Ok. I choose to believe your North Korean ASW helicopter theory. But probably not the Ka-28; there is no clear and convincing evidence that they are still operational. The MD-500s are so important to Special Operations Forces that it's hard to believe they'd transfer them to the Navy, and their small size might limit their feasibility anyway.
I'm thinking about the Mi-2s. Theoretically it could carry the same or better payload than those MD-500s (depending on configuration), with a dedicated passenger compartment and cargo hatch that could, again - in theory, be converted into an operations compartment for a submarine hunting crew.
Also, yeah, a heli drone may also possible too.
if stored in a hangar, the problem for the MD-500 and MI-2 helicopters is the diameter of the main rotor which have non-folding blades that would require the construction of a large hangar, in any case the one for the MD-500 would have more feasible dimensions having a rotor diameter of 8.03 m, while that of the MI-2 is 14.5 m.,
So, certainly, the KA-27/28 which with folded blades measures only 3.8 m in width, would remain the best choice.
We just have to wait and see if
Kim Jong-un wants to surprise us once again by showing the frigate with ASW helicopters, or as with the Amnok and Tunan class, this frigate will be without them, leaving the anti-submarine defense to torpedoes and ASW rockets, leaving all the space saved by the construction of a hangar and flight deck for helicopters to implement additional artillery armament and missile capabilities.
