[dalke]

Where's the passive? "The tank ... ran out of fluid" isn't passive. (If it is, then "the heroes ran out of time", "the car ran out of gas", "I ran out of money" and "the airplane ran out of runway" also use passive voice, yes? What is the active equivalent?)

"hydraulic fluid that powered the fins enabling them to rotate and steer" isn't passive either. Poorly written, certainly.

I double-checked with the examples in http://www.lel.ed.ac.uk/~gpullum/passive_loathing.pdf and still didn't see a match. FWIW, that paper also comments "mistaken charges of using the passive voice are commonplace".

[NamTaf]

My apologies, I read 'to rotate' as passive but it isn't at second pass. I should have tried rewriting it as active voice and it would have become obvious when I failed.