I just spent time unsuccessfully attempting to justify converting my 172A to an Odyssey battery. I basically found only 170/180 STCs and numerous posts on a field approval approach. A field approval is secured for a major alteration or repair. and per 14 CFR part 43 I could not find anything that I could associate to a battery or a battery box.

Did I miss something, or am I truly at the mercy of battery vendors to claim allegiance to my airplane in their PMA drawings?

I’m assuming that since the original drawings called for a specific Cessna part number (and thus the aircraft was certified as such) you cannot simply declare a battery as a generic disposable item.

14 or 28 volt ? done both send me a email direct [email protected]

cowboypilot wrote:I just spent time unsuccessfully attempting to justify converting my 172A to an Odyssey battery. I basically found only 170/180 STCs and numerous posts on a field approval approach. A field approval is secured for a major alteration or repair. and per 14 CFR part 43 I could not find anything that I could associate to a battery or a battery box.

Did I miss something, or am I truly at the mercy of battery vendors to claim allegiance to my airplane in their PMA drawings?

I’m assuming that since the original drawings called for a specific Cessna part number (and thus the aircraft was certified as such) you cannot simply declare a battery as a generic disposable item.

The Odyssey battery is an "airplane part", and is stc'd in the Super Cub at least. Ask your mechanic to READ carefully the battery section in FAR part 43. Having read that a couple times, I am convinced, as are a number of mechanics that I know, that the Odyssey battery can be installed as a "minor alteration" in most aircraft, assuming it's properly secured AND it meets the electrical requirements of the aircraft in question. The big wild card here is how much electrical stuff you have installed, but the landing lights are the big amp draw. If that's too much, consider LED landing light bulbs.

And, of course, you'll have to have the mechanic compute a new weight and balance for the airplane.

In any case, the dang thing is just a battery. Nobody asks "mother may I" when deciding which other brand of "conventional" battery to use.

MTV

I installed one a couple years ago & my IA wrote up a field approval 337 for the mod. The FAA inspector signed off on it no problem, the only thing either one was fussy about was what I used to take up the extra room in the G25 sized battery box. I made a hat-shaped aluminum channel & mounted it inside the box & everybody was happy. Saved an honest (weighed) 8 pounds over the previous Concorde RG25. If you relocate the battery or just use the Odyssey bracket instead of the stock box, expect a G-test to be required for the new mounting.
BTW there is more than one Odyssey battery- I used the one that's PMA'd since I figured less hasle on the approval that way. It might be possible to sign off the Odyssey as a minor with only a logbook entry & W&B revision. Talk it over with your IA and/or the local FAA PMI.
MTV-- the fact that the Odyssey is STC'd for anything (in this case, the PA18) implies that it is in fact NOT a minor alteration- if it was, no STC would be required. But a friend of mine nstalled one without any paperwork at all -- he sez the TCDS and/or the equipment list just calls out "battery" so any battery will do. I don't necesarily agree with him but it's his airplane & his IA went along with it at annual time.

Just because you can get an STC for something doesn't mean you necessarily need to. Since the 4509 bulb is not listed in the TCDS, it would need an STC as well...

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