Just back from the DPE 24 month training. 4 of the areas best helicopter DPE had a chance to talk and we have discovered that we are seeing the same problems among helicopter applicants. Here's the short list.
1. Performance planning. HOGE, HIGE, Cross country planning with power settings, airspeed and fuel burn.
2. Emergency procedures. Retreating Blade Stall, Low G, LTE and Low rotor and Rotor Stall & Settling with power.
3. Privileges and limitations of respective pilot certificate
4. Exceeding limitations. TO MAP, Rotor and Engine RPM,
5. Autorotations (see #4) (see PTS)
6. Power Failure at Altitude (failure to establish safe autoratation in accordance with PTS)
7 Slope. Skill and knowledge. For example, How do you know the slope is too steep for the helicopter
I'm sure there are others but those are the items that where discussed the most.