The aircraft was in compliance with all applicable Airworthiness Directives for the airframe and engines. The aircraft was in compliance with all applicable airworthiness directives for the airframe and engines. Draft guidance pertaining to EFB operational authorization and airworthiness/certification requirements is maintained by the FAA. Certification standards applicable to the airworthiness of an aircraft contain many requirements. Minimum certificated weight for flight as limited by aircraft strength and airworthiness requirements. The FAA declined to issue the Airworthiness Directive. In the US, the FAA requires aircraft to have an airworthiness certificate. The investigation resulted in an emergency Airworthiness Directive that affected 13 Cessna 400s. This resulted in Airworthiness Directives mandating the replacement of the heat exchanger. The aircraft was to be restored to Douglas Sleeper Transport standards, and full airworthiness. The propellers were the subject of Airworthiness Directives in 1955, 1957, and 1958. These tests may form part of the certification process such as for airworthiness certification. The BAe 146 received its Certificate of Airworthiness on 8 February 1983. As of mid-2007, systems integration was ongoing and airworthiness certification works continued. The minimum crew requirement, as specified in the airship's Certificate of Airworthiness, was 15 men.