Hi guys

Can anyone advise why ingestion standards are based on inlet diameter only, and not for instance purpose of flight, ac design inc number of engines on wing, bypass ratio, fan design etc

and point to any documentation to support the theory ?

Both EASA CSE and FAA 33.76 say it’s based on inlet size but don’t actually say why ? I don’t see it being terribly obvious!

For example CFM56-3 is exempt from large flocking test because it’s inlet size is <2.5m^2.

The most popular size/ class of engine thus most passenger carrying commercial opps therefore high risk in my opinion.

The CFM56-5c on the A340 meets the first tier of test for LFB but still an aircraft carrying many passengers thus risk. Why arnt the engines under same test as say GE90 which falls into the largest category.

Thank you.

A=m^2

A<2.50 n/a
2.50< A<3.50 1.85kg
3.50< A<3.90 2.10kg
3.90< A 2.5kg