I can’t give a count of how many batteries I’ve installed over the last four or five decades, but it’s a bunch. Each new battery arrives with instructions for initial servicing, which I read way back in the day and assumed that the batteries hadn’t changed, so the instructions wouldn’t either. It’s just a battery, so what could possibly go wrong? As it turns out, assigning a battery install to a relatively new tech in the shop with instructions to follow the instructions can be an interesting learning experience – for me, the old guy.

If you’ve been reading this magazine for very long, you’re bound to have been exposed to the discussion about what manufacturer maintenance recommendations are mandatory and which are optional. The short answer for those operating under FAA CFR Part 91 is that no manufacturer “when to” requirements are actually required in the eyes of the FAA or your insurance provider. We do want to be careful to understand that sometimes an FAA requirement may appear within a manufacturer’s document and must not be skipped.

We all know the FAA Airworthiness Directives are absolutely required. Another FAA mandatory maintenance item is anything that has the label “Airworthiness Limitation”. This is a phrase that only the FAA can authorize, but it’s found in aviation product manufacturer’s documents. These include the Airworthiness Limitation section of an aircraft’s maintenance manual or Instructions for Continued Airworthiness for alternation per a Supplemental Type Certificate (STC).

Concorde Batteries has current maintenance manual document number 5-0171 which includes an Airworthiness Limitations section in the Intro section in paragraph five on page Intro-3. Since batteries have a relatively short life, the 2015 revision of the Concorde ICA 5-0171 would fit the definition of current for all batteries purchased after that date. As it turns out, the Airworthiness Limitations section basically says that there aren’t any required items listed in the Airworthiness Limitations for our Cessnas. So no problem with the Concorde batteries from an FAA maintenance requirement standpoint. It’s a different story if one is installing a Gill battery.

Each new Gill dry charged battery arrives packaged with a document that includes a section called “Continued Air Worthiness Instructions for Dry-Charged Batteries” on pages 5 and 6.  The header title at the top of the first paragraph is “Airworthiness Limitations”.   Since Airworthiness Limitations is one of those special FAA phrases, one would expect the instructions that follow to be very definitive and without ambiguity. Instead, the first sentence says “To ensure continued airworthiness the battery should….”.  Why would they use “should” instead of “shall” or “must”?

This is the document that ships with the new Gill batteries explaining the service schedule.

I may get too caught up in the details, but “should” implies optional compliance while an Airworthiness Limitation is never optional. The next three sentences in the same paragraph all use the term “shall” which imply compulsory compliance.  My confusion is that if it’s optional to remove the battery for a capacity test in the first sentence, then how can the service period, first check, and capacity test be compulsory in the following sentences? Since the paragraph at the top of page six makes all the dots connect to the FAA for the entire Airworthiness Limitations section, I’ll presume the “should” is in error and should have been a “shall”.

The instructions state that a capacity check shall be performed at 800 +- 50 hours or 11 +- calendar months from the initial installation of the battery.  After that, the same capacity test shall be performed again after the next 400 +- hours or 6 +- calendar months. I don’t know of any FAA CFR Part 91 operators (that’s most all of you) that know this requirement exists, much less have ever had it performed. I don’t see it listed in anyone’s recurring maintenance records, nor do I see anything written on the batteries to alert later maintenance providers when the test might be due next.  

Reading the requirement closely it would appear that only the two capacity tests are required. A typical Part 91 operator isn’t likely to fly 800 hours per year, so the first test happens at twelve months and the second six months after that. There’s no further testing required. I suppose Gill believes a battery that passes these two tests somehow never needs to be tested again. I infer this to mean the test is looking for infant mortality failures, and everything after that is just on condition. Of course warranty claims without proof of the two required tests may play a part in this conversation.

To confirm these requirements, I looked up the full version of the Gill Dry-Charge Maintenance Manual document number Q01-1120 revision B dated 6-30-2005.  Paragraph 7.7.1 has no mandatory verbiage as to when the capacity check is to be performed. It uses the same “should” cautionary statement that the more abbreviated document uses that comes with the battery. It isn’t until the following paragraph 7.7.2 that we discover that Gill considers 7.7.1 as the Airworthiness Limitations paragraph, even though it isn’t labeled as such. The ambiguity makes me nuts.

This is the section of the Gill service manual that describes the Airworthiness Limitations

Assuming we agree that the periodic Gill battery capacity test is truly an FAA Airworthiness Limitation and therefore required, we are now obligated to have the test performed and track its recurrency.  Battery replacement is considered preventive maintenance as defined in FAA CFR 43 Appendix A so you as the aircraft owner/operator can perform the installation. The capacity test is a maintenance function and must be performed by a certificated mechanic.  That means you can remove the battery, take it to your favorite mechanic for the test, obtain a maintenance entry showing the test performed, then you can reinstall the battery. You’ll be responsible to make a proper maintenance entry in accordance with FAA CFR 43.9 for the battery removal and reinstallation.

All this being said, I’ve never heard of anyone specifically tracking the Gill battery capacity test requirement.  Very few mechanics or shops have the required equipment needed to perform such a test, so you’d need to investigate that before pulling the battery from the plane. Many shops that already have the test box make battery capacity test a routine item for annual inspections even if there’s no requirement to do so.

The capacity test box that we use in our shop. It doesn’t look like much, but its cost limits availability to those shops that expect to use it a lot.

One must carefully read the Airworthiness Limitation to ensure a maintenance or inspection action actually exists.  With many of us finding ways to eliminate the antiquated pneumatic instrument systems, the reliability of the back up electrical system (battery) is paramount. Documenting compliance with the mandatory regulatory maintenance items for these backup systems should be on everyone’s radar.

The next time you purchase a new battery, be sure to read all the accompanying documentation. I used to just toss it aside assuming it said the same old stuff it did thirty years ago.  Leave it to the new tech in the shop to point out any lack of attention to the current and important details.