If a helicopter is flying an IFR flight plan, and the airspace around the destination is busy, will controllers tell them to fly holding patterns just like planes do? Or will they hover at the holding fix? Or something else entirely?
Indeed helicopters can be put on holding during IFR.
ICAO DOC 8168 VOL II (PANS-OPS) has helicopter specifics in
Section 4 Chapter 1 HOLDING CRITERIA:
188.8.131.52.2 Helicopter timing. The outbound timing should be:
a) one minute up to and including 1 830 m (6 000 ft); and
b) Category A fixed-wing aeroplane criteria above 1 830 m (6 000 ft).
Table II-4-1-2. Airspeeds for holding area construction specifies that for
Helicopters up to 1 830 m(6 000 ft) inclusive
185 km/h (100 kt)
under normal (non turbulent) conditions.
From the above, we can conclude that timing and airspeed equals flying the pattern and not hover the point.