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No FDs on the PFD and PFD on FOs side blank/not aligned

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    No FDs on the PFD and PFD on FOs side blank/not aligned

    Just took off from LECO and after takeoff when I was about to engage CMD A I noticed how all of a sudden I no longer had any FDs on the PFD. Even when it clearly says FD on the PFD. Looking at the PFD on the FO's side, it's blank like you would see it before the IRSes are aligned.

    I've tried to recycle the FDs but to no avail. I've also checked for failures but there are none.

    With about 3.5 h to my destination, I'm not exactly tempted to hand-fly all the way. Since I can't engage the AP with no FDs for the AP to follow...

    Anyone else seen the same thing or can advice how to handle this situation or what I might have missed?

    This is what it looks like

    2023-01-15 20_35_02-Microsoft Flight Simulator - 1.29.30.0.jpg
    Richard Åsberg

    #2
    The first thing I saw Richard was the ATT and MAP alerts, also note the FMC R is missing from the FO ND. Check the FMC switches to make sure they are normal, and then check that both GPS and IRS are functional. Did you have a power failure when you disconnected ground power?
    Dan Downs KCRP
    i7-10700K 32GB 3600MHz 3080Ti

    Comment


      #3
      Already checked all the switches and everything was fine when I took off. All this happened shortly after takeoff.

      Really odd and guess not much I can do other than quitting this flight and see this as a one time only type of thing...hopefully.

      Thanks anyway.
      Richard Åsberg

      Comment


        #4
        Looks like a right IRS failure. What were both IRS status? No FD bars on PFD show some kind of failure?
        Last edited by Falcon99; 16Jan2023, 04:03.
        George Morris

        Comment


          #5
          The IRS status was fine and again, on the ground and before takeoff, everything was normal.

          A failure of some kind for sure but strange why I had no failures according to the failures page in the FMC.

          Oh well, hopefully nothing I'll see again and never saw this before after thousands of hours in the 73.
          Richard Åsberg

          Comment


            #6
            WebMaximus this is exactly what has just happened to me. No failure or abnormal indication beside what show the PFD and the ND on the FO side (exactly as per the picture above).

            However I had a power failure before pushback because I disconnected the GPU accidently before starting the APU. Can power failure impact the IRS operations?

            DDowns mentioned that the GPS and the IRS need to be checked.

            - How to do that?
            - Is the ATT indication on the PFD/ND the only sign of some kind of IRS failure?
            - Is there any way to recover and return back to normal situation?
            - In case of no recovery possible, Is there any way to use the AP (I had to fly manually the emergency diversion on Vatsim)?


            Samer Haj
            Last edited by Samhaho; 20Jan2023, 21:08.

            Comment


              #7
              Good to hear others seen the same thing. As for being caused by a power failure, I like to think you would then see the issue right away? Rather than after you already took off.

              Haven't seen this happen again.
              Richard Åsberg

              Comment


                #8
                Originally posted by Samhaho View Post
                WebMaximus this is exactly what has just happened to me. No failure or abnormal indication beside what show the PFD and the ND on the FO side (exactly as per the picture above).

                However I had a power failure before pushback because I disconnected the GPU accidently before starting the APU. Can power failure impact the IRS operations?

                DDowns mentioned that the GPS and the IRS need to be checked.

                - How to do that?
                - Is the ATT indication on the PFD/ND the only sign of some kind of IRS failure?
                - Is there any way to recover and return back to normal situation?
                - In case of no recovery possible, Is there any way to use the AP (I had to fly manually the emergency diversion on Vatsim)?


                Samer Haj
                I asked about the power interruption for a reason. Your IRS units have different power sources, so when you pull the plug and loose AC then you have to reset an IRS unit by turning it off for a minute then go through the initialization again.

                You can check the GPS with the FMS, one of the POSITION pages gives you what each IRS and GPS is providing for location.

                The primary attitude information comes from the IRS, you loose IRS you no longer have attitude information (except for backup) and the PFD indicates this with the ATT alert.

                I suspect you took off with this condition, it didn't happen during flight. At least I can't think of any scenario where this would happen in flight other than equipment failure. It is not possible to align the 737 IRS in flight because the aircraft has to be stationary. You can still use it to provide heading information but you are not going to have the AFDS available.
                Dan Downs KCRP
                i7-10700K 32GB 3600MHz 3080Ti

                Comment


                  #9
                  Originally posted by WebMaximus View Post
                  Good to hear others seen the same thing. As for being caused by a power failure, I like to think you would then see the issue right away? Rather than after you already took off.

                  Haven't seen this happen again.

                  Just to share, searching further I figured out how to try recovering in the case of failure of a single IRS :
                  1- Switch both PFD/ND on the remaining functional IRS using the switch "IRS" in the navigation part which is in the left/mid part (not the left/top side) of the overhead panel. This way FD and AP can now operate [EDIT: This is not sure, maybe a single IRS is not enough for AP to operates - to check]
                  2- Turn the IRS switch to ATT position (instead of Nav position), few seconds later a message displays on the FMC requesting "set heading", enter the heading value and the failed IRS get aligned.

                  I tested both. They work fine. Learning every day...

                  Samer Haj
                  Last edited by Samhaho; 20Jan2023, 22:38.

                  Comment


                    #10
                    Originally posted by Samhaho View Post


                    Just to share, searching further I figured out how to try recovering in the case of failure of a single IRS :
                    1- Switch both PFD/ND on the remaining functional IRS using the switch "IRS" in the navigation part which is in the left/mid part (not the left/top side) of the overhead panel. This way FD and AP can now operate
                    2- Turn the IRS switch to ATT position (instead of Nav position), few seconds later a message displays on the FMC requesting "set heading", enter the heading value and the failed IRS get aligned.

                    I tested both. They work fine. Learning every day...

                    Samer Haj
                    The ability to switch flight instruments between left and right is a backup but it doesn't recover the IRS, which can only be used to provide heading information while airborne. Heading only means there is no position, attitude or speed information from that unit.

                    According to QRH this partial capability requires that aircraft be held straight and level while setting the heading.

                    Also according to QRH, when the IRS transfer switch is either BOTH ON L or BOTH ON R the A/P cannot be engaged. Are you claiming that you were able to use the A/P?? If true then that deserves a bug report.
                    Dan Downs KCRP
                    i7-10700K 32GB 3600MHz 3080Ti

                    Comment


                      #11
                      When I saw this, I'm positive things were normal before I took off. Wouldn't have taken off in this state and nothing you miss when scanning everything is looking good before setting thrust.

                      At first, I was positive it was a random failure but as mentioned, no failures active when I checked.
                      ​​​​​​
                      Really odd but at the same time a bit cool having unexpected things happening like that.
                      Richard Åsberg

                      Comment


                        #12
                        Originally posted by WebMaximus View Post
                        When I saw this, I'm positive things were normal before I took off. Wouldn't have taken off in this state and nothing you miss when scanning everything is looking good before setting thrust.

                        At first, I was positive it was a random failure but as mentioned, no failures active when I checked.
                        ​​​​​​
                        Really odd but at the same time a bit cool having unexpected things happening like that.
                        I don't doubt your word, but I questioned this point because you didn't state that you reset the IRS after the power interruption.
                        Dan Downs KCRP
                        i7-10700K 32GB 3600MHz 3080Ti

                        Comment


                          #13
                          Originally posted by DDowns View Post

                          I don't doubt your word, but I questioned this point because you didn't state that you reset the IRS after the power interruption.
                          I didn't have a power interruption, it was the other guy seeing the same thing happening.
                          Richard Åsberg

                          Comment


                          • DDowns
                            DDowns commented
                            Editing a comment
                            Oops.... okay. Doing too many things at a time LOL

                          #14
                          Originally posted by DDowns View Post

                          According to QRH this partial capability requires that aircraft be held straight and level while setting the heading.

                          Also according to QRH, when the IRS transfer switch is either BOTH ON L or BOTH ON R the A/P cannot be engaged. Are you claiming that you were able to use the A/P?? If true then that deserves a bug report.
                          I had edited my post above to caution about AP operation with a single IRS. However here are the results of my tests. Please note that I have simulated the IRS failure by positioning the switch to OFF but this may not be an accurate simulation. Here is what I observed:

                          With the PMDG/MSFS

                          - Indeed FD/AP do not operate with a single IRS regardless the IRS switch position ("Both to the left" or "Normal")
                          - ATT recovery did not work (I kept the aircraft in a level and straight position for several minutes), never got the message "set the heading" although the "aligned" light illuminated during the attempt. I tried to enter the heading directly on the little keyboard next to the IRS module but typing on this keyboard did nothing.

                          With X-Plane/Zibo

                          - FD/AP do operate with a single IRS aligned. Which as you mentioned it is not the "expected" behavior
                          - The ATT recovery works as expected

                          It doesn't look like any of those two B737 simulates single IRS failure accurately, or I am not doing the test correctly

                          Samer Haj
                          Last edited by Samhaho; 21Jan2023, 17:54.

                          Comment


                          • DDowns
                            DDowns commented
                            Editing a comment
                            I'm putting test ATT mode on my list of things to do.... thanks. Alternatively, you can submit a bug report at support.pmdg.com.

                          #15
                          Originally posted by Samhaho View Post

                          I had edited my post above to caution about AP operation with a single IRS. However here are the results of my tests. Please note that I have simulated the IRS failure by positioning the switch to OFF but this may not be an accurate simulation. Here is what I observed:

                          With the PMDG/MSFS

                          - Indeed FD/AP do not operate with a single IRS regardless the IRS switch position ("Both to the left" or "Normal")
                          - ATT recovery did not work (I kept the aircraft in a level and straight position for several minutes), never got the message "set the heading" although the "aligned" light illuminated during the attempt. I tried to enter the heading directly on the little keyboard next to the IRS module but typing on this keyboard did nothing.

                          With X-Plane/Zibo

                          - FD/AP do operate with a single IRS aligned. Which as you mentioned it is not the "expected" behavior
                          - The ATT recovery works as expected

                          It doesn't look like any of those two B737 simulates single IRS failure accurately, or I am not doing the test correctly

                          Samer Haj
                          ATT recovery works as expected here both on the ground and in flight. Perhaps you had a fail light that did not extinguish? I failed IRS R, and while it is failed you cannot use ATT recovery. However, if you fail the IRS then remove the failure then when the ALIGN light extinguishes the SET IRS HDG prompt appears as expect on the POS INIT page.

                          Perhaps your straight and level was not that straight or level due to Asobo atmospherics. Are you sure the ALIGN light extinguished?

                          I found it was much easier to old straight and level by disconnecting A/T and removing the pitch coupling with thrust changes.

                          In any event, it worked for me.
                          Dan Downs KCRP
                          i7-10700K 32GB 3600MHz 3080Ti

                          Comment


                            #16
                            Originally posted by DDowns View Post

                            ATT recovery works as expected here both on the ground and in flight. Perhaps you had a fail light that did not extinguish? I failed IRS R, and while it is failed you cannot use ATT recovery. However, if you fail the IRS then remove the failure then when the ALIGN light extinguishes the SET IRS HDG prompt appears as expect on the POS INIT page.

                            Perhaps your straight and level was not that straight or level due to Asobo atmospherics. Are you sure the ALIGN light extinguished?

                            I found it was much easier to old straight and level by disconnecting A/T and removing the pitch coupling with thrust changes.

                            In any event, it worked for me.
                            I think the difference is in the "failure" action. I simulated the failure just by turning the knob to OFF and then I tried to recover by turning it to ATT.
                            How did you fail the IRS in your side? Using the FMC failure section? If yes it would have been more accurate way to simulate an IRS failure

                            However, how come that turning the knob to OFF and then to ATT (or NAV) would not allow to use it anymore?

                            Thanks for testing and for the feedback, it's been very useful.

                            Samer Haj

                            Comment


                              #17
                              Originally posted by Samhaho View Post

                              I think the difference is in the "failure" action. I simulated the failure just by turning the knob to OFF and then I tried to recover by turning it to ATT.
                              How did you fail the IRS in your side? Using the FMC failure section? If yes it would have been more accurate way to simulate an IRS failure

                              However, how come that turning the knob to OFF and then to ATT (or NAV) would not allow to use it anymore?

                              Thanks for testing and for the feedback, it's been very useful.

                              Samer Haj
                              I used the PMDG OPTIONS Failure menu to fail the IRS.

                              When you test by setting it to OFF, you must allow it to remain OFF for a few moments perhaps a minute. Then switch ATT is you want to use that mode.
                              Dan Downs KCRP
                              i7-10700K 32GB 3600MHz 3080Ti

                              Comment

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