For internships, there are usually two interviews. My first was after a career fair in person with two test engineer I's and a recruiter. The second was over zoom with one of the previous engineers and a principal test engineer. Both interviews were over an hour long and included questions about projects I worked on in the past, and other technical questions about engineering fundamentals: Mechanics of Materials, Thermodynamics, Fluids. Do not expect many personality questions, expect to be pushed to your limit.

Primarily technical interview, very few behavioral questions. Know your engineering fundamentals (i.e. structures, fluids, thermodynamics) well before coming in. Was interviewed for two rounds; the first with a second level engineer, and a second with both them and a team lead. Both interviewers were easy to talk to and were very accommodating with asking questions/advice for questions.