ag.algebraic geometry - Which statements in section 5 of BBD will fail if we consider $mathbb{Q}_l$-adic sheaves there?

A stupid question: which statements in section 5 of BBD will fail if we replace $overline{mathbb{Q}_l}$-sheaves by just $mathbb{Q}_l$-ones? I am especially interested in Proposition 5.1.15.

BBD = Beilinson A., Bernstein J., Deligne P., Faisceaux pervers, Asterisque 100, 1982, 5-171.