Had Both Pilot and Co-pilot WS's go out within six months of each other.....the WS were 6 years old....was told that when they installed the new WS's six years prior to this happening, the MX department didnt remove the old sealant and prep properly, and when the bolts were torqued around the frame, it caused uneven stress points...so BANYO4 mentioned "mandatory removal and reseal of the PRC around the windows each phase inspection" sounds like something to think about during your next inspection.
Remember this video of the KA? He about crashes the aircraft because of a cracked winshield.
YouTube - Emergency Landing - King Air