Need Fuel/ W&B help with M20C

[dpfeffer]

Purchased an M20C Mark 21 (s/n: 670139) back in Dec and have been restoring/upgrading it since then.  Getting closer to flight and am running into a couple questions due to a poor operating manual.

 

1. Can anyone confirm each fuel tank for this model is 26 gal?  Is there no trapped/unusable fuel??  The manual doesn't state this, but uses 26 gal/tank and 52 gal usable in the performance section.

 

2. There is no example W&B in the manual showing basic Fuselage stations for front seat, back seat, oil, fuel, etc, etc.  I can certainly measure all this (the maintenance manual provides the datum point), but I'm positive this is standard out there and I just haven't seen it.  Does anyone have an official copy of an example W&B from Mooney for this aircraft?

 

Thank you!!

David

 

[carusoam]

David,

I hope this starts you in the right direction......(unfortunately it is not a complete answer....)

From the Oct 1977 POH....   (I no longer have my M20C)

Usable fuel = 52Gal (i am sure there is unusable too).

Oil capacity = 8qts, 6qts min for flight

Gross Weight 2575 lbs

Empty weight 1525 lbs

Baggage area 120lbs

hat rack 10 lbs

Center of gravity limits (gear down)

2100 lbs most fwd 42.0 inches

2575 lbs forward gross 46.5 inches

aft cg (all weights) 49.0  inches

Datum station zero is the nose gear attaching bolt centerline, which is 33 inches forward of the wing leading edge at wing station 59.25

___________________________________________________________________________

The final warning from the POH....see weight and balance record for loading schedule.  This is usually kept with the log books for airframe, engine and prop.

Search on this site for type certification.  This usually has additional station information.....

"You can go online to the FAA's website and get a copy of the aircrafts' Type Certificate Data Sheet. It will have lots of useful information about weight & balance and approved equipment and where on the airframe it's located. An IA is supposed to use a copy to make sure the aircraft conforms to type certificate and any STCs or 337s that came along later, during the annual inspection." Kwix-draw

I expect that you are still looking for the stations for fuel, front seat passenger (range), rear seat passengers, baggage compartment, and hat rack....

 

Best regards,

-a-

[flight2000]

Hi David,

I'd recommend downloading a copy of the TCDS for Mooney's and looking over it.  It'll answer a lot of the questions you're looking for.  I cut and pasted the data for the M20C below:

Fuel Capacity: Serial No. 1852, 1940, through 2622 - 48 gals. (Two integral tanks in wings at +48.4)
Serial No. 2623 and up - 52 gals. (Two integral tanks in wings at +48.4) See NOTE 1 for data on unusable fuel.

NOTE 1:
Current weight and balance report, including list of equipment included in certificate empty weight and loading instructions when necessary, must be in each aircraft at the time of original certification and at all times thereafter (except in the case of air carrier operators having an approved weight control system.) The certificated empty weight and the corresponding center of gravity location must include unusable fuel (not included in fuel capacity) as follows: 4 lbs. (+47.6) for the M20 and M20A; 3.4 lbs. (+48.4) for the M20B, M20C, M20D, M20E, and M20G; 15.0 lb. (+48.4) for the M20F and M20J; 48.0 lbs. (+48.59) for the M20K (S/N 25-0001 thru 25-0446); 18 lbs. (+48.59) for the M20K (S/N 25-0447 and ON); 36 lbs. (+48.43) for the M20L (S/N 26-0001 and ON); 36 lbs. (+49.23) for the M20M (S/N 27-0001 and ON) and M20R (S/N 29-0001 and ON) and M20S (S/N 30- 0001 and ON); 36 lbs. (+49.23) for the M20TN (S/N 31-0001 and ON).

I have a copy of the TCDS (rev. 52) on my website: http://www.67m20e.com/m20e_manuals.htm

I also use a version of Roy Epperson's weight and balance spreasheet: http://cnrepperson.com/flightTraining.htm

I haven't seen anything that says there is unuseable fuel in the cells other than what is listed above, which at 3.4 lbs is less than 1 gallon.

[csfahey]

Hey, I would be glad to help you out on this.  I can send you a W&B Excel spreadsheet I use for my 1977 M20C Ranger.  It should be pretty close to what you have.  You should take the time to modify the weights according to your offical W&B sheet.  If you need to adjust it, you will need your manual.  Adjustments to the envelope are done by modifying the envelope box on the right hand side of the spreadsheet in the calculations area where it is hidden normally, column AA.  These value control the settings for the calculations on the left which control the plotting of the graph.  To adjust these, just look at the Owner Manual for the envelope.  The corners of the envelope have two points, one from the bottom and one from the side.  You just set the values by matching them up.  Let me know if you need help adjusting it.

Once you have the spreadsheet adjusted, save it and never touch the right side again.  When ever you need to perform a W&B for a flight, open up the spreadsheet and put the values in on the left side where it is a dark shaded grey then look at the results.

Send me an email to junkmail@faheys.org if you want a copy.

**** WARNING  **** Do not use this spreadsheet without customizing it for your airplane and verifying the results.

 

[richardheitzman]

If the W&B is missing from the aircraft you do not know how much is weighs. I would suggest you borrow a set of scales to weigh the aircraft when you are finished with the restoration. Aircraft "gain" weight as they get older and avionics and equipement is added/removed.

There is always unusable fuel in a aircraft. You will want to weigh the aircraft empy fuel, unuasable onboard (no need to take panels off to drain), oil and  brake fluid full, all required for flight equipment on board (ELT etc) and weigh it in a closed hanger out of the wind. I don't know if you are on a flght line with a service center. I would suggest you get them to do it.