HI Ken
Northward Airlines of Edmonton operated 3 or 4 ST-27 out of Whitehorse YK to service the Yukon including Mayo in the late 70's, after their F-27s, for a year or 2. The ST-27s had a bit of a range issue as they had to be refueled when they landed in Mayo for their return trip to Whitehorse 200 miles away.