Re: Swissair MD-11 (SR 111, JFK-GVA) crash off Nova Scotia

Date:         05 Oct 98 00:27:08 
From:         wb8foz@netcom.com (David Lesher)
Organization: NRK Clinic for habitual NetNews Abusers - Beltway Annex
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"S.L." <look@the.sig> writes:

>Do CVR's have acoustic beacons or pingers? I assume they have RF
>beacons, but I didn't know they had pingers.

Yes, they do. Somewhere I read the specs for what CVR/FDC's must
tolerate and still survive. It's rather staggering - high temp,
pressure, shock... and still bleet for x # of days.

>Do DFDR's and CVR's not have internal backup batteries to continue
>powering the recorders for a while after a power failure? Lithium cells
>with service lives of 10 years or more are common as dirt (in personal
>computers and other electronic systems) now, so this shouldn't pose a
>huge maintenance problem

The general problem is the sensors. They need power, too. As I
speculated in my other post, backup RAT for the CVR might be
possible. Other problems include the fact that you can't assume the
power going off means "deploy backup means" -- what happens when
you shut down for the night ;-?

But retrofitting THAT will be very costly. The FAA would not even
get behind upgrading the existing ?5-7? channels scribed on
stainless ribbon system still in wide use in 737's....

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