Hi RobertActually the schematics that are used in Crew Systems training are quite a bit more simplified than the one Ian has posted. They give enough information to show how the system operates but would not likely the relays and wiringf. The Schematics Ian posted are what a technician would use to get an overview of a system to see what other systems may interface with it or in this case, to show the mechanical portion of an electrical circuit. The Wiring Diagrams get extremely detailed for actual repair but the Schematic gives a better overview. RegardsPaul Gollnick :-coolTechnical Operations/Customer Operational SupportPrecision Manuals Development Groupwww.precisionmanuals.com

"It is the Maint Man. schematic you cut and paste. Many (millions of engineers) find something wrong with this schematic.. BUT..If you adjust your eyeballs and see that the spindle for switch activating cams is right threaded and actuator is links? Meaning that cam is moving opposite of actuator. Now the switch open/close make sense?"Hi, Eker.I assumed that the spindles would drive the contacts in the same direction. I can't say I noticed the thread direction (oops). Looking at the unsimplified Schematics 21-51-14 (Sheet 2), however, I see that my first assumption was correct. The motor gearbox actually turns the spindles in opposite directions, so with the threads in opposite directions, the contacts move in the same direction."By the way - I checked System Schematic for more details. There is a contact set in pack relay in the system, connecting another contact set in ram control relay - controlling power to either pin 26 or pin 36. These pins are "loose ends" - not connected in my costumized manual (for ya311,ya541-590) meaning that must a kind of option here. Have no clue what kind of option - but I am sure that it can not control Ram door position."Unfortunately, I only have Sheet 2 with me at the moment, so I will have to wait until I get back to work to check this out. My diagram numbers appear to be different, but I'm sure I'll find it ;-)Thanks.Cheers.Ian.P.S. The width of the upper spindle contacts seems to be really critical for the actuator to work properly. This is one of the areas I was having a problem with.

"p.s. Yes, I did figure out how the Ram Door opens on touch down based on the schematic. 115VAC C/B thru K23 thru K24 (both in Grd position due to PSEU Ground) into Actuator thru S1 actuator position switch (unless already in open position) to Open coil. While it was fun to find the answer, I doubt that qualifies me as better tech than anyone."Ah.... I think I oversimplified the scenario, Paul. When I first looked at the diagram, I assumed the door opening process (aircraft coming down) was the complete reverse of the door closing process(aircraft going up). Going up, the Ram Air Door transitions from a full open position (ground) to a partially closed fixed position (the motor stops running when the upper spindle moves the switch contact (on the left) up to "S2"). Only putting the flaps up will drive the spindles into the area where the Ram Air Controller is modulating Ram Air Door.When the aircraft is coming down, the flaps come out, so I assumed the Ram Air door would move back to the fixed partially closed position, but I couldn't get the motor to drive the spindles back to this point using this diagram, just with flap movement.Looking at the diagram and going back over all that has been said, it looks like when the flaps are extended, the Ram Air Door remains frozen at the last point where the Ram Air Controller left it. It is only when the aircraft, as you say, uses the closed S1 switch to drive the Ram Air Door fully open.I don't know if this is really how it works. It does seem strange that the Ram Air Door is frozen from the point where the flaps have been extended to touchdown. On the other hand, going up, the door is frozen at the S2 switch position. In flight, it looks like the width of the contacts on the upper spindle is fairly critical. I had to cut out a small piece of paper with markings on it to represent the actuator and spindle contact points and slide the bit of paper over the diagram to figure out what was going on *:-*Anyway, this is getting a bit too technical for your average simmer ;-) ...and a bit too technical for your average technician on his days off.Cheers.Ian.

"I had to cut out a small piece of paper with markings on it to represent the actuator and spindle contact points and slide the bit of paper over the diagram to figure out what was going on " :-lol :-lol :-lol You would LOVE my coloring collections when I get into to one of these. Got different highlighters coloring all the different pathes. Looks like the work of a 2 year old *:-*Looking at the extend circuit it looks like the actuator actually drives to near closed (until it hits the S2 switch) when the flaps come out ??? Maybe thats how those goofy deflector doors come into play. Well my head hurts now so I suppose I should return to working. Enjoy your days off.RegardsPaul Gollnick :-coolTechnical Operations/Customer Operational SupportPrecision Manuals Development Groupwww.precisionmanuals.com

Warning... very booooring....and close to off topic. Guess only Ian and maybe a few other have interest.Remember last refresher course in ATA21 we had a loud discussion about this schematic- nobody agreed how it work. We figured out that the should go opposite direction due to spindle threads. Everybody said... haaa and sigh of relief. :-) :-) and we abandonded the classroom for coffee.Study the schematic with colour pencils at work today I had to drop that theory. Yes the schematic got a few major faults :-)Anyway ... here is my modifications (and it works):1. Drop the cam spindle and imagine that the two cams are welded to the actuator housing. Got it?2. Next... triple increase the length of right hand cam (closest to S3)Situation of schematic as printed:A/C in air - flap up. The Ram air controller in command. And important - the controller has driven the door to max extend - RDFO light on. In addition the "extend" circuit to motor is cut. Only "retract" power avail for the actuator.Suppose that the actuator is commanded to modulate close. The cam (with my extension) activates S3 - RDFO extinguishes and also allow power to retract coil of motor. Now you see the point of extended cam? S3 must be activated all the travel of actuator.Figuring out the rest should be a piece of cake.

BORING, BORING, Who would find this Boring!! :-lolWell o.k. maybe a little. Well thanks to Ian and Eker I now know more than I ever should have about the Ram Air Door system of the 737. Thanks for the Info guys. Test is at 1100z. :-)RegardsPaul Gollnick :-coolTechnical Operations/Customer Operational SupportPrecision Manuals Development Groupwww.precisionmanuals.com

"1. Drop the cam spindle and imagine that the two cams are welded to the actuator housing. Got it?"Got it... understood because of the gearbox cogs anyway (shown in the proper schematics)."2. Next... triple increase the length of right hand cam (closest to S3)"An illegal modification :-lol , but... understood, perhaps because of the gearing in the gearbox and because of the spindle thread pitch (The simplified schematic shows a wider threat pitch (but the non-simplified schematic shows a narrower/finer pitch)."Situation of schematic as printed:A/C in air - flap up. The Ram air controller in command. And important - the controller has driven the door to max extend - RDFO light on."Er... full extend = close = RDFO off? (I thought)" In addition the "extend" circuit to motor is cut. Only "retract" power avail for the actuator."Agreed."Suppose that the actuator is commanded to modulate close. The cam (with my extension) activates S3 - RDFO extinguishes and also allow power to retract coil of motor. Now you see the point of extended cam?Agreed."S3 must be activated all the travel of actuator."Not sure about this one ;-) The BMM says that S3 and S4 are the travel limits in cruise."Figuring out the rest should be a piece of cake."I'm almost ready to take on the real airplane, now :-lolBTW, on descent with the flaps extended, are you saying that the actuator will retract to the S2 switch position? (Or is it still in the Ram Air Controller range?)Thanks.Cheers.Ian.P.S. Folks: You should here us when we get SERIOUS :-)

Jee you two.. maybe its time for the both of you to get your own private forum room! :-lolInteresting discussion even if I am only comprehending about 10% of it. If you two are having difficulting describing what the appropriate function should be when looking at the Boeing schematics, I can only imagine what PMDG is going through to try to model it! :-lol:-abductGeorge

"If you two are having difficulting describing what the appropriate function should be when looking at the Boeing schematics, I can only imagine what PMDG is going through to try to model it!"I'm hoping PMDG can come up with a few short cuts, George.... otherwise we may end up having to programme one of our joystick buttons to turn on the RAM AIR FULL OPEN light at the appropriate times :-)If in doubt, apply the MEL ;-)

"Aural warnings and GPWS - PMDG better start from scratch here. T/O warning OK with engines shut down, with engines running not - Park brake T/O warning?."Are you referring to the fact that you only hear a brief warning... or that the trigger point is set too high, Eker?I noticed it was triggered at about 100% N1....and might not have gone off for engines which had been derated. Looking at the manuals, the warning should be triggered above a (approximately) 20 degree thrust lever angle (from idle). 53 degree switches are mentioned in some manuals, but I think these are Thrust Resolver Angles (TRA's), rather than Thrust Lever Angles (TLA's)... BIG difference!Cheers.Ian.P.S. BTW, I'm starting a new column in this thread... The other one was too long ;-)