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DFC90 - Sudden "Autopilot Disconnect" in Cruise

Achim, i'd expect them to send a SR22 programmed unit to AS, that shouldn't be a problem since SR22 is probably still 90 percent of the market ....

OTHER strategy: If the roll servo is worn out anyway, then i'll simply change it before i make any other steps. It does not make sense to save money on those parts. I want a PERFECT roll servo

I am definitely sticking with my KFC225.

I don't think you have any options here. The DFC90 is not will most likely never be STC'ed for the TB20. The GFC700 is generally not available for retrofit. Not a problem because the KFC225 is a good autopilot (the first digital GA autopilot I think) although having constant IAS mode is a huge benefit, I'd never want to switch to an aircraft that doesn't have it.

What plane do you have?

PA-46

EGTK Oxford

Just got this posting on COPA:

I strongly suggest that you replace the S-TEC 55X's tray/backplate with Avidyne's much improved DFC 90. It's not cheap (about $500), but it solved the spontaneous autopilot disconnect problems that we were saw a couple of times on the test flight on our SR22 after our upgrade. The S-TEC 55X's is quite simply he most poorly engineered avionics tray known to man. Under ideal circumstances, the pins have at best only 1/16" of an inch of mating... which is quite scary. Avidyne's DFC90 rack improves this.

Under ideal circumstances, the pins have at best only 1/16" of an inch of mating

I wonder how many FAA inspectors read that site?

Administrator
Shoreham EGKA, United Kingdom

I only know storys like that.... through all brands of Avionics, airplanes, engines.

The truth is: We have to be very tolerant with this industry. It will not be on the level of a third world car maker for the next 100 years.

We can swallow that, or quit flying.

I'd never want to switch to an aircraft that doesn't have it.

I don't really understand this. Yes, if I bought an aircraft or had to replace an AP for my steed, I would make sure that it is "up to date".

I would make sure in particular that the AP is integrated in any glass cockpit - I just did a ME IR upgrade in a DA42 where that was not the case, and I consider that borderline dangerous, since the altitude bug in the G1000 and in the autopilot were not linked, nor was the QNH setting.

But for my flying, I am happy with heading and altitude hold mode. I would probably pay to retrofit roll steering as well, but that's probably it.

And I say that having flown in aircraft with the STEC 55X, GFC700, and KAP-something-or-other. The GFC700 in particular was awesome.

I rent, however, so I can't bee too choosy, given that if I want turbo, de-ice and weather avoidance the exact number of aircraft I can rent just now is one....

Biggin Hill

I also have a C172 and that doesn't have an AP at all... I'm just saying a really good AP is one of the most important things for IFR and I cannot imagine replaying my DFC90 aircraft with another that has an S-TEC or similar.

Also you are right about AP/glass cockpit integration, this is very important. The DFC90 is very well integrated with the Aspen PFD, everything in one place and never any issues with different modes selected in different places.

One of my biggest issues with the GNS430 and S-TEC was the GPS/VLOC button on the GNS. Numerous times it was in the wrong mode and depending on what is configured, your AP will do something obviously wrong or something slightly wrong that you don't notice immediately. The DFC90 is just set to GPSS and the GNS430 can be in either VLOC or GPS and it doesn't matter.

Another very nice feature is QNH adjustment. When changing the QNH, the DFC90 will automatically adjust its present altitude to the new QNH setting which it takes from the PFD. Previously I'd have to enter the new QNH into the separate S-TEC altitude preselect, choose a VS and arm the altitude again. All on a really crappy piece of hardware (ST-360).

In an Entegra 9 cockpit, the DFC also does VNAV but not with a GNS which cannot do VNAV.

The truth is: We have to be very tolerant with this industry. It will not be on the level of a third world car maker for the next 100 years.

We can swallow that, or quit flying.

The thing that is hard to swallow is that one of major the causes of this situation is regulation that makes innovation so expensive that it is next to impossible. And leads to perverse outcomes where, for example, you cannot use generic (modern) parts that are MUCH better than the original (ancient) part because certifying the blindingly obvious is prohibitively expensive and time consuming.

Biggin Hill

My second plane ;-)) is a 1974 Warrior and I have installed an S-TEC 30+ with GPSS and altitude hold. It is really a nice system, but of course not comparable to the DFC90. But I used it for some GPS approaches and that worked nicely and so does the LOC intercept.

In the SR22 the DFC90 is nicely integrated. Change the QNH and the AP changes the altitude to the selected ALT.

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