a. The Federal Aviation Regulations part 91.117 “Aircraft speed” requires that aircraft do no exceed 250 knots indicated airspeed below 10,000’ MSL, and 200 knots indicated airspeed at or below 2,500 feet AGL within 4 nautical miles of the primary airport of a Class C or Class D airspace area. If a pilot determines that the safe operation of his aircraft requires a speed in excess of 250 knots, he may operate at that minimum speed.

b. Do not approve a pilot’s request or ask a pilot to conduct unusual maneuvers within surface areas of Class B, C, or D airspace if they are not essential to the performance of the flight.
EXCEPTION. A pilot’s request to conduct aerobatic practice activities may be approved when the activity will have no adverse effect on safety of the air traffic operation or result in a reduction of service to other users.

{Reference: FAAO 7110.65 3-1-11 “Surface area restrictions;” 14 CFR 91.117 “Aircraft speed.”}