Not sure I understand what you mean... NWA has PW on the 757-200, 747-200 and the 747-400, and is the launch customer for PW-powered 757-300 and has PW on the A330-300 too. Only a/c it does not have PW on is the A319/320 family and the DC10-30 (which has the CF6-50 engines). So NWA has pretty much been a PW airline...
<font face="Verdana, Arial, Helvetica, sans-serif" size="2">Originally posted by hooverer:
<<dunno why NW is so hung up on PW engines...
>>
Actually NW has GE/CFM 56's on the A319/A320 fleet and GE/CFMs on the DC10-30 fleet having retired the PW DC10-40s.
Given that PW was only original choice for 727 and DC9 which they inherited and the PW on the 707/720/320x not surprising PW influence.</font>