set on the FMC) it suddenly pitched up to 6000 fpm while simultaneously reducing power. It reached stall speed by FL380 with Vnav/Lnav and CMD 1 lights on and 36000 feet set in the altitude window! The aircraft was within proper CG limits (23%/5.2 stab trim) at takeoff and fuel was evenly distributed using the PMDG load facility. It is in proper balance if I hand fly it. The only item mentioned for VISTA OS systems was OOM errors and I have not experience any black outs, lockups or frame rates below 32 fps when using the program. This seems to be an .air file problem but if so, then everyone should be experiencing it. I have Vista 64 and I noticed that both you and George do also. If anyone else out there has been experiencing anything similar, I need to know if it might be hardware related (VISTA or VISTA 64). Craig Udseth


Craig Williams

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It still doesn't like the fms and autopilot are working correctly which indicates that the fms is not set up properly. Also are you using FSX real time weather or an external weather engine? One more time, can you post a screen shot?


George Morris

 

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Thanks again George. I did confirm the V-speeds this time as you suggested and the now APPEAR on the speed tape. Same problem as before with alt or heading hold. I did not know that it is only the left CMD that toggles the AP. I thought it was any of them as it is in the real plane. I have been using the middle one. I shall try your suggestion. It still doesnot explain why the FMC is not controlling the plane with Vnav and Vlat active. One other possibility: I only have SP1 installed for FX Deluxe. I have not installed SP2 since the description seemed to imply that it was more of an inhancement for multi-player operations. I also did not want it to install DX10. If there is an option NOT TO INSTALL DX10 then I can install it if you think that has any bearing on my problems. Please advise and thank you again for helping me.Craig Udseth
Heading Hold and Altitude Hold does exactly what the name suggests. It will hold the aircraft's current altitude and heading regardless of the value set in the MCP. If you want the AFDS to follow a certain heading on the MCP, you need to dump Heading Hold and activate "Heading Select" by left clicking on the center of the heading knob. If you need to climb or descend, you need to leave Altitude Hold and select V/S, FLCH or VNAV.Which CMD channel you select doesn't necessarily matter. If your problem was related to a FCC fault, selecting a different CMD channel would activate it's associated FCC and deactivate the faulty FCC. But, on the opposite side of the coin, the F/D crosshairs would extinguish if the onside FCC failed.It seems the autopilot issues might be related to weather. Try running a flight with one of the default weather themes and see if the issue persists.

Kevin Hester,

 

Indianapolis, Indiana

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It still doesn't like the fms and autopilot are working correctly which indicates that the fms is not set up properly. Also are you using FSX real time weather or an external weather engine? One more time, can you post a screen shot?

Craig Williams

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George: This time I carefully took screen shots of the FMC pages prior to taxi. In the middle of taxi, I noticed a caution indicating I had set crossfeeds wrongly, so I went into the overhead and corrected it. When I closed down the overhead, the plane was creeping backwards instead of taxiing forward. I increased the power to almost full and still it continued to slowly creep backwards. That happened to me once before just as I was about to takeoff. Any clues, other than to save file and reboot the program? My intent was to provide screen shots of everything I had set in FMC and also include a screen shot of the plane when the pitch control malfunctions. I am new to this forum and not sure if the attachments will load with this message


Craig Williams

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Included are the screenshots of my FMC setup. Fuel was loaded using PMDG Load Manager and Trim was set to specs.After rebooting and continuing the taxi to takeoff. I manually flew it up to 1000 and then activated CMD-1 and Vnav and instead of accelerating for flap retract, it pitched up excessively with airspeed decreasing :I then tried to reign in the pitch with the autopilot by switching to FCH and setting speed. This caused and even higher pitch until it stalled:I sure hope this will give someone in this forum a clue as to what I must be doing incorrectly. Again the Vlat works perfectly now and the heading select but it will not respond to correct FMC or AP pitch control. I have to kill the AP and manually pitch it back down. The plane reacts as though it is out of COG but it is in perfect balance according to the load screens and it feels in balance when hand flown. Craig Udseth2.66 GHZ Quad Core/Nvidia 9500 GT ( 1G video ) Vista 64 / 4G DDR2 Ram


Craig Williams

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