Engine Won't Start FSX Learjet or Helicopter

Posting this as a PSA to Google in the future for other lost souls or newbies:

If your engine spools up and down repeatedly without starting in FSX, with the default Bombardier Learjet or the helicopters (Agusta EH-101, for example), this is because you have FSX set to start up default with Mixture fully lean/at Idle Cutoff.

Some aircraft in FSX do not have an obvious Mixture control.

Use the keystrokes CTRL+SHIFT+F4 to set Mixture to Full Rich.

This will solve the problem.