Blossomforth repairing Pinkie Pie's helicopter machine thing. Because Blossomforth is best mechanic. Also because Chengar-Qordath
's "The Life and Times of a Winning Pony" is an awesome fanfic.
Inspired by chapter twelve of the aforementioned fanfic. She wasn't shown directly working on the helicopter in the story, but instead Cloud Kicker came over to visit her while she was in the middle of repairing it, and I just thought the idea was too cute.