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20 Jan 2018, 20:52 [ UTC - 5; DST ]


Greenwich AeroGroup



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 Post subject: DFC90 performance question
PostPosted: 13 Dec 2017, 12:33 
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Joined: 07/26/15
Posts: 81
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Location: Fort Lauderdale, FL (HWO)
Aircraft: Bonanza M35
I recently replaced my STEC 50 after it died with a DFC90. In somewhat gusty conditions (nothing outrageous) on a coupled approach it doesn't seem as steady in roll as I'd expect. It let's the aircraft roll a good bit with a slight delay before it corrects. In pitch its very stable. Granted you could chock some of that up to Bonanza characteristics in general. Unfortunately, I rarely shot an approach with my STEC 50, given the lack of vertical mode besides alt hold, I generally just turned it on during cruise and that was it, so I have little basis for comparison.

For those that have one is this normal? I plan on taking it back to the shop when I get a chance, but just wanted to know what "normal" is.

Also, does the DFC90 have any built in test modes, i.e. to be able to run the servo full speed without engaging it, a way to check the startup voltage, etc, just to make sure the roll servo doesn't have any issues? Seems like with a digital unit they could have easily added a maintenance mode for these handy checks. Unfortunately due to its location in the panel vs. where the STEC 50 was, its hard to get at the wiring to do those type of tests, so I'd have to remove the seats and all that and do it at the servo. Or get one of those extender trays that STEC has for the 55X, but I don't have one and have never seen one come up for sale.


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 Post subject: Re: DFC90 performance question
PostPosted: 13 Dec 2017, 13:29 
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Joined: 12/02/09
Posts: 3155
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Company: Portal Consulting
Location: Deer Valley
Aircraft: Bonanza S35
Tom:



If you don't get the response you need here (but you probably will) , you might also look at Avidyne's board: www.avidynelive.com.

Avidyne folks monitor the board, and might answer your question about test modes, etc.

All I have heard about the DFC90 is that it is a great unit.

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David Gates


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 Post subject: Re: DFC90 performance question
PostPosted: 13 Dec 2017, 15:40 
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Joined: 08/30/10
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Location: Kingston, NY (20N)
Aircraft: 1985 Bonanza F33A
All of the DFC90 equipped airplanes I've flown have been rock steady. However, like any autopilot system, the servos must be in good working condition. If there is an issue with the roll servo then you may get slow/unpredictable performance.


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 Post subject: Re: DFC90 performance question
PostPosted: 13 Dec 2017, 15:42 
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Company: U.S. Army
Location: Richmond, VA
Aircraft: 1968 E33A
If you don't mind sharing, what was the cost to upgrade? I'm leaning towards the DFC90 when my current STEC 60-2 dies (hopefully not for a few more years...).

Cheers,
Brian


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 Post subject: Re: DFC90 performance question
PostPosted: 14 Dec 2017, 15:07 
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Joined: 03/31/15
Posts: 152
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Company: Avidyne
Location: KBED
Username Protected wrote:
I recently replaced my STEC 50 after it died with a DFC90. In somewhat gusty conditions (nothing outrageous) on a coupled approach it doesn't seem as steady in roll as I'd expect. It let's the aircraft roll a good bit with a slight delay before it corrects. In pitch its very stable. Granted you could chock some of that up to Bonanza characteristics in general. Unfortunately, I rarely shot an approach with my STEC 50, given the lack of vertical mode besides alt hold, I generally just turned it on during cruise and that was it, so I have little basis for comparison.

For those that have one is this normal? I plan on taking it back to the shop when I get a chance, but just wanted to know what "normal" is.

Also, does the DFC90 have any built in test modes, i.e. to be able to run the servo full speed without engaging it, a way to check the startup voltage, etc, just to make sure the roll servo doesn't have any issues? Seems like with a digital unit they could have easily added a maintenance mode for these handy checks. Unfortunately due to its location in the panel vs. where the STEC 50 was, its hard to get at the wiring to do those type of tests, so I'd have to remove the seats and all that and do it at the servo. Or get one of those extender trays that STEC has for the 55X, but I don't have one and have never seen one come up for sale.


This sounds like a roll servo issue like Geoffrey had indicated. It should be a relatively easy check for the avionics shop.

As for the DFC90, we do continuously monitor the voltage and current of the servos and match them up to what we expect. We alert the pilot to a servo limit on our Entegra PFD but I am not certain if the Aspen gives a CAS message.

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Avidyne
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 Post subject: Re: DFC90 performance question
PostPosted: 14 Dec 2017, 17:24 
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Company: OAG
Location: Portland, OR (KHIO)
Aircraft: 1962 Bonanza P35
Username Protected wrote:
If you don't mind sharing, what was the cost to upgrade? I'm leaning towards the DFC90 when my current STEC 60-2 dies (hopefully not for a few more years...).

Cheers,
Brian



:popcorn:

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Paul
I heart flying

ABS Lifetime Member


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 Post subject: Re: DFC90 performance question
PostPosted: 14 Dec 2017, 21:24 
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Joined: 07/26/15
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Location: Fort Lauderdale, FL (HWO)
Aircraft: Bonanza M35
Username Protected wrote:
If you don't mind sharing, what was the cost to upgrade? I'm leaning towards the DFC90 when my current STEC 60-2 dies (hopefully not for a few more years...).


For my STEC 50 -> DFC90, not counting the electric trim I had to add, it was $9,995 for DFC90, $1,995 for the Aspen unlock, and 60 hours in labor, not counting the trim servo. So not exactly cheap.

My rationalization process was:

1) Who knows when STEC will have their digital unit out and when it will be certified on 35 Bonanza
2) Garmin's GFC600 is a clear winner in function (with the future VNAV), though I would argue VNAV without auto throttles is of limited use since you're usually going to have to make a power change when it decides to change altitudes anyway. Also not yet certified on 35, and who knows when, but likely before STEC (purely speculating on my part). Downside is its twice the price, and requires installing a new set of servos. Installing a trim servo, at least an STEC, in a Bonanza without prior experience is apparently not easy and requires moving the trim cable. Long story, but the shop lost money on me with that.

Pros of DFC90:

1) Very nice integration with the Garmin GTN / Aspen / Avidyne setup. I can fly my flight plan, load my approach, and it will automatically arm approach mode and shoot the approach without intervention.

2) IAS hold is really nice for climbs, though all the comparable units have this

3) Not having to buy / install new servos

Cons of DFC90:

1) No TOGA button. Seriously Avidyne? How hard could this be? Wings level, x degrees pitch up. The DFC100 has it even.

2) Relies on Aspen for attitude data, and Aspen for whatever reason can't output this data from an MFD1000 in reversionary mode. Seriously Aspen? You have the code for this already on the PFD. Add an external switch like they did for the analog converter thing to choose between EFDs would be really nice and give it a leg up over everyone else (who are deriving attitude data from a built in AHARS in the autopilot itself)

3) Install has some quirks...for example their 14V unit is still 28V. You have to buy a DC-DC converter for a 14V airplane. From a company that no longer exists. The only difference on the 14V version is the power for the servos, the unit itself still needs 28V. Add another $500 or so of unexpected cost. Many shops have very little experience with these units outside of Cirrus.

4) I get why they kept the button style of the STEC, but I hate having to press IAS and ALT at the same time, the keys are very far from each other which makes it a tad difficult in turbulence. If you screw up, you have to start over and put the altitude back in the Aspen since it will just capture the current altitude. For descents, VS and ALT are close so its much easier. Minor, but annoying.

Once I get this roll thing straightened out, I'll like it. I also like having a flight director, though you have to turn off synthetic vision if you have it or its hard to follow, not enough contrast. The only thing I wish I would have done different was to just put a yaw damper in. It never bothered me before, but then I only used the autopilot in (relatively) high altitude cruise which takes no rudder input. but its expensive and I was already suffering from "while you are in there" syndrome.


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 Post subject: Re: DFC90 performance question
PostPosted: 15 Dec 2017, 17:40 
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Joined: 02/16/11
Posts: 206
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Aircraft: Baron 58
Simpson,
Is Avidyne still working toward certification of their own servos. If so any time line on when we might expect complete systems to be available.
Doug


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 Post subject: Re: DFC90 performance question
PostPosted: 21 Dec 2017, 17:08 
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Joined: 07/20/16
Posts: 12
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Company: S-Tec / Genesys Aerosystems
Location: Texas
Tom

Just to address a few of your questions and comments...We will have the new S-Tec 3100 STC'd in the bonanzas in Q1 2018 (projected). We have already started the process, so it's a work in progress. The upgrade from an existing S-Tec autopilot runs between $9,995-11,995 depending on if you have trim already and what S-Tec autopilot you currently have. FYI, Auto Electric Trim comes standard on the 3100. In addition, we have a Go Around button and TOGA, as well as envelope protection, LVL button, and Yaw (for the bonanza), and a ton more. Hope this helps with some of the questions!

Username Protected wrote:
If you don't mind sharing, what was the cost to upgrade? I'm leaning towards the DFC90 when my current STEC 60-2 dies (hopefully not for a few more years...).


For my STEC 50 -> DFC90, not counting the electric trim I had to add, it was $9,995 for DFC90, $1,995 for the Aspen unlock, and 60 hours in labor, not counting the trim servo. So not exactly cheap.

My rationalization process was:

1) Who knows when STEC will have their digital unit out and when it will be certified on 35 Bonanza
2) Garmin's GFC600 is a clear winner in function (with the future VNAV), though I would argue VNAV without auto throttles is of limited use since you're usually going to have to make a power change when it decides to change altitudes anyway. Also not yet certified on 35, and who knows when, but likely before STEC (purely speculating on my part). Downside is its twice the price, and requires installing a new set of servos. Installing a trim servo, at least an STEC, in a Bonanza without prior experience is apparently not easy and requires moving the trim cable. Long story, but the shop lost money on me with that.

Pros of DFC90:

1) Very nice integration with the Garmin GTN / Aspen / Avidyne setup. I can fly my flight plan, load my approach, and it will automatically arm approach mode and shoot the approach without intervention.

2) IAS hold is really nice for climbs, though all the comparable units have this

3) Not having to buy / install new servos

Cons of DFC90:

1) No TOGA button. Seriously Avidyne? How hard could this be? Wings level, x degrees pitch up. The DFC100 has it even.

2) Relies on Aspen for attitude data, and Aspen for whatever reason can't output this data from an MFD1000 in reversionary mode. Seriously Aspen? You have the code for this already on the PFD. Add an external switch like they did for the analog converter thing to choose between EFDs would be really nice and give it a leg up over everyone else (who are deriving attitude data from a built in AHARS in the autopilot itself)

3) Install has some quirks...for example their 14V unit is still 28V. You have to buy a DC-DC converter for a 14V airplane. From a company that no longer exists. The only difference on the 14V version is the power for the servos, the unit itself still needs 28V. Add another $500 or so of unexpected cost. Many shops have very little experience with these units outside of Cirrus.

4) I get why they kept the button style of the STEC, but I hate having to press IAS and ALT at the same time, the keys are very far from each other which makes it a tad difficult in turbulence. If you screw up, you have to start over and put the altitude back in the Aspen since it will just capture the current altitude. For descents, VS and ALT are close so its much easier. Minor, but annoying.

Once I get this roll thing straightened out, I'll like it. I also like having a flight director, though you have to turn off synthetic vision if you have it or its hard to follow, not enough contrast. The only thing I wish I would have done different was to just put a yaw damper in. It never bothered me before, but then I only used the autopilot in (relatively) high altitude cruise which takes no rudder input. but its expensive and I was already suffering from "while you are in there" syndrome.


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