Overweight take off with a Socata TB20

Very good points Tim.
Let me add that if you are overweight, you can more easily compound the two situations: overweight + CG out of lims, since the aft and front limits are likely to more restricted the heavier the aircraft is, so you should move away from the normal CG limits when flying overweight.

I think that @Mooney_Driver is being unfair in slapping down so hard someone who is asking a sensible question of his knowledgeable peers, rather than just trying it.

I agree with the general tenor of responses that being overweight causes performance problems and that being outside the CG limits causes control problems, and also with the view that manufacturers will have done their best to convince their test pilots to push, particularly MTOM, to it’s highest safe figure, to boost sales, so there is unlikely to be much slack in that figure.

But, equally, you might ask, how is it possible for anyone to get a 10 or 15% ferry permit if the aircraft is going to plunge, stall warner squealing, into the sea if they go 1Kg over MTOM? There must be some give and it is perfectly reasonable for @AlexTB20 to ask his friends what it is like in that grey area (the answer, as others have stated, is that, derr, the aircraft performs worse, and you have to go faster to take-off and you will climb slower, so need much longer runways and more forgiving terrain.)

But there is also the question of CG and, I agree, no-one in their right mind would set off knowing that they were outside CG limits. But, fortunately, there is still some experience available. I have accidentally been outside CG limits a couple of times.

The first time was in HS125 when a cargo securing bolt broke from the floor in turbulence and two tonnes of mail bags walked to the tail. The result was that the autopilot disengaged and the aircraft became longitudinally unstable, requiring the pilot continuously to move the nose up and down to counter instability. This is horrible.

Thank goodness, we were two crew and, as the PNF, I was delegated to go to the back and manhandle the bags to the front and secure them again. Hands up anyone who, even as a young man who goes to the gym every day, has moved two tonnes of cargo in a cabin altitude of 10,000’? No, I thought not. Well it took me over an hour, I was absolutely exhausted and pretty much fainting. Only by regularly going back to the flight deck and using oxygen was I able to do the job at all. Don’t fly with a CG outside rear limits.

The second occasion was more recently in a Chieftain. We had removed the seats to load cargo, but the first flight was positioning to collect the cargo. I, stupidly and unthinkingly, carefully did the W&B on the cargo leg, but forgot on the empty leg to remove the seats from the calculation, meaning that we had about 150Kg less than normal empty weight, all of it behind the spar, some of it several metres behind the spar. ILAFFT.

On take-off and for most of the flight, the boss sat in the one remaining seat in the back to do some work, but he moved forward for the landing.
Two crew, even with the seats, is close to the front of the envelope, so, without the seats, we ended up with a very forward CG.

Presumably because he was in the back, I noticed nothing on the take-off and climb, nor in the cruise or descent, but when I applied full flap for landing, at about 300’ I had to trim a long way back, right onto the stops. With the trim on stops I was able to perform a half-decent landing, but it was a big effort.

When on the ground and settled down in a nice restaurant in Coburg, I called my friend, the late and much lamented Dave Philips, to ask him what he thought what might be the issue and it was he who spotted that I had removed the seats without accounting for them (again, derr!!). On the next flight, with cargo, it was fine, of course, and then, before the last positioning flight, I bought four 25 litre plastic jerry cans to fill with water and put in the back.

So, my experience is the same as what others here say, a little overweight probably won’t kill you, any amount of outside CG may well do.

But at least you now have a couple of datapoints of real world experience.

tmo wrote:

Isn’t your plane a N-reg? Don’t all N-regs have to have English documents? I’d not expect the FAA to accept anything in German…

Not in my experience, says he looking (figuratively) at a maintenance manual for a German manufactured FAA-certified aircraft and happy that I have a translator nearby. It is rather amusing to ask for a translation for some very long technical compound word… which the nearby translator has never before heard.

(That said, FAA policy does sometimes change over 50 years… but not often )

Isn’t your plane a N-reg? Don’t all N-regs have to have English documents? I’d not expect the FAA to accept anything in German…

AlexTB20 wrote:

ad thing Urs will probably read this and will just start with me being disqualified as a PIC. Most probably, our Socata historian @Peter can shed some light on this and hopefully take my side.

LOL, not likely! That is a mistake which is very easily made with the usual shape the on board paper AFM’s are in. First time I looked inside mine was to find whether it had unusable fuel mentioned or not, as the normal POH does not. The AFM did not either…

One question which might make your task of determining the current MTOW easier:

Look again on the weighing sheet you used to determine your plane was 901 kgs empty. Somewhere on that sheet should also be the maximum take off weight. If your plane has been updated, then the organisation doing the weighing should have known about it and put the new MTOW in. Also, where does the load and balance sheet you use come from? If it s from the former owners and sais 1400 kg, then chances are good it is 1400. Otherwise:

AlexTB20 wrote:

The owners only had to change the flaps motors and modify the MTOW inside the POH. This was simply forgotten in the mist of history and nobody really knows there are some ‘special’ TB20s around there anymore.

buy a new flaps motor with the correct part number and change the POH :). That should be easy work. Better than if you have to buy new wings or somewhat…

but before you do have a close look: I would not be surprised if you already have a new one. Check the part number of the one in the service kit and the one you have. Troyes should be able to help you there or I presume you now have a maintenance organisation who should be savvy as well.

Apart: I looked through the old threads and saw that your difference training was done in 46 minutes by someone the old owners got you? That explains a lot and is not your fault. A serious difference training would usually include at least 4-6 hours and most definitly a theoretical part which would force you to look up the MTOW amongst other things.

Impressive to have an empty weight of 901kg after full TKS

My 2000 G1 TB20 was 912 kg empty weight with factory TKS.

If you scan the paperwork and need some help with german I’m sure the native german collective on euroga can help you out!

I could clearly see the new empty weight, which was listed at 901 kg.

Impressive to have an empty weight of 901kg after full TKS I guess it was empty of fluid, which would be an extra item on the w&b. I think the pre-GTs, especially the early ones, may be lighter. Does yours have a slaved compass system (KCS55 i.e. the KI525 HSI)?

I’ve just flown 65 kg over the MTOW??

I am not surprised nothing was noticed

I know little about the model history but would be amazed if the need for the different actuators was rooted in solid engineering calculations. It is such a tiny % change in the MTOW…

Thank you for a great post