Any discussion with Cirrus on having a second attitude indicator, for redundance as they have with the electrical cirucuits. This seems to be the most critical instrument in imc, that it would be worth discussion. Larry
Any discussion with Cirrus on having a second attitude indicator, for redundance as they have with the electrical cirucuits. This seems to be the most critical instrument in imc, that it would be worth discussion. Larry
One problem is where can it go in the panel? What about an electric attitude indicator on the SR20 instead of the vacuum gyro? Wouldn’t that be more reliable? Then, with the electric HSI (“C” config), you wouldn’t even need the vacuum system or its backup.
Even the way it is, you still have the backup vacuum pump in case of vacuum failure. With a second vacuum failure or gyro failure, the turn coordinator is your backup and it is tied to the autopilot (not the attitude indicator). Together with the HSI electric gyro (C config) and the turn coordinator-based autopilot, you should be able to navigate and execute an approach.
Larry: You raise a very important question. I agree that the attitude indicator is the most critical instrument in imc. On my SR22 here is my plan:
BFGoodrich makes a backup attitude indicator for 2 1/4" mounting. It is electric, 24 v. I hope that I would be able to move the Davtron clock, oat, voltmeter to the right hand side of the panel in the position that the suction gauge is on the SR20. The attitude indicator is the AIM series. It is shown on the BFGoodrich website under “standy instruments”.
Go to www.bfgavionics.com, then “products” then to the links under “standy instruments”
I would plan to mount the instrument with a switch similar to the turn and bank so that it could be switched from ship power to independent batteries. I am not sure whether the independent batteries could be the same arrangement of 9 v. batteries that Cirrus uses for the turn and bank or whether a gel cell battery would be needed. As far as I know there is no TSO for backup batteries. Cirrus apparantly got FAA approval for the 3 9v. arrangment, so as long as the draw of the BFGoodrich attitude indicator was not too great, it should work there as well.
Cirrus is currently looking at the possibility of making the Insight air data computer a factory option, and if they do, the oat and voltmeter functions of the existing Davtron would be taken over by this unit. This would mean that the only item needed would be a clock. This is an FAA requirement for instrument flight, but I don’t know of any requirement that it be on the left side of the panel. I would much rather have a backup attitude indicator there.
Go to www.strikefinder.com, then click on the link to TAS100 True Air Data Computer for information on this unit. It shows a tremendous amount of data, incliding winds aloft. It calculates bearing and windspeed based on pitot and static inputs together with GPS inputs. There is a long list of calculated air data. See their website for details.
On the subject of panel design, it is also my hope that Cirrus can mount the 6 lamp annunciator unit on the bottom side of the glareshield instead of on the panel. This would free up space above the basic flight instruments. My ideal panel would have the Insight air data computer above the airspeed, the STec selector/alerter above the primary attitude indicator and a Trimble radar altimeter above the altimeter. All of these instruments are the standard 1/2 size rectangular mounting and would fit above the basic flight instruments provided that the annunciator unit could be moved to the glareshield mounting.
The backup attitude indicator would be then in the upper left of the left panel above the vor/loc/gs indicator.
A standard aircraft clock could then be mounted on the upper right side of the right panel. With both a flight elapsed time and count and count down timers in the Garmin transponder, and the fact that the time information is available on your watch, I don’t think that the clock mounting would have any downside to it.
If the company that makes the annunciator unit that has the warning lights makes a unit with the same six lamps that will mount below the glareshield instead of in the panel, the change in that unit should be fairly simple.
I intend to visit Cirrus sometime between now and my November 2001 delivery date to discuss the panel matters with them as well as see the plant and fly the SR22. Anybody have any thoughts on these matters?
Any discussion with Cirrus on having a second attitude indicator, for redundance as they have with the electrical cirucuits. This seems to be the most critical instrument in imc, that it would be worth discussion. Larry
Any discussion with Cirrus on having a second attitude indicator, for redundance as they have with the electrical cirucuits. This seems to be the most critical instrument in imc, that it would be worth discussion. Larry
One problem is where can it go in the panel? What about an electric attitude indicator on the SR20 instead of the vacuum gyro? Wouldn’t that be more reliable? Then, with the electric HSI (“C” config), you wouldn’t even need the vacuum system or its backup.
Even the way it is, you still have the backup vacuum pump in case of vacuum failure. With a second vacuum failure or gyro failure, the turn coordinator is your backup and it is tied to the autopilot (not the attitude indicator). Together with the HSI electric gyro (C config) and the turn coordinator-based autopilot, you should be able to navigate and execute an approach.
Janice, on the EHSI on the SR22, does it have a seperate gyro for the autopilot, than what is used on the attitude indicator? So if you have an attitude indicator problem, you could leave it on autopilot and do the approach? Larry
Janice, on the EHSI on the SR22, does it have a seperate gyro for the autopilot, than what is used on the attitude indicator? So if you have an attitude indicator problem, you could leave it on autopilot and do the approach? Larry
The SR20 autopilot uses the turn coordinator’s gyro. So,if you have an attitude indicator problem, you can do the approach if you use the autopilot and your EHSI works.
The SR22 doesn’t have a vacuum system so you won’t have a vacuum failure. If the instrument fails, you’ve got the same back up in the turn coordinator’s electric gyro that the autopilot uses. If your EHSI works, you can do the approach.
Listen up you IFR folks, Steve Shirley has done his homework on this. I plan a similar set up for an independent attitude indicator on my SR22-B (feb/02, based in Santa Monica CA). With luck we can take advantage of the leg work Steve has done and go to the same shop for the work. Are there any avionics shops out there interested in this job?
DAVE
P.S. Still looking for a 25%,33% or 50% partner at KSMO.