Good Day
I recently had to drain the gearboxes and drain some out the main oil tank on the 777 RB211 Trent 877. Why? becuase someone did not ready the instructions! Do not service the engines when they are cold. This will result in an over serviced condition. The Trent does not have a high pressure bleed off and this will over pressurize the oil system, this could blow out seals and at the very least puke oil out the drain mast. The proper procedure is to add oil to the tank until the sight gauge reads two quarts low. Fire up the engine for fifteen minutes at 70-75 percent so the engine can scavenge the oil from the tank and gear box. Then after 10-30 minnutes check and or service as required. Once there is a known quanity then it ok to service the oil tank for top off only to two quarts low. This should keep anyone using these engines a lot of heart ache.