Airworthiness certification.
CFR · 2024-01-01 · US · Title 14
A Rotorcraft External-Load Operator Certificate is a current and valid airworthiness certificate for each rotorcraft type certificated under part 27 or 29 of this chapter (or their predecessor parts) and listed by registration number on a list attached to the certificate, when the rotorcraft is being used in operations conducted under this part.
official document · source cfr-2024 · id 14:§ 133.51