Jet pack

From Teletraan I: The Transformers Wiki

Jet packs were a type of back mounted thruster system that allowed an Autobot extended level of flight. It was worn easily around the back and was mass produced so many Autobots could journey to locations their ground based forms would not allow them access to.

Considering that most Autobots cannot fly like the Decepticons, this must be their way of nullifying that advantage.

[edit] Fiction

[edit] Generation 1 cartoon

Bumblebee wore his pack while he worked with Powerglide as they explored strange energy readings which turned out to be an island in the middle of the ocean. Bumbleebee would be attacked by a dinosaur which damaged his jet pack which Powerglide attempted to repair when they were suddenly attacked by another larger dinosaur. Powerglide abandoned the jet pack, transformed and took Bumblebee back to Autobot base as the dinosaur stepped on the jet pack; destroying it in the process. Dinobot Island, Part 1

After the energy tapping of Dinobot Island caused instability all across Earth, Optimus Prime and the Autobots used a series of jet packs to fly to the island. Dinobot Island, Part 2