AlexTB20 wrote:
I haven’t flown the airplane with more than 1 passenger or close to its MTOW before.
You did do a type introduction training as you are required to do? Usually a MTOW flight is included in this, I wonder who trained you and thought it was not necessary. I find that training massively deficient if you have never flown the plane close to MTOW.
AlexTB20 wrote:
The intended flight time is about 3.5 hours long, but with the legal fuel reserve for holding time and contingency, I will need about 275 liters of fuel. This will put me almost 50 kilos north of the W&B diagram.
Which makes it no-go. You will need a fuel stop. And apart, legal fuel reserve is hardly ever enough in a GA plane. Particularly in your part of the world there are even large airports that for GA are for all practical purposes isolated destinations without any suitable alternate within 150 NM where reserve fuel can easily cut your flight time down to 1-2 hours even in the TB20.
Usually a MTOW flight is included in this
Never heard of a plane being specially loaded to MTOW during differences training.
I would up the IATA standard weights to 120 kgs per pax, regardless of male, female or child and while this might mean we are going to fly a bit lighter than now, it would err on the safe side
Recently I spoke to an airliner pilot about the allowances they make for passenger+luggage weights and his reply was “the runway is a lot longer than we need” 
I don’t think jet (passenger) transport would work (with the present “call it xxx kg per passenger” system) if one was departing from a critical runway.
Peter wrote:
Vs goes up in proportion to weight, IIRC.
Actually in proportion to the square root of mass, so a 10% increase in mass means approximately 5% increase in Vs. OTOH acceleration in the take-off run will go down proportionally, meaning that distance to a certain speed will go up as the square of the mass increase. So very roughly, take-off distance changes proportionally with mass changes.
Mooney_Driver wrote:
Looking at reality, I would have to say EVERY airliner operating at MTOW or max RTOW is overweight in some regards as it is not possible to determine the correct weight unless they do have inbuilt weight on wheel sensors which do so. Why? They operate with standard pax weights
Don’t airlines also work with average fleet mass for aircraft of the same model, equipment and seating? That would mean that roughly half of aircraft would be overweight if the w&b shows they are at MTOM? But, as you say, this is within what the regulations allow.
JasonC wrote:
The plane can crash and everyone aboard can die.
Although this is absolutely true, this reply reminded me on the answer my brother provided on one exam in medical school. The professor asked him what was the worst complication of burns and he replied death
AlexTB20 wrote:
The intended flight time is about 3.5 hours long, but with the legal fuel reserve for holding time and contingency, I will need about 275 liters of fuel.
I don’t understand the fuel calculation. TB20 burns e.g. 45 l/hour (you can set anything between 40 and 50). 275 l is more than 6 hours of flight (it’s almost full fuel – IIRC full is 312 l). So 3.5 hours to destination, let’s say 1 hour to alternate and 45 min reserve makes 5 hours and 15 min. Why do you need an additional hour? Or your alternate is 2 hours from destination (somewhat unlikely)?
In more conservative fuel burning scenario I would set it to 38 l, have 10-15 min longer flight and end the flight burning some 145 liters in total. Add flight to alternate and 45 min and add whatever you want but you won’t need 275 liters of fuel. I understand it’s nice to have as much fuel as possible but it’s not always feasible.
- The moment you are as much as 1 lb overweight or 1 mm out of CG and it can be proven and written into an accident report
Very true but the reality from many reports that I read is that usually they can only guess the total mass. Passengers with at least some of their stuff are gone to hospital or somewhere else long before any investigator shows up. Often there is a fuel leak into the ground and they can only guess how much was on board. The same applies to the ramp check. The passenger are gone to the toilet while they check the plane etc. This is no excuse to overload any plane as you take care for the safety of your passengers and your own! The risk of getting busted for small MTOW increases however is small which is why this is done so often by many.
Thank you Urs for your blunt answer. Good wake up call about the legal implications, for anyone slowly easing into bending the rules…
However my initial question wasn’t if I can irresponsibly go over the MTOW and simply get away with it regardless of the risks involved, of course that would disqualify me as a PIC. The simple fact that I struggled with W&B calculations taking into account the deicing liquid inside the TKS system (which nobody really cares about) and calculating the system arm for it, planning for 45 mins of holding and contingency, should prove that I am far from that.
Doing the W&B calculations I realized how easily one can go over MTOW, for various reasons, some of them already discussed here (passengers lying about their weight, not taking into account spare parts, TKS system or liquid, oil reserves, tow bar, etc). My question was specific to the TB20 and I simply asked what can happen if you take 3 passengers and full tanks in a TKS equipped model, simply expecting an answer from Peter or someone with a similar airplane.
The rest of the conversation was a simple technical exercise, with questions on how the airplane will handle with imaginary 50 or 100 kilos overweight. Of course this doesn’t apply to me or to my intentions, at full tanks and 3 pax I am about 45 kilos overweight, but I can simply take out 25 liters of deicing liquid, and 25 liters of fuel, or simply better manage the baggage weight or trip duration. It would also be stupid to ask on a public forum if I can break the law and get away with it, or expect an answer to encourage me to do so.
It seems I’ve opened a sort of Pandora’s box here, and I am sorry if I have offended anyone with my attitude or hypothetical questions.
Nice to see the the responsible experienced pilots still on guard duty and not too many complacent attitudes on the forum. And hopefully most of us will learn something of value from this, as always.
Speaking of learning, today I will slowly approach the MTOW by taking 2 then 3 passengers with almost full tanks and no baggage, just to see how the airplane feels and how weight affects the handling on take off and landing. Despite flying for about 200 hours with the TB20, and regularly practicing stalls and special procedures, I never had a chance to fly with more passengers or close to the MTOW in this type.
I will let you know how it went.
AlexTB20 wrote:
However my initial question wasn’t if I can irresponsibly go over the MTOW and simply get away with it regardless of the risks involved, of course that would disqualify me as a PIC. The simple fact that I struggled with W&B calculations taking into account the deicing liquid inside the TKS system (which nobody really cares about) and calculating the system arm for it, planning for 45 mins of holding and contingency, should prove that I am far from that.
When you fit the TKS, is a new W&B not issued as part of complying with the STC?
what can happen if you take 3 passengers and full tanks in a TKS equipped model, simply expecting an answer from Peter or someone with a similar airplane.
My TB20GT has an empty weight of 900kg, so with full fuel (235kg) and full TKS (about 50kg) the payload is 215kg. So the Q is: what can you fit in which weighs 215kg or less? Not much, if you want to “go places”. Even with an empty plane, with 3 people, that is 72kg each, which is very unlikely in modern times. An average size man plus two quite slim ladies, perhaps and no luggage.
It seems I’ve opened a sort of Pandora’s box here, and I am sorry if I have offended anyone with my attitude or hypothetical questions.
Perfectly good questions!
Once the illegality has been pointed out, this is a good discussion.
just to see how the airplane feels and how weight affects the handling on take off and landing
It won’t really feel any different, except for the rate of climb. The TB20 has no dodgy handling.
Rather than say 5% over MTOW, a plane suffers much more through conditions like ISA+20 which affects it dramatically: the ceiling goes down from say FL200 to FL160.
