Quest Objectives
Bring the Spare Part to the tinker known as Kaylaena in lower Hyjal.
Provided: 
Spare Part
Description
This looks like something that the tinker in the hills, Kaylaena, could make use of. She barely visits ever since the loss of her mentor, Yaely.
Look for her workshop in the hills to the north. After Archimonde's fall in the great battle, the two of them scavenged what they could easily bring back themselves, picking many of the machines on these foothills clean.
Putting this debris to new use is better than allowing it to rust here. Your errand helps new life sprout where it was choked by metal.
