Learning to fly, or thinking of learning? Post your questions, comments and experiences here

Moderator: AndyR

By onedaypro
#1624306
I have my PPL skills test in a few days.

I've gone over the W&B for the C152 I'll be conducting the test in a couple of times. Each time the airplane is slightly out of the COG gross weight/datum limits (beyond the envelope marked on the chart). The plane is full with fuel, 2 POB, and 10kg of luggage.

I can only assume this is common practice and the logic would follow that having done some taxying, power checks and the take off roll the plane will have burnt enough fuel to fall within the limits? I'm thinking this will be the answer the examiner would be looking for?

Thanks
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By Dusty_B
#1624313
It is up to you to ensure the aircraft is within its limits.
If there is a maximum ramp mass published, that must not be exceeded.
At the start of the take-off roll, you must be within CoG and at or below MTOM. How much fuel may be assumed to have been burned during start-up and taxi *may* be in the POH or in the school’s Ops manual. If there isn’t a figure, you’ll have to assume zero and taxi within limits too.
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By Morten
#1624334
You may want to ditch the luggage. Or maybe add to it if you have margin on MTOW but are forward of the CG.
Or just not fill the tanks to the brim.
I assume you have asked the examiner for his/her weight?

If it happens with the examiner, it should also have been close to happening with the instructors before - has it not been highlighted by them before?
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By Balliol
#1624335
I'd be amazed if any 152 operated with two average sized adult people and full fuel would be within limits to be honest, every test I have ever done in one has had to be below full fuel.

Most have a usable load of about 500lbs, so about 8 Imp Galls a side is the most I have seen workable.
By malcolmfrost
#1624349
I presented the W&B calcs to the examiner, and had highlighted that it was slightly over MTOW. I just said "however, that's assuming the tanks are completely full to the brim and the runway is about 4 times longer than the calculated take-off run. We'll be under the MAUW within about half an hour and I'm comfortable with the handling characteristics as my instructor is a similar build to you. As it is a really hot day and we have a lot of runway available, I'll intend to use a slightly higher speed for rotation".

Crikey, you were lucky!
I'm not sure what the insurance company or AAIB would say in those circumstances....
My recent skills test, the examiner told me his weight and as a result I had to limit the fuel to "tabs" or put a sack of cement in the baggage to keep within the forward limit.
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By Dusty_B
#1624360
Yes, yes you should have been more acurate!
YOU are (acting as) the commander of the aircraft. If it is overweight, it is uninsured and you are a test pilot. Demand the aircraft is defuelled (the school knew you were going to be on test with a particular examiner, so they shouldn't have allowed the aircraft to be fully fuelled), or demand another airframe.
By iaindings
#1624369
On reflection, I've removed my comments. Not for personal pride or anything like that, I'm inexperienced and still learning myself - I mentioned my experience partly as a desire to reassure the OP that it might not be too big a concern on test day but in reality I can see that this could be taken in the wrong context or encourage others to make bad decisions around W&B which wasnt my intention.

I'm fairly confident that my flight was safe, I think I just approached the problem a bit back to front and that something I personally can learn from
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By Paul_Sengupta
#1624384
malcolmfrost wrote:I'm not sure what the insurance company or AAIB would say in those circumstances....


Well, all I can see is "deleted", but I take it he didn't crash, so I wouldn't have thought they'd have anything to say in the matter...

Dusty_B wrote:you are a test pilot


Though repeating the same tests that have been flown ad-infinitum since at least the 1970s! :D
By iaindings
#1624387
Not wanting to derail this thread with (deserved) criticism of my approach, and nor do I want my comments to be misunderstood leading to people taking risks.

The reality of my comments, which I could have worded better is that I made the mistake of doing the W&B calcs in the planning part of the test based on maximum fuel, which I then discussed with the examiner. I checked the fuel later in the morning and was satisfied that it was sufficient based on my fuel planning and top-of-head calculations said it would be under MTOW. I shouldn't rely on top-of-head calculations and in reality I should have used the W&B sheet to calculate how much fuel we could carry safely and ensure the aircraft was fueled to that level - which is what the OP should do.
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By onedaypro
#1624389
Thanks for your comments. I wont find out the NAV route until the morning of the test therefore I cannot complete a PLOG and the fuel required. The plane will probably be refilled to full the night before thus it's going to be overweight. I think I'll have to phone up the day before the test and ask for it to be filled too three quarters of a tank. This will give me 3 hours flying time with enough capacity for diversion aerodromes + a spare 45 minutes on top. I can always request more fuel on the day if appropriate.
By TopCat
#1624411
onedaypro wrote:I can only assume

Never assume in aviation. One day, your assumption will be wrong and you might die as a result, or kill someone.

Take the trouble to find out. Do the W&B calculation with varying amounts of fuel - including the difference between full, and amount you'll burn in the taxy and runup - and find out for sure which way the CG moves and how far

Sorry to be blunt, but 'I can only assume' really just means 'I can't be bothered'.
By malcolmfrost
#1624413
Thanks for your comments. I wont find out the NAV route until the morning of the test therefore I cannot complete a PLOG and the fuel required. The plane will probably be refilled to full the night before thus it's going to be overweight. I think I'll have to phone up the day before the test and ask for it to be filled too three quarters of a tank. This will give me 3 hours flying time with enough capacity for diversion aerodromes + a spare 45 minutes on top. I can always request more fuel on the day if appropriate.

That sounds a wise way to deal with it. :D
W&B is all guesswork, the only thing you know for certain is the weight of the aircraft when it was last weighed! Is 100 litres of 100LL heavier than 100 litres of UL91? Warmer fuel weighs less than cold, etc. What you can't do in a test situation is discover you are overweight, then adjust your flying techniques to mitigate it!!
In the big aircraft world, there are aircraft taking off all the time without knowing their precise weight, after all there aren't weighbridges at the holding points! Assumptions are approved and best estimate weights used. A loadsheet can't even be issued that is overweight.
#1625681
I am a PPL examiner. Please don’t come to me with a weight and balance calculation out of limits telling me you are confident it will work.
I will check the fuel in the aircraft too!
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