540 and CDI needle/ blue tooth
Printed From: Avidyne
Category: Avidyne General
Forum Name: IFD 5 Series & IFD 4 Series Touch Screen GPS/NAV/COM
Forum Description: Topics on Avidyne's IFD 5 Series and IFD 4 Series Touch Screen GPS/NAV/COM
URL: http://forums.avidyne.com/forum_posts.asp?TID=992
Printed Date: 09 Nov 2024 at 2:53pm
Software Version: Web Wiz Forums 12.01 - http://www.webwizforums.com
Topic: 540 and CDI needle/ blue tooth
Posted By: 1964-m20e
Subject: 540 and CDI needle/ blue tooth
Date Posted: 06 Mar 2016 at 7:24pm
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OK I have a newly installed 540 with a KI209 and STEC30 autopilot went for my first two test flights this weekend since the 540 has been installed. I have several issues and want to know if it is operator error or if I need to call the shop. 1. When I enter a direct to destination and the GPS screen paints a button hook flight path left or right the CDI needle is deflected to the opposite direction of the turn. i.e the CDI needle and the magenta flight path are showing two different things and if on autopilot the AP will follow the CDI needle. This happens for all angles of turns. Is there a possibly setting in the 540 that I do not have set correctly? 2. In the VLOC mode the CDI needle is correct but I the AP will not track the CDI needle. The AP will track the GPS output perfectly. This maybe a shop question. 3. How do you get into the maintenance mode to set up Bluetooth for the keyboard? |
Replies:
Posted By: DavidBunin
Date Posted: 06 Mar 2016 at 7:50pm
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Sounds like the shop never set the calibration of your CDI. This can be done in maintenance mode, which is described in the pilot guide, but it sounds like there is more than one thing that didn't get set up the way you wanted. I think it would be unfair to the shop if you don't go back to them to correct it. (In other words, if you go in and fix it, how do they know you didn't also unfix something else while you were in there?) David |
Posted By: MysticCobra
Date Posted: 07 Mar 2016 at 7:25am
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I'm not familiar with how STEC a/p's work, but...does your install include GPSS? If not, then your autopilot may not be able to handle the buttonhook. Does your system operate as expected if you manually turn to approximately the proper heading before selecting Direct-To, so that there's no buttonhook required? (You said this happens "for all angles of turns", but not all Direct-To entries require a buttonhook, so I'm not clear.) If your CDI's wired in reverse, then you should always have issues recovering from any deviation from your course, because the feedback would always tend to push you farther away from the magenta line. If the situation only occurs when you're ~180 deg off from your course, then it may be operating as-designed, and you may just need to understand the system performance limitations.
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Posted By: 1964-m20e
Date Posted: 07 Mar 2016 at 8:30am
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I do not have GPSS and the STEC was already installed and working in the plane. The STEC will not keep up with procedure turns or large course changes in route without out GPSS. It would be nice if Avidyne programmed some course anticipation into the unit and could be turned on and off as desired. I noticed it with 180 degree course reversals when using the direct to button as well as 90 degree course changes. My issue is when selecting a new direct to course that has a turn greater than approximately 45 degrees the CDI needle will fully deflect in the opposite direction of the turn and course line shown on the 540 screen. It also does this on the course reversal portion of the approach i.e. flying away form the intended airport and you make the turn out for the tear drop course to align with the runway. If the tear drop turns to the right the CDI needle will be fully deflected to the left even when right of the course. I know you are supposed to fly the CDI needle but when flying the needle the turn will be made completely in the wrong direction weather hand flying or letting the AP fly it. It is not until you get somewhat aligned on the inbound course that the needle finally indicates correctly with the intend course. |
Posted By: AviSimpson
Date Posted: 07 Mar 2016 at 9:48am
#3. There is a step by step on how to pair the keyboard in maintenance mode in the IFD540 PG (Section 6-46 Rev. 2)
------------- Simpson Bennett Avidyne Corporation Product Manager |
1964-m20e wrote:Posted By: 1964-m20e
Date Posted: 07 Mar 2016 at 10:35am
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Simpson thanks I saw that the question was how to enter the maintenance mode. However, I just read the part that says I need to have the jump drive in to enter the maintenance mode. |
Posted By: PA20Pacer
Date Posted: 07 Mar 2016 at 11:01am
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Hi 1964-m20e Unless I misunderstand something, you are describing the normal and expected behavior of a CDI needle. The CDI needle should point toward the course as long as the heading is within +/- 90 degrees of the selected course. If the heading is more than 90 degrees from the selected course, the CDI needle will be deflected toward the side opposite the course. For a GPS system, the "selected course" is whatever is displayed as Dtk or Desired Track. As an example, if you have a 60 degree course change to the right at a particular waypoint, and the IFD540 sequences to the new leg prior to reaching that waypoint, then the CDI will deflect to the left because the new Desired Track over the ground is to the left of your position. An autopilot with course capture capability or GPSS would fly this course change well, but an Stec without GPSS may not make the turn smoothly. If you were hand flying, you would see the CDI needle deflection to the left when the IFD540 sequenced to the new course, and hold your intercept heading as the needle began to center, turning right as desired to intercept the new course. I may not have described this well, or I may have misunderstood what you are describing; it would be easier to discuss this with a diagram than with words. Regards, Bob ------------- Bob Siegfried, II Brookeridge Airpark (LL22) Downers Grove, IL |
Posted By: AviSimpson
Date Posted: 07 Mar 2016 at 11:17am
Using a USB is one way to boot the IFD into maintenance mode. Another is to use the AUX page, SYS tab and pressing the LSK until it gives you the option to boot in MX mode. ------------- Simpson Bennett Avidyne Corporation Product Manager |
Posted By: MysticCobra
Date Posted: 07 Mar 2016 at 12:04pm
Yes, this is the way autopilots without GPS work.
This is what GPSS is for.
This is all about understanding what the CDI is really telling you. Just like when you use your CDI with a VOR, you need to read the needle within the context of the geometry. In this case, the CDI is showing your deviation from the desired course, *assuming you are pointing in the same direction as the desired course*. When you're flying opposite the desired course, then the needle is going to look "backwards" to you. This is normal and expected operation.
Maybe it would be a good idea to spend a little time with a CFII to refresh you on how all the gear works, and how to safely fly with it. |
Posted By: 1964-m20e
Date Posted: 07 Mar 2016 at 12:29pm
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The CDI may be behaving correctly as you explain. I just have not seen this behavior with my other GPS |
Posted By: 94S
Date Posted: 07 Mar 2016 at 1:43pm
I have noticed this behavior also and often wondered why it does that. I get it in regards to VLOC and reverse sensing, it's a limitation of the technology. But one of the basic tenets of RNAV is that you are always (or mostly always) navigating TO a waypoint. So what if that waypoint is around a curved flight path. I get that GPSS is currently what makes tracking the magenta line possible with RNAV, but why can't the IFD output signals to the CDI that indicate left or right of the magenta line when the magenta line is a curve. It's able to calculate the curve, why not whether it is left or right of the curve? And then output that to the CDI just like it would a straight segment. I have noticed this same behavior with G*n's stuff too. i fly with the Civil Air Patrol and a couple of our airplanes have GNS 4xx and a couple have GTN 6xx, and non of those have GPSS. We also have a few G1000s which have GPSS integrated into the system. It sometimes throws a pilot that flys the G1000s for a loop when they get into a plane that doesn't. They expect the CDI to give guidance along the magenta line the first time they fly a course reversal without a G1000. Having flown both G's stuff and the IFD, I really appreciate the IFD and Avydine's philosophy behind it. It is so much easier to use than G*n. |
Posted By: MysticCobra
Date Posted: 07 Mar 2016 at 3:39pm
It does that because it that's how the CDI behaves with VOR and ILS tracking, so it's consistent.
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Posted By: 1964-m20e
Date Posted: 07 Mar 2016 at 3:58pm
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With my previous GPS when a new waypoint was activated by direct to the needle would center and then begin to deviate accordingly as you "wandered" off course. Unlike here where it goes full deflection opposite the direction you should be turning to make the smallest turn. Not necessarily complaining just trying to understand the logic. |
Posted By: MysticCobra
Date Posted: 07 Mar 2016 at 5:09pm
Your old GPS didn't include a buttonhook; it just drew a straight line from the position you were at when you pressed the final "Enter" button. So at the instant you pressed the last "Enter", you were on track and the CDI needle would be centered, but unless you were already aligned along the magenta line the CDI needle would immediately start to deviate. It would also have had the "reverse sensing" logic that you see with your IFD (the CDI deflecting "opposite direction" if you were heading away from the waypoint).
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