 |
Matronics Email Lists
Web Forum Interface to the Matronics Email Lists
|
| View previous topic :: View next topic |
| Author |
Message |
bicyclop(at)pacbell.net
Guest
|
 Posted: Fri Nov 14, 2008 9:40 pm Post subject: Lessons Learned, Lessons Forgotten, Tools for Sharing |
 |
|
Bob,
I didn't build the plane, but I did maintain it for more than 3 years
(and annual condition inspections) without noticing the danger posed by
the proximity of the two. I will never overlook this particular issue
again. The builder used a stainless braided line for the brake which
crossed near the battery cable at 90 degrees. The last time I replaced
the battery, apparently I failed to insure separation and it rubbed
through causing the short. The current was conducted along the brake
line to the gear leg mount where it was also rubbing, another oversight
on my part. The 5606 was all boiled off and filled the cabin with smoke.
My nephew declared emergency and shut off the master and E-busses while
holding the canopy part open, so he could breathe, with one hand and
flying with the other. He found an airport and landed and yes, the brake
was not functional. The voltage was measured after the fact, as you
surmised, Bob. When I got there 90 minutes later, the brake line was
still in contact with the cable. The cable had a total of 3 broken
strands and some localized discoloration. There was about a half a
square inch of insulation missing. It was returned to service with a
few layers of heat shrink over the scar. The braided line was limp and I
made a replacement in the field out of the aluminum tubing that Van's
supplies. There is now very positive separation between it and the
battery cable, believe me. I have replaced the fluid with the high temp
variant, MIL- PRF-83282. I also replaced the O-rings in the calipers
with Viton for higher temperature capacity.
I just wanted to share this story in the hope that people designing,
installing or maintaining systems take a hard look at the way the
battery cable to the contactor is protected from harm. This is pretty
much the only place in the plane where an insulation failure cannot be
mitigated by turning off a switch or automatically by circuit protection.
The other issue, as has been mentioned, is that if 2 electronic
ignitions are hooked to 1 battery, bad stuff you hadn't accounted for
could take them both down at once. I don't particularly like magnetos
and I think that, barring a failure in the power provided to them, an
electronic ignition is probably way more reliable. The thought of having
an magneto, which will almost certainly crap out at some point, as a
backup to a more reliable system offends my sensibilities. My next
airplane will have 2 EIs on board, and 2 batteries also. One of them may
wind up being little to save weight, but I don't want all my eggs in one
basket.
Pax,
Ed Holyoke
Robert L. Nuckolls, III wrote:
| Quote: |
<nuckolls.bob(at)cox.net>
At 09:53 PM 11/13/2008 -0800, you wrote:
>
> <bicyclop(at)pacbell.net>
>
> We found a way to not have any electrons for keeping the engine
> alive. Easy enough not to have our problem, but very critical that
> you do it right. The fat wire from the battery to the contactor
> shorted out on a brake line and filled the cabin with smoke. Shutting
> off the master didn't help since it was downstream of the short.
When the industry accepted the notion that fat wire
protection wasn't useful or necessary in TC aircraft,
they were also cognizant of a need for due-diligence in
the installation of said wires . . . separation and
support being chief amongst concerns.
The scenario cited above could also have caused a
landing accident. If the short had been a soft fault,
it might have slowly eroded a hole in a brake line
causing loss of brakes.
|
| | - 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 |
|
|
|
| Back to top |
|
 |
rv9jim(at)juno.com
Guest
|
| Posted: Sat Nov 15, 2008 6:21 am Post subject: Lessons Learned, Lessons Forgotten, Tools for Sharing |
|
|
Ed,
Consider having a E-Mag air "P-Mag" as at least one of the
ignition sources. That requires no outside source of power after
starting. I have two of them on my Rv. They are great.
Jim
____________________________________________________________
Save hundreds on an Unsecured Loan - Click here.
http://thirdpartyoffers.juno.com/TGL2141/fc/PnY6rw2QH0Bxn54hc1Q3cSHOASOOlkzcB7rdFTA0otj784iAHvBCB/
| | - 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 |
|
|
|
| Back to top |
|
|
henador_titzoff(at)yahoo.
Guest
|
| Posted: Sat Nov 15, 2008 7:12 am Post subject: Lessons Learned, Lessons Forgotten, Tools for Sharing |
|
|
Jim,
How many flight hours do you have on these P-Mags?
Thanks.
Henador Titzoff
---
| | - 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 |
|
|
|
| Back to top |
|
|
rv9jim(at)juno.com
Guest
|
| Posted: Mon Nov 17, 2008 7:54 am Post subject: Lessons Learned, Lessons Forgotten, Tools for Sharing |
|
|
Hernando,
I'm in my Phase one and have 20 hours on them. My engine starts
quickly and I love the timing method if you have to remove them for any
updating.
Jim
____________________________________________________________
Security Camera for your small business. Click Now!
http://thirdpartyoffers.juno.com/TGL2141/fc/PnY6rw1urM11iqlfAiHlBaHHo1RYt7UF0MedUEVZXNA7ABNobfZ2J/
| | - 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 |
|
|
|
| Back to top |
|
|
henador_titzoff(at)yahoo.
Guest
|
| Posted: Mon Nov 17, 2008 5:36 pm Post subject: Lessons Learned, Lessons Forgotten, Tools for Sharing |
|
|
Jim,
Come back in 500 hours and tell us about how fabulous they are. 20 hours ain't nothing in light of the reliability problems they're having.
Henador Titzoff
---
| | - 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 |
|
|
|
| Back to top |
|
|
|
|
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum
|
Powered by phpBB © 2001, 2005 phpBB Group
|
Get Email Distribution Too!
FAQ
Search
Memberlist
Usergroups
Register
Profile
Log in to check your private messages
Log in
