Oil servicing on the RB211 flight engine.

[f4dj79]

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.

[j79guy]

Reminds me of an engine we run on the test cell. The customer insisted that we dip the oil sump before and after test running, to measure oil consumption. Of course, the engine was stone cold at first dip, and after run, we "made" oil. The customer was impressed, and wrote in his report; "Oil consumption negative 2 pints"

Robin.

[f4dj79]

Robin
Even our customers are impressed when our engines make oil, its a miracle. I think many mechanics do not even realise that oil volume increases when the oil gets hot. Just the other day and before delivering BAB (British Airlines) we recovered the airplane after flight and the flightdeck oil quanity readings were 25L/24R and there was a big painic about the oil system being overserviced again, twnety minutes later the oil quanity dropped to 20L/21R which is normal and evryone could not understand it. So out Rolls Royce techs came agian to explian once more how their engines oil systme works. It's very fuuny to watch the unqualified work on these engines. They cause so much work by not knowing what is going on.
WB