Can anyone help. Running FS9 (and FSX) and recently added PMDG 747-400 Queen of Skies to FS9. Worked fine. Then tried to add PMDG 737NG Xmas present to FS9 and all went pear shaped. Despite uninstalling both PMDGs, can not start up FS9 now. I get error message - 'Aircraft initialisation failure 747-400 Lufthansa' - I press OK and FS9 quits. A search fails to find this Lufthansa file. Have tried reinstalling FS9 over the top but error message persists and FS9 quits. So currently - no PMDG 747, no PMDG 737, and no FS9.Gordie66.

I suspect you have a default flight set in your FS9.cfg file that uses the 747 as a past or default flight. Rename FS9.cfg to save it and restart FS9 to see if it starts (it will build a new FS9.cfg). If it still does not start, delete the FS9.cfg just created (if it got that far) and rename the one you saved back to FS9.cfg.Go into your FS9 modules folder and you may find a module called pmdg_options.dll or similar. Rename that and then try starting FS9. If it still crashes check the version of FSUIPC.dll. It must be later then 3.65 (3.71 is current) to work with the FS9.1 patch. Perhaps these modules got installed in reverse order.Instructions state that if you have the 747 and you want to install the 737 series, you have to remove the 747, install the 737, reinstall the 747. If you did not do it this way you placed older common modules and perhaps gauges over the newer ones causing a conflict. I'm primarily thinking of something in the modules folder because FS loads all modules into memory.Reinstalling FS9 over the top does not eliminate modules and a config file that already exist because the same folders are used and files are left in there.See if that helps.

Thanks very much for your help. I have now resolved the problem but still not sure what caused it. I again uninstalled the 747, installed the 737, followed by the 747. I think the key element might have been I also re-installed the 747 Lufthansa livery which was the subject of the error message. All this was done with antivirus switched off. Now 737, 740 and FS9 working.Just one prob I can see at moment. Somewhere along the line I have lost the FS9 update (to 9.1 I believe). Am looking to re-install this but am a bit wary about Fl Sim site saying this might now cause conflicts with add-on scenery. I might have to bite the bullet though.

If you place the 9.1 patch in a fresh version of FS9 it will create a backup folder asnd provide an uninstall utility. In putting in the 9.1 patch make sure you have a version of FSUIPC 3.65 or greater. The current released version is 3.71. You will not need to pay for the upgrade if you have the full version or if your appllication is licensed to use it.

Thanks for your additional information re 9.1 patch for FS9 and FSUIPC. Very kind of you.Regards and best wishes for New Year.Gordon Evans (Gordie),Dursley, England