flat out

Translations
на пределе возможностей
He was working flat out to meet the deadline.
Он работал на пределе возможностей, чтобы уложиться в срок.
Definitions
The phrase 'flat out' means to do something with maximum effort or speed, or to be completely honest and straightforward about something.
Words
flat

adverb
полностью
out

adverb
изо всех сил