Greetings all,

When the TCDS reads: "Empty Weight C.G. Range, +15.1, to, +21.2, with standard fuel tank only. +15.1, to, +18.3, with Item 309,b, installed. When the empty weight C.G. falls within these ranges, computation of critical fore and aft C.G. positions is unnecessary. Ranges are not valid for non-standard arrangements."

The aircraft doesn't not nave "Item 309,b, installed," can I legally just weigh the empty aircraft, produce a single W&B and if the empty CG is between: "+15.1, to, +21.2," never do an individual W&B on the aircraft again?

I ask because I stink at non-linear geometry and the previous line in the TCDS reads "C.G. Range, +13.9, to, +12.2."

Thanks

Lisa

* Quote modified to remove parenthesis because virus software hates parenthesis.

I wonder how they know that the loaded aircraft is within the CG limits without completing a weight and balance for the load?

What is 309 b? (technically it doesn't matter if it's an engine or an ashtray) If your airplane is not in compliance with the specific description, then you're required to do the aft and forward checks.
I've had a few different airplanes fall in the empty CG range, but I still like to do a few "scenarios" every time I do a weight and balance. It only takes a few minutes.
John

tcj wrote:I wonder how they know that the loaded aircraft is within the CG limits without completing a weight and balance for the load?

You can easily do a theoretical W&B using the limits for each possible load station. On this aircraft "in standard configuration" I can only put 9 pounds at -33, 90 pounds at -15, 200 pounds at +11.5, 200 pounds at +44, and 50 pounds at +64. Maxing each station out puts me at 111% of my useful load. But it is within the CG limits IF THE DIGITS HADN'T BEEN TRANSPOSED IN THE TCDS, "+12.2" was printed instead of "+21.2" which is obviously correct.

Figure the weight and moment of your fore and aft limits in the air and you can easily find where the empty airframe limits have to be when you are at minimum, which as I tried to tell college-boy isn't at empty, and at the max fore and aft full gross weight.

Another "error" in many TCDSs is that some early specifications use as synonyms words that the CAA and FAA later defined with associated but slightly different meanings. IE: "empty weight" and "operating weight." If I took what the dweebs say literally I would balance at -3 to 11 percent of MAC and could legally carry three people in a 2 PCLM. Well, if I don't crash on takeoff and die.

hardtailjohn wrote:What is 309 b? (technically it doesn't matter if it's an engine or an ashtray) If your airplane is not in compliance with the specific description, then you're required to do the aft and forward checks.
I've had a few different airplanes fall in the empty CG range, but I still like to do a few "scenarios" every time I do a weight and balance. It only takes a few minutes.
John

Item 309, b, is an auxillary eight gallon fuel tank. The TCDS gives two empty CG ranges for flight, one for the standard tankage, and one for aircraft with the auxillary tank.

But long ago the CAA / FAA transposed the numerals publishing the TCDS. The line that states the CG in flight should read "+21.2" instead of "+12.2." So the aircraft WILL NOT FLY if the CG is "correct according to the TCDS" unless the TCDS somehow trumps the laws of physics.

Its been this way for decades, but probably hasn't been corrected because its an obvious error. But somebody who is pissed off about another issue wants to be an %^$#@ and make a new issue out of it.

My response is I don't have to do individual W&Bs at all, to be compliant, just a single empty W&B.

Lisa

PS: I don't trust anyone, especially those clueless people who call both Taylorcraft Bs and Luscombe 8s "cubs" when they ramp check them, to protect me. I do theoretical W&Bs on aircraft before I consider flying them. I have three on the aircraft I normally fly tucked in the manual. Just me, me and baggage, me my fishing buddy and baggage. Each of those has a plot line from full fuel and oil to zero fuel and unconsumed oil because the fuel sits well forward of the CG.

Yep, I agree with you. Just one necessary to prove it falls within the EWCG range.... but I'm with you..I have a few that are tucked in the folder.
John