Sandia SAI-340 Install PIREPs?

[Tony_Hale]

Are you on software version 14?

[kevinw]

8 hours ago, Tony_Hale said:

Are you on software version 14?

Forgot to mention that. Unfortunately yes. I wish I knew there was an update because I would've had it sent back before install.

[Tony_Hale]

12 minutes ago, kevinw said:

Forgot to mention that. Unfortunately yes. I wish I knew there was an update because I would've had it sent back before install.

You may not care about the new features of version 15.  I think it's probably simple to detach from the instrument panel, but you have to disconnect the p/s lines, and I think that requires a static re-cert, doesn't it?  The fact that the software can't be field updated suggest to me they don't expect new software to be a frequent need.  Just bad timing.

[LANCECASPER]

8 hours ago, kevinw said:

I'm interpreting this a little differently. It reads:  A single function vacuum-driven attitude indicator may also be replaced with an electronically-driven attitude indicator that provides a secondary (advisory) function (such as turn & slip indication). The "such as" tells me that altitude and airspeed are also "advisory" functions and therefore I'm within the requirements. In any case I want it to be legal. I plan on talking to the installer next week. In regard to your second Aspen, I was told by my installer that it qualifies as backup as long as a standby battery backup is also installed. He doesn't believe the backup battery included with the Aspen qualifies.

He is correct - that is why on my Ovation with dual Aspens with backup battery, a Lifesaver Midcontinent Electric Attitude had to be installed when the previous owner re-did the panel. By doing all of this he was able to remove the vacuum system.

[Marauder]

So I went up today and played around with the SIA340 a bit. It performs very well. I'm impressed with the resolution of the display. I think once the smoke clears and we all know definitively whether or not this can be used as a backup to the Aspen and G500 I think it's going to be very popular. You'll see from the video that the airspeed is just a hair off from the Aspen but the altitude is 35 ft off. I went into the settings once on the ground and corrected for both so now they should match. Next flight will tell for sure. What surprised me the most is the fuel flow in the 830. I knew it was reading too high burning 12.5 gal/hr in cruise. After I landed it showed that I burned 18.5 gal total. When I topped it off I put in 15.9 gal. I do the math and the K-factor goes from 29.34 to 34.16. Can that be right? I thought this number sits between 29.00 and 31.00. Weird. One last thing. As I was putting my plane back in the hanger a G-V landed. I get everything squared away and as I'm leaving this it sitting there. It's Hillary Clinton's ride. Can't say I'm a Hillary fan but that's a big ship for KCIN.

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I can't remember what my 830 k factors were but I know on my 900, the values changed pretty dramatically. I have been able to get the fill-ups to match within a few tenth S of a gallon. I would just double check the calculations and use the number to see if it gets closer to the actual.

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[kevinw]

12 minutes ago, kevinw said: Forgot to mention that. Unfortunately yes. I wish I knew there was an update because I would've had it sent back before install.

You may not care about the new features of version 15.  I think it's probably simple to detach from the instrument panel, but you have to disconnect the p/s lines, and I think that requires a static re-cert, doesn't it?  The fact that the software can't be field updated suggest to me they don't expect new software to be a frequent need.  Just bad timing.

I agree. Perhaps when it's in the shop the next time I'll get it done. For now everything is fine and I'll get by without the added features. Thanks Tony for your help and insight.

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[peter]

On ‎1‎/‎30‎/‎2016 at 10:52 AM, Marauder said:

I know with the second Aspen, if I purchased the extended battery for the MFD, I can remove my ASI and altimeter. Wonder if that extends to the AI?

I think the verbiage "advisory" is intended to be a non critical flight instrument. Airspeed and altimeter are primary.

Did your installer re-do the IFR cert after installing? Anytime the static system is opened, I believe it needs to be re-checked for at least leaks.

Let us know what your installer says about all this. I'm going to call mine on Monday to talk ADS-B and will ask as well.

It truly is muddy...

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A second Aspen is not approved to act as an AI backup for the first. This is a limitation of the Aspen STC related to the AHRS in each unit relying on air data info to derive attitude (meaning that if air data is bad then the attitude solution is no good and removed - yes, attitude, as in which way is up).  The Aspen AHRS air data dependency is a single point vulnerability in the system architecture, and is why the Aspen STC requires a backup instrument that doesn't rely on air data to figure out attitude.

An advisory instrument is one that is not primary.  In the case of an Aspen equipped aircraft, the airspeed and altitude shown on the Aspen is primary. Airspeed and altitude shown on another instrument is advisory.  Same goes if you install an SAI 340 as replacement for a mechanical AI and retain the mechanical IAS and ALT. Those instruments are primary, the IAS and ALT indications on the SAI340 are advisory.

As always with aircraft certification, clear as mud, right? 

Edited February 22, 2016 by peter

[Marauder]

On ‎1‎/‎30‎/‎2016 at 10:52 AM, Marauder said: I know with the second Aspen, if I purchased the extended battery for the MFD, I can remove my ASI and altimeter. Wonder if that extends to the AI?

I think the verbiage "advisory" is intended to be a non critical flight instrument. Airspeed and altimeter are primary.

Did your installer re-do the IFR cert after installing? Anytime the static system is opened, I believe it needs to be re-checked for at least leaks.

Let us know what your installer says about all this. I'm going to call mine on Monday to talk ADS-B and will ask as well.

It truly is muddy...

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A second Aspen is not approved to act as an AI backup for the first. This is a limitation of the Aspen STC related to the AHRS in each unit relying on air data info to derive attitude (meaning that if air data is bad then the attitude solution is no good and removed - yes, attitude, as in which way is up).  The Aspen AHRS air data dependency is a single point vulnerability in the system architecture, and is why the Aspen STC requires a backup instrument that doesn't rely on air data to figure out attitude.

An advisory instrument is one that is not primary.  In the case of an Aspen equipped aircraft, the airspeed and altitude shown on the Aspen is primary. Airspeed and altitude shown on another instrument is advisory.  Same goes if you install an SAI 340 as replacement for a mechanical AI and retain the mechanical IAS and ALT. Those instruments are primary, the IAS and ALT indications on the SAI340 are advisory.

As always with aircraft certification, clear as mud, right? 

I'm having a problem following the part about the ASI and altimeter portion of what you wrote. When my Aspens were installed, there was an option to purchase an extended battery pack. With this extended pack, I could remove both my ASI and altimeter. Why would this be allowed?

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[peter]

16 hours ago, Marauder said:

I'm having a problem following the part about the ASI and altimeter portion of what you wrote. When my Aspens were installed, there was an option to purchase an extended battery pack. With this extended pack, I could remove both my ASI and altimeter. Why would this be allowed?

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It's allowed because the second Aspen with the battery backup meets all the certification requirements to act as the backup airspeed and altitude display for the first Aspen.  However, the attitude display on the second Aspen cannot be used as a backup to the attitude display of the first Aspen because attitude is more critical, and a single point of failure exists (loss of airspeed) that will cause the loss of all attitude on the Aspen displays.

The FAA rules are set up in a way that recognizes that attitude display is more critical than airspeed and altitude display, even more so in a glass equipped aircraft. 

For example, with conventional instruments if you are in IMC and you lose airspeed and altitude, but still have attitude you can still fly the airplane. Likewise, if you have conventional instruments and you lose attitude and heading, but still have airspeed and altitude and a turn coordinator, you can still fly the airplane.  However, if you lose attitude, heading and the turn coordinator, then you are likely to lose control. 

In a glass airplane if you are in IMC and lose airspeed and altitude, but still have attitude, you can still fly the plane.  However, if you lose attitude (which comes from an AHRS, so also implies loss of heading and rate of turn) then all you will have left to fly with is airspeed and altitude, and you are again likely to lose control. 

Because of this, the FAA rules say that there can be no single point failure that causes the loss of all attitude information to the pilot, but loss of airspeed and altitude from a single point failure is allowed (hence the reason why the rules only require one pitot tube, airspeed instrument, and altimeter for light aircraft).  Conventional instrument aircraft address these issues with an electric TC and partial panel techniques. Glass equipped aircraft address these issues with backup instruments that use different power sources.

 

Separately, I think you were also asking about what I said about primary and secondary/advisory data display.  Hopefully the following clarifies:

When the Aspen with EBB is installed and the mechanical altimeter and airspeed indicator are removed, the display of altitude and airspeed on the Aspen is primary.  In this configuration the Aspen IAS and ALT tapes are locked on, and cannot be turned off by the pilot.

When an Aspen is installed and mechanical altimeter and airspeed indicators are retained, the mechanical indicators are primary and the airspeed and altitude display on the Aspen is secondary/advisory. In this configuration the pilot can select to turn the IAS and ALT tapes on and off.

 

Hopefully this helps thin the mud a little.

[carusoam]

Peter,

Thanks for sharing that piece of logic.  

Electronic box technology is powerful.  It helps to have somebody with your skills/background to explain it for me to be able to make it useable.

Best regards,

-a-