Originally Posted by
safetypee
Recall the 737 forced landing when rain put the 'engine-fires' out.
I'm not here to discuss the importance of the "investigation" of the aerodynamic effect of heavy rain. The question should be asked. However, if the question relates to operating the aircraft I do feel the same old question popping up: "how much safety do you need?"
There were multiple instances of these with engine flameouts in heavy rain. A story many times told to explain why the classic engines have a different cone (NG has pure pointy conical shape, on the classic has a rounded off conical shape). This is pure related to fan engine design, has nothing to do with aerodynamics. The problem was solved after the modifications (there were other problems by the way, including many false fire warnings up to the dangerous point pilots started to neglect them).
When it comes to aerodynamics, one thing you really have to keep in mind is that our "operational" envelope is already developed with safety margins. There is a remark about bank angles, well, we do have 25°+ 15° overshoot. Not sure if anyone ever tried 40° bank in heavy rain to be honest, the wing loading you would feel instantly and you would feel instantly uncomfortable. If you look at terminal maneuvering, just look at the difference between maneuvering speeds schedule during deceleration and acceleration and your actual minimum maneuvering speed. The difference is huge. You are more than protected aerodynamically.
Non-normal situations you might want to take into consideration. Just to give a realistic example from the top of my head: with flap problems on a 737 you might end up with 15°+15° limitations in the turn and that might catch people out in high speed final turns. Would you push on in heavy rain and take 30° bank despite what the NNC is saying in heavy rain, or skip it and come back for a second try? As said before, I think we all are adult enough to be risk avert and re-evaluate the situations a little bit (or at least I would hope).
So again "how much safety do you need?"