December 2013.when your ELT uses D cell batteries that have a date of 2015 on them and you placed them in service today when are they due for replacement?
And then again whenever my annual is done to keep everything in synch, so that every other annual I'd change the batteries. D cells are cheap for the price.
The opinions and statements of this poster are largely based on facts and portray a possible version of the actual events.
The "useful life" from FAR 91 is not explained and open to interpretation.
The term "useful life" has at least three definitions that I can think of:
1) useful life with the ELT in operation drawing current
2) useful life in the airplane fully charged but self discharging while in standby mode (rechargeable only)
3) useful life uncharged but on the shelf waiting for installation (rechargeable only)
I would go with the ELT manufacturer instructions.
Bill
The date on the batteries does not correspond to the 50% rule. It would be correct to change them at 1/2 way to that date.Originally Posted by Tom Downey
Maybe now you see why this isn't so simple to interpret..........
Last edited by flyingriki; 11-26-2011 at 01:20 PM.
I agree, this part of FAR 91.207 is not as simple as it should be.
After reading 91.207 again, I think the FAA was confused when 91.207 was written.
The FAA is confused over the difference between "useful life" and "shelf life".
Useful life is the quantity of energy remaining in the battery. FAR 91.207 (c)(1) requires replacement if the quantity of energy has been depleted by ELT use of one hour or more. (from this I infer the FAA's definition of "useful life", since the FAA does not define the words in FAR 1.1)
On the other hand, the date on the Duracell D-cell is a shelf life date. This date has nothing to do with useful life while in operation.
I think this date is a manufacturers suggested date after which an unused battery may not have 100 percent of the new batteries total energy, but that is my opinion. I just checked a Duracell from my shelf dated MAY 2010, it still checked at full voltage. But voltage is not an accurate measure of remaining energy, and I have no means to check the quantity of energy left in this battery. Eveready and other brands have no shelf life dates. And that is why Duracell is usually specified by the ELT manufacturer, I think.
I don't think there is any suitable method to determine 50 percent of useful life by inspection, so FAR 91.207 is flawed in my opinion.
To summarize my thoughts, follow the ELT manufacture approval, or if this information is not available, use the the date on the Duracell battery as an expiration date.
Bill
The instructions that came with my ELT that uses "D" cells says to use the date on the batteries.
I would suggest that you check the ELT manufacturers instructions that came with your unit.
The orange 406 ELT instructions say
SECTION 11 E-04.0 LITHIUM BATTERY REPLACEMENT
THE LITHIUM BATTERY (P/N E-04.0) MUST BE REPLACED ON OR BEFORE THE BATTERYEXPIRATION DATE MARKED ON THE BATTERY. IT IS NO LONGER AIRWORTHY AFTERTHIS DATE. SEE FAR 91.207 FOR OTHER ELT REQUIREMENTS.
ACK tech yellow box (121.5)
BATTERY REQUIREMENTS: TRANSMITTER EIGHT DURACELL D CELLS
REMOTE CONTROL ONE DURACELL PX28L OR EQUALBATTERY REPLACEMENT INTERVAL: TRANSMITTER UP TO FIVE YEARS
REMOTE CONTROL UP TO 8 YEARS
Last edited by Tom Downey; 11-26-2011 at 01:43 PM.
crystal clear......
BATTERY REPLACEMENT INTERVAL: TRANSMITTER UP TO FIVE YEARS
REMOTE CONTROL UP TO 8 YEARS
I don't know who this guy is but he suggests he knows what he's talking about (always scary?):
This expiration date IS the half‐life of the battery, aka when 50% of thebattery’ useful life has expired. Look for the maintenance logbook entry when the ELT batterywas last replaced and you will find an indication of the half‐life of the new batteries.
http://www.aerotechservices.com/reso..._Conundrum.pdf
At the end of this video Dick (as an A&P, IA and Tech Advisor) suggests the logbook entry wording he uses:
http://www.eaavideo.org/video.aspx?v=77829561001
Last edited by flyingriki; 11-26-2011 at 04:33 PM.
I think the video I quoted above will answer your original question with authority in addition to Mike's.
Dick is simply an A&P-IA just like I am, using the same rule 91.207, He says nothing that contradicts what I have been saying, but the unit he is talking about and using as a demo, is an old Narco Shark 7 which is no longer authorized to be used in the US airspace. See the FCC rules for that. If you really want to know the proper sign off for any return to service see FAR 43. it's all in there. My return to service statement is simple, and came directly from my PMI at FSDO.
" I have inspected this __(ELT make and model)__ system in this aircraft according to applicable aircraft and ELT manufacturers instruction and applicable FAA guidance and found that it meets requirements of section 91.207 para 1 thru 4"
FAR 91.207 requires that you have an ELT installed that is in operable condition but does not call out which type that is.
Last edited by Tom Downey; 11-26-2011 at 05:33 PM.
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.
My humble opinion of the rule 91.207.
As written it is out dated and incomplete at giving the pilot and passengers the best equipment available. This rule should be rewritten to say that the pilot is responsible for carrying an impact activated PLB. in FAR 91.7. That would place the responsibility on the pilot and remove the junk that causes all the false indicators that we have and the over burdening of the inspection rules.
Last edited by Tom Downey; 11-26-2011 at 05:54 PM.
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