In this brave new post 9-11 and low cost short turn round world, it's hard to get to talk to anyone on the aircraft these days
Let me help you then...
1) Look above you and locate overhead Passenger Amenity Panel.
2) Locate crew call button.
3) Press it.
During the flight, it wasn't a sufficiently serious issue to be causing concern about the safe conduct of that flight
How do you know? Are YOU an engineer?
I've done enough flying as SLF and pilot that I wasn't concerned for the safe operation of that flight
Good for you. However, as you don't know jack about the aircraft or its systems, perhaps you would be doing everyone a favour by reporting what you saw.
I was concerned that if the
same symptom continued, there was a risk, as mentioned by MOR, that a problem could occur that would disrupt normal operation.
On some aircraft, cracking of the exhaust duct can lead to the serious risk of fire within the engine nacelle. Any crack that starts CAN (but may not) propogate extremely quickly. I know because it happened to me once, we ended up shutting down the engine 10 mins into the flight with a fire warning in Zone 3 of the nacelle.
Think back to Kegworth. If the pilots had known what the passengers were seeing, the chances are they would have landed safely. You are not in a position to make the judgement about what is important and what is not. Why not let the pros deal with it? Not reporting ANYTHING out of the ordinary is irresponsible.
Nothing irritates me more than SLF/spotters/armchair experts who fulfil the adage "a little knowledge is a dangerous thing"...