Can the EPR ever be less that 1?

Question

Can the EPR ever be less that 1?

Answer 1

Yes it can.

It can happen during a compressor stall or surge.  The high pressure air from the compressor reverses and enters the inlet where the first probe (PT2) is.  There is also a lost of thrust (due to no air going into the combustion chamber, turbines, and exhaust nozzle) which causes low pressure on the second probe (PT7).

It's not something you want to see.  It would only be momentary since the result would either be catastrophic or continue on intermittently (buzzing or surging).

Answer 2

not sure. i don't thnk so

Answer 3

no