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  #1  
Old 03-01-2013, 01:36 PM
7DeltaLima 7DeltaLima is offline
 
Join Date: May 2005
Location: Senoia, GA
Posts: 160
Default In the spirit of lessons learned....

There has been some interesting discussions on accidents, accident prevention and safety in general. So in the spirit of ?I learned from that??

My ride: A RV10 that is equipped with xxxxx autopilot. I have dual xxxxxxxx screens with a ?dumb? xxxxxx as a display for the co-pilot. I attempted to design this system with complete redundancy, dual busses, dual magnometers, etc. Even to the point that when I asked Stein about another ?redundant? point he basically said something to the effect that if it gets that far it?s probably your time. (Maybe not that direct but then again it is Stein.)

My story ? My daughter and son-in-law live in San Antonio and we live in the Atlanta area. We?ve always been a close family and do enjoy using our plane to visit family. I have been traveling on business a significant about this past year or so with much of this being international travel. So while I have logged many miles in the air the past 18 months, I haven?t logged as many as usual with me at the controls.

This past weekend was one of the first opportunities that we have had to load up the RV and head to Texas. I made the commitment to both my wife and daughter that we?d be there if the weather would allow us to fly. To some maybe foolishly, but my personal comfort level allows me to fly the RV in IMC.

In preparation for this trip, I logged a couple of hours at night shooting a few approaches with a pilot friend of mine. It wasn?t the best I?d ever flown but I was comfortable with the level of proficiency that I could safely fly an approach. My personal minimums don?t allow the overcast at 200ft and then break out but at 800 ? 1000 ft overcast, I would not have problems with my level of flying.

I noticed in this prep work for the long XC that the dual systems would sometimes report an AHRS miss-match. Not really a big deal on the surface as the screen that I was using for attitude information was dead on accurate. I don?t ever use the other screen / system for attitude as it?s always on the moving map. After all, we all, well most, learned to fly with one AI that we relied upon 100% of the time. I gave xxxxxxxxxx a call and as always they are quick to respond with some suggestions and ?check this? type things. One thing they suggested as a way to isolate the problem was switching up which system was the master and which was the slave of the XM weather processing and then giving it a try.

Thursday night, the weather for Friday morning wasn?t looking very promising but the forecast called for the front to pass through mid-morning with the rain ending but clouds remaining. I informed the family that we weren?t leaving early but I thought it might be possible to get out around noon. It looked like we would be in the clouds for an hour, maybe two but then it would be windy but relative clear flight on down to San Antonio. Couple hours in the clouds? been there, done that so don?t give up the trip yet.

Friday morning, the actual weather was aligning with the forecast the previous night. I was checking Weathermeister and Foreflight and it was going to be a couple hours in the clouds then breaking out as previously forecasted.

Mike Stewart mentioned that Team AreoDynamics has a '3 mistakes from dead? rule. I?m prepared for that step but not wanting to rush it so I have the ?if there are two alarms or apprehensions? rule. In this case, apprehension one - I hadn?t flown as much as I usually fly and alarm two - it hit me that I didn?t have the redundancy that I required when I designed the avionics.

At noon on Friday, I cancelled the RV flight, told my wife that Airtran left at 2:15 and if she could be packed and ready in 15 minutes we?d go commercial but I wasn?t flying the RV10. (Didn?t know it was humanly possible for my wife to move that fast Guess when you want to visit your daughter and her husband, anything is possible.)

Remember that simple comment about changing the master / slave relationship on what controlled the XM weather of the redundant screens?. I had completed that change one night when I ran out to the airport to update the charts prior to the planned Friday flight. It was cold (relative to Atlanta cold) so I didn?t pull the plane out and fly after changing the configuration.

Yesterday, I had a colleague from Finland here and I offered to take him up for a flight around the area. After 20-30 minutes, I paged through a couple of screens showing all the cool things that we as experimental avionic consumers have available to us. During this paging, I had a remote AHRS fail message pop up. We landed, I reset the configuration back to where it was previously and we flew for another hour or so and all was well. No big deal VMC.... IMC would have been interesting......

Lesson Learned: Simple changes can bite you in the butt. Fly the plane VMC after any change to avionics no matter how insignificant it seems. We?ve all heard this following annuals or repair work but I will definitely expand this to simple changes in the avionics world as well. (I know this is common sense but that?s what most lessons learned are based upon.)


Just food for thought.
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  #2  
Old 03-01-2013, 02:55 PM
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scrollF4 scrollF4 is offline
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Default Outstanding debrief

Hey DL,
Wow, what a great debrief. You had what we call a Class E HAP (High Accident Potential) by USAF safety reporting rules. Great lesson learned, and awesome wingmanship by sharing it with the rest of us who stand to learn. Thanks again, Brother.

So what caused the AHRS mismatch fault and remote AHRS fail?
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  #3  
Old 03-01-2013, 04:18 PM
DeltaRomeo DeltaRomeo is offline
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Default

Thank you for sharing that!

I hope you don't mind, but I moved this thread to 'Safety' from 'Temp'. This is the kind of stuff I would like to have stick around.

V/r,
dr
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  #4  
Old 03-06-2013, 10:44 AM
7DeltaLima 7DeltaLima is offline
 
Join Date: May 2005
Location: Senoia, GA
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Default

Quote:
Originally Posted by scrollF4 View Post
Hey DL,
Wow, what a great debrief. You had what we call a Class E HAP (High Accident Potential) by USAF safety reporting rules. Great lesson learned, and awesome wingmanship by sharing it with the rest of us who stand to learn. Thanks again, Brother.

So what caused the AHRS mismatch fault and remote AHRS fail?
I haven't determined the cause of either at this point. As far as the AHRS failure, I pulled the system logs and sent them in to be reviewed but I'm back on the road again in Europe for a couple of weeks and won't have the opportunity to continue to debug until I return.

It appears that the configuration changes that I made with the Master / Slave set up caused confusion to the network but that is total speculation on my part at this point in time. While trying to debug while flying, I wondered if I might have changed the IP addresses but that wasn't the case. Hopefully the logs will point to something specific. Once I reset the config, everything worked well.

The AHRS mismatch cause is also yet to be determined. This error was not present for the first 150-200 hours or so. Either some piece of system hardware is going bottom up or my wiring is at fault.

TBD....
Doug
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  #5  
Old 03-06-2013, 01:22 PM
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RV7Guy RV7Guy is offline
 
Join Date: Jan 2005
Location: Chandler, AZ
Posts: 3,000
Default Great write up!!!

I always love safety discussion like this, especially self evaluation. You absolutely did the right thing in not going and then sharing it with everyone.

I fly medical helicopters and our company has a "3 to go, 1 to say no," policy. That is the 2 crew plus pilot and our Emergency Operations Center. If any of them says, "no," it is a no go. Never any pressure to fly.

I think in our RV world if others followed such a policy some lives might be saved. I feel all people in the aircraft must be informed and comfortable. If not it's a no go.

Good job, Doug!!!
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