A B737-300 CREW USING LNAV NOTES THAT THE ACFT DID NOT TURN AS EXPECTED AT THE DRYHT INTXN ON THE DRYHEAT 2 DEP OUT OF PHX; AZ.

Narrative

I WAS FLYING THE DRYHEAT 2 DEP OUT OF PHX TO TUL. THE MCP WAS ON AUTOPLT 'A' WITH LNAV SELECTED. THE HSI SELECT SWITCH WAS ON 'NAV.' THE AIRPLANE WAS CLRED DIRECT TO BAYTA INTXN THEN THE DRYHEAT 2 DEP. THE LNAV TOOK US TO BAYTA; THEN CHOPR; THEN GILAA; THEN ADYAN JUST LIKE IT WAS SUPPOSED TO DO. THEN IT FLEW THE 055 DEG HDG AS DEPICTED ON THE SID. IT CONTINUED ON THIS HDG TO DRYHT. OUR CLRNC FROM PHX CLRNC DELIVERY HAD US CLRED AFTER DRYHT; J74; CORONA; WHICH WAS PROGRAMMED INTO THE FMC. AT DRYHT; THE ACFT DID NOT TURN ON COURSE FOR J74. WE SUBSEQUENTLY WENT N OF COURSE A FEW MI BEFORE I CAUGHT IT; FIGURED IT OUT AND CORRECTED BACK. WE ADVISED ZAB AND THE CTLR DID NOT SEEM TOO CONCERNED. HE SUBSEQUENTLY HAD US ROLL OUT ON A 075 DEG HDG FOR TFC AND SHORTLY CLRED US DIRECT TO IRW ARPT. ALSO WHILE FLYING THE 055 DEG TOWARD DRYHT ON THE SID WE NEVER RECEIVER A VECTOR FOR DRYHT FROM ZAB. WHAT I LEARNED FROM THIS IS THAT THE FMC MIGHT NOT MAKE THE TURN WHEN YOU EXPECT IT TO; SO THIS WILL HAVE TO BE MONITORED EXTREMELY CLOSE. IF I HAD TO DO IT OVER AGAIN; I WOULD HAVE QUESTIONED ZAB FOR RTE CLRNC WHILE ON THE 055 DEG HDG ON THE SID. I AM STILL RESEARCHING WHY THE ACFT DID NOT TURN DOWN J74 AFTER PASSING DRYHT.