Williams technical director Sam Michael conceded Thursday proved to be a disappointing day for the team after being unable to get significant running done.
Pastor Maldonado completed an installation lap early on, but then spent most of the day in the garage as the team worked to solve an issue with the rear wing actuator. The Venezuelan only returned to the track with half an hour of the session left and managed just a handful of laps on his way to the slowest time of the day.
"It has not been a productive day for us I'm afraid," said Michael. "After the installation lap we had a problem with a bleed screw for the rear wing hydraulic actuator. "It is straightforward to correct, however, during the day it caused a lot of downtime as we shuffled parts around to get the car out on the track.
"On the positive side, in the late afternoon we did complete all the aero testing that required the front tire rake, so that will come off tonight."