So there we are taking off into the soup while looking at our redundant dual screen 180/100 combo when at 25ft, the pitot swallows a bug just as we enter the clouds. What happens to the EFIS when this happens other than the obvious loss of airspeed data? Are we going to die if we do not have backup steam gauges?
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EFIS RELIANCE ON PITOT????
- Thread starter Brantel
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- Mar 23, 2005
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The attitude indicator does indeed rely on airspeed information to work properly. If you lose airspeed for any reason, the EFIS's attitude should be treated skeptically.
Related, pitot ice shouldn't be a factor in IFR-equipped panels since legally you need to have a heated tube (we now have a heated AOA/Pitot on the market again) to fly IFR.
Additionally, know that broadly speaking, if the EFIS doesn't have airspeed, the attitude indicator's biggest enemy at that point is acceleration. The less the airplane is maneuvered (power application/reductions, and changes in direction), the better it will be at portraying attitude.
The only way to absolutely PERFECTLY guarantee redundancy would be to have each system paired with its own pitot, or, as you suggest, using another instrument as backup.
Related, pitot ice shouldn't be a factor in IFR-equipped panels since legally you need to have a heated tube (we now have a heated AOA/Pitot on the market again) to fly IFR.
Additionally, know that broadly speaking, if the EFIS doesn't have airspeed, the attitude indicator's biggest enemy at that point is acceleration. The less the airplane is maneuvered (power application/reductions, and changes in direction), the better it will be at portraying attitude.
The only way to absolutely PERFECTLY guarantee redundancy would be to have each system paired with its own pitot, or, as you suggest, using another instrument as backup.
aceflyingservice
New Member
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As an aside to this thread, as most of us fly under Part 91 rules, part 91-205 (IFR equipment requirements) does not require a heated pitot.
Roger Johnson
Roger Johnson
The EFIS relies on the pitot tube like a vacuum gyro relies on a vacuum pump. I have been flying for 30 years and have had more vacuum pumps failures than I can remember, and two pitot tube failures, one was a wasp and it was plugged before take off and it was apparent long before I would have ever entered the clouds. The other was a failed pitot heater solid IMC and I shot an ILS to mins without Airspeed. A Garmin 90 gave me ground speed and it was a non event. With a Dynon, It would have been needle ball and A/S or turn around and find better weather.
Nothing is perfect, and a Dynon needs pitot. I would not fly IFR with a Dynon, or a vacuum horizon unless I had it backed up with a T/B and better yet a rate based autopilot like a Trutrak, or a Stec.
NO one should be flying IFR in anything without a heated pitot tube.
Tailwinds,
Doug Rozendaal
F-1 Rocket D100 lotsa IFR.
Nothing is perfect, and a Dynon needs pitot. I would not fly IFR with a Dynon, or a vacuum horizon unless I had it backed up with a T/B and better yet a rate based autopilot like a Trutrak, or a Stec.
NO one should be flying IFR in anything without a heated pitot tube.
Tailwinds,
Doug Rozendaal
F-1 Rocket D100 lotsa IFR.
Still doesn't answer my question. From my initial observations and a one-time encounter with pitot-tube icing before I chucked the nonheated (but AOA) tube for one that's heated, the D100 agreed with other instruments in roll, but was sluggish in pitch.
My question remains: If, worst case, you lose pitot or static, can the Dynon's be counted on for accurate roll information. If they can be, then you already have your T&B and need only decent pitot/static backups.
--Marc
My question remains: If, worst case, you lose pitot or static, can the Dynon's be counted on for accurate roll information. If they can be, then you already have your T&B and need only decent pitot/static backups.
--Marc
Sorry Marc,
I missed the question, I have never disconnected the Pitot tube, but Stein has and he told me it the Dynon got pretty wild without it. Even if the bank was accurate, it would be pretty hard to diregard the pitch info if it was oscillating. If the pitot failed in IMC, I believe I would turn it off so I could effectively ignore it.
I need to put that on my LSTD. (list of "stuff" to do) Disconnect the pitot and go fly it.
Maybe there is a story in it?
Doug
I missed the question, I have never disconnected the Pitot tube, but Stein has and he told me it the Dynon got pretty wild without it. Even if the bank was accurate, it would be pretty hard to diregard the pitch info if it was oscillating. If the pitot failed in IMC, I believe I would turn it off so I could effectively ignore it.
I need to put that on my LSTD. (list of "stuff" to do) Disconnect the pitot and go fly it.
Maybe there is a story in it?
Doug
Well, I did just that yesterday. And, as the Dynon folks surely know, the device goes pretty stupid without pitot. It indicates the bank angle correctly at first and then gently moves toward wings-level, even in a sustained 45-deg bank. Pitch seems to do the same, but it's hard to hold a slow, constantly changing pitch rate in my airplane. (It goes upside-down but not with a great deal of willingness.)
So, long story short, two Dynon EFISes aren't a truly redundant attitude reference system without independent pitot sources. But, to be fair, outright pitot failures are pretty uncommon, at least they have been for me.
So, long story short, two Dynon EFISes aren't a truly redundant attitude reference system without independent pitot sources. But, to be fair, outright pitot failures are pretty uncommon, at least they have been for me.
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Yes, this is a possibility, as are some other things that we are considering. Nothing will be as good as pitot, but it should be able to keep you basically level in a failure situation.
The other was a failed pitot heater solid IMC...With a Dynon, It would have been needle ball and A/S
Doug,
Where are you gonna get A/S for your "Needle, Ball and A/S" if the pitot is blocked?...
I do agree with you that a rate-based autopilot is your best backup for an AI failure.