Weight/Balance Cherokee 180

I'm sorry, I can't find the initial thread on this subject by a person who
calculated a forward CG on his Cherokee...if I missed the pertinent
newsgroup, would somebody please repost for me?


1. It would have helped if you had given us the serial number of the
airplane to be sure we looked up the correct version in the Type Certificate
Data sheets.

2. The empty weight and CG look a little bogus to me. Did you take them
from the aircraft logbook or from a "typical" aircraft in the POH?

3. Even if you took them from the logbook, most mechanics aren't
mathematicians. I've seen more than one to be a few inches or pounds in
error. Go all the way back to the beginning of that airplane's time and see
if the W&B as delivered from the factory is even reasonably close to the
current W&B. If you want to be meticulous about it, check each subsequent
calculation to see if you can find something that doesn't make sense.

4. The front seats are at arm 85.5, not 80.5. You forgot 2 gallons of oil
at arm 32.5.

5. The aircraft under the conditions that you specified with the
recalculations shows a weight of 2174 and a CG of 85.5. The graph in the
TCD sheets shows that the max forward cg under these conditions no less than
89.9, which is one HELL of a forward CG IMHO.

Jim




Here is the pertinent data from the TCD sheets:


III - Model PA-28-180 (Cherokee), 4 PCLM (Normal Category), 2 PCLM (Utility
Category) (Cont.)

Center ofGravity Range

Utility Category (See NOTE 9)




(+84.0)
to
(+86.5)
at
1650 lb. or less

(+85.8)
to
(+86.5)
at
1950 lb.


Normal Category (See NOTE 15)
(S/N 28-671 through 28-5859)




(+84.0)
to
(+95.9)
at
1650 lb. or less

(+85.9)
to
(+95.9)
at
1975 lb.

(+89.2)
to
(+95 9)
at
2200 lb.

(+92.1)
to
(+94.5)
at
2400 lb.


Normal Category
(S/N 28-7105001 through 28-7205318)




(+84.0)
to
(+95.9)
at
1650 lb. or less

(+87.0)
to
(+95.9)
at
2150 lb.

(+87.8)
to
(+95.9)
at
2200 lb.

(+91.0)
to
(+94.5)
at
2400 lb.


Straight Line Variation Between Points Given



Empty Weight C. G. Range

None



Maximum Weight




Normal Category:
2400 lb.

Utility Category:
1950 lb.


No. of Seats




Normal Category:
4
(2 at +85.5, 2 at +118.1)

Utility Category:
2
(2 at +85.5)













III - Model PA-28-180 (Cherokee), 4 PCLM (Normal Category), 2 PCLM (Utility
Category) (Cont.)



Maximum Baggage

Eligible Normal Category Only:
125 lb. at (+142.8) on S/N 28-671 through 28-1760, and 28-1760A. See NOTE
8.
200 lb. at (+142.8) on S/N 28-1761 through 28-5859, and 28-7105001 through
28-7205318.

Fuel Capacity

50 gallons at (+95) (2 wing tanks)
See NOTE 1 for data on system fuel.



Oil Capacity

8 quarts at (+32.5) (6 quarts usable)
See NOTE 1 for data on system oil.