Current status re. S-TEC autopilot:
I received an e-mail from Cirrus Monday 10-30-00 as follows: “the point of concern from the faa has only to do with whether or not a pilot might accidently turn on the autopilot…given the switching on and off regime of the 40 and 50 “x” series. nothing more. regardless of how the issue is resolved with the faa, production will not slow down or halt on the sr22. there are plenty of other capable autopilots on the market should the question not be resolved in an appropriate time frame. we’ll keep ya posted, tom bergeron”
Background:
I noted a posting on the Avionics West website (www.avionicswest.com/stecsales.htm)dated 10-11-00 quoting a memo from Dennis Tolleson, Asistant Director of Sales and Customer Service indicating “Until further notice the sale and production of the System FourtyX/FiftyX autopilots has been suspended. These autopilots will be removed from the next printing of the Autopilot Selection Guide and the Dealer Price List”
The person at Avionics West indicated “I’ve known Dennis for years so I thought I’d give him a call to see why the suspension. Dennis explained that the System FourtyX/FiftyX are based on the CWS (Control Wheel Steering) and that the FAA is looking closely at theis subject at this time. Until whatever issue it may be between the FAA and S-Tec as related to CWS S-Tec is halting production and sales. To be honest, I’ve never seen a FourtyX or FiftyX system yet. The GPSS system which will work with any S-Tec autopilot and the Garmin GPS is not an issue. The GPSS is certified for just about any general avaition aircraft”
Further background:
On 10-26-00 I received an e-mail from Dennis Tolleson reading “S-TEC is currently in discussions with Cirrus regarding the suspension of sales on the System FiftyX and a decision is pending”
Discussion:
This subject should be watched closely. At this point it is not certain that S-Tec will be the autopilot in the SR22.
Ironic, given that CWS is the one feature that is disabled in the SR20 (and presumably the SR22 as well).
This is a side effect of using the trim servos for the autopilot as well. In CWS (in S-Tec autopilots), when you let go of the CWS button, the plane holds whatever attitude it was in when you let go of the button. This requires a/p servos with a clutch that can “grab” the controls more or less instantaneously. With the Cirrus setup, you’d hit the button and let go, and the plane would then have to hunt around to find the attitude again as the trim servos cranked around.
CWS doesn’t seem to be a big deal as far as I’m concerned, since in pitch you can get almost the same effect using VS mode, and holding an attitude other than flying straight seems less than useful. (Attitude-based a/p’s like the KFC 200 only do CWS in pitch anyhow.)
Isn’t Control Wheel Steering a feature of the System 55 in the SR20C and the SR22B also? Do all you C model drivers have this? An S-Tec installation bulletin (http://www.s-tec.com/newsletters/approach499/secrets499.html) says that CWS is “required” on the 55 and “not applicable” on the 40 and 50. What’s different about the FortyX and FiftyX?
The person at Avionics West indicated "I’ve known Dennis for years so I thought I’d give him a call to see why the suspension. Dennis explained that the System FourtyX/FiftyX are based on the CWS (Control Wheel Steering) and that the FAA is looking closely at theis subject at this time. Until whatever issue it may be between the FAA and S-Tec as related to CWS S-Tec is halting production and sales.
Ironic, given that CWS is the one feature that is disabled in the SR20 (and presumably the SR22 as well).
This is a side effect of using the trim servos for the autopilot as well. In CWS (in S-Tec autopilots), when you let go of the CWS button, the plane holds whatever attitude it was in when you let go of the button. This requires a/p servos with a clutch that can “grab” the controls more or less instantaneously. With the Cirrus setup, you’d hit the button and let go, and the plane would then have to hunt around to find the attitude again as the trim servos cranked around.
CWS doesn’t seem to be a big deal as far as I’m concerned, since in pitch you can get almost the same effect using VS mode, and holding an attitude other than flying straight seems less than useful. (Attitude-based a/p’s like the KFC 200 only do CWS in pitch anyhow.)
It’s not clear that CWS will be disabled in the S-Tec, or even that S-Tec will be the autopilot that Cirrus will be using.
It’s not clear that CWS will be disabled in the S-Tec, or even that S-Tec will be the autopilot that Cirrus will be using.
It doesn’t appear that CWS is possible, regardless of which a/p vendor is in use, without a change in the way the a/p and trim servos are shared. Perhaps there will be separate a/p servos in the SR22, dunno.
It’s not exactly “disabled” in the S-Tec 55, there’s just no connection to the pins that turn it on…
Isn’t Control Wheel Steering a feature of the System 55 in the SR20C and the SR22B also? Do all you C model drivers have this? An S-Tec installation bulletin (http://www.s-tec.com/newsletters/approach499/secrets499.html) says that CWS is “required” on the 55 and “not applicable” on the 40 and 50. What’s different about the FortyX and FiftyX?
CWS is an S-Tec 55 feature, but it is not implemented in the SR20 (by virtue of not putting in the switch.) The POH supplement for the 55 makes it official for FAA purposes.