PT6A-67D Engine Test
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PT6A-67D Engine Test
When engine is up to power in the Test Cell there is a stream of oil running out of the metered hole in the Fuel Pump. Any ideas why?
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PT6A-67D Test Issues
Mono,
Thanks for the input. We have changed the seal with the old style and new style and it still has a stream of engine oil coming through the metered hole in the Fuel Pump gear and out the AGB housing drain hole. When we remove the vent line from the AGB the oil stops. We have checked for restrictions in the vent line and there is none. We are stumped.....
Thanks for the input. We have changed the seal with the old style and new style and it still has a stream of engine oil coming through the metered hole in the Fuel Pump gear and out the AGB housing drain hole. When we remove the vent line from the AGB the oil stops. We have checked for restrictions in the vent line and there is none. We are stumped.....
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MTL
Don't know if you have found your problem yet but here are a couple of things that might help.
The oil tank on the 67 is pressurized to about 5 - 7 psi higher than the AGB - the pressure is controlled by the "Oil Tank Pressurizing Valve". It is possible that you have a problem with the valve and at higher power settings the AGB is being over-pressurized.
Another possibility - unlikely - but I had it happen to a - 42 engine - is excessive flow through a labyrinth seal that allowed too much air to be dumped into the scavenge system - resulting in an over-pressure of the oil tank and AGB as the oil tank pressurizing valve could not cope with the increased flow rate.
The last possibility that I can think of is a restriction of the overboard vent that is not allowing the discharge air free flow. I know that you stated that you checked the line - but the fact that the leak stops when the line is disconnected tells me that the problem is associated with the vent line.
It is a long shot - but try a different length of vent tube as you could possibly have a standing wave backpressure condition - think of tuned exhaust theory.
There must be a tap point in the system that you can connect a pressure gage to the AGB / Oil Tank so you can get a pressure reading - that might point you in the right direction.
If you do find the problem - or have found the problem lets us know - it adds to the information bank.
Regards,
Mx
Don't know if you have found your problem yet but here are a couple of things that might help.
The oil tank on the 67 is pressurized to about 5 - 7 psi higher than the AGB - the pressure is controlled by the "Oil Tank Pressurizing Valve". It is possible that you have a problem with the valve and at higher power settings the AGB is being over-pressurized.
Another possibility - unlikely - but I had it happen to a - 42 engine - is excessive flow through a labyrinth seal that allowed too much air to be dumped into the scavenge system - resulting in an over-pressure of the oil tank and AGB as the oil tank pressurizing valve could not cope with the increased flow rate.
The last possibility that I can think of is a restriction of the overboard vent that is not allowing the discharge air free flow. I know that you stated that you checked the line - but the fact that the leak stops when the line is disconnected tells me that the problem is associated with the vent line.
It is a long shot - but try a different length of vent tube as you could possibly have a standing wave backpressure condition - think of tuned exhaust theory.
There must be a tap point in the system that you can connect a pressure gage to the AGB / Oil Tank so you can get a pressure reading - that might point you in the right direction.
If you do find the problem - or have found the problem lets us know - it adds to the information bank.
Regards,
Mx
