Converted my FS2 Apache to FS4, It's a WIP as FS4 changed quite a lot. Most things are simulated, fuel burn, engines, electrics, hydraulics, APU etc.
If starting cold and dark, you will need air to start an engine so its not a fault. Air sources are APU, External or an engine already started. APU start takes time so don't expect it on straight away, wait for 'rectifiers' lights to disappear and 'APU on' in the warning panel.
When starting ready to fly, do wait a few seconds for the rotors to spin up fully. I have only recently been given new engine and governor code which is a little complicated for my very old and tired brain. I am also working on getting the Lynx into FS4 (that will not have the new code as the Lynx is an awkward b*****d at the best of times as I modelled it too accurate)
Let me know of any issues and I will try to fix them, not guaranteed I can .
https://flight-sim.org/filebase/index.php?entry-add/&categoryID=155
EDIT, You can use ADF or Tacan/VOR navigation but the knob is hidden so here is a little pic to help
Steve