A B737 ON TKOF ROLL FOUND THE CAPT WINDOW FAILED TO SEAL BECAUSE OF A HEADSET CORD JAMMED IN THE TRACK. RETURNED TO DEP ARPT AND CLRED JAM.

Narrative

GND STAFF HAD TOWED THE ACFT TO THE GATE AT CYYZ AS WE REACHED THE GATE. ENTERING THE COCKPIT; BOTH SLIDING WINDOWS WERE CLOSED AND LOCKED. DURING THE BEFORE STARTING ENGS CHKLIST; THE WINDOWS WERE AGAIN CONFIRMED CLOSED AND LOCKED. ENG START AND TAXI OUT WERE NORMAL AND WE RECEIVED TKOF CLRNC. ON TKOF ROLL; THERE WAS MORE WIND NOISE THAN NORMAL FROM THE CAPT'S WINDOW; BUT ONCE AGAIN THE WINDOW WAS CONFIRMED LOCKED; AND AFTER FLYING THE MD80; I EXPECTED THE NOISE TO DIMINISH AS THE ACFT PRESSURIZED. AFTER LIFTOFF; HOWEVER; THE NOISE WAS DEAFENING AND THE ACFT WAS NOT PRESSURING AT A NORMAL RATE. THERE WAS OBVIOUSLY AN OBSTRUCTION IN THE CAPT'S SLIDING WINDOW. I WAS THE PF AND LEVELED OFF AT 3000 FT AND SLOWED TO 180 KTS; AND REQUESTED A VFR RETURN FOR LNDG. I GAVE THE ACFT TO THE FO WHILE I MADE A PA; AND CONFIRMED WITH THE FLT ATTENDANTS WE WERE RETURNING. I CHKED LNDG VREF AND BEGAN THE BEFORE LNDG CHKLIST. AFTER ONCE AGAIN TAKING CTL OF THE ACFT; THE LNDG WAS NORMAL AND UNEVENTFUL. WE CLRED THE RWY AND STOPPED ON A TXWY AND OPENED THE WINDOW. THE SPARE HEAD SET PLUG WAS ON TOP OF THE SLIDING WINDOW AND WAS CAUSING THE AIR LEAK. THIS WAS CLRED; AND THE FO CALLED LCL OPS TO INFORM DISPATCH WE HAD RETURNED. WITH NO MAINT ISSUES AND THE FUEL WAS ONLY 400 LBS BELOW MINIMUM TKOF FUEL; WE REQUESTED A RE-RELEASE TO CONTINUE THE FLT. DISPATCH ISSUED THE RE-RELEASE AND WE COMPLETED ALL THE RELEVANT CHKLISTS. WE THEN TAXIED TO THE DEP RWY AND DEPARTED.