Today's Message Index:
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1. 04:11 AM - Re: Re: ELT Antenna (William Schertz)
2. 06:44 AM - Re: Re: ELT Antenna (Robert L. Nuckolls, III)
3. 07:48 AM - Lancair 235 Accident (user9253)
4. 01:04 PM - Re: Re: ELT Antenna ()
5. 11:01 PM - Re: Lancair 235 Accident (mmayfield)
Message 1
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My experience indicates that it is not a rumor. When I started testing I
found the ELT being triggered by one of my COM's, and solved that by moving
the position of the ELT itself, not the ELT antenna.
Since repositioning, it has not been a problem
Bill Schertz
-----Original Message-----
From: Robert L. Nuckolls, III
Sent: Saturday, January 18, 2014 10:23 AM
Subject: Re: AeroElectric-List: Re: ELT Antenna
<nuckolls.bob@aeroelectric.com>
At 07:01 AM 1/16/2014, you wrote:
<nuckolls.bob@aeroelectric.com>
I wrote: I've heard the rumor that some ELT's were triggered
by local radiation from a comm transmitter . . . but
I've not seen any documentation or FMEA that supported
the assertion.
----------------------
I was informed by an astute reader that the ACK E-01
series ELTs were demonstrably plagued with a tendency
to trigger in response to on-board COMM transmissions.
This fact (and perhaps others like it) may have been the
foundation for advising installers to add separation
between the ELT and ship's COMM antennas.
While the 'fix' is valid, the premise under which
the fix is exercised assumes that the ELT was
properly qualified to be on the airplane in the
first place. Any ELT that goes through the lab
where I work would have demonstrated immunity to
RF interference many times stronger than the ship's
transceivers.
The consumer has every reason to expect certain
levels of performance in their ELT for it has
been decreed and . . . it's a matter of practical
utility.
With better information, a retraction is in order
for my assertion that the RF triggering event
was a 'rumor'. At the same time I would advise
that compromising the installation of your
own 'antenna farm' in recognition of the
historical fact is unnecessary. If the ELT you
have demonstrates such sensitivity, then
there is good reason to suspect a defect in
design and/or manufacturing that needs attended
to . . . defects that may go beyond the sensitivity
to RF.
If the ELT is the last bastion of defense for
your survival, then offer no quarter in
your expectations for its performance.
Bob . . .
Message 2
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At 06:10 AM 1/19/2014, you wrote:
><wschertz@comcast.net>
>
>My experience indicates that it is not a rumor. When I started
>testing I found the ELT being triggered by one of my COM's, and
>solved that by moving the position of the ELT itself, not the ELT antenna.
>
>Since repositioning, it has not been a problem
What make and model of ELT was this?
Bob . . .
Message 3
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| Subject: | Lancair 235 Accident |
In the January 2014 issue of Sport Aviation is an article, "What Went Wrong", about an accident involving N235MW, a Lancair 235. http://tinyurl.com/myzgxkv
The NTSB probable cause is , "The pilot's decision to operate the airplane with known electrical system problems . . ." Even more significant, in my view, is that the pilot took off without first filling the 11 gallon header tank. The pilot did not build the aircraft. A builder would have known how to repair the electrical system and would have been more familiar with fuel management. There is a more detailed report here: http://tinyurl.com/krf4dk9
It says, " . . .fuel pumps which received their electrical power from the main
electrical bus." Since the fuel system was electrically dependent, it would have
been prudent to power the fuel pumps directly from the battery or from an
E-Bus. Or the main bus should have had two supply paths as in Z-0 (attached).
The accident report mentions a corroded wire between the battery and master contactor.
But that does not explain why there was power to the starter but not
to the main bus. I think there must have been a bad connection between the
master contactor and the main bus.
Joe
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=417180#417180
Attachments:
http://forums.matronics.com//files/simple_elect_system_106.pdf
Message 4
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I had the same problem with a client's composite aircraft, it was the
Ameri-King AK-450 ELT unit that was susceptible to com RF triggering. It
could have also been the un-shielded RJ-11 style phone cable used for the
remote display.
-James
-----Original Message-----
From: Robert L. Nuckolls, III
Sent: Sunday, January 19, 2014 8:42 AM
Subject: Re: AeroElectric-List: Re: ELT Antenna
<nuckolls.bob@aeroelectric.com>
At 06:10 AM 1/19/2014, you wrote:
><wschertz@comcast.net>
>
>My experience indicates that it is not a rumor. When I started testing I
>found the ELT being triggered by one of my COM's, and solved that by moving
>the position of the ELT itself, not the ELT antenna.
>
>Since repositioning, it has not been a problem
What make and model of ELT was this?
Bob . . .
Message 5
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| Subject: | Re: Lancair 235 Accident |
The fact that the pilot was not the builder should not be used as an excuse for
anything at all. I haven't built any of the aircraft I've flown during 30 years
of professional aviation, but I still always knew how their fuel system worked
and what their system serviceability status was!
--------
Mike
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=417241#417241
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