C-GSOC, a Cessna 680 aircraft operated by Sunwest Aviation, was conducting flight CNK771 from Duluth Intl, MN (KDLH) to Calgary Intl, AB (CYYC) with only 2 pilots on board. During the number 2 engine start in KDLH, the flew crew observed abnormal N2 acceleration. Smoke and some fire was observed emanating from the engine and the pilots were advised. The engine was shut down and motored for 10 seconds with no further issues. There were no flight crew warning system indications for fire and the fire suppression system was not activated.
A post incident inspection discovered heat damage on the inlet fan blade shroud for the number 2 engine (Pratt and Whitney Canada PW306C).