VAF Forums

VAF Forums (https://vansairforce.net/community/index.php)
-   Glass Cockpit (https://vansairforce.net/community/forumdisplay.php?f=35)
-   -   AFS AHRS failed in IMC (https://vansairforce.net/community/showthread.php?t=156512)

BobTurner 01-01-2018 06:22 PM

Quote:

Originally Posted by Chippster1 (Post 1229135)
Hey Vic,
Is there a way to quickly slave the AP to the other screen?

I have a Trio Pro/GRT HX set up, but I suspect the answer is similar to your set up: You need to switch 3 wires (1 RS232 line, 1 ARINC pair) from EFIS 1 to EFIS 2.
OR, switch the 3 wires to your GPS (430W, etc) and run the autopilot directly from the autopilot controls (you will lose some functions, like VOR tracking and heading tracking (but have ground course tracking)). This is what Vic was referring to in his last post. It's amazing how fast you forget how to run the autopilot off its own controls! I'm guilty here.

rleffler 01-01-2018 06:34 PM

Quote:

Originally Posted by Chippster1 (Post 1229135)
Hey Vic,
Is there a way to quickly slave the AP to the other screen?

There?s not an easy way with the Trutrak and 4500s. You would have to have a method to switch both the rs232 line from the gps and the Arinc line, then reconfigure it on the fly. assuming thats possible in the air.

I think it would be easier and more effective to put the AP in AP mode and fly manually via the AP course knob.

If you upgrade to the Vizion, you can simply hit the blue button to maintain current course and altitude until you can come up with a plan of attack to address the situation.

rv8ch 01-02-2018 01:39 AM

Failure simulation
 
Quote:

Originally Posted by vic syracuse (Post 1229113)
... A good BFR should simulate failures of the various pieces of equipment such that you know how to instinctively react when failures occur. And one should practice every once in a while on the ground. ...

Vic, totally agree - and I know you know this, but the major challenge is to simulate realistic failure modes. So much software here that can fail in ways that are not obvious to the user, and not as clean as powering off the device. That said, even a simple paper failure scenario walkthrough in the safety and comfort of a warm kitchen would be very valuable and connect some neurons.

vic syracuse 01-02-2018 04:47 AM

I will try to respond to both questions:

There is no way to swap to the other EFIS. That's why dual AHRS are a must for IMC flight (in my opinion). It is quite easy to jsut hit the buttons on the A/P and fly it in ground track mode and manually fly the altitudes. It's one of the reasons I keep the A/P separate. I actually had to do this a couple of weeks ago. I engaged the A/P right after take-off and the vertical would not engage, only the lateral. First I disengaged to make sure it wasn't going to do something stupid, made sure the airplane was trimmed for what I wanted, then engaged the A/P. I saw the GS Flag, which meant there was no vertical guidance from the EFIS. For the rest of the day I just managed the vertical through the A/P front panel interface. At the time I didn't know if it could be the EFIS or the ARINC.

I will chalk my reaction up to I fly a lot of solo cross countries and when I am sitting there bored I do play a bunch of what if scenarios.

That's the answer to the second question posed about trying to simulate real world failures. Granted, they ALL can't be simulated (if you have your ARINC on a separate fuse/breaker, you can simulate some insidious things). However, you can spend time talking about what-ifs, and you'd be surprised what you can dream up when you are sitting there on Autopilot during a cross country flight.

Even today, as I am getting ready to fly to Frederick, MD for a prebuy, with it being 16 degrees here and 11 there, I am thinking of cold weather scenarios as I go through the preflight planning. Being in Atlanta, it is rare to fly in these kind of temps.

Vic

RONSIM 01-02-2018 06:26 AM

Installed switch to change AP control
 
between my 5600T or direct from the G650 (TT Vizion 385) -- also have independent Dynon D10A for backup.

ChiefPilot 01-02-2018 07:22 AM

Quote:

Originally Posted by vic syracuse (Post 1229113)
This is one of the weak areas I see with many pilots who are now flying glass cockpits. A good BFR should simulate failures of the various pieces of equipment such that you know how to instinctively react when failures occur. And one should practice every once in a while on the ground. After all, we can't go flying all of the time.

I agree with this, but would go further. Leaving aside the concept of currency vs. proficiency, if you need to do six approaches and a hold every six months to stay current, shouldn't a similar number of done using some equipment in a (simulated) failed mode? Shouldn't currency include use of standby/backup/alternate equipment as well?

BobTurner 01-02-2018 12:34 PM

Quote:

Originally Posted by ChiefPilot (Post 1229254)
I agree with this, but would go further. Leaving aside the concept of currency vs. proficiency, if you need to do six approaches and a hold every six months to stay current, shouldn't a similar number of done using some equipment in a (simulated) failed mode? Shouldn't currency include use of standby/backup/alternate equipment as well?

+1
The issue comes down to, do we need more regs to protect us from ourselves?
As a cfii I get to give IPCs to pilots who have flown for years managing to get in 6 approaches every 6 months, but then they lapse. Some of them are extremely rusty on partial panel. At least one claimed it was not possible to fly under the hood without the autopilot.

N402RH 01-02-2018 03:27 PM

Quote:

Originally Posted by Chippster1 (Post 1229070)
Yesterday I was in solid IMC coming from PMP to RYY when my AFS 4500 AHRS quit for about 5 mins. It started tumbling like a failed gyro. Luckily the plane (RV-10) has 3 independent AHRS and 3 screens so it was really a non event. However, I did notice that my AFS pilot, which was in efis mode at he time, went down with it, so I had to hand fly the plane.
My question was that I thought the AFS autopilot(really a trutrak) was slaved to the GPS and not the AHRS. My other question was, if I had put the AFS pilot in AP mode rather than EFIS mode, would it have held the headings and altitudes.
BTW, after about 5 mins of straight and level, the AHRS re erected itself and the flight home was uneventful( with the exception of dropping temps and having to descend to stay the heck out of the icy clouds)
Ted Chipps
N498EC

You should email your system and data logs to info@advanced-flight-systems.com

You have the older Crossbow AHRS and it sounds like the AHRS or Crossbow Magnetometer had a problem.

"My question was that I thought the AFS autopilot(really a trutrak) was slaved to the GPS and not the AHRS":

If you were in EFIS Autopilot NAV mode the EFIS should be passing the ROLL steering commands from your external navigator directly to the Autopilot. In this mode I don't believe a failed AHRS would cause any problem with the AP. The EFIS only sends GPS Track, Desired Roll Angle, and Vertical Speed to the TruTrak. In EFIS Nav mode the external navigator is calculating the desired roll angle and the TruTrak is using it's internal AHRS for attitude.


"if I had put the AFS pilot in AP mode rather than EFIS mode, would it have held the headings and altitudes"

In AP mode the Trutrak is following the GPS track and vertical speed set on the Autopilot Controller.

With our newer AF-5000 systems the ARINC, EMS, and ADAHRS are all on the Dynon SV-Network. You can see and change ADAHRS from any EFIS screen.

Rob Hickman
Advanced Flight Systems Inc.


All times are GMT -6. The time now is 05:10 AM.