I believe you'll love to read this:

Cameron addresses the obvious: “we could’ve run a CG helicopter under the freeway overpass, but it was so much more fun to do the real thing.” In other words: it’s not that alternatives to flying an actual helicopter under an overpass weren’t possible, it’s just that those alternatives were for cowards.

The stunt was performed by Charles A. “Chuck” Tamburro, a veteran stunt pilot as well as an actual, you know, veteran (Tamburro learned to fly helicopters in Vietnam). You might not know his name, but you’ve almost certainly seen Tamburro’s work. He’s piloted helicopters in everything from Predator, to Furious 7, to Scarface, to Blade Runner.

According to James R. Chiles’ The God Machine: From Boomerangs to Black Hawks, The Story of the Helicopter, Tamburro put his helicopter on wheels and rolled it under the bridge to measure the clearance, which came to five feet above and four feet on each side. Tamburro flew the stunt at a speed of sixty knots, roughly 70 mph or 111 km/h, (aka highway speed for those of you who don’t drive).

With a lot at stake and not a lot of room for error (quite literally), as Tamburro, himself put it: “If I made a mistake, I would be killed.” The stunt was so obviously dangerous that the scheduled camera crew tasked with shooting the close-ups refused to take part in it. Proving that he’s not one to ask of others what he isn’t willing to do himself, Cameron said “okay fine, I’ll shoot it” and shot the stunt with the help of a very courageous insert car driver.

The only thing more impressive than Tamburro pulling off this stunt is that he pulled it off twice. See, Cameron needed to capture two different angles: one from behind the helicopter and one in front of it. How Tamburro was able to pilot the helicopter with his enormous balls we’ll never know.

https://filmschoolrejects.com/terminator-2-helicopter-stunt/