Hotel mode operation on ATRs
I am fairly new on the ATR as a fisrt officer and have been wondering about the hotel mode operation on the number two engine.
For those not familiar with ATR hotel mode, it's ATRs version of an APU. The prop is stopped through a prop brake giving full advantage of AC environmental services available.
My question is: Since the engine is running in idle power the ITT on that engine reaches around 485 C with bleed valves off and around 530 C on some of our fleet aircraft with bleed valves on. The aircraft are all cargo mods so we often operate at night and it is often neccesary to run hotel mode for extended periods on the ground while the aircraft is offloaded and then reloaded. I am wondering if those temperatures are detrimental to the engine life since the hot gases are directly expelled onto the stator blades and the stopped turbine section. The only limitation that the ATR FCOM states regarding hotel mode operation is a max ITT of 785 C.
Since there's a debate amongst our aircrew regarding this issue, I would be grateful for any info.