DFC100 - Underspeed Alerts on Roll Out

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   A number of new DFC100 customers have noted that the Underspeed alert is issued during rollout and taxi back following a flight.     It has been understandably characterized as a nuisance alert during these ground operations.
This has been confirmed and is a result of an incorrect handling of a virtual weight-on-wheels determination.  In addition to full-flaps and a manifold pressure of less than 12", a suppression of the Underspeed alerting should also occur when ground speed is less than 50 knots.  It is the ground speed condition that is not working per the design intent.

We intend to address this on the next DFC100 software release and will notify all customers when that release is available.

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AviJake Members Profile Send Private Message Find Members Posts Add to Buddy List Admin Group Joined: 26 Mar 2009 Location: Lincoln MA Status: Offline Points: 2815	Post Options Post Reply Quote AviJake Report Post Thanks(0) Quote Reply Topic: DFC100 - Underspeed Alerts on Roll Out Posted: 13 Mar 2011 at 6:38pm
	A number of new DFC100 customers have noted that the Underspeed alert is issued during rollout and taxi back following a flight. It has been understandably characterized as a nuisance alert during these ground operations. This has been confirmed and is a result of an incorrect handling of a virtual weight-on-wheels determination. In addition to full-flaps and a manifold pressure of less than 12", a suppression of the Underspeed alerting should also occur when ground speed is less than 50 knots. It is the ground speed condition that is not working per the design intent. We intend to address this on the next DFC100 software release and will notify all customers when that release is available.
	Steve Jacobson sjacobson@avidyne.com

AviJake Members Profile Send Private Message Find Members Posts Add to Buddy List Admin Group Joined: 26 Mar 2009 Location: Lincoln MA Status: Offline Points: 2815	Post Options Post Reply Quote AviJake Report Post Thanks(0) Quote Reply Posted: 19 Mar 2011 at 7:50am
	The software will suppress the Underspeed alerting when below 30 KIAS, not 50 kts ground speed at this time. The design intent of the system is to avoid nuisance alerting during a benign landing and roll out. We believe we have an improvement that will achieve that original intent and we will be sure to include that on the next software release of the DFC100.
	Steve Jacobson sjacobson@avidyne.com

AviJake Members Profile Send Private Message Find Members Posts Add to Buddy List Admin Group Joined: 26 Mar 2009 Location: Lincoln MA Status: Offline Points: 2815	Post Options Post Reply Quote AviJake Report Post Thanks(0) Quote Reply Posted: 22 May 2011 at 10:57am
	I have personally flight tested the new nuisance suppression logic in the last few days and firmly believe the issue has been fully resolved. It will be included in the next SW release of the DFC100.
	Steve Jacobson sjacobson@avidyne.com

AviJake Members Profile Send Private Message Find Members Posts Add to Buddy List Admin Group Joined: 26 Mar 2009 Location: Lincoln MA Status: Offline Points: 2815	Post Options Post Reply Quote AviJake Report Post Thanks(0) Quote Reply Posted: 14 Sep 2011 at 8:37pm
	I know there is confusion on the recent mailing about Rel 9.2.3 and if it really addresses this issue. Two points: 1. For the underspeed alerting suppression improvement on short final, in the flare, and on roll out to work, you will need both the 9.2.3 software update AND release 2 of the DFC100 software. We are still waiting on FAA approval of the DFC100 code. 2. I am on travel through the weekend with limited access to the detail I need but when I can get access to that data, I will add a much more specific explanation of the new design and support that with a lot of interesting detail.
	Steve Jacobson sjacobson@avidyne.com

AviJake Members Profile Send Private Message Find Members Posts Add to Buddy List Admin Group Joined: 26 Mar 2009 Location: Lincoln MA Status: Offline Points: 2815	Post Options Post Reply Quote AviJake Report Post Thanks(0) Quote Reply Posted: 16 Sep 2011 at 9:08am
	Here is that additional detail that I mentioned in previous post: http://www.avidyne.com/downloads/media/underspeed-alerting.pdf
	Steve Jacobson sjacobson@avidyne.com

AviJake Members Profile Send Private Message Find Members Posts Add to Buddy List Admin Group Joined: 26 Mar 2009 Location: Lincoln MA Status: Offline Points: 2815	Post Options Post Reply Quote AviJake Report Post Thanks(0) Quote Reply Posted: 04 Oct 2011 at 3:58pm
	4 Oct 2011 Update: We think we're about 2 weeks away from STC approval of the combined IFD update and DFC100 update that will address this issue. Right after FAA certification, we expect to run a small pilot program for about a calendar week before widespread distribution of the code updates.
	Steve Jacobson sjacobson@avidyne.com

AviJake Members Profile Send Private Message Find Members Posts Add to Buddy List Admin Group Joined: 26 Mar 2009 Location: Lincoln MA Status: Offline Points: 2815	Post Options Post Reply Quote AviJake Report Post Thanks(0) Quote Reply Posted: 22 Feb 2012 at 6:19pm
	I know it's popped up in other threads on this forum, but just to tie this one up, the combined DFC100 Release 2 and IFD Release 9.2.4 have been fielded and seem to have resolved this issue to the satisfaction of all those who have upgraded to those software versions. Pilot programs have all been completed. We did find some installation drawings that needed updating as part of the pilot program so that was a helpful program.
	Steve Jacobson sjacobson@avidyne.com