bleed air failure
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L382Medman
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bleed air failure
Question for the pros, you have a bleed air failure indication on a b20, what other indication or clues from the engine would you see to confirm if it's an indication problem or a real bleed air failure
Re: bleed air failure
Can you be more specific?......
but normally if you lost bleed air somewhere, ITT and FF goes up so you can monitorize it on both gages.
but normally if you lost bleed air somewhere, ITT and FF goes up so you can monitorize it on both gages.
Re: bleed air failure
you cant thats why the system is there, 99.9% of the time it is a broken sense line. the only real way to tell is to shut off the opposite side and see if you have any air coming in. but if it is a small leak some air might still be getting through, and then you are taking a chance that a small bleed air leak might turn into a large one. remember P3 air is in the range of 400 degrees when it comes out of the engine. it has the potential of causing catastrophic damage to the aircraft.
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Pat Richard
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Re: bleed air failure
What is your vacuum gage reading? Going from memory, if its low, you could have a 18 psi regulator failure . Anti ice would be mediocre also.
You could also try swapping the pressure switches(left/right) under the cojoes seat and see if the problem follows, I had shitty switch once. The most common problem was the bleed sense(18psi) being damaged where they split up under the floor to go out along the fwd spar. With the center floors up + people walking in/out, they tend to be stepped on and damaged.
Actual bleed air leaks/melted sense line is also not uncommon.
I've never seen engine parameters being affected with this type of leak on a king air. The sense lines are tiny, and the volume escaping small.
You could also try swapping the pressure switches(left/right) under the cojoes seat and see if the problem follows, I had shitty switch once. The most common problem was the bleed sense(18psi) being damaged where they split up under the floor to go out along the fwd spar. With the center floors up + people walking in/out, they tend to be stepped on and damaged.
Actual bleed air leaks/melted sense line is also not uncommon.
I've never seen engine parameters being affected with this type of leak on a king air. The sense lines are tiny, and the volume escaping small.
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PanEuropean
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Re: bleed air failure
I am not familiar with the BE-20, but on other aircraft with similar engines (e.g. the Twin Otter), you will see a slight increase in torque and a slight decrease in fuel flow and T5 when the bleed air valves close. The opposite applies when the bleed air valves open. Probably the easiest of those three to spot is the change in T5.
This takes place regardless of whether or not there is a demand from airframe services (e.g. heating, de-ice boots) for bleed air, because in most aircraft that use pneumatic boots for de-ice, suction is applied to the boots at all times when bleed air pressure is present. The suction is created by dumping a small amount of the bleed air overboard through a venturi.
This takes place regardless of whether or not there is a demand from airframe services (e.g. heating, de-ice boots) for bleed air, because in most aircraft that use pneumatic boots for de-ice, suction is applied to the boots at all times when bleed air pressure is present. The suction is created by dumping a small amount of the bleed air overboard through a venturi.
Re: bleed air failure
I have dealt with alot of eva tubing failures on the BE02 pm me with your specifics what lights are you getting, have you plumed in shop air and had a listinen for leaks?
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longestboat
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Re: bleed air failure
L382
Check the EVA tubing which runs along side the bleed air pipework for the "failure" side, like others have said the tubing runs under the cabin floor up to the floor beneath the P2 seat where the pressure switches are. It also runs out to the engine via the inboard leading edges and into the under carriage bays.
These lines have no air flow through them, they are capped off at one end. The EVA tubing melts...if you have a genuine bleed leak or very easily especially if routed to close to an unprotected bleed air pipe (i.e the insulation has come adrift from around the pipe) and hence melts - the pressure then bleeds off enough to make the pressure switch close which brings the master warning on.
I think if you had a substantial actual bleed air leak i.e not just the leak sense line melted you may see an ITT split, i.e a higher reading on the defective sides engine.
It is possible to repair the EVA tubing via splicing in replacement sections but you have to obtain parts from HBC or replace the damaged run.
Pat is correct when he says this could be caused by the regulator but I would expect you to get bleed air fail on both sides as the left and right side EVA tubing gets its air supply from the same regulator / venturi under the right side cabin floor aft of the main spar.
Like "Fixinit" says, if you plumb in shop air via the engine firewall at shop air pressure (100 psi- ish) connection this will prove the airframe regulator is providing the correct output pressure (via the cockpit gauge- P2 side). If I remember correctly the Beech regulators fail to 21psi from 18psi by default before they go totally tits up -- with luck.
Check the EVA tubing which runs along side the bleed air pipework for the "failure" side, like others have said the tubing runs under the cabin floor up to the floor beneath the P2 seat where the pressure switches are. It also runs out to the engine via the inboard leading edges and into the under carriage bays.
These lines have no air flow through them, they are capped off at one end. The EVA tubing melts...if you have a genuine bleed leak or very easily especially if routed to close to an unprotected bleed air pipe (i.e the insulation has come adrift from around the pipe) and hence melts - the pressure then bleeds off enough to make the pressure switch close which brings the master warning on.
I think if you had a substantial actual bleed air leak i.e not just the leak sense line melted you may see an ITT split, i.e a higher reading on the defective sides engine.
It is possible to repair the EVA tubing via splicing in replacement sections but you have to obtain parts from HBC or replace the damaged run.
Pat is correct when he says this could be caused by the regulator but I would expect you to get bleed air fail on both sides as the left and right side EVA tubing gets its air supply from the same regulator / venturi under the right side cabin floor aft of the main spar.
Like "Fixinit" says, if you plumb in shop air via the engine firewall at shop air pressure (100 psi- ish) connection this will prove the airframe regulator is providing the correct output pressure (via the cockpit gauge- P2 side). If I remember correctly the Beech regulators fail to 21psi from 18psi by default before they go totally tits up -- with luck.
