A B747 CAPT REPORTED THAT THE ACFT MONENTARILY DEPARTED THE RWY DURING TKOF ROLL AT GIG; WHICH WAS LATER FOUND TO BE DUE TO FAULTY ANTI-SKID MODULES.

Narrative

DURING THE APPLICATION OF PWR FOR TKOF; AND AFTER STABILIZING THE ENG PWR; THE ACFT MADE A VIOLENT AND RAPID TURN TO THE L. DESPITE THE APPLICATION OF FULL ABORT PROCS; INCLUDING FULL BRAKE APPLICATION; THE ACFT'S L SIDE DEPARTED THE RWY AT WHICH POINT SOME CTL WAS REGAINED. BY APPLYING A SMALL AMOUNT OF FORWARD THRUST IT WAS POSSIBLE TO KEEP THE AIRPLANE MOVING AND STEER IT BACK ON TO THE RWY. AN INSPECTION OF THE GEAR REVEALED #'S 2 AND 4 TIRES DEFLATED ON THE L SIDE. I BELIEVE THAT THE INITIAL SWING WAS CAUSED BY THESE TIRES DEFLATING PRIOR TO TKOF. THE VERY WET CONDITIONS; LIGHT ACFT WEIGHT; AND AFT CTR OF GRAVITY CONTRIBUTED TO THE DIFFICULTY IN STOPPING THE ACFT. DUE TO CONTINUAL HIGH LNDG WEIGHTS; MOST B747 CARGO ACFT ARE FITTED WITH 200 SERIES HVY DUTY GEAR. THIS ACFT HAD THE LESS DURABLE 100 SERIES GEAR. THE ACFT HAD MADE A MAX WT LNDG AT XA10Z; FOLLOWED BY ANOTHER AT XG56 FOLLOWED BY A 3 MI TAXI PRIOR TO THE INCIDENT. THEREFORE; THE TIRE FAILURES WERE PROBABLY CAUSED BY ACCUMULATIVE HEAT BUILD UP. BECAUSE OF THE 'LIGHT GEAR' FITTED TO THE ACFT; BRAKE TEMP GAUGES ARE INSTALLED ON THESE TYPE ACFT. HOWEVER; THE COMPANY RECENTLY PERMANENTLY DE-ACTIVATED THESE ON THE GROUNDS OF COST. HAD THESE GAUGES BEEN WORKING; THE CREW MIGHT HAVE HAD SOME WARNING OF THE HEAT BUILD-UP. I RECOMMEND THEY BE RE-ACTIVATED. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: SUBJECT ACFT WAS REPAIRED (TIRES CHANGED); BUT AFTERWARD ON SEVERAL SUBSEQUENT FLTS; HAD SIMILAR PROBS. SOMETIMES THE ACFT WOULD SWERVE RAPIDLY TO THE L WITH OR WITHOUT FLAT TIRES. RPTR'S COMPANY MAINT NEVER DID FIND THE PROB. BUT; AFTER SELLING THE ACFT TO ANOTHER ACR; AND; WHEN IT WAS GOING THROUGH 'C' CHK; IT FINALLY WAS DISCOVERED THAT FAULTY ANTI-SKID MODULES ON THE L GEAR WERE CAUSING THE PROB. UNTIL THE FAULTY ANTI- SKID WAS DISCOVERED; RPTR ATTRIBUTED THE PROB TO HEAT BUILD-UP CAUSED BY LNDGS AT MAX WTS AND A VERY LONG TAXI. POST INCIDENT FOLLOW-UP THE RPTR CHKED THE BRAKE/WT CHARTS AND DETERMINED THAT THE BRAKES SHOULD HAVE BEEN COOL. HOWEVER; WITH MALFUNCTIONING ANTI-SKID MODULES; HOT BRAKES COULD HAVE RESULTED WITH THE BLOWN TIRES. RPTR FAULTS HIS COMPANY MAINT FOR NOT DISCOVERING THE PROB DURING THEIR TROUBLESHOOTING. RPTR IS A CHK AIRMAN AND HAS DISCUSSED AT LENGTH THE LNDG GEAR SWERVING WITH HIS FELLOW LCA'S. RPTR'S COMPANY HAS NO INTENTION OF REACTIVATING THE BRAKE TEMP GAUGE OR REPLACING THE 100 SERIES LNDG GEAR WITH THE MORE SUBSTANTIAL AND RELIABLE 200 SERIES.