The pinched wires, I would suppose, are on the wiring between the battery and the connector to the PCB, which could be subject to being moved and not fixed in location and routing. More like the design of a portable phone battery than a cell phone. Only fuses right at the place where the wiring enters the battery, or inside the battery casing, would be total protection.

However, they add another layer of risk in the failure flowchart, and engineers could have decided the cost outweighed the benefit.

Of course, this is all guessing, that could be halted by one decent picture of an open unit.

I don't know if it is any help, but here is the company product brochure for the Honeywell RESCU406AFN2

http://www51.honeywell.com/aero/comm...U_406_AFN2.pdf

The Roadie
 

Very true and the FIT number for thermal fuses is horrid but given the aviation world's dislike of battery powered equipment and their potential failure modes, I would have hoped the fuse would have won out. Especially as there was, by the look of it, scope for a good margin between fault and operating current?

Electic
Meanwhile everybody should be aware, as it was already posted in post 581,

post 581

Karel_x posted it in post 769,
Post 769

What has not been discussed is, how they could save over 50% of weight by maintaining the same power output. Could this weight saving be on behalf of less built in safety, insulation and more risk when using 2 cells instead of 6 cells?

checks for Honeywell ELTs on other model aircraft
 

Bloomberg is posting a story stating that Boeing "asked specific operators of 717, next-generation 737, 747-400, 767 and 777 airplanes to also inspect aircraft with fixed emergency locator transmitters, or ELTs, from Honeywell". This is described as pursuant to an AAIB recommendation.

The Bloomberg story is directly sourced to Randy Tinseth's (Boeing marketing VP) blog, which you can find easily enough, but which when updated will no longer carry this entry at the top.

Except it, that new battery could have greater capacity, I can imagine one more way. I suppose that in standby mode the consumption of ELT is very low, lower then 1 mW and battery life is limiting by its self discharging process. In case of emergency, I suppose that the transmission of data is not continuous, that between data blocks could be time breaks, eg. 5s "telegrams" in 30s interval. If you have not energy enough, you can make intervals longer. My speculation.

And of all the airplanes it decides to catch on fire on:uhoh:

I did, only 13 posts ago! :ok:

http://www.pprune.org/rumours-news/5...ml#post7964412

@ SoS

Following from Honeywell -Note the 12 year battery life.

I believe there are 2 packs comprising 4 cells in each and most likely of the Li-MnO2 type.

Can anybody tell me the cost per life saved by fixed ELTs in heavy transport aircraft? My strong suspicion is that not a SINGLE life has been saved and the cumulative cost over the last thirty years probably in the hundreds of millions of dollars. As well as the cost, the PROVEN increase in risk must be taken into account.

Just because a thing CAN be done doesn't mean that it is sensible that it should be done*.

In my view fixed ELTs MIGHT be justifiable in aircraft up to light twins but that is all.

*In the mid seventies the head of training, on F27, of a national carrier, carried out a GA from 1500 ft on final on glide path below all cloud, with gear down and locked**, after there was an explosion in one wheel well. He could do it, but should he have? Nah.

** There were still three greens after the explosion. That's all one needs to land an F27 on 10000'.

mm43
 

Thanks for that.

There seems to be a number of data sheets around giving different information.

I'm still struggling to understand how a greatly reduced number of cells can provide the same amount of power or even more, using the same Li-MnO2 chemistry. :confused::confused:

Bigger capacity cells, combined with more modern electronics that run at a lower voltage = lower cell count?

As others have said too, we don't know how long the transmissions have to last when used in anger perhaps the MKI battery was over specified in that respect?

mm43
 

The 12 year life for the battery is the same for the portable RESCU 406 ELT that Honeywell makes, which is also fitted to some B787 aircraft.
My guess would be the same type of battery, but l am not in a position to check at this time.
The batteries are replaced however at 10 years as per the MPD for the fixed ELT.
It is the same interval also for the portable ELT, which aligns with the second 5 year off wing inspections.

Mangere1957,
As you suppose, the answer is NIL!
See my posts a few pages back, the in-service failure rate in accidents for fixed ELT is better (or worse)than 95%, or 100% in water.
They are simply not justified on any aircraft. The Australian research and results on the subject is very clear.
Fixed ELT are an utter waste of money, without regard to any additional risks they may introduce.
What other piece of equipment with a 95%+ failure rate is tolerated on an aircraft??
Tootle pip!!

787 Chief Project Engineer at Boeing, Mike Sinnett, sidelined :

Boeing changes chief 787 engineer in management shuffle | Reuters

fenland787
 

That 's what I am getting at.

If the same, or greater power can be derived from a 60% smaller volume of cells, then the energy density of those cells must be more than double.

Energy efficiency savings gained by better circuit design would be somewhere around 5-10%, and only then if the mark one electronics were very inefficient to start with.

A further thought on battery size and life...
The monthly system self-test described in the data sheet is declared as having a total duration of 5 seconds (unchanged between unit types), elsewhere the data sheet states "Enhanced ... and self test".
There is a merit in keeping the outside observable maintenance procedures unchanged, to eliminate possible adverse risks of forward and backwards compatibility.
A reduced battery size can be speculated, based upon a system self-test using less power per usage (month), by enhancement to the test sequences and better test result data integration.

Agreed, do we know the cell volume is decreased by 60% or just the housing/battery pack? Not disputing, just asking! :)

On the BBC Business news:

BBC News - Boeing requests worldwide inspection of aircraft

In the Bloomberg report Boeing changes chief 787 engineer in management shuffle | Reuters


is the following throwaway line...

Obviously, a fire in another aircraft type would be of zero interest to the baying peanut gallery - but when it happened in a 787 it is suddenly worldwide news. So the various regulatory bodies only took action after the media interest?