Yaw Dampers inop

[Guest sean maxwell]

Hi all,I'm sure this has been covered, but I have searched and can't find much relevant.I have been flying the PMDG 747 since it came out. It's fantastic! I've recently decided to go deeper and try cold starts. I have followed tutorials etc. and can start the APU, all engines, but cannot get rid of the "Yaw Damper" inop message, and "no autopilot"I'm aligning the IRS' and hydraulics and gens are all on. Any clues?Thanks in advance, and waiting for the MD11!Sean Maxwell

[downscc 1,327]

AOM Pg 6-36: Make sure switch is on. You didn't mention this, so I had to.

[Guest sean maxwell]

Thanks Dan,I have tried the upper and lower YD switches, on or off doesn't affect the "inop" lights.Sean Maxwell

[basa 0]

I think this happens after the recent PMDG-744 update.I can figure that when aligning the IRS, the YDs are automatically disconnected to prevent any undesirable small movement or vibration.Just my guess...

[Guest j-mo]

I believe that before the engines are started, you press them to 'arm' them. After the engines have started, 'inop' should no longer be lit.Experts might correct me on my explanation, but the 'inop' lights do go off after engine start.

[basa 0]

>Experts might correct me on my explanation, but the 'inop'>lights do go off after engine start.Not at all, in the updated PMDG 744 they go off after IRS alignment.

[Guest sean maxwell]

OK guys,I've found what I was doing wrong. I didn't enter the FMC POS "twice" when aligning the IRS'.Thanks for your help though, as you can tell I'm a weekend pilot. You really wouldn't want to fly with me!RegardsSean

[Guest j-mo]

>Not at all, in the updated PMDG 744 they go off after IRS>alignment.Thanks for the correction, Jose. I knew the lights were off by the time my engines were running, but I never noticed what the trigger was.Regards,

[Guest j-mo]

Sorry to bring this one back. I had some time to kill on a long flight today, so I spent some time with the manual, then did some checking after my flight was over.The Upper Yaw Damper is powered by the Main Battery Bus, and the Lower Yaw Damper is powered by DC Bus 2. The Upper Yaw Damper 'INOP' message extinguishes when HYD DEMAND 3 is switched to 'ON,' and Lower Yaw Damper 'INOP' will extinguish when HYD DEMAND 2 is switched to 'ON.'Someone correct me if I am wrong.Regards,

[Qavion 19]

"The Upper Yaw Damper is powered by the Main Battery Bus, and the Lower Yaw Damper is powered by DC Bus 2. The Upper Yaw Damper 'INOP' message extinguishes when HYD DEMAND 3 is switched to 'ON,' and Lower Yaw Damper 'INOP' will extinguish when HYD DEMAND 2 is switched to 'ON.'Someone correct me if I am wrong."On the real aircraft (and in PMDG), during preflight, the INOP lights will extinguish with just IRU alignment (Hydraulics not required). The Yaw Damper Modules(Computers) do receive hydraulic pressure information, but it's not clear in the manuals how this information is processed. Maybe this hydraulic pressure information is used only when the Yaw Dampers are operational (i.e. in the air)... or maybe this hyd pressure information is used to inhibit the INOP lights and EICAS messages when there are no hydraulics (i.e. the Yaw Damper Systems are not really inop... but the hydraulics ARE....and you have bigger problems to worry about :().Unfortunately, switching off the hydraulics in the air to test my theory is not really an option in the real world.The PMDG team may be the best people to ask about this (I can't recall what logic they decided upon).BTW, when you refer to the "manual"... do you mean the PMDG manual or the real world manual? (I don't have copies of either with me at the moment).Cheers.Q> Ян

[Guest j-mo]

On the real aircraft (and in PMDG), during preflight, the INOP lights will extinguish with just IRU alignment (Hydraulics not required).I don't wish to be argumentative, but this is exactly the behavior I see, both passenger and freighter models, all engine variants. I'm pretty meticulous about following the PMDG checklists, too. Again, I have no idea about what others experience, but that is what I see. The INOP lights do not extinguish for me unless and until hydraulics are activated. IRU alignment has never achieved this for me. I just started another flight (400F) and observed this once again. I can't explain the discrepancy between what I see and what others experience.This is not any kind of issue for me, and I apologize for coming across as being 'corrective.' That wasn't my intent. Since it never worked for me that way, I dug into the manual and posted follow-up on this.The only manual I referred to was PMDG's, and I see now that what I posted is somewhat ambiguous: only the part about buses came from the manual. The part about needing hydraulics powered before INOP lights extinguish was my personal observation. Sorry for any confusion.Can anyone from PMDG explain why I am getting this this way? Am I overlooking something?Regards to all,

[Guest Raptor]

I've got the same issuewhen setting the IRS, YDs become INOPI couldn't fly because of this.how to solve this problem?RegardsAbraham

[Guest j-mo]

After aligning the IRS, are you setting them to NAV?They always extinguish for me when the following conditions are met:1. IRS set to NAV following alignment;2. FMC POS is set (all prompts);3. HYD set to ON (I do this during pushback);This is from a cold & dark cockpit. It sounds that the lights go off for others with IRS alignment only. I'm not sure what causes the difference.I can also say that after landing and parking at the gate/ramp, I can go through the "Parking and Shutdown" list, and so long as I have power from the APU or ground/external, then the INOP lights do not come on. I can then, if so inclined, set up for another flight, and the lights do not come back on.So I'm wondering if the difference has to do with C&D or not. Definitely not an issue for me as I know how to get everything working for me. Just a curiosity.Regards,

[Guest Raptor]

well, instant IRS alignment has solved this issue :)Abraham

[cavaricooper 2,611]

I am hesitant to ask but are you going to ALIGN? If so, just going to NAV and allowing for alignment may resolve your issues- there was a typo in the PMDG manual..........just a suggestion brought on by the "instant alignment fixed it" comment.Best-Carl F. Avari-Cooper BAW0225http://online.vatsimindicators.net/980091/523.png| XP Pro SP3 with FS-GS System Unification | 2 x APC UPS | Coolermaster Stacker 830 SE | Asus P5E-Deluxe (X48) | e8500 | Tuniq Tower 120 | EVGA 8800GT 512MB | Sony 40" Bravia XBR | 2 x 1 GB Corsair XMS2 | 500GB Seagate Barracuda 32MB SATA2 | Corsair HX620W PS | CH Products Yoke-Pedals-Throttle Quadrant | Aerosoft 747MCP-EFIS-EICAS |