Or getting it certified that it's safe. https://www.faa.gov/aircraft/air_cert/airworthiness_certification https://www.faa.gov/aircraft/air_cert/airworthiness_c

Or getting it certified that it's safe. https://www.faa.gov/aircraft/air_cert/airworthiness_certification https://www.faa.gov/aircraft/air_cert/airworthiness_certific... "Amended type certificates typically take 3-5 years to complete. By comparison, the certification of a new aircraft type can take between 5 and 9 years."