Primarily for general aviation discussion, but other aviation topics are also welcome.
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User avatar
By Moli
#378627
Having just read through some of Novembers AAIB reports (not usual for me but there were a couple I particualrly wanted sight of), I was amazed to read that in 2 fatal GA accidents, aircraft were significantly overweight.......180 & 140 Lbs.

Without commenting on specific incidents, how does this happen? Are some pilots completely unaware having forgotten what they were taught? Do some pilots become or have they always been chancers and are prepared to take excessive risk? It astounds me how this could happen, a few Lbs perhaps a miscalcualtion but a whole person overweight in a 2 seat ac :shock:

Moli
User avatar
By Adrian
#378634
I suspect that if you weighed them, you'd find that most small 2 seat training aircraft are overweight just before their first take off of the day. I think a PA38 has a payload of about 230kg, so if you put two typically overweight pilots in it, together with a bit of junk in the cabin, then fill the tanks (so that you can have a quick turnaround between lessons), it will be considerably overweight.
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By KNT754G
#378640
Similar situation in any C150/152 with two reasonable sized adults and full fuel.
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By ray
#378643
KNT754G wrote..

'Similar situation in any C150/152 with two reasonable sized adults and full fuel.'

I agree, but it seems common practice at many training schools to do this in C150/152's, does the POH need re writing, or are they really pushing their luck (and setting an apalling example that might later have terrible consequence)?

Doing a proper W&B in some PA28's (not just PA28-140's either) can also be a sobering experience - we abandoned one trip when we reckoned we could take about 5 litres of fuel with us :shock:

The 4 diets are slowly working, and I'm trying to fly the Arrow 3's more often!

Ray
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By Flyingfemme
#378647
Overweight is not as dangerous as out of CG. In a ferry configuration it is quite common to fly smaller aircraft up to 25% overgross - that's a lot of fuel! Care is required for the first couple of hours and the difference, on climbout, between stall and progress is a breath on the yoke.
By johnm
#378649
The MTOW is set if I remember so that the aircraft will achieve its book performance figures and probably has a bit of a margin for variation in engine performance.

If you can sacrifice performance you can overload a bit, but I'm always uneasy about the view the insurance company would take if anything went wrong.

My Archer 2 will take 4 adults luggage and tabs fuel and just fit in the envelope. A bit more fuel doesn't have a big impact on performance but takes it outside the envelope and makes me nervous. It doesn't bother the aeroplane at all :)
User avatar
By Captn P
#378651
KNT754G wrote:Similar situation in any C150/152 with two reasonable sized adults and full fuel.


I can confirm that.


As to your original question... I think this is a case of understanding what the weight limit means and why it was set. Putting aside that fact that these are legal limits So taking the example of a 172 if you look at the changes in all up weight over the years some of the reasons that the wieght changed are quite interesting. One of the weight changes involved lowering the service ceiling by 1000', this led to an increase in wieght of 50 lbs. Another change was when the flap angle was restricted to 30 degrees. So if your were flying an early 172 and your wieght and balance came out 100lbs over I could see the logic in saying. I won't use 40 degrees flap on landing and I'll be ok.

Another factor is that most of the time that you fly you don't fly near your full weight, so I think the tendency is not to calculate the wieght and balance as a matter of course. As this is not a habit I would guess (and in my opinion, my opinion only) that this calculation for a lot of pilots is just not done.

Cheers
CP
By cotterpot
#378661
OK I admit I don't calculate W&B for every trip in the PA28.

What I have done is set up W&B for a range of possibilities i.e 2 up full fuel, 3 and tabs/full, extra luggage, varying temp etc. and am happy that as long as the passengers are within 'range' the aircraft will remain in the envelope.

I will be interested to know what aircraft weighs after its repaint and will re factor results.

As has also been said - when I was training the C152 with full tanks was always overweight with the CFI in it! Had to make sure it was not full to produce an acceptable W&B for the GFT :wink:
User avatar
By SteveC
#378665
I would say it is pretty rare for most GA aircraft to be flown Weight. My 152 was always over weight with 2 adults and full fuel, it was the only way to ever get a trip done. My 172XP actually has a massive payload, full fuel and 4 adults and it is still inside the weight but add a few bags and it goes over weight but not balance.

The Senneca is the same, if I want 6 people I have to leave most of the fuel and bags behind and spinning 2 engines needs a lot of fuel!
User avatar
By Irv Lee
#378671
I've seen elements of:

-"it worked last time"

-regular flying well within W&B (eg: same 2 in a 172 every weekend) and W&B calcs not done more than once, then it is no longer is part of the routine, then after many trips like that, a change of plane or extra passengers happens, and it's never thought of.

-syndicate/club rule' on 'must fill aircraft with fuel every night'. Pilot + pax turns up in morning, find it full, only wanted/needed/should-have half fuel, flies regardless.
User avatar
By Flyin'Dutch'
#378672
I would say it is pretty rare for most GA aircraft to be flown Weight.


Speak for yourself.

My 152 was always over weight with 2 adults and full fuel, it was the only way to ever get a trip done. My 172XP actually has a massive payload, full fuel and 4 adults and it is still inside the weight but add a few bags and it goes over weight but not balance.

The Senneca is the same, if I want 6 people I have to leave most of the fuel and bags behind and spinning 2 engines needs a lot of fuel!


How clever.
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By YellowBirdToo
#378675
Weight (Mass, under JAR) obviously affects gust penetration and vertical loading. Overweight therefore would have a bearing on the Va envelope. For an aerobatic aircrraft this may prove to be even more significant.

As far as Cotterpot mentions, this is a perfectly allowable and sensible way of operating. It is also legal provided that the flights are private. As the Commander you must 'satisfy' yourself regarding the loading of the aircraft. Therefore, you need not produce a loadsheet in this eventuality.

m
User avatar
By Dave Phillips
#378682
I certainly recognise Irv's scenario. Ordinarily, we fly our 172SP 2-up (+Dog :D ) and on full tanks. Do the W&B and you will find yourself nicely placed within the 'envelope' with no need to even consider re-checking each time you fly. I suspect that there are those who would replace Dog with another forty-something adult and a couple of "hand-baggage size (!)" bags in the compartment without doing the W&B (and for us shortish field operators the TODR).
User avatar
By Pete L
#378685
But a PA28-161 with two adults will be well below weight and beyond the forward C of G. No dog, so all the **** goes in the baggage compartment.
User avatar
By Dave Phillips
#378686
Pete L wrote:But a PA28-161 with two adults will be well below weight and beyond the forward C of G. No dog, so all the **** goes in the baggage compartment.


I could lend/hire you the Dog. :lol:
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