Exit the ventilation shaft through the left side and head down the stairs toward the spinning blades. You can find the parts to the left of the gate and blades.
(Must Have Completed "Back in the Game") Disrupt the blades and head down the catwalk until you can drop down. To the left, you can find the electronic parts.
When exiting the Lair, you pass through a ventilation shaft. Don't jump down. Turn to the left and jump over to the small awning where a document sits.
Exit the ventilation shaft through the left side, and head to the staircase ahead. Stick to the left near the yellow piping to find the document on the ground.