I have been struggling with this for a while now.  I've done many searches here in the PMDG forums as well as out on the web, but haven't found a solution yet.  I am trying to operate a flight on -900WL NGX variant (PMDG United N75410) but cannot load a ZFW above 136.x, when I should be able to go as high as ~149.2.  I use PFPX for my flight planning and it shows I should be setting my ZFW at 143.1.  Whenever I try to add that value, I get the "Invalid Entry" message on the CDU.  My NGX "Weight Units" in P3Dv4 are set to LBS and PFPX is set the same.  The CDU will not accept a ZFW above 136.x with any of my installed -900WL variants, but all the other (-600, -700, and -800) variants work just fine.

I've searched PFPX, ZFW, PMDG, -900WL, Invalid Entry, in all manner of combinations to no avail.  What am I missing? It's probably something obvious, right in front of my eyes, but, for the life of me, I can't see it.

Thanks for your time.

Edit:  This is a brand new home-built PC (see sig) and a brand new install of P3Dv4.  So everything is vanilla at this stage.

Hi Doug, I advise against using PFPX as a reliable source for aircraft weights.  FCOM L.10.4 typical MZFW is 138.3 kLbs. and typical implies that there is variance.  136.1 is the apparent MZFW for the house B739 with winglets.

I usually adjust all the PFPX weights to match the PMDG, it is made easier in the 747/777 because they are easy to find in the aircraft.cfg. except for maximum fuel and cargo and those I get by using the FS Actions menu items.

Thanks, Dan.  That's disappointing to hear about the PFPX profiles.  Not sure I understand the disconnect, but will research and plug in more accurate values.  Thanks for responding, my friend.

20 hours ago, dmiannay said:

That's disappointing to hear about the PFPX profiles.

The issue is that aircraft vary even among exact same type, especially in a fleet as large as the B737 with as many operators.  Even things you wouldn't expect to change like MZFW.

6 hours ago, downscc said:

The issue is that aircraft vary even among exact same type, especially in a fleet as large as the B737 with as many operators.  

Yea, great point, Dan.  I do appreciate the heads-up... have changed my PFPX profile values and will test the -900WL tomorrow.

Thanks again, and Happy Easter!

Update:  Couldn't wait, so tested the new profile just now and works like a charm.  You always seem to hit the nail on the head, Dan.  Again, thanks.