TC holder responsibilities in following ADs and providing technical support to keep the type design current with the applicable airworthiness requirements, even after the production of the aircraft type has stopped but many out-of-production aircraft continue useful lives. STCs are also bound by the same rules. When the holder decides to stop supporting the aircraft type without the transfer of TC holder responsibilities, the TC is returned to the issuing regulatory authority and the remaining aircraft fleet can be grounded by the current states of registry until further decisions on the registered aircraft continuing airworthiness. In this manner the whole Concorde fleet was finally grounded when Airbus SAS surrendered its TC. See also Experimental aircraft Unapproved aircraft part References External links Federal Aviation Administration - Certificate Types - Type Certificate Data Sheets List of US Approved Type Certificates; 1927 - 1958 List of US Group 2 Memos; 1929 - 1947 FAA Guide For Obtaining a Supplemental Type Certificate; 2007 Aviation licenses and certifications