When Brymon first took delivery of the Dash-8-102's GBRYG/H (first on uk reg) there were almost continuous reports of orange sparks from the brake discs. I've witnessed it myself on landing at CDG many years ago, and I did report it to maintenance control!! although it was more like a Catherine Wheel than the 'odd spark'....It's just a common feature of the Dash-8 like ' elevator horn heat failure' and 'hydraulic leaks'......etc etc