The Aviation Hub

  What is the Relationship Between Airworthiness Directives (AD,s) Service Bulletins (SB’s) & Alert Service Bulletins (ASB’s) Airworthiness Directives Airworthiness Directives (ADs) are legally enforceable rules issued by the Regulatory Authority of the Type Certificate Holder, (TCH) Supplemental Type Certificate Holder (STCH) or Original Equipment Manufacturer (OEM) (may also be issued by other Regulatory Authorities). Now Consider the Following Statements :        ⁰  Airworthiness Directives (AD,s) are Mandatory         ⁰  If an Aircraft is not in compliance with AD requirements its Certificate of Airworthiness is not valid and the aircraft shall not fly legally.         ⁰  AD,s are only issued by Regulatory Authorities – most usually the authority of the State of Design of the Aircraft or Product Service Bulletins & Alert Service Bulletins A Service Bulletin is a notice to an aircraft operator from the Aircraft Engine or component manufacturer informing of a product change o

 we can all agree that flying helicopters is an extraordinary hobby. it is also a fast and efficient means of transport but as with many hobbies and means of transports there are risks and danger. the best way to avoid accidents is to know the hazardous flight conditions well. the goal of this article is to study the vortex ring state one of the different hazardous helicopters flight conditions, to learn to recognize and avoid them and most of all ,know how to get out of them. ok, how do we define the vortex ring states ? Vortex ring state, in which airflow is upward on the inner blade section, producing a secondary vortex in addition to the normal wingtip vortices. Turbulent airflow results in loss of rotor efficiency. If allowed to continue, uncommanded pitch-and-roll oscillations may occur, with a large descent rate in normal flight condition, the air flow comes from above passes through the rotor disc and is pushed underneath.in other words, the induced flow at the the rotor tips t