Switch on/off position!?

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Switch on/off position!?

Postby Loco » Wed Jan 16, 2013 5:50 pm

Hi guys

I'm used to switch position down for "off" & up for "on" (easy for me to remember because "off" sounds like "af" (down) in Afrikaans :))

But on many occasion I've seen trikes which have it the other way round (eish on my trike I have a combination of the two :oops: )

If you look at this report http://www.caa.co.za/resource%20center/ ... 8/8464.pdf it states:
During the investigation, it was noticed that all the electrical switches on the
instrument panel were incorrectly installed: if selected ON, the switch was in the
down position and if selected OFF, the switch was in the up position.
This is in contradiction to the norm in the aviation industry: if a switch is selected
ON, it will be in the up position and if selected OFF, it will be in the down position.
But that aluminum cover looks like the standard Solowings Aquilla cover

Under "SAFETY RECOMMENDATIONS":
It is recommended that the SACAA Certification Department meet with the
manufacturer of the aircraft type to discuss conformance to the build standard
requirements. Specific attention should be given to the instrument panel installation.
Did Solowings release a statement after this accident telling everybody with Aquilla's/Windlass's to go change their instrument panel layout!?

Cheers
Ant
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Re: Switch on/off position!?

Postby Mc Guyver » Thu Jan 17, 2013 7:45 am

Airborne is down for on as well and from memory all trike mnfs do this
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Re: Switch on/off position!?

Postby Bundy » Thu Jan 17, 2013 7:56 am

My Aquilla also has the switches down for off and up for on.....

....makes sense to me as all Electrical DB's work this way too!
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Re: Switch on/off position!?

Postby Loco » Thu Jan 17, 2013 7:59 am

Hi Alan does DBP have a Solowings switch plate? If so then they must have changed it subsequently...
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Re: Switch on/off position!?

Postby D2O » Thu Jan 17, 2013 8:24 am

Strange. All the planes I've flown in (5 x school trikes, 2x my own, varying from Aquilla to Windlass) ALL have their switches with off=up, on=down orientation. Seems to be a manufacturer standard?
By reading the safety recommendations in the report, it would seem that the CAA was requested to discuss the orientation of the switches with the manufacturer in order for it to become an industry norm, but I did not pick up anything about it being required, or necessary by law. They just stated that it was an aviation "norm".
I also noticed the panel was a standard panel from the manufacturer.
I'd say if the majority of microlights are done this way, then leave it this way. Swapping it just creates confusion resulting in someone accidently switching mags off one day as he is familiar with off=up orientation.
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Re: Switch on/off position!?

Postby Loco » Thu Jan 17, 2013 8:29 am

D2O wrote:Strange. All the planes I've flown in (5 x school trikes, 2x my own, varying from Aquilla to Windlass) ALL have their switches with off=up, on=down orientation. Seems to be a manufacturer standard?
By reading the safety recommendations in the report, it would seem that the CAA was requested to discuss the orientation of the switches with the manufacturer in order for it to become an industry norm, but I did not pick up anything about it being required, or necessary by law. They just stated that it was an aviation "norm".
I also noticed the panel was a standard panel from the manufacturer.
I'd say if the majority of microlights are done this way, then leave it this way. Swapping it just creates confusion resulting in someone accidently switching mags off one day as he is familiar with off=up orientation.
My 2c
Agree changing something like this could have serious implications when the paw paw hits the fan, muscle memory is a b!tch...
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Re: Switch on/off position!?

Postby Bundy » Thu Jan 17, 2013 8:31 am

Negative....we have a banana pod with toggles.
gggghj.JPG
This photo was taken before the vinyl "on/off" stickers were added. I dont think there is any "legislation" dictating the switch position for NTCA WCM's?
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Re: Switch on/off position!?

Postby skybound® » Thu Jan 17, 2013 9:15 am

I think one needs to consider the root of this 'standard', where down was On. When trikes were very much in their infancy, and Mag switches were under the seat (very few had instrument pods)- if you were to bump the switch - the direction you would bump it would be down. If down was off - you would end up with a dead stick - hence the reason they made down position as On.
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Re: Switch on/off position!?

Postby Loco » Thu Jan 17, 2013 9:25 am

skybound® wrote:I think one needs to consider the root of this 'standard', where down was On. When trikes were very much in their infancy, and Mag switches were under the seat (very few had instrument pods)- if you were to bump the switch - the direction you would bump it would be down. If down was off - you would end up with a dead stick - hence the reason they made down position as On.
Very interesting thanks
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Re: Switch on/off position!?

Postby Madman » Thu Jan 17, 2013 9:49 am

Bundy wrote:My Aquilla also has the switches down for off and up for on.....

....makes sense to me as all Electrical DB's work this way too!
Mine is also Down for On and Up for Off...on my Windlass it was like that as well now on my Aquilla.

Although on the DB its the other way around...on the light "switches" its as it is on my Aquilla...down for on and Up for off ##

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Re: Switch on/off position!?

Postby KlapperKnop » Thu Jan 17, 2013 12:56 pm

When a switch is open circuit, is that off or on? Depending what logic is applied; assume positive logic. Open circuit even in electrical is an off condition. When a MAG is off, the switch is on an ON condition causing a short circuit. In my aerie and the schools tikes I have flown, when the MAG was on, the switch was in a down position (OPEN CIRCUIT) and the panel read ON.
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Re: Switch on/off position!?

Postby Loco » Thu Jan 17, 2013 1:11 pm

KlapperKnop wrote:When a switch is open circuit, is that off or on? Depending what logic is applied; assume positive logic. Open circuit even in electrical is an off condition. When a MAG is off, the switch is on an ON condition causing a short circuit. In my aerie and the schools tikes I have flown, when the MAG was on, the switch was in a down position (OPEN CIRCUIT) and the panel read ON.
I'm confused you'll have to explain to me at the ML talk this Sat please :lol:
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Re: Switch on/off position!?

Postby mulderpm » Thu Jan 17, 2013 1:48 pm

skybound® wrote:I think one needs to consider the root of this 'standard', where down was On. When trikes were very much in their infancy, and Mag switches were under the seat (very few had instrument pods)- if you were to bump the switch - the direction you would bump it would be down. If down was off - you would end up with a dead stick - hence the reason they made down position as On.
My reasoning is the same as skybound. (^^) Mine is down, mags on, up, mags off. When you get into the aircraft and you accidentally bump the switches they will be bumped down i.e. on...when you get out of the aircraft you would bump them up i.e. off. :?: I think that is the safest sequence. To avoid the possible confusion Faizel has raised, mine are not marked. :) ...down = on. :)

Ja Faiz, mags on = open circuit....mags off = closed circuit. puff
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Re: Switch on/off position!?

Postby D2O » Thu Jan 17, 2013 3:16 pm

KlapperKnop wrote:When a switch is open circuit, is that off or on? Depending what logic is applied; assume positive logic. Open circuit even in electrical is an off condition. When a MAG is off, the switch is on an ON condition causing a short circuit. In my aerie and the schools tikes I have flown, when the MAG was on, the switch was in a down position (OPEN CIRCUIT) and the panel read ON.
Ok, that's just confusing (**) :lol:
With an electronics background, I can safely say that an off switch is ALWAYS open circuit, or am I missing your point completely?
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Re: Switch on/off position!?

Postby Bundy » Thu Jan 17, 2013 4:42 pm

Sheesh this is even more interesting than the oil debate :lol:

Thanks for the info SB...make sense for that config on the older models. 8)

I dont think there is an industry norm for this guys, lots of planes have the switches in either position....have a look.
172cessna.jpg
InstrumentPanelsycamore mk1.jpg
InstrumentPanelwcm.jpg
Jabiru Panel.JPG
...so unless someone can answer this:
Bundy wrote: I dont think there is any "legislation" dictating the switch position for NTCA WCM's?
,,,then as long as the PIC knows, it doesnt matter I guess? Must say, the onlt aircraft I've seen with the switches down for "on" are trikes. :wink: My trainer CGD was also like that. ^
Last edited by Bundy on Thu Jan 17, 2013 5:00 pm, edited 1 time in total.

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