SeldomFixit is correct. HAECO did change a RB211-524C on a CX747-200 in just under 3 hours chock to chock. The aircraft was on a test flight and taxied to the hangar area and redeparted from the hangar. At least 2 engine change teams were used (guys crawling all over and under it) and the replacement engine only needed a quick leak check and Grd Idle/Flt Idle check engine run. It completed the CAA test flight in daylight after returning around 1400.
On the other side of the coin the first DC10 No. 2 engine change took 3 days. UTA ferried in from SIN with a failed #2 engine. Captain jokingly said "see you in 3 days". Everyone laughed but he was right. Main problems were all the engine change gear and engine were GE property and HAECO had not bothered to practice assemble it so numerous things did not fit properly and no-one in HKG had ever done it before. It was a purely manual bootstrap kit with ratchet chain hoists that left dozens of exhausted chinese mechanics laying on the hangar floor panting.