I had a low side failure on the Sea King at sea about a thousand years ago.
Affected engine went to idle Ng and low Nf so it was easy to diagnose. Happily it was during the day and fine weather, so easy free deck landing. We burned some fuel off and practiced with the emergency throttle a bit then I had the FO fly for the landing as I “flew” the emergency throttle, keeping the affected engine about 20 percent Q behind the good engine. Just have to remember the Q goes down much quicker when the collective is lowered so you have to be brisk getting the Q down on the emergency throttle.
Had a FCU fail on the 412 too. We were practicing gov fail, rolled throttle down, checked idle numbers, etc with dual concurrence, flipped the gov switch to manual and the TOT went to 1000+ in about a second. Shut down and OEI approach back to pad. Visual insp, no damage to engine. FCU change. Only time I ever had a snag on the PT6. Well..except that time as an FO when it wouldn't start...until the tech came out and turned on the fuel switches....sigh. LOL