So, the Collings Foundation and their touring warbirds were in town recently, and we went to visit them. While out on the ramp though, my father managed to lose one of the Styrofoam coffee/drink cups the FBO provides (for their complimentary ice water and iced tea, of course). How much FOD hazard could that runaway Styrofoam cup pose, considering its relative lack of hardness and stiffness/strength compared to most other FOD hazard items?
Probably very little. There's the very slight chance that it could stuck on a pitot tube or some other terrible scenario in a Final Destination type film which, coupled with another issue, could cause a problem but again very unlikely.
The underlying hazard is the attitude towards FOD in general. It's a bad habit to build complacency towards any FOD sitting on a parking apron or letting it "get away". If it's SAFE to pickup the FOD then it should be picked up. It's possible the next time someone ignores a cup, it could have been used by a wayward mechanic to hold a sticky chemical that would ruin a pilot's windshield and his day if it smacks and smears on the glass on takeoff. Again very unlikely but why risk it!
$\begingroup$ It was the "thing that you knew you stuck in your pocket but came out at some point" sort of scenario, BTW... $\endgroup$ Jul 23, 2017 at 1:46
If any engine fails due to a foam cup it was already failing. Obviously you never want fod on the flight line but there's a significant difference between soft and hard fod.
Chances of it causing a real damage are slim but not at all negligible. Shredded by a propeller may end up in a pitot probe and clog it. Best example of this sort of small thing big trouble is the coin in the elevator mechanism that happened a few years ago to a glider (no damages or whatsoever, luckily). At my club we had a passenger losing an earring while in flight and quite a bit of take apart followed....
$\begingroup$ A coin is so different from a styrofoam cup that it's hard to see how any comparison could be relevant. $\endgroup$ Aug 4, 2017 at 10:47
2$\begingroup$ The thing that a styrofoam cup and a coin have is common is being peircived as small, lightweight and irrelevant. The comparison is to point out that when talking aircraft safety no object is small enough not to have to worry about. $\endgroup$ Aug 4, 2017 at 11:42
$\begingroup$ I don't see ramp workers wearing hair nets, so a human hair is clearly an object that is small enough not to have to worry about. But I didn't say that either a styrofoam cup or a coin is so small that you'd not have to worry about it: I said that they're so different that knowing about one tells you next to nothing about the other. $\endgroup$ Aug 5, 2017 at 21:08
1$\begingroup$ You can either choose to understand what my point is (Object that are small and not perceived as an hazard for vehicles people are familiar with, such as cars, may be a problem for aircrafts) or go on nitpicking. Either way, enjoy your day. Oh, by the way, a human hair in a i.e. micro mechanics assembly shop where your avionics are being manufactured may be quite a problem... $\endgroup$ Aug 6, 2017 at 9:39
$\begingroup$ A coin is self-evidently dangerous: coins are a lot like stones and stones can clearly cause damage (also, this). Human hairs show that there are some objects that definitely are not a problem. Styrofoam cups aren't obviously safe like a hair or obviously dangerous like a coin. That's the whole point of the question: the answer isn't obvious, so the person asked a community that knows more. I agree with your general message; I just don't think that a coin is a useful example. $\endgroup$ Aug 6, 2017 at 12:48