THE ACFT RAN OFF THE END OF RWY 24 AT THE MCCLELLEN-PALOMAR ARPT. LIGHT RAIN WAS REPORTED AT THE TIME AND THE WINDS WERE REPORTED TO THE PLTS AS BEING FROM 340 DEGS AT 10 KTS. THE RWY IS CONSTRUCTED OF A POROUS FRICTION COURSE (PFC) MATERIAL WHICH PROVIDES GOOD BRAKING ACTION AND A HYDROPLANE RESISTANT SURFACE. WITNESSES STATED THE ACFT TOUCHED DOWN LONG AND FAST. THE PLTS STATED THEY TOUCHED DOWN ‘A LITTLE LONG’ AND THE BRAKED FAILED AS THEY NEARED THE END OF THE RWY. TESTS ON THE BRAKE AND HYDRAULIC SYSTEMS INDICATED THEY OPERATED SATISFACTORILY WITH NO FAILURES NOTED. THE PLTS STATED THEY DID NOT UTILIZE THE EMERGENCY BRAKES AND DID NOT STATE WHY THEY DIDN’T. THE PLT STATED THAT THE LANDING DATA COMPUTED WAS FOR A 10 KT HEADWIND COMPONENT ON A DRY RWY. Probable Cause: