Haas team principal Guenther Steiner said a combination of downforce loads and Austin's kerbs led to the team's cars falling apart during Friday practice.

The 'monkey seat' winglet that sits above the exhaust fell off both cars during the two sessions and on the second occasion resulted in a red flag to allow marshals to clear the debris. The problem occurred as the cars ran over the kerbs in the Esses at the start of the lap and Steiner said the team will make changes for qualifying day.

"When you design stuff you calculate loads, and it seems like the vibration in the downforce meant they broke off where they are bonded," he said. "We need to make a mechanical fix for this weekend and a better part for the future. We know why it broke off, but we didn't anticipate this."

The Haas drivers finished 18th and 20th in second practice, but Steiner said the problems they faced limited meaningful running.

"You always worry if you are not there with performance. Worry is big word, we try to find the performance, and if you're worried that doesn't sort your problem. We know where to go, but the lack of unstable running doesn't help to find performance and the set up.

"That's the biggest problem we've got, so with the engineers and the limited amount of data we've got we can find a solution for FP3. But worried, no. It's just another day, we need to work hard and find something, until you wring everything you are always trying to find it."