Yaw damping would add a servo, other accessories might be required, so I would think 16-20k for the equipment. I won't hazard a guess on installation but will try to get numbers for other AC.
I'm on the fence about this. Already having a KAP140 and with GNS WAAS units I'm trying to decide if the incremental gains are worth the cost. The installation has the potential to be considerably less of an expense because I already have the mount points for the basic servos, as well as the cable bridles and linkage for them. And wiring between the FC and the servos. Also any wiring to the GNS is all behind-the-panel work. Yaw damping (does this include some provision for rudder trim?) I would think would require some additional wiring, another servo and hardware to connect to the rudder cable system.
Improvements:
- Probably smoother operation overall.
- Removes one repeated task during the missed approach (and hold?) - namely the tweaking of the course selection via the HSI.
- Constant airspeed hold in normal climbs is handy - removes the necessity of tweaking VS during AP-directed climbs.
- Yaw dampening would be very nice in some circumstances.
- MAYBE: getting rid of the annoying porpoising during climbs/descents?
Some reality checks:
- I've only ever had to do one missed approach for real and that used a non-published MAP at ATC's direction and my concurrence. The MAP published for the approach in question is unusable when there's traffic waiting behind you. I've noted that in recent years this has gotten quite common. In any case when practicing I rarely use the published approach.
- For sure with the GNS units, the AP can not really fly a missed approach without input from you. The basic weakness is that the nav data does not have the various altitude - related information. And you still need to transition the plane from approach power, flap, etc. to climb mode. In some cases the MAP delays the turn until reaching a specified altitude, which as I said is not in the nav data. Even the decision to go missed still needs to be made by the pilot.
So the question in my mind is whether the incremental improvements worth the (probable) $20K investment given my situation. So far - maybe.
blsewardjr wrote:I did a quick price comparison with the Garmin GFC500 autopilot, which is not available for the DA40 but provides a price comparison for a comparable autopilot. Assuming the 16K STEC 3100 comes with three servos and everything needed to interface with the Garmin G530, the price differential for steam gauge DA40s may not be as large as it first appears. While the Garmin autopilot alone sells for only 7k, we would also need additional devices. Specifically, we would need a G5 AI (which is also not currently approved for the DA40) to provide AHRS (2.2k), a third pitch servo for pitch trim (1.7 for the certified version based on the cost difference for 2 versus 3 at Sarasota Avionics), and a GAD 29B interface for the Garmin Nav/Com (.5K), for a total of 11.4K before installation. The actual price delta would appear to be less than 5K.
It would be great to have more than one option.
I don't think the number of steam gauge AC can justify an STC for a new AP, but providing an upgrade path for the KAP140-equipped G1000 fleet might.
Does anyone have an idea of the number of steam gauge AC vs KAP140 G1000 AC (vs. GFC700 AC)?
I'm also on the fence on this but leaning towards committing. As I see it, the main reasons for adding this AP are:
-Improved reliability over the KAP 140
-Improved precision/stability on the approach (KAP 140 tends to wander back and forth even on LPV approaches, sometimes to an unsettling degree close to the DA)
-Constant IAS climbs reduces workload and opportunity for AP induced stall (not as critical in the DA40 as in other aircraft)
The nice to haves are:
-The AP flys more of the missed approach procedure then the KAP140
-Envelope protection/leveling function
Bernie Seward, IR, AGI
2003 DA40 N377DS
KCHO Charlottesville, VA
I haven't had any problem with my KAP140 being flaky on approaches. But I do remember that on the acceptance flight in London all those years back Jeff Owen did note that some gain adjustment was needed, which was done that day by the factory.
It did have reliability problems for the first couple of years, where it would take itself off line. But a Bendix field rep applied a software update and the pitch trim servo was replaced. Not one incident since - in 13+ years. So I'm not putting a reliability improvement in the plus column for mine.
Mine has taken to randomly failing its startup test and occasionally going off-line in the middle of a flight. Requires pulling the circuit breaker then waiting 5+ minutes to restore. Going into the shop tomorrow to have it looked at. I'll ask about the gain issue.
Bernie Seward, IR, AGI
2003 DA40 N377DS
KCHO Charlottesville, VA
blsewardjr wrote:Mine has taken to randomly failing its startup test and occasionally going off-line in the middle of a flight. Requires pulling the circuit breaker then waiting 5+ minutes to restore. Going into the shop tomorrow to have it looked at. I'll ask about the gain issue.
There are various failure codes that the shop should be able to extract. That's what the factory rep did with mine to diagnose the problem.
Colin wrote:I would think that the control forces being so different on the DA42 it would be a non-starter. The price would have to be higher.
I also think you'd be much better off putting that money toward a GFC-700 which offers the yaw-damper and flight level change. And, eventually, envelope protection.
I sent an email to Diamond Canada and also called and left a message but nobody got back to me. Do you have a contact over there?
The installation times will vary depending the experience level of the installer plus the panel setup and type of installation. As a rough guide here is what we predict:
Other AP upgrade to 3100: 25 to 35 hours
New installation: 80 to 100 hours
One of the advantages of S-TEC STC kits is that we provide all of the components required for the installation, which saves the installer sourcing and purchasing various parts. Other avionics companies require the dealer/installer to source and supply many of the components which increases the installation time and price.