Malte,
nice table, quite informative too. I’d love to get it for my database in excel format.
The question of course is: Who is flying with fuel for just 90 minutes on board. And how do you insure that there is never more fuel than that on board before you take the airplane.
Of course the only way to do this properly is to make a wnb every single time you go fly and take action if you see it can’t be done. That is where many people cave in and fly anyway if they see that they are over gross. Particularly if you rent, how do you assure that the plane is not fuelled over what you can take? The question then is what can the plane take with full fuel?
There are some planes which have a very practical “filler neck” which allows accurate fuelling to a certain level. The PA28 series have this in some models.
It surprises me that differnce training is not mandiatory for types never flown, even within the same class rating. I am aware that in the US it is the insurances which usually dictate such a training, not the FAA, but I don’t know any school or rental organisation who would rent out planes to someone without any experience on the type. Personally I would not fly a plane I’ve never flown without difference training with someone of whom I can learn something. And even within the same airplane type, there are huge differences in equipment and how they have to be operated. So even if it’s not mandiatory, I would definitly do it, particularly if it is a step up from what you flew before.
What we do when we introduce a new pilot to the airplane is to supply all the documents for self study plus a questionaire we fill in during the first lesson of difference training which covers all aspects of the airplane such as technical, avionics, performance, administration. The difference training itself with a reasonably experienced pilot will include usually 2-3 sessions in which normal and abnormal ops are covered, landings with various flap settings, at least one flight is done at MTOW. I was under the impression that it is a legal requirement but certainly we require it to be comfortable with a new pilot and the new pilot to be comfortable with the airplane and it’s rather complex avionic. I suppose it’s just good airmanship to get introduced to something you have not flown before with someone who has. I don’t know any rental organisation who allow people to fly planes they have no difference training for. Many even require a certain number of landings on type per a time period to stay current. With today’s many 12 hour per year pilots, that is something which can be quite useful.
Mooney_Driver wrote:
Of course the only way to do this properly is to make a wnb every single time you go fly and take action if you see it can’t be done. That is where many people cave in and fly anyway if they see that they are over gross. Particularly if you rent, how do you assure that the plane is not fuelled over what you can take? The question then is what can the plane take with full fuel?
In my club we solve this with a policy that the aircraft are never to be refuelled after a flight and when they are refuelled, do not put in more fuel than you need to feel comfortable. I.e. there is no point in having full tanks (≈5 hrs endurance) for a 1 hour local flight.
I am myself on the heavy side and haven’t had problems.
Mooney_Driver wrote:
Of course the only way to do this properly is to make a wnb every single time you go fly and take action if you see it can’t be done.
Yes but you can also this properly in your head in many cases (not all), if you have carefully studied the loading moments and done several pre calculations for common loadings. That way you can be sure that your are within the limits for that flight. It also ensures you actually understand what your doing as opposed to just doing something by wrote…
You can apply the same for take and landing distances etc. When I did differences training (that required a signature) I would ask a student to do some basic calcs to show me that they understood the relevant limitations of the aircraft.
As I posted before, it is practically impossible to overload a TB20 other than exceeding the MTOW. So the w&b stuff is pretty simple: just add up the weights, and fly if ok.
When I was doing my JAA IR, the examiner didn’t quite believe me so he downloaded the POH and checked it, and the following day, when we did the test, agreed.
The only time you can get close is when e.g. you are flying back home alone but are carrying luggage for someone who is flying back on an airline 
It is better to put anything heavy on the back seat, not in the luggage compartment.
You can fuel a TB20 accurately using the markers in the fuel tanks.
Nobody would fly with 90 mins’ fuel. You would have to be brain-dead. Look up the report on G-OMAR for a very fine example of practices in the UK PPL training establishment You should never depart with fuel below the visually inspectable level, which for most piston tourers is about half tanks. The TB20 will fly for about 3-4hrs on that and with an awesome payload.
Peter wrote:
Nobody would fly with 90 mins’ fuel
That is 45min fuel on each tank, gives you 15min flying on each tank
The last 30 min is not what I would call usable fuel or reserves: engine starts to cough at 29min the same way as it does at 1min, if you need to fly on reserves you better have 2h or good rudder and ball skills
The LOW FUEL light comes on when either tank is down to 8 USG, so if you are really pushing things to the limit, you start a timer when that light comes on, and say you are burning 8gph then wait for half an hour and then you know that tank has only about 4 USG, so fly the rest of the trip on the other one.
Running a tank dry is not a good idea. It is supposed to work, but…
Peter wrote:
You can fuel a TB20 accurately using the markers in the fuel tanks.
This feature is simple and works great on the TBs.
Flying with low fuel in a tank is very different from plane to plane.
Some have ridiculous amounts of unusable fuel (Beech for instance) wheres in other models it is actually SOP according to POH to fly a tank dry, even though most people won’t.
e.g. the procedure in the C Mooney goes:
The following method is useful for monitoring remaining fuel.
After take-off with both tanks full, use one tank only until one
hour of fuel is depleted frorn it. Then switch to the second tank
and record the time of switch-over on the elapsed time indicator
on the panel clock. Use all the fuel in the second tank. Then,
the time of fuel remaining in the first tank is the time it took
to deplete the second tank, less one hour.
Obviously that method dates back to before we had fuel computers :)
Mooney_Driver wrote:
the procedure in the C Mooney goes:
Don’t these have wing fuel sight gauges?
They are very accurate on ground (and in the air if you manage to see them )
Urs, I just wanted to correct your claim that most 4 seaters were between 250 to 350 kg, where the data shows the lowes 4 seat SEP has 341 kg useful load. The norm of 90 min fuel was based on the discussion, that lead to this table. Anyway, compare average seat masses for 90 min. among the aircraft and you will see interesting differences between the classes, esp. on two seaters.
Keep in mind, that these are actual real aicraft data and not poh samples. They are weighted by me or the BFU.
