nuckolls.bob(at)aeroelect
Guest
|
 Posted: Sun Nov 01, 2020 3:40 pm Post subject: Breaker then pump failure |
 |
|
| Quote: | | Bob, if I get the old pump back, I'll send it to you along with the breaker. |
Thanks
| Quote: | | BTW, I just became aware of an AD fromĀ 2008 to replace this type of CB switch in Beechcraft products. |
Bingo . . . I worked the failure analysis team
on that fiasco.
As I recall, the risk of failure came to light
when a pilot reported, "smoke squirting from
around the handle on the prop de-ice switch
breaker."
Here's link to relevant pictures and
documents:
https://tinyurl.com/y48y93rk
That was a real can of worms.
There were tens of thousands of switch breakers
in the field covering decades of production in
Bonanzas and Barons. Being a commercial off the
shelf product, it was unclear which fielded
aircraft might be vulnerable to this condition.
I.e. smoke AFTER failure of the braid.
As it turns out, only the prop de-ice switch
breaker had a risk for generating some smoke.
Switches carrying lower currents would
continue to function although loss of the
braided jumper on alternator control switches
increased field supply path resistance
which MIGHT lead to regulator instability.
It was finally deduced that this failure
did not represent any greater hazard than
failure of the protected device . . . hence
removal/replacement of a breaker could
be left 'on condition' as opposed to a fleet
wide swap out.
Of course, ongoing production and spares
breakers have the magic insulator so
the risk of smoke has been mitigated
for the future.
Bob . . .
| | - The Matronics AeroElectric-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?AeroElectric-List |
|
|
|
Get Email Distribution Too!
FAQ
Search
Memberlist
Usergroups
Register
Profile
Log in to check your private messages
Log in
