Document ID: chunk:federal_register_of_legislation:F2006B03522:body:0:p2
Version: federal_register_of_legislation:F2006B03522
Segment Type: other
Provision Reference: 
Character Range: 3224–4897

conditions must be re-applied. Operators are responsible to ensure flight crews and maintenance personnel are made aware of this requirement according to the dictates of their respective internal procedures.

             Compliance: 1. Before installation of a modified engine or no later than 31 December 2003 whichever occurs first.

2.    On any occasion a fully modified aircraft is to be operated with the altitude limitation in icing conditions removed, but no later than 31 December 2003.

3.    Within 2 months after the effective date of this airworthiness directive or prior to operating a fully modified aircraft with the altitude limitation in icing conditions removed, whichever occurs first.

4.    Whenever an aircraft is operated after the effective date of this airworthiness directive with an unmodified engine installed in any position.

           This Airworthiness Directive becomes effective on 4 November 1999.

           Background: ALF502 engines installed on BAe146 aircraft are prone to a phenomenon known as "rollback" which is an uncommanded power reduction condition and loss of thrust control in certain icing conditions. There have been instances where simultaneous rollback occurred on multiple engines on the same aircraft.

           Altitude restrictions have been successful as an interim means to prevent rollback events. The modifications mandated by this directive will restore the full certificated operating envelope of the aircraft.

           This AD also identifies actions that are required if an unmodified engine is installed on an aircraft and removes CASA imposed altitude restrictions from the aircraft flight manual.