Today's Message Index:
----------------------
1. 01:24 AM - Analogue Engine instruments near VHF radio. (Bob Verwey)
2. 05:08 AM - Re: Clarify Z101 (johnbright)
3. 05:23 AM - Re: Clarify Z101 (wsimpso1)
4. 05:39 AM - Re: ****SPAM**** Analogue Engine instruments near VHF radio. (Peter Pengilly)
5. 11:29 AM - Re: ****SPAM**** Analogue Engine instruments near VHF radio. (Robert L. Nuckolls, III)
6. 03:04 PM - Re: Contactor Failure (Robert L. Nuckolls, III)
7. 03:34 PM - Re: Clarify Z101 (bcone1381)
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| Subject: | Analogue Engine instruments near VHF radio. |
Is there any issue placing conventional electric VDO guages very close to
the " round hole" Becker comm?
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| Subject: | Re: Clarify Z101 |
bcone1381 wrote:
>
> .
> .
> .
> 3) Does your Electronics International CGR-30P Engine Monitor stay on line during
engine start, or will it reboot?
The installation manual says it works between 7.5 and 30V.
--------
John Bright, RV-6A, at FWF, O-360
Z-101 single batt dual alt SDS EM-5-F.
john_s_bright@yahoo.com, Newport News, Va
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| Subject: | Re: Clarify Z101 |
user9253 wrote:
> If the battery contactor fails open during flight (unlikely), how will the pilot
know it?
When the pilot pulls the throttle to idle, voltage drop from 14 might be noticed.
A further point is to review the failure modes and their effects. Looking at things
that way may be enlightening. With the battery contactor failed open and
wired per legacy designs, if the pilot (for whatever reason) attempts a reset
of the alternator, the airplane goes dark and the alternator will not be re-energized.
Why would a pilot do that? It is an instructional tool used by some instructors
and some pilots check alternator function this way. Not saying it is
right, but it is out there. Seems to be pretty low likelihood...
With the designs we find dear to us from AeroElectric Connection, we have alternate
methods of repowering the fields of our main and aux alternators. Z-12 has
E-Bus Alternate Field switch, Z-14 has always hot buses, etc. Failure tolerant
design changes the rare failed contactor from a full blown emergency into a
ramp failure, and a simple repair.
Billski
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| Subject: | Analogue Engine instruments near VHF |
radio.
It depends
Becker comms do not consume much current when not transmitting so are
unlikely to cause a problem until the PTT is pressed, if at all.
The Van=99s manifold pressure gauge I had was very susceptible to
EMI and would read zero when the PTT was pressed, even with the antenna
in the back of the aeroplane.
Some of the other gauges were less sensitive but I suspected the were
not well shielded.
The only real way to find out is suck it and see.
A good grounding scheme will always help along.
Some manufacturers recommend twisting the power wires, but I=99m
not convinced that helps and it always assumes the power and ground
points are close together which is often not the case.
Peter
From: owner-aeroelectric-list-server@matronics.com
<owner-aeroelectric-list-server@matronics.com> On Behalf Of Bob Verwey
Sent: 22 October 2022 09:23
Subject: ****SPAM**** AeroElectric-List: Analogue Engine instruments
near VHF radio.
Is there any issue placing conventional electric VDO guages very close
to the " round hole" Becker comm?
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| Subject: | Analogue Engine instruments near |
VHF radio.
At 07:38 AM 10/22/2022, you wrote:
>It depends=85
>
>Becker comms do not consume much current when
>not transmitting so are unlikely to cause a
>problem until the PTT is pressed, if at all.
90% of time, Comm Tx interference to panel
accessories is due to deficiency in accessory
design . . . not the fault of the transceiver.
I've tested a number of steam guages that
were affected by expected RF energy
sources. Some were affected by extra
strong signals like hand held transceivers
and bubble canopy a/c with an antenna laid
up inside the canopy behind the pilot's
head.
I've seen a couple of instances where a comm
system with satisfactory service history suddenly
becomes a strong antagonist to panel accessories.
Both cases involved the shield connection to
coax connector at the back of the radio becoming
disconnected. This turns the coax feedline
into an antenna that illuminates wiring behind
the panel with strong RF.
>The Van=99s manifold pressure gauge I had was
>very susceptible to EMI and would read zero when
>the PTT was pressed, even with the antenna in the back of the aeroplane.
>
>Some of the other gauges were less sensitive but
>I suspected the were not well shielded.
Agreed.
>The only real way to find out is suck it and see.
>
>A good grounding scheme will always help along.
System ground have virtually no influence
on RF interference issues.
>Some manufacturers recommend twisting the power
>wires, but I=99m not convinced that helps and it
>always assumes the power and ground points are
>close together which is often not the case.
A mythical practice not supported in demonstrable
physics.
>Is there any issue placing conventional electric
>VDO guages very close to the " round hole" Becker comm?
Vulnerability of the panel accessory can be roughly
evaluated on the bench. Hook it to a power supply
and use a hand-held vhf ratio to check for effects.
If there are no observable effects with the handheld
a foot or so away, the instrument is probably well
designed for such issues. I've seem some Van's
gages go crazy with the radio 2 feet away.
Bob . . .
Un impeachable logic: George Carlin asked, "If black boxes
survive crashes, why don't they make the whole airplane
out of that stuff?"
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| Subject: | Re: Contactor Failure |
At 07:22 AM 10/22/2022, you wrote:
>
>
>user9253 wrote:
> > If the battery contactor fails open during flight (unlikely), how
> will the pilot know it?
>
>
>When the pilot pulls the throttle to idle, voltage drop from 14
>might be noticed.
This may not even happen with belt driven alternators.
They often support light loads at normal bus voltage
at taxi idle rpm.
>A further point is to review the failure modes and their effects.
>Looking at things that way may be enlightening. With the battery
>contactor failed open and wired per legacy designs, if the pilot
>(for whatever reason) attempts a reset of the alternator, the
>airplane goes dark and the alternator will not be re-energized. Why
>would a pilot do that? It is an instructional tool used by some
>instructors and some pilots check alternator function this way. Not
>saying it is right, but it is out there. Seems to be pretty low likelihood...
agreed. but some alternators, particularly belt
driven, will self excite at cruise rpms or even
less. The Bonanza and Baron alternators will do
it . . . in fact, it's a requirement.
>With the designs we find dear to us from AeroElectric Connection, we
>have alternate methods of repowering the fields of our main and aux
>alternators. Z-12 has E-Bus Alternate Field switch, Z-14 has always
>hot buses, etc. Failure tolerant design changes the rare failed
>contactor from a full blown emergency into a ramp failure, and a simple repair.
Speaking of contactor failures:
There are two primary causes for contactor
failure (1) loss of coil current which produces
the magnetic engagement force and (2) degradation
of switched power conduction path (worn out or
corroded contacts). Perhaps we could consider
a sub-set of (2), stuck or welded contacts.
Loss of contact integrity is the most common . . .
the thing just wears out or succumbs to environmental
stresses. One such example is seen here:
https://tinyurl.com/226jcjnl
We've seen examples of coil 'failures' . . . this
one was a manufacturing defect . . . failure to
solder the joints!
https://tinyurl.com/me767pxn
In general, failure to energize is rare . . .
electro-magnets just don't 'wear'. Most
failures are due to compromise of the
current carrying contacts and those will
start to get 'fussy' before they absolutely
quit.
Had a hangar renter on our airport that
bragged about getting his airplane started
by rapping the battery contactor with
a screwdriver.
Contactors are cheap. The cognizant owner/
operator will replace one the FIRST time
it gets fussy. A teardown of the old one
is always in order too. Worn contacts?
Signs of corrosion? Perhaps evidence of moisture
ingress? Was it mounted with proper orientation
(cap down) and a drain hole added to the cap?
A failure to energize in flight is more
likely to be in the contactor's control
path. Lose hardware, bad crimp, master switch
going south? Again, age and environment
are the biggest stresses on switchgear.
The ONLY switch I ever replaced on a piece
of heavy iron was in a Beechjet where a $high$
toggle switch that carried very low signal
current went 'open'. The tech I was working with
got out his pen to write up a requisition for
the $100 switch (two hours away in a warehouse).
I got a constant current bench supply out of
the crib, set it for 10A and connected the
offending switch to 'dead short' the power
supply. I wiggled the switch a few dozen times
against the corrosion burning power source
and put the switch back in the panel where it
would probably run another ten years.
If your project's low cost toggle switches
with fast-on tabs are getting long in the tooth . . .
the cost of replacing all the power management
switches is an hour's effort and fewer dollars
than a family trip to MacD's. That's why I've
favored them from day-one.
In any case, loss of a contactor or switch
in a well considered architecture (even while
airborne) is rare and no big deal.
Bob . . .
Un impeachable logic: George Carlin asked, "If black boxes
survive crashes, why don't they make the whole airplane
out of that stuff?"
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| Subject: | Re: Clarify Z101 |
johnbright wrote:
>
> bcone1381 wrote:
> >
> > .
> > .
> > .
> > 3) Does your Electronics International CGR-30P Engine Monitor stay on line
during engine start, or will it reboot?
>
>
> The installation manual says it works between 7.5 and 30V.
Awesome, Thanks for hunting that down John! Feedback I'm getting fro a supercub
owner agrees that it stays on line during start.
--------
Brooks Cone
Bearhawk Patrol Kit Build
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