Just recently the Air Canada flight AC837 from Madrid to Toronto had problems with the gear right after take-off and they decided to abort the flight and go back to Madrid. It was a B767-300 (C-GHOZ) which, AFAIK, cannot dump fuel so they circled approximately four hours southeast of Madrid in order to burn the fuel before landing:
(Source: Flightradar24, https://www.flightradar24.com/data/flights/ac837#23be1953)
Four hours is quite a long time and I wonder if the pilots actively do something to increase the rate at which fuel is burnt to somehow speed up the whole process. Like running the engines at full thrust and/or putting speed brakes/flaps in place. I don't know if they retracted the gear (which dramatically decreases the fuel consumption), but I doubt so because its damage was the whole reason for the circling.
If it matters: they circled approx. 1h @4500 ft and then approx. 2h 45m @7500 ft before heading back in Madrid.
