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.
Any item listed in a TCDS, Example: TCDS H3EA (see note 10). An Annual Inspection (FAR 91.409). Service Bulletions, when associated with an A.D. What is the Airworthiness Limitations (AL) section ? Is a section of the Aircraft Maintenance Manual (generally chapter 04) where all the mandatory items are listed.