Bell 412 EP versus HP performance
I'm trying to understand the performance differences between the Bell 412 HP (with -3BE engines) and EP (with -3D engines). I've read other threads on general Bell 412 performance, and, aside from the different AFCS, I had thought that the main HP to EP difference was OEI performance - but have found that some AEO differences are also apparent. The graphs in the flight manual are the same for hover ceiling IGE and OGE (TOP) but differ for hover ceiling at MCP. TO distance is the same, as is AEO climb at TOP. AEO climb at MCP is different as is OEI climb at MCP, although OEI landing distance using 2.5 min power as required is the same. Why are the AEO MCP curves different? I know that the engine Tq, N1 and ITT limits are higher for the EP, but isn't AEO MCP = 81% mast Tq for both? Assuming 100% mast Tq is the same 'real' Tq for both, is it just that you can maintain 81% for a bigger Hd envelope with the -3D than you can for the -3BE? In other words, would the climb performance of an HP at engine limits be the same as for the EP when flown to the same parameters, but that the EP could then be taken beyond those parameters?