I have a very good FD (DFC90) but I rarely use it. I do not see when I should use the FD but not the AP. I usually transition to AP very soon after takeoff (i.e. still in the runway extension phase where raw data is as good as FD) and very late in the approach — on final.
For manual corrections, I use my CWS button. I was never trained to use the FD and never had one until recently so I never got the habit of using it. On the other side, I don’t miss it either…
Same for me, but after I started trying it, i found out it’s a lot of fun and a good compromise between hand flying and A/P. Also since the servos are the weakest part of the whole system it might be very helpful one day. If you have an active approach in your 430W it will lead you you through the whole approach …
I typically hand fly to FL100 on the FD. If things get busy I can always just engage the A/P. If I hand fly the approach I will also usually use the FD.
I suspect you mean “ground speed range”?
Both. Ground speed determines the rate at which you will be closing the localiser and airspeed, together with some bank angle limitation, will determine your turn radius. Most often we see that our turn radius is larger than what would be required to intercept the localiser (either due to steep intercept vectors or high speed – more often the latter…) and we overshoot. If one sees that this is about to happen and the nerves of one’s passengers support it, one can increase the bank angle by pressing the TCS button. Limited again by the aircraft shouting “bank angle – bank angle!” or the first passenger starting to scream 
The FD won’t work better than the AP. If the AP is not satisfactory, chances are the FD won’t be either.
We are very happy with the S-TEC 55X in the Mooney, but I am aware that other people are very unhappy with theirs in other types. It appears that it depends on the installation and on the way they are programmed for that type by S-TEC.
OK… I know it doesn’t do it very well. I was in an SR20 with a 55X and even in light turbulence it was snaking along, with lots of yaw. But on some types it reportedly works adequately.
That is what I heard from the two guys who testflew my plane after the installation. They only flew the 55X on the Cirrus and were gobsmacked by the result they got on the Mooney. One told me that for the Cirrus, the optional Yaw damper is a very good investment, while other planes don’t need it at all.
In order to use an FD and/or AP correctly training is required by someone who KNOWS the system not just about it or who reads what is on the forums. I’d think people with in depth knowledge of larger systems such as Jet AP’s can figure this stuff out largely for themselfs, but they are in danger of overexpecting what the thing can do. Most likely, your plane will need specific checklists and procedures drawn up if you want to use the AP/FD realistically and with best use of equipment. If you do that, then it is a huge help.
The performance of the S-TEC55X in Cirrus aircraft (all i can talk about) is very dependent on the quality and condition of the servos and the rigging of the flight controls.
While some SRs fly very nicely with the 55X, others always have problems, mostly of the kind Peter described. Before the days of the GFC700/DFC90/100 digital autopilots the 55X was one of the top products in this class, even many heavier and faster aircraft still use it without problems.
very dependent on the quality and condition of the servos and the rigging of the flight controls.
The problem with autopilots is that almost nobody in the avionics business understands them. In the UK, there is IME just one man who does, and he is very hard to get hold of because he gets called out on bizjet AOC jobs a lot, since he sold his business.
All other avionics can be installed just by getting the IM, not really reading it much, and turning to the back pages for the wiring diagrams.
On the TBs, the KAP/KFC issues (the ones where the AP works but for some reason not well) are generally blamed by the “experts” on a poor installation but mostly they are defective servos.
The stuff is impossible to diagnose (apart from swapping parts until it works, and billing the lot to the customer) without a knowledge of electronics. For example you need to know that say +9V on the KS271C input gives you 15rpm ACW (or whatever). Once you know that, troubleshooting everything is easy. But almost nobody in avionics does understand electronics. I know Jesse here does, but he is rare.
When the KAP/KFC boxes work, they work brilliantly. The KFC225 is outstanding, including heavy turbulence. Honeywell characterised them properly, with test flights and various loading envelopes, for the STCs. But STEC – it is widely believed – did not test most of theirs in any aircraft; they just got the STCs on the back of a few actually-tested STCs. They have way too many STCs to have actually tested them properly. The obvious way to make an AP “work” is to have a low proportional gain and a high integral gain, but then you get a crap transient response, especially in some loading configs (the SR20 scenario, probably).
I have a Century41 A/P on my Beech and love it it has GA mode (pitch up) and full Flight Director. I flew recently a coupled ILS and was amazed hoe well it preformed given the heavy X-wind during the final Approach.
Its fully integrated with auto slewing on my SN3500 flying an LNAV approach (KLN90B) goes very well…(don’t see a need for GPSS steering upgrade yet with teh current set-up.
From the website:Unlike competitive autopilots which are either rate- or position-based, the Century 41 uses both for more precise control and a smoother ride. Other features designed to reduce pilot work-load and fatigue include precisely synchronized pitch attitude and altitude hold modes, a pitch modifier, automatic and manual electric trim, and automated preflight testing. Anticipative VOR/LOC/GS capture automatically compensates for ground speed, intercept angle, wind direction, and distance from the station. “Automatic gain reducing soft enroute VOR tracking” means perfectly mannered station passage.
When using the go-around mode in dealer installed systems, the pilot has only to press the go-around button, clean up the airplane and add go-around power. The autopilot flies to a calibrated pitch up attitude that is set for the single engine safety speed of the airplane and heads to the pilot preset go-around heading
If anybody in Germany is looking for a very good autopilot specialist – contact Martin Scheifl at Avionik Straubing. He’s one of the few guys I know who understands this stuff, other than (let’s say) the German Cirrus Dealer who told me that “everything is okay” when it was not and the A/P disconnected itself 5 times per hour …
In order to use an FD and/or AP correctly training is required by someone who KNOWS the system not just about it or who reads what is on the forums.
Really? I got much farther by reading the manual and grilling the manufacturer on the forum than by flying with any boffin who might be a superior aviator but does not have in-depth knowledge of a specific autopilot.
Getting good avionics training is very difficult because there are very few people who really understand it well, given the large number of devices and the differences in installations. One exception might be the Cirrus with a very standardized environment but show me a CFI who really knows more about the Avidyne R9 than I would if I owned an airplane and spent significant time reading all documentation and the forums.
I know “somebody” who got his EFIS checkout by a CFI who I think has never flown an aircraft with an EFIS
