Weight and balance question

[integritywood]

Just trying to amend my weight and balance with my larger tires. Found TCDS lists tire arm under listed equipment as 22" My weight and balance document has weights on wheels figured as 21". shouldn't this be the same. Have a question as with two of us and full fuel I've needed 50 lbs or so of ballast in baggage compartment to bring c of g into envelope moving the 1200 lbs or so on the wheels to 22" as TCDS says for tire arm would take care of a bunch of that. I have 48 with early soft gear.

[Bruce Fenstermacher]

The wheels are located at +22. If your W&B says otherwise it is wrong. Here is another mistake that is made. ALL 170s came with the Scott 3-24B as the standard tailwheel. The arm for that wheel is 246. Most 170s have been converted to the Scott 3200. This tail wheel has an arm of 249. If a mechanic looks at an original W&B report for the datums for the main wheels and tail wheel he may get the wrong one because it might be for the 3-24B and the airplane has a 3200.

BTW most Cessna's have never actually been weighed. At the factory they used a calculated weight for most coming off the assembly line. This calculated weight was corrected for equipment installed or not installed from the base line. Then of course mechanics have added or subtracted as needed.

My current 170A has never in it's history been on a set of scales. I started at day one and made a historical record of weight and balance changes for all work performed to this day and made several corrections. For one the W&B weight still accounted for a stretcher installed in the stowed position.

[bagarre]

BTW most Cessna's have never actually been weighed. At the factory they used a calculated weight for most coming off the assembly line. This calculated weight was corrected for equipment installed or not installed from the base line. Then of course mechanics have added or subtracted as needed.

Mine will be on the scales for the first time in her life this annual. I currently have no honest clue what she weights as the equipment list over the years is comical.

[integritywood]

If I redo the weight and balance calc with wheel arm at 22" then my instructor and I only need 20 lbs or so in baggage to keep us in envelope instead of 50. I'm also hoping to get actual scale weight during my annual next week or so.

[rydfly]

Is there a specific type of scales recommended for this process?

[blueldr]

Hey, Integretywood,

Just as a matter of curiousity, what was the difference in weight between what two sizes of tires you are talking about?

[integritywood]

BL
set of 8.50's weigh 20 lbs more then 6.00
Kim

[blueldr]

Thanks, Kim.