Okay dudes, I need your advice ASAP. I am flying a C-172 tomorrow, with an inop stall warning horn. Today a fellow CFI terminated a flight early today because the stall warning horn was not working. While I was out there today we went back and forth whether or not the airplane was airworthy. I think it is Airworthy, via 91.213 (here is the link http://ecfr.gpoaccess.gov/cgi/t/tex...v8&view=text&node=14:220.127.116.11.10.3.7.7&idno=14 ) by the same reg, the other CFI says it is un-airworthy. The part won't be in until tomorrow at 10 a.m. and to add to that the mechanics are saying it can't fly because it doesn't have a working aural working stall warning device. Which to that I said, "I am pretty sure that I've flown pipers that didn't have aural stall warning devices, only a light." I can see how I can be wrong about 91.213, so what is the verdict?