On page 11 of this A320 FCOM (power plant section only), a "thrust rating limit" mechanism is described. However, it doesn't go into much detail, and I could find little other information about it.

I have a few questions about its operation:

  • On the previous page (page 10), it says "The FADEC prevents the thrust from exceeding the limit for the thrust lever position in both manual and automatic modes". Is this limit the same thing as the thrust rating limit? If it is, how could the limit be exceeded in manual mode?
  • Why is there a limit for "on ground engine not running"? If the engine is not running, what is the FADEC even limiting?
  • For "on ground engine running", the bars for "TO GA" and "FLEX" overlap. What is this supposed to mean? Does some other parameter determine whether the "TO GA" or the "FLEX" limit applies?
  • What is the actual limit value for "MAX REV"? Is it defined as a percent N1 or something else? Also, can it varied manually by the crew based on performance calculations?


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