A Captain reports noticing the Q-400 main gear outboard brakes anti-skid caution light had come on for a few seconds during taxi out though the system tested normal. On arrival inboard brakes were found to be very hot and the outboard brakes cool and apparently deactivated by an undetected anti-skid failure.

Narrative

On taxi out; the OUTBOARD ANTI-SKID caution light illuminated for several seconds before extinguishing. We tested the anti-skid and it tested normal; so we continued the taxi for take-off with no further abnormalities. The flight proceeded on to our destination; landed and taxied to the gate with no further indications that anything was out of the ordinary. The deadheading crew that we brought in who were to fly the aircraft on; performed the post flight walk-around and noticed that the left inboard brake/wheel assembly was very hot and smoking. Both main inboard brakes were too hot to touch for more than a second. Both main outboard brake/wheel assemblies were cool. There was a huge difference in temperatures between the inboard and outboard wheel temps. After talking to the outbound pilot and Maintenance Control; the flight was delayed until a mechanic could arrive about 2 1/2 hours later. Maintenance action was to MEL the anti-skid; and the flight then continued 210 minutes late.The interesting and unusual item that I noticed was that since the anti-skid system was apparently not operating; thereby taking the outboard brakes off-line; I would have expected the outboard anti-skid caution light to remain illuminated rather than coming on for a few seconds and then extinguishing.