This is on the Convention Infilitration quest.
I missed this on the first form of the task but got it on the weekly. However, per Maxumilli0n you can do this on the first iteration.
You'll need to talk to the mechanic after collecting balloons and parts (one of the parts vendors will tell you to tell Mella to say hello) and before selecting the orange dialog option to continue the quest, pick the option underneath that says "Baryll Hardbridge says hello" (thx again Maxumilli0n). If you don't see it, try pursuing all dialog options with the vendors.