Jump to content

Sign in to follow this  
Guest alby

737 NG - Uncommanded roll after T/O

Recommended Posts

Guest alby

Hi guys,I have no idea what is going wrong with me or the sim. I set everything up and get "FMC preflight complete" an also nothing showing when I press Recall.My problem is when ever I takeoff I select gear up everything is fine at 400ft press LNAV and at 1000 ft I engage the Autopilot. Everything is ok until this point at which the aircraft enters a steep left turn and hits the ground. I have the latest AIRAC and I am puzzled as to why this happens. The autopilot definately doesnt follow the SID when I press LNAV. I am at a loss to explain this. Also the trim is set and I don't get any configuration warnings or anything. WHat is the problem?? Can anyone help as I am getting so frustrated.Thank you

Share this post


Link to post
Guest neeraj.pendse

Hm,How many days have you been using the 737? ... did it NOT do this before and only started doing this now? I think the transition from manual flight to autoflight after T/O is the most confusing part for beginners: at least it was for me.One suggestion I could offer to you is to set up the AP in heading mode / FL CHG with runway heading and then transition to autoflight. Later on, either smoothly change the heading bug to point to the course and then hit LNAV/VNAV <- this is just a test. If you are able to do that with no problems, then there must be something wrong with your procedures. Hope this helps a bit.- Neeraj

Share this post


Link to post

What happens if you set the max bank limit control on the main panel? Until your airspeed is high enough to full manuvering speed the bank should be limited. I suspect at the current flap setting and airspeed at the trouble spot bank limitation below 30 degrees is required. Do you know what your IAS is at this point?


Ron Ginsberg
KMSP Minnesota, Land of 10,000 Puddles
rcv4bannersupporter.jpg

Support Team

 

Share this post


Link to post

Exactly how do you turn "on" the A/P? You must engage in CMD (i.e. push cmd A or :( then select a MODE.And what is controlling the VERTICAL profile you have planned? LNAV is lateral only so either you are controlling the vertical profile and SPEED or VNAV/LVL CH or V/S but LNAV alone will not do it.[h4]Randy J. Smith[/h4]AMD 64 4000+|ASUS K8V DELUXE|SAPPHIRE ATI X800XT PE|MUNCHKIN 3200|80 gig SATA|DELL 1905FP 19" LCD|TRACKir PRO|PFC JEPPESEN MOONEY YOKE|CH PRO PEDALS|


Randy J Smith

Share this post


Link to post

Make sure if you decide to use VNAV shortly after takeoff (not before 800 AFL) that the last thing you program in the FMC is the TAKEOFF page setting what is needed for parameters based on weight keeping your Vref speed entries for last and executing that page. At the very least even without VNAV coupled it will provide information to the flight director for offering you the correct pitch indications and supply the speed numbers for each stage of the takeoff and Vref for each flap setting on the speed tape.This way even with coupled autothrottle but not coupled VNAV you know what speed settings are required, what pitch to use for getting that speed at the advised power, and other indications.As far as LNAV make sure you are not getting a negative intercept warning on the scratchpad. You may have to use heading select to get to your first waypoint close enough to engage LNAV. If you are taking ATC vectors heading select after engaging CMD would be used. If you are vectored past any SID/DP waypoints, you will to delete them from your FMC legs page, close-up any discontinuities, activate/execute to modified route, and continue using heading select to a point where you can get within merging orientation to activate LNAV without warnings.You might find yourself activating VNAV before LNAV. It depends on where your first waypoint is after being vectored that the situation allows allows LNAV engagement. Keep your eye on the track on the ND and on legs page 1, and see if your current position matches what is displayed.


Ron Ginsberg
KMSP Minnesota, Land of 10,000 Puddles
rcv4bannersupporter.jpg

Support Team

 

Share this post


Link to post
Guest alby

Hi guysThanks for your responses. Nothing seems to work. I am trying to depart off a SID at YBBN rwy 01. Nothing seems to work. I program the FMC completely with the LAV6 departure and when I get airborne and engage the CMD A autopilot and select LNAV the light lights up then extinguishes. Heading select wont even work. The aircraft just goes into a step uncommaned left turn. I havent even got around to engaging VNAV yet. Something is really wrong here. It is frustrating me no end. I have never had this problem with other sims.What is going on ????Deperate

Share this post


Link to post
Guest alby

Sorry to answer the question I have no route discontinuites and there is nothing shown in the scratchpad eg not on intercept heading as I am trying to depart from a SID so shouldn't be off track at all. Heading select to remain rwy hdg won't even work. Something is up.HELLLLLLLLLLLLLLLLLLLLLLLLLLLP!!!

Share this post


Link to post

Nameless,Please sign your posts with your real name as per the forum rules.What modes do you have engaged? Check your FMA (Flight Mode Annunciator) You'll find it at the top of the PFD. Three fields for throttle, roll and pitch modes. Some screenshots of your Main Panel could be helpful. Important is the PFD/ND and the MCP. Could you also attach your flightplan and I will try to see what is going on.Hope it helps,


Mats Johansson
PMDG Flight Test Dept
Boeing777_Banner_BetaTeam.jpg

| Asus Z270-A | Intel i5-7600K @ 4.8 GHz OC/H2O | nVidia Geforce GTX 1070 8GB OC/O2|

Share this post


Link to post
Guest navneet_cxp

> Exactly how do you turn "on" the A/P? You must engage in CMD>(i.e. push cmd A or :( then select a MODE.>>And what is controlling the VERTICAL profile you have planned?>LNAV is lateral only so either you are controlling the>vertical profile and SPEED or VNAV/LVL CH or V/S but LNAV>alone will not do it.>>[h4]Randy J. Smith[/h4]>AMD 64 4000+|ASUS K8V DELUXE|SAPPHIRE ATI X800XT PE|MUNCHKIN>3200|80 gig SATA|DELL 1905FP 19" LCD|TRACKir PRO|PFC JEPPESEN>MOONEY YOKE|CH PRO PEDALS|Hi Randy,But according to the procedures isn't it supposed to be "LNAV" followed by "VNAV" and then select the CMD button.Correct me if i'm wrong.-NavneetFS 2004 Version 9.1AMD Athlon 64 3000+ATI Radeon 9600 128MB - Anti-Aliasing 6x1GB DDR400 Kingston RAMWestern Digital 30 GB - Seagate 120 GB (7200 rpm)Sony DVDRW - 16XLG Flatron 775FT 17' MonitorCreative SBLive! X-Gamer 5.1Creative Inspire 5.1 5200Windows XP Pro SP2 v.2180Microsoft Sidewinder Precision Pro 2Logitech Cordless Optical Mousehttp://www.precisionmanuals.com/images/forum/747400.jpg-|http://www.precisionmanuals.com|-

Share this post


Link to post
Guest alby

Hi,My flight plan is as follows.YBBN- YSSY (DCT BN H62 CORKY H39 SY DCT). RWY 01. Laravale 6 departure and in the CRS window if have 016 in the HDG window I have 016 and the ALT I have 5000. And I have V@ set in the Speed window. Sorry I dont know how to take a screen shot.On the PFD I have several modes. Passing through 400 feet I select LNAV and it is armed From between 400 and 1000 feet. Other modes are THR HOLD and TOGA and then at 1000 ft I I select the autopiloT CMD A switch. I then go into this huge steep turn LNAV lights goes off and that is when the trouble starts. When the autopilot comes on even though I press the CMD A button. There is CWS P and CWS B I think written in small red letters either side of the CMD in green.Almost had enough of this program. I have tried so many times and yet seem to have all these problems. Also when I press the S button I get this horrendous noise through my speakers when I change the view. Sounds like really bad static. So I can't press the S button anymore. It is impossible to get rid of this noise without resetting the flight.Very frustratedAlex Curtis

Share this post


Link to post
Guest neeraj.pendse

Alex,> When the autopilot comes on even though I press the CMD A>button. There is CWS P and CWS B I think written in small red>letters either side of the CMD in green.This could be an AHA! for your problem: CWS P and CWS B means that althought the autopilot is ON, you are in manual control for bank as well as pitch. This happens when excessive control input is detected at the control wheel.What is the position of the joystick when you engage A/P? If you are NOT at all moving the joystick after engaging the AP, then I suggest you recalibrate your joystick. Or try a different one if possible.- Neeraj.

Share this post


Link to post

This IS his problem. You are somehow touching the controls (Yoke or stick) after engaing the A/P in CMD. Do not touch the controls if you want the AFDS to fly it for you. Control Wheel Steering is somewhat like fly by wire in that you can set the pitch and or HDG "let go", the flight system will then hold what you set until you re set either pitch or hdg. [h4]Randy J. Smith[/h4]AMD 64 4000+|ASUS K8V DELUXE|SAPPHIRE ATI X800XT PE|MUNCHKIN 3200|80 gig SATA|DELL 1905FP 19" LCD|TRACKir PRO|PFC JEPPESEN MOONEY YOKE|CH PRO PEDALS|


Randy J Smith

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  
  • Tom Allensworth,
    Founder of AVSIM Online


  • Flight Simulation's Premier Resource!

    AVSIM is a free service to the flight simulation community. AVSIM is staffed completely by volunteers and all funds donated to AVSIM go directly back to supporting the community. Your donation here helps to pay our bandwidth costs, emergency funding, and other general costs that crop up from time to time. Thank you for your support!

    Click here for more information and to see all donations year to date.
  • Donation Goals

    AVSIM's 2020 Fundraising Goal

    Donate to our annual general fundraising goal. This donation keeps our doors open and providing you service 24 x 7 x 365. Your donation here helps to pay our bandwidth costs, emergency funding, and other general costs that crop up from time to time. We reset this goal every new year for the following year's goal.


    2%
    $705.00 of $25,000.00 Donate Now
×
×
  • Create New...