The iron and sulphur still behave like iron and sulphur in the mixture, but iron sulphide has different properties from both iron and sulphur. You can separate the iron from the mixture using a magnet but this does not work for iron sulphide. 1  Page.
Search for: An Airworthiness Directive (A.D.) is a directive issued when the FAA realizes that a perilous condition exists in a product (aircraft engine, airframe, appliance or propeller). They notify aircraft operators and owners of potentially unsafe conditions that need special inspections, alterations, or repairs.
Airworthiness. The term âairworthyâ is important to understand when seeking an FAA aircraft certification. The definition is not published in the regulations, but FAA case law has identified two conditions that must be met for an aircraft to be considered airworthy. The following two conditions are stated in FAR Part 21.183(a), (b), and (c) and must be complied with before the FAA will issue an airworthiness certificate: 1.