Be careful when attempting to approach a Yutyrannus as it may have Carnos with it (That are probably damaged buffed), if you have a quetz (or anything that can pick up Carnos), attempt to grab the carnos to draw them away from the Yuty (Or kill them outright, although the Yuty may take damage), making it less dangerous. At this point, when the carnos are gone, build and lead the Yuty into the trap WITHOUT A DINO. If you bring a dino with you at this point, it will likely be scared from the roars, screwing you over. After the Yuty is detained, it's a simple wailing of torpor till the big fluffy dinos gives up the ghost, which is when you feed it to have a cute, deadly, strength inducing badass that is the Yutyrannus!
It really is that simple though, they can't reach you or your flier on a big enough rock, so if you don't want to make a trap you can just shoot down from a rock or cliff once the carnos are dealt with. Be ready for a goose chase once it starts running.