AS350 - Arriel problem?
In the last week there have been two instances (one a B2 and the other a B3) where the oil breather line from the accessory gearbox has become blocked with with carbon where the line protrudes into the exhaust stream. This resulted in back pressure blowing oil past the labyrinth seal and into the engine core with some oil going through the combustion chamber (lots of smoke!) and some out the bleed valve (lots of mess!). In each case the aircraft were using Mobil 254, whether this is a factor or not is yet to be determined. Anybody experienced this and if so what fix do you suggest, apart from checking and clearing the line regularly?