The Cessna 120-140 Association Forum

I just completed the fabrication of a new battery box to hold the SBS-J16 battery.

Nice lightweight battery and good looking work Dave. I see for now field approval is required. I would hope we'll see an STC in due time.

6863 wrote: ↑Sun Nov 08, 2020 7:40 amI see for now field approval is required.

I don't agree. I wrote mine up as a minor alteration. I did not, however, fabricate a new box; I used the original one.

(If I had, I seriously doubt it would have looked as good as his.)

6643 wrote: ↑Sun Nov 08, 2020 7:52 am

6863 wrote: ↑Sun Nov 08, 2020 7:40 amI see for now field approval is required.

I don't agree. I wrote mine up as a minor alteration. I did not, however, fabricate a new box; I used the original one.

When I had mine installed my IA wrote up the block he installed in the original battery box as a minor alteration. He did not, however, consider the battery itself an alteration. The reasoning is our type certification just says "12V battery," and the Odyssey is produced under a PMA, so everything is already legal.

it’s all open to interpretation, and can get ugly, but almost certainly won’t.
Even the fabricated battery box can be an issue. Logically an inspector can see it’s stronger than the original, and most are logical.

6643 wrote: ↑Sun Nov 08, 2020 7:52 am

6863 wrote: ↑Sun Nov 08, 2020 7:40 amI see for now field approval is required.

I don't agree. I wrote mine up as a minor alteration. I did not, however, fabricate a new box; I used the original one.

Many items that are pretty obviously a minor alteration come with an STC. Rosen sun visors that clamp on to down tubes for example. Or used to be LED landing lights.
The lights I understand as there were no published standards for a light bulb to meet, but the sun visors I can’t get there.

Many, many STC’s don’t meet the requirement of a major alteration, in my opinion.

Certification basis of the aircraft has a lot to do with it of course, but there is a clause that says that we can be held to FAR 23 standards if it can be shown to materially improve safety.
I can’t reference that, but I have been shown it in a conversation before.

All the debate around the necessity of a 337 and/or field approval had me a bit worried about whether I could legally do this modification. My mechanic/IA said not to worry, he'll just make a logbook entry. Good enough for me.

When I say field approval required I'm taking that from Aircraft Spruce which shows STCs for various aircraft, the closest to our's being a Cessna 170.

Very Nice!

I put a piece of 2x6 lumber in my battery box with my Odyssey J16 battery.