Front seat weight & balance question

[David Lloyd]

Penny gave me an iPad for my birthday, first I've had...and used.  Loaded Garmin Pilot on it and have it talking to my GTX375.  All good, some is easy to use.  Only 572 pages in the user guide.

My M20C has modifications including 3 blade prop, rear mounted battery, and the articulating seats from a M20K.  Last year after some new radios were installed and old taken out, the airplane was weighed per the instructions in the service manual.  I have studied and know the numbers are correct.  The weight and balance was actually fairly close to the last, 20 year old paperwork calculation.  Eyeing the 30 pound pile of old gear and another 15 pounds of undocumented foam insulation, well those old numbers had to be off by at least 30 pounds.  Calculating the weight and balance for any light load appeared to be near the forward edge of allowable CG.  Two up front and no back seater or significant load appeared to be out of range.

Garmin Pilot has a weight and balance calculator, it will give takeoff and landing CG for any trip.  A lot fancier than my old home brew Excel spreadsheet.  Now I can see that two up front results in an out of CG condition without question.  So I start playing around with the numbers. I'm 5'10" with a short 31" inseam. Butt to the top of my head is long enough to rub the ceiling in some cars.  So I slide the seat full forward in the Mooney. Did that in the Bonanza previously, the RV had a huge range of adjustment.  I have now found if using the second most forward adjust hole for both front seats makes quite a difference in the CG situation.  I think there are 6 adjustment holes: 36.5", 38", 39.5", 41", 42.5", and 44".

No where in the 1975 POH, no where I have ever seen, not in the Garmin Pilot calculation do they take into account the actual weight of the front seats being moved forward or aft.  Pilot and front passenger of course but not the seats themselves.  I think my front seats weigh 20 pounds each.  Why not?  Does this show up anywhere in the new POHs?

[Hank]

Weight of the seats is not in my 1970 C C Owners Manual or thr Type Certificate, which is where I found the three (3) seat location arms. I fly in the middle one, and use homebrew Excel to figure W&B.

As a new owner, I spent some time runing various loading combinations for one to four seats with varying baggage weights. Then I added fuel in 10 gal increments from 10 to 50, figuring everything up and running through the calculation page. Those that failed (out of CG envelope, over Max Gross) I made red, then printed the page and stuck in the seatback pocket with the Owners Manual and Garmin book.

Since then, I've looked at that sheet but only redid calculations when my sheet shiwed I was close to a limit somewhere. 

How do you have SIX seat locations in a C????

[PT20J]

Here’s the info for an M20J from the POH. In Foreflight, you have to pick an arm when you set it up. Assume that Garmin Pilot is similar.Following Hank’s suggestion, here’s the TCDS entry for the M20C

[David Lloyd]

38 minutes ago, Hank said:

Weight of the seats is not in my 1970 C C Owners Manual or the Type Certificate, which is where I found the three (3) seat location arms. I fly in the middle one, and use homebrew Excel to figure W&B.

As a new owner, I spent some time running various loading combinations for one to four seats with varying baggage weights. Then I added fuel in 10 gal increments from 10 to 50, figuring everything up and running through the calculation page. Those that failed (out of CG envelope, over Max Gross) I made red, then printed the page and stuck in the seatback pocket with the Owners Manual and Garmin book.

Since then, I've looked at that sheet but only redid calculations when my sheet showed I was close to a limit somewhere. 

How do you have SIX seat locations in a C????

Sounds like we've done similar with the Excel.  Worked for me since the 80's.

Seems like I read there were six seat adjust holes on 1.5" centers.  Works out for 36.5" thru 44.0".  Yes, next trip or two to the airport, I will look, count, measure...as long as I can remember.

34 minutes ago, PT20J said:

Here’s the info for an M20J from the POH. In Foreflight, you have to pick an arm when you set it up. Assume that Garmin Pilot is similar.

 

The chart from the M20J is for the weight of the seat occupants in various positions.  Ignores the fact that the seat weighs something and moves between 36.5" and 44.0" in the C and 34.0" and 39.0" in the J.  In the Garmin Pilot, using 0 weight in the front seat, I changed the seat position from full forward to full aft.  I did not recalculate even though the moment in reality increased by 150 ((44-36.5)x20 lbs).  Not a whole lot I know but each of us was trained to pay close attention to weight and balance yet we were taught an inexact method.

[PT20J]

6 minutes ago, David Lloyd said:

The chart from the M20J is for the weight of the seat occupants in various positions.  Ignores the fact that the seat weighs something and moves between 36.5" and 44.0" in the C and 34.0" and 39.0" in the J. 

No, the weight of the seats is built into the chart. Consider 250 lb. front seat occupants with seats at the rearmost position. The moment due to the front seat occupants alone is 250 lb. x 39.0 in. = 9750 in-lbs. From the chart, the moment is 10,000 in-lb. The difference is due to the weight of the seats. It's really a small effect. 

Skip

[Patrick Lyons]

Just an FYI about front Seats . At your next annual stand on a normal BR scale with and without the seat.

The front  articulating seat your holding is very close to 26 pounds. ... if you have taken all the junk out of the seat back pocket.

I've tooted MY HORN  multiple times on the forum that I frequently have the right front in the hangar. .not soo much for the weight but the convenience.

Easier loading and exiting Pax(s) in rear, and pilot.  On X country tie a cooler where seat was for me and cheap seats... for cold or hot refreshments.

Yes the cooler is just tall enough to be kicked forward before you pull the chute handle for quick exit. YES a frequent flyer made me a brite RED Emergency exit handle for the Top. of the cooler.  Its now part of the preflight announcements.

PAT

 

[RLCarter]

Calculate your W&B as an Empty Aircraft moving both seats full forward and full aft and you see your answer 

[carusoam]

Interesting...

i don’t think I have confirmed my WnB calcs took the seat weight into consideration...

Or it’s been so long, I don’t remember...

need to dig a little deeper.

Best regards,

-a-

[RobertGary1]

Do you have the separate w&b manual that came with your Mooney? Mooney put all the charts in that booklet not in the owners manual (there is no poh until the J). 

[David Lloyd]

I did not have the original weight & balance and equipment list for my airplane.  It was exported to Canada in 1977 and when imported 25 years later, the original logs for N6835V weren't with the plane (1975-1977 missing), nor the original weight & balance. Friday afternoon I emailed Mooney asking if they still had the records.  Within 2 hours, Kevin Kammer, Director of Customer Service answered back that he would try to find what I needed.  Monday, 11 AM, Kevin emailed copies of the original weight & balance and equipment list dated 6/19/1975.  I am impressed with that kind of service.  There were a couple things in the information he sent that brought understanding to a few things.

Looking at the TCDS (possibly old and out of date) for the M20C, it showed the front seats as being from 36.5 to 44.0" aft of datum.  There is a 1966 C weight & balance available for download on MooneySpace showing those numbers stating the seats have 6 adjustment positions in 1.25" increments.  Oops, do the math on that, something is off. That would give an adjustment range of 6.25", not 7.5.  With the original weight and balance in hand, it lists the range of adjustment from 37.75 to 44.0" with 6 positions, 1.25" increments.  That fixes my main problem of a too forward CG with only two on board.  Nothing like having correct information.

As far as taking the seats themselves into account, the 1975 info does not appear to do that.  But as Skip pointed out, the chart may.  Pretty hard to see such a small number on those charts. The 1966 C weight & balance available for download on MooneySpace does have a line for the position of the empty seat itself.  It lists the weight at 17 pounds each.  Yesterday I weight my leather covered articulating seat with headrest at 20.5 pounds.

Friday I emailed Garmin Pilot asking why the seat weight itself was not taken into account as it moves it's full range.  They emailed back today (anonymous customer service) their developer were looking into that.

RobertGary1, the format of my owners manual is just about the same as the 1977 J POH.  I meant to look a the front cover to see exactly what it was called, but forgot.  It was even on my checklist and still forgot.

[PT20J]

The seats are included in the airplane empty weight and moment so if you want to include the weight and moment of the seats with the occupants, you would need to subtract the weight and moment of the seats from the aircraft empty weight and moment. According to the M20J POH, the aircraft empty weight and moment is calculated with the seats in the most forward position.

Thought experiment: If your front seat passenger has the seat forward at takeoff and then decides to slide the seat back to the aft stop during flight, do you need to recalculate weight and balance?

Skip

[ArtVandelay]

The seats are included in the airplane empty weight and moment so if you want to include the weight and moment of the seats with the occupants, you would need to subtract the weight and moment of the seats from the aircraft empty weight and moment. According to the M20J POH, the aircraft empty weight and moment is calculated with the seats in the most forward position.
Thought experiment: If your front seat passenger has the seat forward at takeoff and then decides to slide the seat back to the aft stop during flight, do you need to recalculate weight and balance?
Skip

I’d have to have an empty copilot seat, a full size adult in rear seat and 100 lbs in the baggage area to exceed rear balance and don’t think I can exceed the forward balance. Under normal circumstances, I won’t have to worry about it.

[carusoam]

One way to know you are really at the front of the WnB envelope...

You run out of trim while flying slowly...

Like final approach...

-a-

[carusoam]

Front cover vs. Front page...

Is it an OM or a POH?

This is from a 1977 M20C POH obtained directly from the factory, sent by Bill Wheat... around y2k.

+1 for the nice pirep for Kevin Kammers... very outgoing and easy to talk Mooneys with at KOSH...

-a-

[PT20J]

28 minutes ago, carusoam said:

Front cover vs. Front page...

Is it an OM or a POH?

This is from a 1977 M20C POH obtained directly from the factory, sent by Bill Wheat... around y2k.

+1 for the nice pirep for Kevin Kammers... very outgoing and easy to talk Mooneys with at KOSH...

-a-

According to the TCDS, it’s a POH.