John and everyone, thank you for your attention to this.
Can't immediately see which model you are looking at but the comments are generic.
Aircraft in question: PA-28RT-201T
Actually it's built in another country under license from Piper, but the specs are the same.
Not too sure what you mean by "buffer" but let's not get bogged down with that one.
I meant CG range, sorry, english isn't my native language.
I've got another PA-28RT-201T w&b form to compare its empty weight CG.
I'm doing unit conversions here, so I'm going to be very specific in decimal places.
- Aircraft I'm worried about:
Basic Empty Weight and CG: 1808 lbs (820.24 kg) / 79.96 in (2.031 m)
- Other comparison aircraft:
Basic Empty Weight and CG: 1 876.6 lbs (851.2 kg) / 82.24 in (2.089)
According to both aircraft serial numbers and the AFM, they are the latter ones produced, so I suppose there shouldn't be a large discrepancy.
As you can see, the comparison aircraft has a BEW CG closer to the CG range, but it's not that different from the 1st aircraft.
I was actually putting in question the maintenance personnel who did the latest Empty Weight and CG measurement, but after comparing to this other aircraft, I don't think its a miscalculation anymore, since they were weighed on different places.
Since there is the fact my calculations must be wrong, I'll give you 2 examples of how the aircraft is being operated.
The units will be metric, hope you don't mind:
(You're welcome to redo the same calculations in Imperial units)
Basic Weight - 820.24kg - Arm 2.031 m
Pilot & Copilot - 130kg - Arm 2.04 m
Pax Rear Seats - 0kg - Arm 3.0 m
Fuel 190L*0.72 - 136.8kg - Arm 2.41 m
Baggage - 5kg - Arm 3.63
Total - 1092.04 kg (2407 lbs)- Total Moment - 2278.9454
CG = 2.09 m (82.28 in) -> Out of CG range envelope
Another common configuration used:
Basic Weight - 820.24kg - Arm 2.031 m
Pilot & Copilot - 157kg - Arm 2.04 m
Pax Rear Seats - 60kg - Arm 3.0 m
Fuel 291 Liters*0.72 - 209.52kg - Arm 2.41 m
Baggage - 3kg - Arm 3.63
Total - 1249.76 kg (2755 lbs)- Total Moment - 2682.02064
CG = 2.15 m (84.64 in) -> Out of CG range envelope!
If the weight was below 2240lbs, since it's more heavy, the CG further forward of the limit, and this configuration is with a full tank, used for at least a 2 hour flight, meaning that at landing, the fuel burned will be approximately 191L (50L per hour), meaning the CG will have moved further forward to 2.13 m (83.86 in), endangering the operation even more.
According to john's cited TCDS:
Center of Gravity Range (+89.0) to (+93.0) at 2900 lb.
(+85.0) to (+93.0) at 2240 lb. or less
Straight line variation between points given.
Moment due to retraction of landing gear (+819 in-lb.)
"is it 3 or 4 inches forward of the cg limit (if the forward limit is 85 inches, I'm talking here 81, 82 inches) not to worry about?
I do hope that you are not serious with this question. "
John, since all I hear here from supposedly more experienced pilots is that W&B for these aircraft are all wrong, or when I question them about this, they tell me that there was probably an AFM revision update, so I shouldn't rely on my AFM copy at hand (and I wondered, I never really knew of any aircraft that had such a manufacturer AFM revision to CHANGE the envelope of the aircraft, or in other words, to actually change the CG range. But that's what I keep hearing.)
And then, the original AFM is nowhere to be found, but I honestly don't believe the envelope did change.
One other person told me his instructor once told him that just a few centimeters (or inches) off the limits isn't a concern, since all you have to do is rotate with a little higher airspeed, I dropped my jaw.
But with so many persons here telling me this, I was questioning my judgement.
I'm coming here to this forum as a last resort, since no one here really bothers even to listen to my concerns.
I think it's a dead serious matter, but I can't call the attention to anyone here, specially the ones who fly this aircraft.