Primarily for general aviation discussion, but other aviation topics are also welcome.
  • 1
  • 3
  • 4
  • 5
  • 6
  • 7
  • 10
By DavidG
#378860
To me, as a relatively new PPL, there are two clear things here:

1. Out of CofG limits - especially beyond the aft limit, will lead to the aircraft being harder to control, or in extreme cases it may be un-controllable.

2. If you're 20Kg overweight at take off, you will fly and be no more likely to crash than if you were on the weight limit. However, if you encounter head winds, or have to divert, being 20Kg under-fuelled will give you a much greater problem!

One question to those in the know - in the report on the AA1, the CofG appeared to be less the 1" behind the aft limit - is there really that little tolerance in the M&B limits that being this far over can give significant problems???

Cheers,

David
User avatar
By Flyingfemme
#378861
Adrian wrote:
Flyingfemme wrote:Others, like our Timothy, will buy a much cheaper machine with more robust performance and take the operating hit.


Or fly it VFR a lot!


Yes....but it sort of negates the usefulness of a big, butch multi :wink:
User avatar
By Flyin'Dutch'
#378862
its the method of getting it to 1999kgs that I am questioning.


Paper exercise.

That is different to the uprated MTOWs that are available to some airframes.

Just because there are similar airframes with different MTOWs does not mean that you can just fly any of those airframes at that MTOW.

The M5 Maule comes in 2 variants. To get the higher MTOW you need to have some adjustments made to the flap mechanism etc.
User avatar
By KevinH
#378864
Moli wrote:Is there a deep rooted attitude of being a bit overweight is okay in GA that can lead to pilots becoming too blase about the whole thing and eventually find themselves in a situation where being overweight hurts.

Moli


You are right to question accepted attitudes as they can often be wrong. You need to start with the POH but then don't assume this is exactly right either. On the one hand the aircraft might be old and not perform as well, on the other hand there may be better ideas for some speeds/techniques that have been tried and tested in the 20-40 years since the POH was written.

As an example I offer the climb information for one Mooney. The POH says 40", full rich , with 75KTs initially and then 90KT. In practice you don't want to climb to 10,000 ft using 40" full rich nor do you want the lack of cooling you get from flying at 90Kts with the turbo at full tilt. So you ignore the POH nd take advice from people who have flown them for years and decide to climb at 105Kts using 36" and with some leaning. The effect is that you use 60% of the fuel, have a cool engine and the difference in performance isn't that great.

My own opinion is that, under certain circumstances, the MTOW is an example of something which can be bent with experience but not through ignorance. If you know the effect of being 5% overweight and know that identical aircraft in the US are heavier then it does no harm. If you put too much weight on board and don't know you have done it then this is in the same league as forgetting to put in enough fuel.

One of the crashed from November has an aft CofG which is quite different to being overweight. Being overweight is one thing, putting that extra weight at the back is silly. In this case the trim was full nose down so it must have been bad.

In the second crash the CofG was within limits but the aircraft was heavy. The AAIB say this would have increased the stall speed by 2Kts. This is a tiny difference, which might have played a tiny part but the real issue was turning back and doing so by using a steep bank angle.
User avatar
By Flyingfemme
#378867
critic99 wrote:Anyone care to post what overweight they have operated to safely in a 172 or PA28? 30kgs? 60?


I've personally flown a PA28 about 500lbs overweight. It wasn't a particularly pleasant experience and I have no urge to do it again. Takeoff required every bit of the available 11,000 feet and climbout was pathetic (not to mention finely balanced). I also had the benefit of some of the best advice available.

Don't forget that you have to burn off a lot of fuel before you can safely land again. Put that one in your weight and balance calcs - chucking out the odd passenger before touchdown may not be too popular :oops:

The other thing to stress is that, whatever the weight configuration, you never launch unless the CofG is within limits - at both ends of the leg. This is done the old-fashioned way - with pen and calculator - since the graphs only cover the normal operational envelope.
User avatar
By Moli
#378873
Hmmm very interesting. Thanks for all the replys.

Moli
By Lefty
#378998
I've found when renting in the US that they are very prone to refueling right to the gills after every flight.

At Ralegh Durham last year they were astounded when I told them I planned to fly a 172SP with 4 POB, they told me it could only be flown 2 up. When I argued that you could take 4 if you didn't have full fuel - they argued that they always flew with full fuel and 2 up.

I insisted that I wanted the aircraft with 3/4 tanks for my trip (with 4 up). I got it. But it took a whole lot of discussion and leaving personal notes with the refueller, in the aircraft and with FBO desk to get it organised.

Still the flight out to Wright Flyer Field at Kittyhawk was well worth it. (even if I did need to refuel at Mantea on the way home).
By Paragon
#379025
It would be interesting to hear from FIs on this subject. Particularly those who teach on C152s and PA38s.

I have a friend who shall remain nameless who recently had a guy turn up for a trial lesson in a 2 seater and who weighed approx 145kg. (320lbs) This put the aircraft in the region of 70 kg (150lbs) overweight. Thats around 10%.

Now, whether or not the aircraft or pilot can handle this, there is a safety leaflet in my office stating the need to remember that operating an aircraft out of its limits is illegal and perhaps invalidates all insurance. Very significant for an FI in this day and age.

It says "Instructors are reminded to check that they are opeating within the loading and performance limitations of thei a/c on every flight. Operating an a/c outside it max weight and CoG invalidates its CofA (and most probably its insurance). Whether done knowingly or unwittingly this is dangerous practice on any flight and is in contravention of ANO Article 52. On training flights this sets a poor example to student pilots...."

However, I do not hear instructors refusing to fly 2 seaters, probably because everyone eles is doing it and if they didn't some other 200hrs Frozen ATPL would come along and fly it.

What the solution is I've no idea. If its not necessarily dangerous, but is illegal do you still refuse to fly thus necessitating the need to find a new job to pay the bills?
Last edited by Paragon on Fri Nov 10, 2006 11:20 pm, edited 1 time in total.
User avatar
By LIONHEART
#379026
However, I do not hear instructors refusing to fly 2 seaters, probably because everyone eles is doing it and if they didn't some other 200hrs Frozen ATPL would come alon and fly it.


My "fleet" includes PA38s. I'm a sort of well built macho type of guy (ie fat); so I don't go near them with a passenger. I simply erase them from my thoughts as an available aircraft. Why? Cos I refuse to fly overweight - my choice - my life.
User avatar
By Duncan
#379037
There is a Seneca V with all the kit at our field (registered with the under Euro charges 1999kg MTOW).

Fill up the tanks to full and its useful load is UNDER 100lb. So did Piper really design a fifth generation plane that when an owner ticks all the options on his order renders the plane useless to anything other than a bulimic pilot with no friends or family.

So the answer......fill the tanks to the tabs...............oh sorry can't do that as its a Seneca and does not have tabs and you can't see the fuel in the tanks unless quite full :wink: So the practical answer - fly overweight its only paperwork that makes it a different aircraft to the ones in the States. Know your plane!

My aircraft was issued with a 10% overwieght permit which increased MTOW by 300lb in a 200hp single. Nice to know it handles it in its stride.
User avatar
By BigCat
#379046
My 172SP, a 2004 model, has an MTOW of 2550lb but with an empty weight of 1731lbs so with full fuel (318 lbs) it becomes a 2 + 2 seat aircraft or 2 seats with lots of luggage. The C o G limits at MTOW are quite generous and I have never found a situation where I have come close to being outside these even with 4 adults on board and a much reduced fuel load. Checking the weight and balance, is just part of the planning process and with FliteStar it takes less than a minute and then knowing where I am within the C of G limits I 'm prepared for any subtle changes in the handling.

Of interest I also have the delivery certificates and note that for its ferry flight to the UK it was certified to operate to a maximum overweight condition of 130% and 2860 lbs max within specified C of G limits. There were several other restrictions on cruising speed, VNE, not to overfly cities etc. For the longest leg of the flight from St Johns, Newfoundland, to Cork in Ireland (log =12 hours and 37 minutes) it weighed 2785 lbs and carried 146 USg of fuel. So this implies the 2550 lb could be exceeded by a small margin without harm but as it's not specified I don't and that's my choice. I wonder how long the take off run at St John's was?
User avatar
By AlanB
#379047
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.

For the better (stalling as opposed to ripping the wings off that is)....

I have a nice Excel spread sheet. Enter the loads and positions and it calculates max weight and plots the C of G.

I think everyone who has flown a PA28 type has probably or will probably fly overweight at some time.
User avatar
By AlexL
#379054
I'm making the Assumption that we all understand that flying outside CofG limits is an absolute no-no, and this is a discussion of weight, rather than weight and balance.

I think there are two separate issues here on the weight issue.
What people do on their own time, with there own dollar is really up to them. However if you have a paying punter, who doesn't know any better, turn up to a flight school, then I think that it is absolutely out of order to operate the aircraft outside of limits (bear in mind that it is illegal). wether or not the weight issue caused the accident, the school, adn the estate of the instructor, have exposed themselves to financial risk by doing this in this case. Even if the family of the dead student don't seek reparations, its highly likely his life insurance company will.
I know how close to the edge (financially) most schools have to operate in this competative environment. They have already lost an aircraft that will be uninsured, and there is possibly more to come. Is the risk / reward scenario for operating overweight really worth it for a commercial operation? I think not.
By SteveX
#1839012
I'm interested to know from this old discussion what others think would work in terms of overweight in a C150/152. Clearly 100kgs is unacceptable (to me at least although perhaps not with a ferry tank across the Pacific). But ignoring runway length, assuming one is ok with a climb rate of 500ft/min (rather than 1000 in a lighter aircraft), what would be a guess as to an upper limit? 50kg?

As for balance, I assume with the above that an imaginary line beyond the top of the chart that shows it 'would' clearly be within balance at that weight is ok. I'm talking about just off the published charts, not something daft eg 300kgs overweight.
By As I CFIT
#1839014
SteveX wrote:But ignoring runway length, assuming one is ok with a climb rate of 500ft/min (rather than 1000 in a lighter aircraft), what would be a guess as to an upper limit? 50kg?


My guess would be that the MTOM constitutes the upper limit.
JAFO, AndyR, Flyin'Dutch' liked this
  • 1
  • 3
  • 4
  • 5
  • 6
  • 7
  • 10