Cate Blanchett was on the Santa Fe set of “The Missing,” playing an American frontier woman — one of many non-native accents for the Australian thesp — when she got the call from Martin Scorsese about the role of Katharine Hepburn in Howard Hughes biopic “The Aviator.”

Scorsese wanted to know what Blanchett knew of Hepburn.

“I knew of the cliches about Howard Hughes and Katharine Hepburn …,” says Blanchett, but she knew little more about the screen icon’s private side.

Of course, that subsequently became Blanchett’s mission.

“I read everything about her and Marty screened a lot of her films. I’d seen the greats, but they were mostly films from when she was older.”

So, films such as 1932’s “A Bill of Divorcement” and 1935’s “Alice Adams,” from the era depicted in “Aviator,” were an important component of Blanchett’s preparations.

But given the relative little ink and broadcast footage of the private Hepburn, Blanchett had to piece together clues from what was available.

“I had to strip away the perception of her and get behind who the real person was.”

She studied a Dick Cavett TV interview with Hepburn, when the actress was in her 70s, and extrapolated from it what the younger woman might have been like. She also listened to audio recordings of Hepburn’s films.

“I had to separate the physical manifestation of her and listen to the energy of her voice,” says Blanchett. “She was so known for the way she spoke, so I just drilled that, really.”

Still, it remains a tricky proposition for anyone — much less a non-American — to attempt to embody such a known and beloved Hollywood legend. To keep it real, the thesp trusted her director.

“Marty’s a great audience; he’s really exacting and we talked about how far to go. It’s a matter of taste. You have to be aware of the style of the film you’re in.”

Despite few vocal and physical similarities between the two women, Blanchett nailed it, including Hepburn’s Connecticut lockjaw.

Says Scorsese: “I was confident that she would not do a caricature yet have the courage to broach that at times. You don’t know where to pull back from if you don’t take it too far. Her intelligence guided it for me. I just gently prodded here and there.”

It’s a quality the helmer had been impressed with before. Scorsese remembers seeing Blanchett in the title role of 1998’s “Elizabeth”: “There’s no other Queen Elizabeth for me.”

“It was definitely one of the most difficult things I’ve ever had to do,” the thesp adds about her “Aviator” work. “It seemed insurmountable at first, but it was about chipping it away and chipping it away.”