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Ellehammer
14th Jan 2019, 15:24
Using SAGEM to analyze a DFDR readout, rudder position is denoted +/-.
Which is LEFT rudder position?
Which is RIGHT rudder position?
TYI

lobby
16th Jan 2019, 17:35
Negative would usually indicate left and positive right. If you are still unsure you will need to check the logical frame layout document for that specific aircraft.

Ellehammer
17th Jan 2019, 11:00
Negative would usually indicate left and positive right. If you are still unsure you will need to check the logical frame layout document for that specific aircraft.
Hi Lobby,

I forgot to inform it is an A321.

VinRouge
18th Jan 2019, 20:22
You can validate it by checking the other traces, ev aircraft heading and yaw rate. Heading is usually 0 to 180 with a bitwise operand to indicate 1-180 and 181-360.

Ideally, you need the LFL as indicated above

Ellehammer
19th Jan 2019, 05:14
Hi guys,
thanks for your replies.
However, still struggling with the FDR readout.
I have a column on a FDR readout which puzzles me.
However, I am not allowed to poste a picture until after 10 posts.
Any suggestions.
Can I reach anyone outside PPRuNe?

underfire
19th Jan 2019, 17:13
No matter ac variant. Clockwise is positive and counterclockwise is negative. Left rudder turns you counterclockwise.

From autopilot programming data return: Rudder Position Readout

https://cimg5.ibsrv.net/gimg/pprune.org-vbulletin/195x224/rudder2_034d66379f6195e0f1bce75951d2e2b6d5f02e29.gif https://cimg0.ibsrv.net/gimg/pprune.org-vbulletin/195x224/rudder3_030c22c65c6ab67a4fb4da01b3cc2045bd633fbe.gif

On the DFDR data, you mention using SAGEM , can you provide the reference MFDAU program for the FDR information? I may be able to provide $$ an engine/transmission for that.

Owain Glyndwr
21st Jan 2019, 18:45
As underfire says, clockwise is positive and counterclockwise negative, but you need to connect that with direction of view.
Normally this follows the right hand rule - hold out your right hand with thumb down, first finger forward, second finger out to your right.. These are the positive directions for forces and movements. Looking out along these axes positive rotations are clockwise.
So looking down your thumb, left rudder is positive but the consequent counterclockwise rotation is negative.
Looking out along your first finger right wing down bank is positive, RH aileron down is positive but gives a negative rolling moment
Looking out along your second finger nose up rotation (pitch) is positive, as is down elevator or THS movement.

underfire
21st Jan 2019, 19:44
Owain, in the programming, when you see a negative number, it is rudder left.

Owain Glyndwr
22nd Jan 2019, 10:14
underfire - Then I am left wondering whether there is a difference between NTSB and BEA practice. In the AF447 final report it is specifically stated that positive pedal position is left and positive rudder surface is turn left. In the Concorde accident report it is stated that positive pedal is turn left.

underfire
23rd Jan 2019, 00:19
Owain, I understand. I just know the programming. AS far as the output, I dont know what the different formats report.

Ellehammer, send the image by PM