Safety recommendations A-06-70-76
Safety recommendations A-06-70-76
The National Transportation Safety Board recommends that the Federal Aviation Administration.
For aeroplanes equipped with CF34-1 or CF34-3 engines, require manufacturers to perform high power, high altitude sudden engine shutdowns; determine the minimum airspeed required to maintain sufficient core rotation; and demonstrate that all methods of in-flight restart can be accomplished when this airspeed is maintained (A-06-70).
Ensure that aeroplane flight manuals of aeroplanes equipped with CF34-1 or CF34-3 engines clearly state the minimum airspeed required for engine core rotation and that, if this airspeed is not maintained after a high power, high altitude sudden engine shutdown, a loss of in-flight restart capability as a result of core lock may occur (A-06-71).
Require that operators of CRJ-100, -200, and -440 aeroplanes include in aeroplane flight manuals the significant performance penalties, such as loss of glide distance and increased descent rate, that can be incurred from maintaining the minimum airspeed required for core rotation and windmill restart attempts(A-06-72).
Review the design of turbine-powered engines (other than the CF34-1 and CF34-3, which are addressed in safety recommendation A-06-70) to determine whether they are susceptible to core lock and, for those engines so identified,require manufacturers of aeroplanes equipped with these engines to perform high power, high altitude sudden engine shutdowns and determine the minimum airspeed to maintain sufficient core rotation so that all methods of in-flight restart can be accomplished (A-06-73). For those aeroplanes with engines that are found to be susceptible to core lock (other than the CF34-1 and CF34-3, which are addressed in safety recommendation A-06-71), require aeroplane manufacturers to incorporate information into aeroplane flight manuals that clearly states the potential for core lock; the procedures, including the minimum airspeed required, to prevent this condition from occurring after a sudden engine shutdown; and the resulting loss of in- flight restart capability if this condition were to occur (A-06-74).
Require manufacturers to determine, as part of 14 Code of Federal Regulations Part 25 certification tests, if restart capability exists from a core rotation speed of 0 indicated rpm after high power, high altitude sudden engine shutdowns. For those aeroplanes determined to be susceptible to core lock,mitigate the hazard by providing design or operational means to ensure restart capability (A-06-75).
Establish certification requirements that would place upper limits on the value of the minimum airspeed required and the amount of altitude loss permitted for windmill restarts (A-06-76).
