Sign in to follow this  
Guest Ian_Riddell

No Pressure In Right Duct (Quick Quiz)

Recommended Posts

Help AVSIM continue to serve you!
Please donate today!

Hi Ian,Nice idea!APU bleed is ON. Engine bleed is ON. Isolation valve is in AUTO. Due to logic (IF BOTH ENG BLEED VLV ON THEN ISO VLV CLOSE?) the isolation valve will close. And pressumably at least the right engine is not running yet thus no pressure in right duct even if the APU is running. Am I right? ;-)Regards,

Share this post


Link to post

APU running ,no engines , all bleed switches on, Dual bleed annunciation, isolation valve closed.

Share this post


Link to post

Mats,Hi how are you?> Due to logic (IF BOTH ENG BLEED VLV ON THEN ISO VLV CLOSE?) the isolation valve will close. Isolates left and right pneumatic system.AUTO > Valve Opens automatically if any pack or engine bleed switch is placed in OFF Position.OPEN > Connects left and right pneumatic system.Istolation Valve: The isolation valve isolates the left and right sides of the pneumatic manifold during normal operations. The isolation valve is AC operated. With the isolation valve switch in AUTO and both Engine Bleed Air Switches ON and Both Air Conditioning Pack witches AUTO or HIGH the isolation valve is closed. The isolation valve opens if either Engine Bleed Air Switch or Air Conditioning Pack Switch is positioned OFF. Isolation valve position is not affected by the APU Bleed Air Switch. ***Later I will try to include some diagrams to make it easier.Cya,Bruno Francescoli.

Share this post


Link to post

I agree.By the way, Very nice idea Ian !Bruno Francescoli.

Share this post


Link to post

APU & Engine must both be running to get the Dual Bleed annunciator.Engine 2 fail & APU started to compensate in flight? Since the annuciators beside the Dual Bleed are not lit, you must be in flight.Not sure why you have zero pressure in the right duct because I don't know the flow on a 737. Perhaps we are looking at a duct leak on the right side. Since the isolation switch does not look to be in the closed position, I don't know what causes it to trip? Right Pack blown? Lots of possibilities.Closest I can get:http://forums.avsim.net/user_files/33906.jpgRay

Share this post


Link to post

>CLOSE > Isolates left and right pneumatic system.>>AUTO > Valve Opens automatically if any pack or engine bleed>switch is placed in OFF Position.>>OPEN > Connects left and right pneumatic system.I agree on that one, and because there is no ram door light, it must be in flight with flaps up.http://www.b737.org.uk/schemeaircon300small.gifbut i need to think a little more to get to the point what is wrong, hmmm might be a sensor fault :-)Dennis

Share this post


Link to post

Hi BrunoI'm fine thank you! How are you? :-)I will have to correct both you and myself: ;-)ISLN VLV in AUTO:- The ISLN VLV is switch sensitive not valve sensitive.- If both ENG BLEED are ON and both PACKS in AUTO or HIGH, ISLN is CLOSED- ISLN VLV looks at the four "corner" switches. If either of them are OFF, ISLN VLV will open- APU BLEED switch has no effect on ISLN VLV position. OPEN ISLN VLV!All this according to Cpt. Bulfer. But he has been wrong before apparently?So according to this. Either ENG 2 is out and the captain has something more important to take care of. Or there is a leak in the right air supply system.Here's another one for ya. If you are connected to ground air. Which pack would be pressurized if you had the ISLN VLV closed?TGIF

Share this post


Link to post

>ISLN VLV in AUTO:>>- The ISLN VLV is switch sensitive not valve sensitive.>- If both ENG BLEED are ON and both PACKS in AUTO or HIGH,>ISLN is CLOSED>- ISLN VLV looks at the four "corner" switches. If either of>them are OFF, ISLN VLV will open>- APU BLEED switch has no effect on ISLN VLV position. OPEN>ISLN VLV!That is the right, it is switch sensitive, i allmost forgot that.So you are right, eng 2 must be off.About the ground pneumatic source, then it is the right duck.Dennis

Share this post


Link to post

"APU running ,no engines , all bleed switches on, Dual bleed annunciation, isolation valve closed."CORRECT.... Go to the top of the class, Wallace :-)No Engines are running. Nothing is broken.On the real aircraft, Isolation Valve operating logic is based on SWITCH position (not the availability of air from engines).In this situation, only the APU is running. It is providing bleed air to the Left duct, but the Isolation Valve is closed because of the positions of the Pack SWITCHES and the Engine Bleed SWITCHES.If ALL four Engines and Pack Switches are on, the Valve will close. If ANY are OFF, the Isolation Valve will OPEN.The DUAL BLEED is slightly different. It looks at Engine SWITCH position, but also at the ACTUAL position of the Isolation Valve (where applicable) and the APU Bleed Air VALVE. Unfortunately, they won't let me play with the engines just yet ;-)Cheers.Ian.P.S. Is there a real life option to have the APU Switch latched? I've noticed that in PMDG, the APU bleed Switch seems to do some things by itself (E.g. Can't switch it on if the APU is not running).

Share this post


Link to post

"Dr Spock, something's not working on the Enterprise !No, I believe Scottie fixed it up yesterday after the ion drive had a meltdown ;-)"Please beam Ian up !"Er.... Sunscreen factor 10, Mr Sulu.... There's a KliNGon on the Starboard bow.Silly season is definitely open ;-)Cheers.Ian.P.S. You canna change the laws of physics.... except in MSFS, perhaps :-lol

Share this post


Link to post

>CORRECT.... Go to the top of the class, Wallace :-)>>No Engines are running. Nothing is broken.I have to disagree, unless some CB

Share this post


Link to post

Ian, the apu bleed valve switch is not magnetically latched ,its a 2 position mechanical switch .Its either on or off regardless of whether there is an apu running or not, IE: they will stay in the position you put them. Blusey might have been right about aircraft in air mode though, usually "ram door full open" lights are illuminated on ground unless AP is on jacks or air grnd brkrs 1 & 2 are open(or the gear could have been slugged if this was a classic), or is the case of the NG, PSEU is in air mode.

Share this post


Link to post

"I have to disagree, unless some CB

Share this post


Link to post

"Ian, the apu bleed valve switch is not magnetically latched ,its a 2 position mechanical switch .Its either on or off regardless of whether there is an apu running or not, IE: they will stay in the position you put them.'Thanks, Wallace :-) (actually, it was less of a question and more of a hint for PMDG ;-)). "Blusey might have been right about aircraft in air mode though, usually "ram door full open" lights are illuminated on ground unless AP is on jacks or air grnd brkrs 1 & 2 are open(or the gear could have been slugged if this was a classic), or is the case of the NG, PSEU is in air mode."Copy that.... I'm looking into it at the moment... but as the aircraft was definitely on the ground with no jacks present or breakers pulled, I'm working on the theory that the annunciator lights were dimmed ;-)Cheers.Ian.

Share this post


Link to post

>There wouldn't have been any circuit breakers pulled at that>point, Dennis... The aircraft had just come in and was making>a quick turnaround... and I'm sure I would have spotted some>U/S labels if there had been anything wrong with the aircraft>ECS system. All I can think of is that the camera is not>picking up the blue lighting very well.That might explain it :-)>I may have to check the Master Dim and Test Lighting>Schematics to see if the DUAL BLEED light is a non-dimmable>type... and if the RAM DOOR FULL OPEN light is a>dimmable type (which may help explain why the camera is not>picking up the light properly).The ram air light is dimable, all blue lights are :-) so we might have an explanation here :-)>>Excellent observation! :-)Thanks, well it is my job to know these things ;-) ot at least pretend i do heheheDennisLicensed on the B737NG and the Airbus 319-321 as a technician (B1 and B2)

Share this post


Link to post

Hi Mats!>Here's another one for ya. If you are connected to ground air. Which pack would be pressurized if you had the ISLN VLV closed?

Share this post


Link to post

I guess! At least Cpt Bulfer states the ground air connection's on the right side of the ISLN VLV!Good work! ;-)Mats

Share this post


Link to post

Hi Dennis!Just some add info about the "Ram Door Full Open" light.You can get the blue light on in flight with the flaps up.Possible problems may be:- The heat exchangers are dirty- The ram air system may have a blockage- Electrica failure//Christian

Share this post


Link to post

>Just some add info about the "Ram Door Full Open" light.>You can get the blue light on in flight with the flaps up.>Possible problems may be:>- The heat exchangers are dirty>- The ram air system may have a blockage>- Electrica failureim just mentioning the logic for the lights, not errors that can produce the light.Dennis Licensed on the B737NG and the Airbus 319-321 as a technician (B1 and B2)

Share this post


Link to post

"The ram air light is dimable, all blue lights are so we might have an explanation here"Tried it on an aircraft yesterday afternoon... The blue lights dimmed to the point where they were barely visible. The amber lights also seemed to dim (slightly), yet remained much brighter than the blue ones.I think we have a winner here :-)Cheers.Ian.

Share this post


Link to post

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this