ELT battery replacement

[flyingriki]

Originally Posted by flyingriki
I think the video I quoted above will answer your original question with authority in addition to Mike's.

Dick does a nice presentation, but never talks to the "D' cell battery type of ELT. or mentions the "D" cell battery life. Using his demo as a reference where he says the battery should be changed before the date stamped on it, could carry over to the "D" cell.

NOT the original question ...

[Mike Busch]

Although this does not answer the regulatory question, there's an interesting Technical Bulletin about Duracell alkaline batteries at http://www.duracell.com/media/en-US/...20Bulletin.pdf

Among other interesting facts, the Bulletin indicates that at 70F the batteries lose only 3.5% of their capacity per year. They retain 85% after four years and better than 70% after eight years. Shelf life is worse at higher temperatures and better at lower temperatures.

To directly address the question of battery replacement for the ubiquitous yellow ACK E-01 that uses standard drug-store-variety Duracell MN-1300 D-cell alkaline batteries, the manufacturer's guidance appears at http://www.ackavionics.com/pdf/E-01%...9.04.20071.pdf and staties in pertinent part:

"The battery replacement date is found on each Duracell MN1300 cell. It reads as follows: 'Best if installed by (date)'. The (date) indicated is the date by which the batteries must be replaced. All cells must have the same date."

Other than the ACK E-01, every ELT I've ever seen use special battery packs that are clearly placarded with a replacement date. I personally have never encountered a situation where the replacement date needs to be calculated on the basis of the 50% rule of 91.207(c)(2). My theory is that the FAA lawyer who wrote that regulation inadvertently omitted the word "OR" from the sentence, and that it should actually read:

"(2) When 50 percent of their useful life (or, for rechargeable batteries, 50 percent of their useful life of charge) has expired, OR as established by the transmitter manufacturer under its approval."

But what do I know?

[Frank Giger]

Yet another reason I'm glad I'm building a single seat aircraft - no ELT required!

So what's the "rule of thumb" consensus?

Assuming that the batteries aren't terribly expensive, is "every two years whether they need it or not" okay, assuming the darned thing hasn't gone off?

[Tom Downey]

Although this does not answer the regulatory question, there's an interesting Technical Bulletin about Duracell alkaline batteries at http://www.duracell.com/media/en-US/...20Bulletin.pdf

Among other interesting facts, the Bulletin indicates that at 70F the batteries lose only 3.5% of their capacity per year. They retain 85% after four years and better than 70% after eight years. Shelf life is worse at higher temperatures and better at lower temperatures.

To directly address the question of battery replacement for the ubiquitous yellow ACK E-01 that uses standard drug-store-variety Duracell MN-1300 D-cell alkaline batteries, the manufacturer's guidance appears at http://www.ackavionics.com/pdf/E-01%...9.04.20071.pdf and staties in pertinent part:

"The battery replacement date is found on each Duracell MN1300 cell. It reads as follows: 'Best if installed by (date)'. The (date) indicated is the date by which the batteries must be replaced. All cells must have the same date."

Other than the ACK E-01, every ELT I've ever seen use special battery packs that are clearly placarded with a replacement date. I personally have never encountered a situation where the replacement date needs to be calculated on the basis of the 50% rule of 91.207(c)(2). My theory is that the FAA lawyer who wrote that regulation inadvertently omitted the word "OR" from the sentence, and that it should actually read:

"(2) When 50 percent of their useful life (or, for rechargeable batteries, 50 percent of their useful life of charge) has expired, OR as established by the transmitter manufacturer under its approval."

But what do I know?

You knew where the reference was. Thanks for that. The reference is the ICAs for the ELT. and must be followed

[Tom Downey]

Yet another reason I'm glad I'm building a single seat aircraft - no ELT required!

So what's the "rule of thumb" consensus?

Assuming that the batteries aren't terribly expensive, is "every two years whether they need it or not" okay, assuming the darned thing hasn't gone off?

The installation instructions for your ELT are the Instructions for continued airworthiness, the FAA has deferred to the manufacturer for what's legally airworthy.

[FlyingRon]

The information on your D cell ELT is contained in the documentation that came with it that you should have before attempting to do any servicing of it.
According to the AK-450 docs the DURACELL (only legal battery) expiration date is the expiration date. They give you a place on the case where you are to write the new expiration date when you change it.

I had a bit of an argument with my mechanic over this one who said it was only half the interval between now and the battery date. I pointed out that that interpretation was first a GROSS misapplication of the ELT battery rules and second TRUMPED by the manufacturers specific approved instructions for continued airworthiness.

[flyingriki]

Thank you Mike, best information yet and answers all my questions! That "or" makes a poorly written sentence actually make sense.....! Will go by the mfg. and, thanks to you, I have a copy of the missing manual.
Between that and Dick's video on inspection and log entry I think I'm all set.
Thanks again.

[Mike Busch]

You knew where the reference was. Thanks for that. The reference is the ICAs for the ELT. and must be followed

At risk of serious thread creep -- and I know I'm going to hate myself in the morning for pointing this out -- it is NOT true that ICAs must be followed, at least for a Part 91 operator. Manufacturer-specified maintenance intervals (including inspection, overhaul and replacement intervals) never need to be complied with by a Part 91 operator UNLESS:

-- Compliance is mandated by Airworthiness Directive

-- The interval appears in a clearly identified "Airworthiness Limitations" section of the manufacturer's maintenance manual or instructions for continued airworthiness

The ACK E-01 ICA do not contain an Airworthiness Limitations section. Therefore, compliance with the battery replacement intervals specified therein is not required by regulation. Those intervals are "acceptable to the Administrator" but they are not required.

Of course, if you don't comply with the manufacturer-specified interval, then you need to comply with some other acceptable guidance to comply with 91.207. The only other acceptable guidance available would appear to be the "50% rule" of 91.207(c)(2). Since that rule is (a) ambiguous and inscrutible, and (b) less generous than what the manufacturer specifies, nobody in his right mind would do anything OTHER than comply with the manufacturer's guidance.

But you don't HAVE to comply with it. It's not an Airworthiness Limitation and it's not mandated by AD.

[flyingriki]

Thanks again Mike. Seems a lot like the tax code, gotta have real pros to interpret!
And I was asked what was so hard to understand....
Had me feeling kinda dumb - briefly.

[Tom Downey]

At risk of serious thread creep -- and I know I'm going to hate myself in the morning for pointing this out -- it is NOT true that ICAs must be followed, at least for a Part 91 operator. Manufacturer-specified maintenance intervals (including inspection, overhaul and replacement intervals) never need to be complied with by a Part 91 operator UNLESS:

-- Compliance is mandated by Airworthiness Directive

-- The interval appears in a clearly identified "Airworthiness Limitations" section of the manufacturer's maintenance manual or instructions for continued airworthiness

The ACK E-01 ICA do not contain an Airworthiness Limitations section. Therefore, compliance with the battery replacement intervals specified therein is not required by regulation. Those intervals are "acceptable to the Administrator" but they are not required.

Of course, if you don't comply with the manufacturer-specified interval, then you need to comply with some other acceptable guidance to comply with 91.207. The only other acceptable guidance available would appear to be the "50% rule" of 91.207(c)(2). Since that rule is (a) ambiguous and inscrutible, and (b) less generous than what the manufacturer specifies, nobody in his right mind would do anything OTHER than comply with the manufacturer's guidance.

But you don't HAVE to comply with it. It's not an Airworthiness Limitation and it's not mandated by AD.

If we believe the installation instructions are not mandatory ICAs, and we are not required to comply with them, why would we believe the date code requirement in the same instruction is required?

I can't imagine any A&P-IA, Owner, or operator defending them selves in a NTSB hearing, or civil court by telling the Judge we are not required to comply with the maintenance instructions written by the manufacturer, when the FAA requires the manufacturer to write them prior to certifications of all components that are not on the type certificate.