CS 27 and CS 29 cover the Airworthiness Requirements applying to small and large rotorcraft respectively.

According to CS 29.1 - Applicability:

• Large rotorcraft must be certificated in accordance with either the Category A or Category B requirements. A multi-engine rotorcraft may be type certificated as both Category A and Category B with appropriate and different operating limitations for each category.

• Rotorcraft with a maximum weight greater than 9072 kg (20 000 pounds) and 10 or more passenger seats must be type certificated as Category A rotorcraft.

• Rotorcraft with a maximum weight greater than 9072 kg (20 000 pounds) and nine or less passenger seats may be type certificated as Category B rotorcraft provided the Category A requirements of Subparts C, D, E, and F are met.

• Rotorcraft with a maximum weight of 9072 kg (20 000 pounds) or less but with 10 or more passenger seats may be type certificated as Category B rotorcraft provided the Category A requirements of CS 29.67(a)(2), 29.87, 29.1517, and of Subparts C, D, E, and F are met.

• Rotorcraft with a maximum weight of 9072 kg (20 000 pounds) or less and nine or less passenger seats may be type certificated as Category B rotorcraft.

According to CS 27.1 - Applicability:

• Small rotorcraft with maximum weight of 3 175 kg (7 000 lb) or less and a MOPSC of 9 or less are certified under CS 27.