If you have Flywithlua installed you can fix the bank roll limit by creating a lua script with the following content:
if (AIRCRAFT_FILENAME == "LES_Saab_340A.acf" or
AIRCRAFT_FILENAME == "LES_Saab_340A_Cargo.acf" or
AIRCRAFT_FILENAME == "LES_Saab_340A_AEW.acf") then
function les_bank_fixer()
dataref("SBankLimit","sim/cockpit2/autopilot/bank_angles_values","writable")
SBankLimit = 27.0
end
do_often("les_bank_fixer()")
end