RG Helicopters
 

So my knowledge of helicopters is pretty much nil but I was watching the local hospital bird land today and it suddenly struck me, do chopper pilots have to have an endorsement for retractable gear equipment? I know as a fixed wing pilot I got the high performance/complex endorsements; part of which covered retractable gear. Is there a similar add-on to the rotorcraft license?

61.31 just says "airplane."

Are there piston powered helos with retractable gear or only turbine powered equipment?

USMCFLYR