Cary wrote:....... Ultimately after so many modifications, my airplane's calculated weight and balance disagreed with its actual W&B when it was actually weighed. .....

I suspect this is more common than not. In fact, I'll go a step further by saying that the W&B is probably the thing most often goofed up on an old airplane. People using the wrong datum, wrong means of levelling, wrong (or poorly estimated) weight, or just goofing up the measurements or math. I'm a good example, this is one of my pet peeves but yet I initially goofed up the measurement of the arm for the t/w when I recently re-weighed my 180. Caught it when I went to type up the new W&B report, so went back, re-levelled, and re-measured.

"Cary wrote:
....... Ultimately after so many modifications, my airplane's calculated weight and balance disagreed with its actual W&B when it was actually weighed. ..."

Agree.
Cessna was no help, either. They are said to have pencil whipped most off the line.

The original typewritten copy from Cessna for my 1957 A shows the stall horn at 8 pounds, 47.5 inches aft.
(Switch is labeled 6 oz., horn labeled like a pound. Switch=leading edge, horn at <10 inches)

Maybe trying to get CG into the envelope?

Next day it was rolled it over to Yingling, who changed the crosswind gear to conventinal. That calc is screwed up, too.

Flys good, though.
Actual weighing is the only thing to trust.

--Bill

c180bill wrote:............
Cessna was no help, either. They are said to have pencil whipped most off the line. --Bill

I have the original W&B sheet from Cessna for my 53 180. I think they weighed the first one off the line and just used that for all the rest. It's a dead give-away when the actual weights at each wheel are not shown, just the total weight and CG.

I'm about to order the parts to accomplish this mod. Somewhat for weight saving, but mostly so that I can put in the flat floor baggage compartment modification.

I have the Cessna three blade prop/seaplane motor mount. IO-550 and MT three blade.

The Atlee Dodge paperwork talks about lowering and tilting the battery to clear the motor mount. I've seen one that straddles the mount, possibly Burl's? No field approval is possible. Has to be STC'd. Which do I choose?

From photos, it appears that both the Dodge & Burl battery boxes stand the battery off the firewall enough to clear the vertical tube on the engine mount. I think maybe Dodge is talking about lowering/tilting the box to allow the battery to clear the mount when being removed upwardly?

hotrod180 wrote:From photos, it appears that both the Dodge & Burl battery boxes stand the battery off the firewall enough to clear the vertical tube on the engine mount. I think maybe Dodge is talking about lowering/tilting the box to allow the battery to clear the mount when being removed upwardly?

Hotrod is correct. The Dodge box is one piece so most mount it at an angle, and I have some Dodge paperwork that illustrates this, so the battery can be removed without removing the box from the firewall. I've also seen the Dodge box mounted horizontally (lower on the firewall) but replacing the battery would require removing the box from the firewall. Burl's box is two piece, so the battery can be removed forward as opposed to upward, more convenient for sure, but at a higher cost then the Dodge box.

I have the dodge box on my 180. It is angled a bit for battery removal, as rhe last 2 posts say. It is well built and I would recommend it to anyone.

Helpful discussion. Thank you!

It appears that Atlee Dodge is the only one with an STC. I don't really want to mount it at an angle. Their instructions mention the need to attach to the hot air duct in at least one location. Possibly it can be mounted to catch the lip of the duct on both sides. It also calls for nut plates, so removing the box to change the battery every 5 years or so can't be that hard.

I'd like to business with Burl, but can't get a field approval.

I thought Burls box was STC'd, but interestingly it's listed on his website under PMA'd parts:"180/185 firewall-mounted battery tray- landplane or seaplane" with no mention of an STC.
http://www.burlac.com/parts_catalog.htm (toward the bottom of the page)


My C180 is fitted with what appears to be a Burl's battery box, installed in 2002 with a field approval, but the paperwork just says "installed .032" stainless steel battery box tray on left side of firewall...."-- no mention of Burl's having fabricated or supplied it.

The Dodge set-up complete with STC is probably the most hassle-free way to go, but I'd be glad to scan my approved 337 & email it to you for your use as "accepted data".
Burl might also be able to supply copies of approved paperwork.

The Burl's STC is: SA02361AK

Thanks BS. Using that STC number, I found these links via the FAA library website:

http://rgl.faa.gov/Regulatory_and_Guida ... =sa02361ak

and

http://rgl.faa.gov/Regulatory_and_Guida ... 2361AK.pdf

and

http://rgl.faa.gov/Regulatory_and_Guida ... %20AML.pdf

Thanks Barnstormer. The STC number helped me over the edge. I've ordered from Burl.

Unfortunately, I may have hit a roadblock. I've searched the baggage compartment STCs, and it doesn't appear that any of the flat floor baggage extension offerings are approved for the A185F. I'll speculate that the factory extended baggage front support is structural, and getting approval to remove it was too difficult. I'll call a couple suppliers that offer it for models up to the A185F and see what's possible.

Pinecone wrote:...I've searched the baggage compartment STCs, and it doesn't appear that any of the flat floor baggage extension offerings are approved for the A185F. I'll speculate that the factory extended baggage front support is structural, and getting approval to remove it was too difficult...

Pinecone (and everyone else), what I'm about to say is from the archives of my gray matter internal hard drive as my 185, parts manuals, log books, etc are in Texas and I'm back in Alaska - so keep that in mind in what I'm about to say.

The A-E models of the 185 did not come with an extended baggage from Cessna. So the reason the A185F is not included in the STC of, for instance the Airglas Carbon Fiber flat-floor extended baggage, is (and this is speculation on my part but I think makes sense):
1. the F model 185's would require removing an existing extended baggage that didn't exist with the A-E models which probably would require a totally different STC.
2. since the F model now had a factory extended baggage the market would be much smaller then the market for the A-E models cause only a knucklehead like me (and you) would replace one extended baggage with another, even though it gives extra cargo space.

So having said that according to my A&P/IA none of the stuff that needs/can be removed to clean up the A185F’s factory extended baggage and allow the installation of the Airglas Carbon Fiber kit is structural. It’s only purpose was to support the factory extended baggage and the battery, cables, etc located under it.

Which begs the question what engineer thought it would be a good idea to use a piece of canvas as the back wall for the factory extended baggage AND THEN snap it from the back so if anything fell against it with any force the snaps could give way and the item go all the way to the tail moving the weight and balance and fouling up the rudder/elevator/trim cables in the process?

Anyway, if you decide to mount your 406 ELT out of the way under the new flat floor be sure and check the FAA’s relatively new mounting requirements. Requires an attachment that accounts for shear loads so just A COUPLE of rivets through the skin isn’t sufficient.

Gray matter time. I BELIEVE my A&P/IA determined that installing the Airglas Carbon Fiber kit was a minor modification because:

1. Burl’s battery box STC allowed us to move the battery to the firewall which meant we could remove everything battery related from in/around/and attached to the factory extended baggage.
2. The Airglas Carbon Fiber kit is STC’d for models A-E, the difference with the F model already discussed.
3. There was nothing structural about the factory extended baggage that was removed.
4. Removing the factory extended baggage components and replacing them with the Airglas kit did not take the plane out of it’s approved weight or balance limits.

Again this is from memory but I’m pretty sure it’s accurate. I think.

scottf wrote:

Barnstormer wrote:Current travels on the outside of the strands, so the more strands you have in a wire the more current it can carry.

I am nit-picking here, but the "skin effect" where current travels mainly along the outside of a conductor is only true for alternating current. DC current flows uniformly across the cross-section of the conductor. I'd suspect the primary advantage for more, finer conductors would be for flexibility and vibration resilience.

And only then at high frequency. Skin depth of 60Hz AC signal is about 8.5mm (or 1/3") - way bigger than any conductor in stranded cable. But it is the whole reason for stranded cable versus solid core to begin with.

At DC and low freq AC, current pretty much travels uniformly - a function of the cross-sectional area of all the conductors. It's also easier to crimp lugs on a larger # of fine strands I would imagine.

Barnstormer, I think your hypothesis is correct. I called Todd at Hitchcock. They may get the A185F added later, maybe as soon as August, but it's not there now. I'm not waiting. I called Air Metal Fabricators, but they didn't answer. Their website shows a shelf like I already have, not flat floor.

Selkirk has an STC SA01102SE with the A185F on the AML. I'm going ahead with that. They gave me a verbal assurance that removal of the non-structural shelf support is detailed as a step in the installation documents.

I'm not OK with the minor mod report, and I doubt my mechanic would sign it off. That floor is fairly critical, separating 50 lbs of baggage from my empennage control cables. I'll be quite protective of the Fiberglas. I'll probably cut some plywood that fits in there for when we're working in the tail. I have a hydraulic pump to install back there next month.