DISTRS DUE TO RWY CHANGES WHILE PROGRAMMING THE FMC RESULTS IN B767 CREW PASSING HOLDING LIMIT DUE TO BEING IN HDG MODE RATHER THAN LNAV.

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ATC CLRED US TO HOLD OVER VCN. THE CAPT (PF) PROGRAMMED THE FMS AND ACTIVATED THE HOLD. AS WE APCHED THE FIX THE ACFT DID NOT START TO TURN INTO THE HOLD AND WE BOTH REALIZED THAT AUTOPLT WAS IN HDG MODE NOT LNAV. ABOUT 2-3 MI PAST VCN CAPT TURNED INTO THE HOLD; AS WE STARTED THE TURN ATC INFORMED US WE NO LONGER NEEDED TO HOLD AND GAVE US A 270 DEG VECTOR FOR THE APCH. ATC DID INFORM US PRIOR TO THE HOLD THAT THEY WERE CHANGING RWYS AND IF WE COULD ACCEPT RWY 17 AT PHL; WE INFORMED THEM THAT WE COULD NOT USE THAT RWY. THE OLD ATIS WAS USING ILS RWY 9R SO PF CHANGED THE RWY IN THE FMS TO ILS RWY 27R. WE LATER OBTAINED A SPECIAL ATIS AND IT STILL HAD ILS RWY 9R FOR THE APCH; WE ASKED ATC AND THEY INFORMED US THAT THEY ARE STILL USING ILS RWY 9R. SO CAPT NEEDED TO CHANGE THE RWY BACK TO RWY 9R IN THE FMS AND NEEDED TO REBRIEF THE APCH FOR THE THIRD TIME. ALL OF THIS HAPPENED A FEW MI PRIOR TO HOLDING. WE BOTH SHOULD HAVE NOTICED THAT WE WERE IN HDG NOT LNAV BUT I BELIEVE WITH ALL THE INPUTS IN THE FMS AND 3 DIFFERENT APCH BRIEFINGS IN SUCH A VERY SHORT PERIOD OF TIME TO HOLDING THIS COULD HAVE POSSIBLY LED THE PF TO SOMEHOW INADVERTENTLY TURN OFF LNAV. LESSON LEARNED; VERY BASIC 'AVIATE; NAVIGATE; COMMUNICATE.'