Hi Charlie, I too have had BL failures with one leading up to an inflight fire similar to yours. When the FET's fail they burn very hot, hot enough to melt solder. If a FET near the capacitor legs burns up it will likely cause the solder around the capacitor legs to melt and bridge over causing a short which then accelerates your problems and fire usually follows. Having been through this I now wire up my power, I2c and BL's as separate components....no more MK power distribution boards for me although a FET can still fail and start a fire, it just won't do as much damage to other components. your experience was a while ago, hopefully you got it all fixed and have been enjoying a trouble free helicopter for your efforts. Bart