This is basically what caused the recent Boeing 737 MAX crashes
Not quite the same.
The 737 pitch protection looks like having been bodged but the key factor is that the B737 type rating didn’t include the knowledge of which buttons to press to disable the runaway trim.
Whereas in GA the pilot is supposed to know how to turn it off, and it is really obvious. The fact that lots of autopilot owners don’t really know what the box is doing and when, is a separate matter; it is wrapped up with all the other “aircraft systems knowledge” stuff and if you addressed it properly you would have a “type rating” for each different avionics installation, which presumably nobody wants because most people just want to buy a plane and fly it away…
Peter wrote:
It is the autopilot trim servo driving the pitch trim continuously. Certified autopilots that have pitch trim are required to annunciate if the trim has been running continuously for something like 10 seconds, and are required to disconnect the autopilot if the trim has been running continuously for something like 15 seconds. The pilot’s guide for your autopilot should have these details and you need to obtain all these and read through them. Actually a lot of that stuff should be in the AFMSs (flight manual / POH supplements).
This is basically what caused the recent Boeing 737 MAX crashes, so if you have electric trim you must know how to detect and deal with it. This can happen in light aircraft, too. A Cessna 172 crashed on takeoff after an undetected trim runaway when the A/P was inadvertently engaged on the ground. This was with the KAP140 A/P which was subsequently updated with new software to prevent this situation.
Yes Christian is still based in EDLM with his TB20. He had the place right beside me but I moved to northern germany with my plane last saturday. For ever.
@OliverB: I have still a steel locker in the hangar if you‘re interested drop me a mail
Welcome to TB20-ownership and always happy landings!
AFAIK, there is another TB20 stationed at EDLM. The owner, Christian, is a very friendly and helpful guy. I have not been in touch with him for a while but believe his plane is still based there.
What is an elevator trim runaway?
It is the autopilot trim servo driving the pitch trim continuously. Certified autopilots that have pitch trim are required to annunciate if the trim has been running continuously for something like 10 seconds, and are required to disconnect the autopilot if the trim has been running continuously for something like 15 seconds. The pilot’s guide for your autopilot should have these details and you need to obtain all these and read through them. Actually a lot of that stuff should be in the AFMSs (flight manual / POH supplements).
And Can I practice an emergency gear extension? I mean more than once? Is the gear not locker after this extension?
Yes, as many times as you want. It should be tested at least after the Annual service, because various things are then done which might affect it e.g. the two gas struts which lower the nose gear (against the airflow) get replaced.
Follow the checklist procedure strictly. If e.g. the gear pump power is ON when you pull out the emergency release valve, you will trash the seals in the valve, as the pump squirts in the hydraulic fluid at 1000+ PSI trying to maintain the pressure in the system.
If you go to my vimeo videos (they are not all mine; I put some other peoples’ ones there also, for hosting) here and put “gear” in the search box, you will find various videos showing the landing gear operation. Also here and here.
Thanks for the helpful Tipps.
I have already read the POH more than once so I feel at least theoretically well prepared for this adventure.
I have two more question:
What is an elevator trim runaway?
And Can I practice an emergency gear extension? I mean more than once? Is the gear not locker after this extension?
Nothing wrong with your plan, but I would add some conditions.
As Peter says, the TB-20 is a pilot-friendly type. No bad manners. Your training should make it clear that manoeuvring does use more geography in the TB-20 than in a Cessna so remember to make more room for turns, especially when you arrive back home and everything looks familiar and you have to turn base.
+1 on energy management, which is not really an issue with the little Cessna’s.
The thing is that while I assume you can absorb all you need to know in the program you describe, and the basic handling will be easy as long as things are normal, you will still not have your normal ressources in case of problems and deteriorating conditions, so your margins for the long flight back home should be wider.
My thoughts: You should plan the flight so well that you practically know all of it by heart including possible en-route diversion options, you should be more weather conservative, you should have peace in mind by knowing not only emergency procedures but also how you will detect any problem. Things like How will you actually detect a generator problem? Will the autopilot work in case of a vacuum failure? What is the minimum runway length you will accept in case you need to land flaps up, and what approach speed is that based on? How will you handle an elevator trim runaway? What are the normal engine and system instrument indications during cruising flight? How will you remember to change fuel tank frequently, being used to aircraft where that is not necessary/possible. How will you remember to lower gear before landing, being used to fixed gear aircraft. You don’t just trust the gear alarm, do you?
And emergency gear extension practise seems to be missing from your plan. I know, in part from experience, that having trained that in the air with an instructor, will reduce stress levels considerably in case of a real problem. As will training any non-normal scenario.
Of course, tell everyone and yourself that you will only depart if conditions are right. And after that, you will only fly all the way to your destination if everything continues to be fine. Consider keeping external pressure low by not telling friends/family your ETA, but rather surprise them by calling after arriving.
I miss the years I frequently flew the TB-20. It could well be the best all-round family tourer in existence. Among many other virtues, you’ll love the ride in turbulence and the cross-wind landings, compared to Cessna’s. Congratulations!
I converted from the C172 to the TB20 a couple of years ago. I did five hours of flying time with an instructor covering more or less the things you’ve outlined and in a similar order, and much more time reading the POH and the manuals for the various bits of kit. I had about 200 hours total time when I converted.
It still took me a few flights on my own to really get the hang of energy management when arriving somewhere. You can’t just chop the throttle, and you can’t easily go down and slow down.
That said it’s a fantastic aeroplane. Congratulations on your acquisition.
Peter wrote:
you cannot arrive overhead the airport at 5000ft and 140kt and hope to land
I think you can. It all depends how many orbits you do! 
A TB20 conversion from the basic training types, for a reasonably bright pilot, is about 10hrs. The plane flies very well and has no vices / weird behaviour, so most of it will be dealing with technical stuff like planning ahead (you cannot arrive overhead the airport at 5000ft and 140kt and hope to land ), engine management and of course very importantly the specific avionics installed. You do have to understand all of it.
