Narrative:

Prior to landing; before all landing checks were completed. Clearance to land was given and landing commenced on runway xx. Normal landing occurred with minimal braking applied after flight/ground spoilers and thrust reversers deployed. Once the aircraft was parked; shut down and secured (chocked); line crew indicated to us that we had blown a tire on landing at the point of touchdown. We did not feel anything related to a blown tire on landing. Myself; nor my co-captain thought this was normal. This concerned us somewhat so we had our director of maintenance look further into the issue. Due to his persistence with the troubleshooting; he discovered (what the bombardier rep told us) was the first example when an anti-skid system tests normal but has actually failed. (Verified multiple times.) we had no indication in the cockpit of a failure while one existed. Repairs occurred and parts were replaced. Subsequent operations are normal.callback conversation with reporter revealed the following information: reporter stated they performed the brake anti-skid system test in the cockpit of the cl-600 aircraft prior to departure; without any fault indication. They performed another anti-skid system test after being informed they had a blown left outboard main tire with a big flat spot; no tread and a hole in the tire. Again the cockpit brake anti-skid test indicated all systems normal. Reporter stated their director of maintenance continued to troubleshoot this inconsistency of all anti-skid tests normal; but everyone realized the outboard tire blew because of a failure of the brake to release. Reporter stated the cl-600 does not have automatic-brakes. Their director of maintenance (dom); did a wheel speed sensor spin-up test at the blown left outboard tire and noticed the brake would not release when he stopped spinning the sensor; this would indicate a skid condition. But the cockpit indication still showed a normal; no fault condition. He swapped the left outboard with the left inboard wheel sensor; thinking the sensor was bad; but when he spun-up the outboard sensor at the inboard position and stopped; the inboard brake released. He then went over to the right main outboard tire and checked the wheel sensor; the brake would not release. But all cockpit indications were normal; no faults. The director then performed a bite check of the anti-skid computer control box. Again; no faults were displayed and none showed during the wheel sensor spin check. Reporter stated there are two identical printed circuit boards in the anti-skid control box; one for the outboard main brakes and one for the inboard. His director of maintenance decided to swap the two internal pcb's and sure enough; the outboard brakes released; but not the inboard brakes. But the cockpit and control box continued to display normal conditions. The anti-skid control box was removed and found to have a 1981 manufacturing date. They replaced the box and sensors and all brakes were tested and released normally.

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Original NASA ASRS Text

Title: PLT OF A CANADAIR CL-600 (CHALLENGER 600) RPTS THAT THE L MAIN OUTBOARD TIRE BLEW ON LNDG TOUCHDOWN DUE TO AN ANTI-SKID FAILURE. THERE WAS NO COCKPIT INDICATION OF ANTI-SKID FAULT OR FAILURE.

Narrative: PRIOR TO LNDG; BEFORE ALL LNDG CHKS WERE COMPLETED. CLRNC TO LAND WAS GIVEN AND LNDG COMMENCED ON RWY XX. NORMAL LNDG OCCURRED WITH MINIMAL BRAKING APPLIED AFTER FLT/GND SPOILERS AND THRUST REVERSERS DEPLOYED. ONCE THE ACFT WAS PARKED; SHUT DOWN AND SECURED (CHOCKED); LINE CREW INDICATED TO US THAT WE HAD BLOWN A TIRE ON LNDG AT THE POINT OF TOUCHDOWN. WE DID NOT FEEL ANYTHING RELATED TO A BLOWN TIRE ON LNDG. MYSELF; NOR MY CO-CAPT THOUGHT THIS WAS NORMAL. THIS CONCERNED US SOMEWHAT SO WE HAD OUR DIRECTOR OF MAINT LOOK FURTHER INTO THE ISSUE. DUE TO HIS PERSISTENCE WITH THE TROUBLESHOOTING; HE DISCOVERED (WHAT THE BOMBARDIER REP TOLD US) WAS THE FIRST EXAMPLE WHEN AN ANTI-SKID SYSTEM TESTS NORMAL BUT HAS ACTUALLY FAILED. (VERIFIED MULTIPLE TIMES.) WE HAD NO INDICATION IN THE COCKPIT OF A FAILURE WHILE ONE EXISTED. REPAIRS OCCURRED AND PARTS WERE REPLACED. SUBSEQUENT OPS ARE NORMAL.CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATED THEY PERFORMED THE BRAKE ANTI-SKID SYSTEM TEST IN THE COCKPIT OF THE CL-600 ACFT PRIOR TO DEP; WITHOUT ANY FAULT INDICATION. THEY PERFORMED ANOTHER ANTI-SKID SYSTEM TEST AFTER BEING INFORMED THEY HAD A BLOWN L OUTBOARD MAIN TIRE WITH A BIG FLAT SPOT; NO TREAD AND A HOLE IN THE TIRE. AGAIN THE COCKPIT BRAKE ANTI-SKID TEST INDICATED ALL SYSTEMS NORMAL. RPTR STATED THEIR DIRECTOR OF MAINT CONTINUED TO TROUBLESHOOT THIS INCONSISTENCY OF ALL ANTI-SKID TESTS NORMAL; BUT EVERYONE REALIZED THE OUTBOARD TIRE BLEW BECAUSE OF A FAILURE OF THE BRAKE TO RELEASE. RPTR STATED THE CL-600 DOES NOT HAVE AUTO-BRAKES. THEIR DIRECTOR OF MAINT (DOM); DID A WHEEL SPEED SENSOR SPIN-UP TEST AT THE BLOWN L OUTBOARD TIRE AND NOTICED THE BRAKE WOULD NOT RELEASE WHEN HE STOPPED SPINNING THE SENSOR; THIS WOULD INDICATE A SKID CONDITION. BUT THE COCKPIT INDICATION STILL SHOWED A NORMAL; NO FAULT CONDITION. HE SWAPPED THE L OUTBOARD WITH THE LEFT INBOARD WHEEL SENSOR; THINKING THE SENSOR WAS BAD; BUT WHEN HE SPUN-UP THE OUTBOARD SENSOR AT THE INBOARD POSITION AND STOPPED; THE INBOARD BRAKE RELEASED. HE THEN WENT OVER TO THE R MAIN OUTBOARD TIRE AND CHECKED THE WHEEL SENSOR; THE BRAKE WOULD NOT RELEASE. BUT ALL COCKPIT INDICATIONS WERE NORMAL; NO FAULTS. THE DIRECTOR THEN PERFORMED A BITE CHECK OF THE ANTI-SKID COMPUTER CTL BOX. AGAIN; NO FAULTS WERE DISPLAYED AND NONE SHOWED DURING THE WHEEL SENSOR SPIN CHECK. RPTR STATED THERE ARE TWO IDENTICAL PRINTED CIRCUIT BOARDS IN THE ANTI-SKID CTL BOX; ONE FOR THE OUTBOARD MAIN BRAKES AND ONE FOR THE INBOARD. HIS DIRECTOR OF MAINT DECIDED TO SWAP THE TWO INTERNAL PCB'S AND SURE ENOUGH; THE OUTBOARD BRAKES RELEASED; BUT NOT THE INBOARD BRAKES. BUT THE COCKPIT AND CTL BOX CONTINUED TO DISPLAY NORMAL CONDITIONS. THE ANTI-SKID CTL BOX WAS REMOVED AND FOUND TO HAVE A 1981 MANUFACTURING DATE. THEY REPLACED THE BOX AND SENSORS AND ALL BRAKES WERE TESTED AND RELEASED NORMALLY.

Data retrieved from NASA's ASRS site as of May 2009 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.