M20C Weight and Balance

[Schinderhannes]

I am currently doing an avionics upgrade and starting looking at the original weight and balance and found a lot of inconsistencies.  For example the direction gyro is listed at station +20.0, the cigarette lighter at station +16.0 and the factory installed KX170 at station 19.3.  Due to the instrument specific CG the lighter should be at least 4"-5" aft of the panel mount instruments.  I measured 28” from the panel to the nose gear support bolt (Datum centerline).  The math on all  those numbers doesn’t seem to add up and I was wondering what the correct station for the panel should be.

 Thank you,

Frank  

 

[Hank]

Frank--

I'm no A&P, but prior to measuring from the datum, the plane needs to be leveled as it does not sit on the ground in the correct attitude. Second, the distances to the various instruments should be measured to the CG of each instrument, which is neither the panel face nor the lengthwise center of the instrument, and will not be the same for any of them.

My Owner's Manual says the Datum Point [station zero] is the nose gear attaching bolt center line, 33 inches forward of the wing leading edge at wing station 59.25. I can't readily find documentation of the panel position. See below for what I have on leveling and W&B of the whole plane, paying attention to 2.10 for leveling and 2.11.8 for finding the zero point.

Good luck!

[carusoam]

You might look to the Type Certificate information for some of the major parts, weight and station....

http://www.airweb.faa.gov/Regulatory_and_Guidance_library/rgMakeModel.nsf/0/60107bc8954c93a686256c24005b5075/$FILE/2A3.pdf

Best regards,

-a-

[rdav]

I had a similar issue trying to decode my weight and balance sheet.  I have a few mods on my plane, and the W&B amendments for each one will have some margin of error.  That error just accumulates the further you get from factory new.  To be certain of the result in the end, I had the shop put the aircraft on scales and give me the true weight and C of G numbers.

[PilotDerek]

Quote: rdav

I had a similar issue trying to decode my weight and balance sheet.  I have a few mods on my plane, and the W&B amendments for each one will have some margin of error.  That error just accumulates the further you get from factory new.  To be certain of the result in the end, I had the shop put the aircraft on scales and give me the true weight and C of G numbers.

[jetdriven]

Its all paperwork.  The airplane was not likely weighed at the factory, it was determined from a sample of airplanes off the line.  Then, anything less than one pound is not required to update the weight and balance. Over the last 30 years how much can that be?

The airplane is, on paper, legal.  Safe, Legal, pick any one, sometimes two. It flies. It is within the CG envelope and most lilkey a few pounds overweight.  If yo want to cost yourself some useful load, and are really concerned about it, reweigh it.  You can spend 200$ while simultaneously reducing your useful load by 75 pounds and at the end of the day nothing changes.

Given the responses here about losing 27 lbs of useful load due to a bladder installation, and claims of full-fuel-plus-1-pilot Acclaims being overgross, I can say there will be no takers.