Не один раз... пока не...
The phrase is:
Не один раз Егор Дрёмов водил свой танк в атаку, пока не случилось с ним несчастье.
I translate: "No one time had Egor driven his tank to attack, in which (ocassion) he had suffered a misfortune". More plainly: "Up to then, Egor has suffered no misfortune when driving his tank to attack". Is it acceptable?
Thanks.