Narrative:

Upon landing, air brake was deployed as were the thrust reversers. At approximately 70 KTS, the left antiskid shorted out and left no brakes on the left side, and normal brakes on the right side, resulting in our exiting the runway on the right side. The aircraft missed the runway lights and came to rest in the soft mud/dirt about 20' from the runway edge (right edge). The aircraft was towed by the main landing gear. No visible damage was done to the aircraft. Upon further inspection by the mechanics, it was determined that the left antiskid had shorted out leaving the left main gear brakes in the released pressure condition. The right brakes remained functional. Had we realized the left brakes had failed, we could have chosen our #2 backup system which does not have antiskid. However, because of the WX conditions at the time (800' broken, 1200' overcast, 4 right/F wind 060 degrees at 15 KTS, peak gusts 27 KTS and low level wind shear reported by previous aircraft), it was not apparent that the left brake had failed. It just seemed as though we were hydroplaning. Nose wheel steering was ineffective due to the strong yawing movement caused by asymmetrical braking. Ground crew reported that they saw our nose wheel turned the other way, however it was ineffective with all the water on the runway. On this light transport, there is only 1 antiskid box per side instead of per wheel. Had each wheel had its own, then only 1 of the left main gear tires would have lost brakes, leaving the aircraft far more ctlable. Suggest the aircraft should have antiskid failure lights such as on another type light transport. Training crews should be taught that anytime the aircraft has a directional control problem of unknown origin that the crew transfer immediately to backup! With only about a 1 1/2 seconds till run-off, there is not enough time to analyze the situation.

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Original NASA ASRS Text

Title: GA LTT ANTISKID FAILURE LNDG IN A CROSSWIND. LOSS OF ACFT CONTROL.

Narrative: UPON LNDG, AIR BRAKE WAS DEPLOYED AS WERE THE THRUST REVERSERS. AT APPROX 70 KTS, THE LEFT ANTISKID SHORTED OUT AND LEFT NO BRAKES ON THE LEFT SIDE, AND NORMAL BRAKES ON THE RIGHT SIDE, RESULTING IN OUR EXITING THE RWY ON THE RIGHT SIDE. THE ACFT MISSED THE RWY LIGHTS AND CAME TO REST IN THE SOFT MUD/DIRT ABOUT 20' FROM THE RWY EDGE (RIGHT EDGE). THE ACFT WAS TOWED BY THE MAIN LNDG GEAR. NO VISIBLE DAMAGE WAS DONE TO THE ACFT. UPON FURTHER INSPECTION BY THE MECHS, IT WAS DETERMINED THAT THE LEFT ANTISKID HAD SHORTED OUT LEAVING THE LEFT MAIN GEAR BRAKES IN THE RELEASED PRESSURE CONDITION. THE RIGHT BRAKES REMAINED FUNCTIONAL. HAD WE REALIZED THE LEFT BRAKES HAD FAILED, WE COULD HAVE CHOSEN OUR #2 BACKUP SYS WHICH DOES NOT HAVE ANTISKID. HOWEVER, BECAUSE OF THE WX CONDITIONS AT THE TIME (800' BROKEN, 1200' OVCST, 4 R/F WIND 060 DEGS AT 15 KTS, PEAK GUSTS 27 KTS AND LOW LEVEL WIND SHEAR RPTED BY PREVIOUS ACFT), IT WAS NOT APPARENT THAT THE LEFT BRAKE HAD FAILED. IT JUST SEEMED AS THOUGH WE WERE HYDROPLANING. NOSE WHEEL STEERING WAS INEFFECTIVE DUE TO THE STRONG YAWING MOVEMENT CAUSED BY ASYMMETRICAL BRAKING. GND CREW RPTED THAT THEY SAW OUR NOSE WHEEL TURNED THE OTHER WAY, HOWEVER IT WAS INEFFECTIVE WITH ALL THE WATER ON THE RWY. ON THIS LTT, THERE IS ONLY 1 ANTISKID BOX PER SIDE INSTEAD OF PER WHEEL. HAD EACH WHEEL HAD ITS OWN, THEN ONLY 1 OF THE LEFT MAIN GEAR TIRES WOULD HAVE LOST BRAKES, LEAVING THE ACFT FAR MORE CTLABLE. SUGGEST THE ACFT SHOULD HAVE ANTISKID FAILURE LIGHTS SUCH AS ON ANOTHER TYPE LTT. TRNING CREWS SHOULD BE TAUGHT THAT ANYTIME THE ACFT HAS A DIRECTIONAL CTL PROB OF UNKNOWN ORIGIN THAT THE CREW TRANSFER IMMEDIATELY TO BACKUP! WITH ONLY ABOUT A 1 1/2 SECS TILL RUN-OFF, THERE IS NOT ENOUGH TIME TO ANALYZE THE SITUATION.

Data retrieved from NASA's ASRS site as of August 2007 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.