In permit world:
The builder of an experimental can declare his own max take-off weight but if he imports that aircraft to the UK he may find a different set of rules apply!
in the microlight scene, there is hardly ever a departure that isn’t over MTOM.
That is perhaps too much said. Myself will never take pax on long flights, because of weight issues (among other reasons). At several clubs I know, it is common practice to plan a tour abroad for one or two weeks, flying all the microlights with two people on board but have one with a single pilot who will take the majority of the (very limited!) luggage.
That said, very many microlights are indeed flown overweight routinely, not only because of people and luggage and fuel but also due to the vast amounts of options that some people install. Germans are especially good at that, and I’d not be surprised to find the Italians even better.
And – not entirely proud to announce the fact: I have never done a weight and balance sheet for my microlight. There is no point really, as I never take luggage, rarely fly with a passenger, and the variable factors (pax, fuel) are on or very close to the centre of gravity anyway. The one thing I could perhaps do is to fly some circuits with increasing loads in the, ahem, luggage compartment and judge the effect on flying characteristics. And yes, fill out the official sheet for once and forever and add it to the, ahem, documents. I really should, one day.
achimha wrote:
Being overweight is not a huge problem as long as
It is if you crash and survive! It also leads to increased fatigue life on many components. I.e. landing gear, engine mounts, wing mounts etc. etc. that were all designed with a certain weight in mind. Also the airworthiness limits (such as maneuvring speed, Vsi, Vso, maneuvring loads) are designed with a certain weight in mind, so your airspeed indicator is no longer accurate either.
If a pilot takes off overweight, he is are deliberately reducing his margins that have been put in place to keep him safe. I suggest he/she has a good look at his/her personality to see if he/she suffers from a macho, or anti-authority treat.
It’s not advisable to estimate the weight of people. Based on my extensive experience of weighing people (1000’s), some people look very slim, but weigh a “tonne”. Others looks like they weigh a “tonne”, but are surprisingly light. If you get anywhere near MTOW, you need to use accurate weights.
Regarding the CoG. Again, there is a margin for your benefit, so why ignore it.
It doesn’t look good on a ramp check either. 
Archie wrote:
If a pilot takes off overweight, he is are deliberately reducing his margins that have been put in place to keep him safe. I suggest he/she has a good look at his/her personality to see if he/she suffers from a macho, or anti-authority treat.
So you’re making a statement about 80% of the PPL instructors? I’ve mentioned the C150/C152 training fleet before. It all starts there!
It’s not that simple, a “flying overweight is bad and people doing so are bad” doesn’t work. It’s being done all the time and should therefore be done with appropriate knowledge which comes from open and informed discussion.
If people understand that a rearward COG at MTOM is much worse than 100kg over MTOM with a centered COG, we’ve already made progress. Countless times I’ve seen those C172/Archer with 3 strong guys going for a summer day outing, not knowing how close to disaster they are. And putting people on a scale just doesn’t work. I have rarely ever seen that being done. It just doesn’t feel appropriate and there is a great reluctance, it’s basically an insult to your passengers because you don’t trust their statements.
If I go on a VFR trip with 3 guys and a C172 I might have two options:
1) Plan with 15 min fuel reserve: LEGAL
2) Fly 50kg over MTOM: ILLEGAL
I would always go for 2) because it’s safer and smarter. So you can’t reduce this to the legalities, you have to know what you’re doing.
I tend to agree with Achim on the need for knowledge of how to play this.
A huge % of performance related accidents in GA have overloading as a component. Some of the worst ones I recall are ones where the plane never got out of ground effect and crashed at a fairly high speed and consequently caught fire. This happens with grass runways especially, where the required allowance is indeterminate anyway.
I am fortunate that the TB20 is impossible to load out of the envelope without exceeding MTOW – well not unless you have very unusual conditions e.g. a 40kg (probably anorexic) pilot, front RHS empty, 250kg rear seat loading and 65kg luggage. But that amount of elevator authority is very rare in GA.
But it is like instrument flight within the PPL. It isn’t going to be taught for fear of people doing it as a routine operating mode.
NIL: Most FAA N reg’d planes have NEVER been weighed and rely on calculated W&B …
On a recent plane with none or very few mods, this is perfectly acceptable.
OTH, when you have a 40 year old spam can that’s had multiple avionics re-works, paint jobs and who-knows-what-else , well you can bet that it’s REAL weight is going to be well North of the theoretical figure !
I had a new-to-me plane in for Annual and a EDM 900 install last week and after a quick survey of the paperwork, it was evident that the W&B was a joke.
So I emptied the tanks and put the plane on the scales. Turns out it wasn’t that bad, just 50 pounds more than the “old” W&B.
NIL: Most FAA N reg’d planes have NEVER been weighed and rely on calculated W&B …
Well, they have been weighed at the factory. And if W&B corrections (after modifications) have always been done at least half-diligently, you will have a realistic W&B.
One of the good points of being N-reg… Not needing periodic re-weighing.
Not needing periodic re-weighing.
You sure that’s a good thing? Some of the Belgium ultralight owner/pilots could well do with it! (their planes, I actually mean).
boscomantico wrote:
Well, they have been weighed at the factory.
Not true .
Read the Weight & Balance Information in the POH, and you will learn that most [all ? ] are “computated” since the manufacturers’ do not systematically weigh every airframe.
What typically happens is they will pull one out and check it against the "normal’ weight .
This is true for my 1947 Cessna 140 as well as my 2002 Lancair Columbia. When I have a sec I will scan & post the appropriate pages .
Perhaps you can show me a “real” weigh sheet performed at the factory on a new aircraft ?
Well, all Cirrus aircraft come out of the factory with very different weights.
While I don’t know how they do it (either weigh them or just “calculate” the empty weights based on exact model and options installed) but either way, I am confident that the numbers are quite accurate.
