Mag switch safety

[frankmcm]

I managed to accidentally switch off one mag during a go-around recently. While tempted to remain silent, and maybe disguise a clumsy mistake, I wonder if there may be a learning point worth passing on.

 

My cockpit could be described as "snug" when I am inside, and the dash is within easy reach.

 

I aborted a bouncy touchdown by applying full revs and climbing away. I then reached up to take off 2nd stage flaps.

 

The Jab throttle handle is between my knees near the front of the seat, My left hand, in sweeping up from between my knees to the flap lever over the pilot door, contacted the mag switch. The cover flipped open and the switch toggled off.!

 

No harm done this time, but I dread to think of the consequences had I managed to open both switches. They are about an inch apart, and could easily have both been affected. I believe the panel layout is fairly standard.

 

Apart from being a lot more aware of the problem, I am considering if alternative switches may be a good idea. Any suggestions??

 

 

[fly_tornado]

is it a toggle switch? if it is, why not just invert it?

 

 

[facthunter]

relocate or put guards over the mag switches. you will generally lose some power with one switch off. Because the Jabiru has the plugs close together the power loss is not as much as with some other engines, but it is still there and it will run hotter as well . The reason is that you can run LESS advance when you have two plugs and then with one out the engine will effectively be running more retarded than it should. Nev

 

 

[Guest davidh10]

In the Airborne trikes, they are recessed in a channel, just wide enough for a finger, on the outside of the seat frame. While it is conceivably possible to do the same, I think they are pretty well protected and therefore it is unlikely.

 

Part of my PAX briefing is identifying the mag switches, choke, hand throttle and asking the PAX to "...try and avoid bumping them." That said, you always have to be prepared to check them if you think the PAX may have accidently bumped one. During my training, the CFI surreptitiously flipped one mag off during flight one day. At the time, I didn't pick what it was, and after scrutinising the engine instruments for something abnormal and not finding anything, continued on until he alerted me to what he had done. It was a good lesson.

 

 

[Guest 4aplat]

Hi

 

IN my avid flyer I used to have a "ACS twin ignition rotary keyed switch" but after a"lifting" of the dash board now I've got 2 swithes as it's easy to quick check if they are in the good position

 

I put them at the top of the dash board where "no hand" is supposed to be !

 

 

If you can't put yours switches elsewhere, just use something like this to protect them (ref eaton 8492K1)

 

 

http://www.farnell.com/datasheets/63906.pdf

 

MicheL

 

 

[frankmcm]

Thanks for the suggestions.

 

Inverting would probably have prevented this episode, but would still have the potential for catching should I be making the opposite hand movement i.e. flap to throttle. So I dont think that will solve it.

 

The existing switch cover should protect the switch. It didnt, which is what made me interested in exploring options.

 

I like where your switches are positioned 4aplat. I think my switches are in the wrong place for me. They are right beside my knee, exposed to occasional knocking during entry, Time to redesign the dash? There isnt really a lot of free space on the dash for new holes, but I think it should be possible to make adjustments without a total rebuild.

 

Rotary switch is tempting, but I hadnt thought of the risk of breaking the key off.

 

Finally, as a general safety issue, it may be unwise to have them so close together. Maybe a minimum separation of a hand span should be recommended.??

 

 

[Spin]

As with most things aviation, placing the switches is a compromise - I'm not sure that I'd want to separate them though, I've already had one occasion where I quickly killed the motor just before taxi because I was unhappy about the movements of someone else's passenger in the vicinity of my prop. It was very useful to be able to stick out two fingers and stop the engine in a second or two.

 

 

[frankmcm]

My engineer favours separate mag toggles, as occasionally there may be a need to have both off but the avionics on.

 

As you point out, rapid switchoff can sometimes be essential.

 

I think I am looking at better shields, like Farnell...

 

thanks for suggestions.

 

 

[Deskpilot]

Many years ago (and in the UK) toggle switches were down for on, and up for off. I believe it was the aircraft industry and or RAF that reversed that in order to be able to swipe ones hand down, over a bank of switches for a rapid shut-downs, a feature that I feel is very important. Spin's example of someone walking into a prop is the perfect example. To this end, I would suggest that switches should be carefully grouped so that all systems that need to be shut down in a hurry can be (think crash landing) by one swipe down of the left hand. If this can't be arranged, then appropriate guarding is a must, particularly in a confined cockpit. I fly a Jab LSA55, am 6ft tall and weigh 100kilos but I don't find the cockpit cramped. To accidentally hit the mag switches moving from throttle to flaps................? My solution would be to place a guard plate under the switches but keep the 'down for off' orientation.

 

 

[Guest Baphomet]

What about the GA type solution i.e. a keyed rotary switch for Mags. Off - L - R - Both - Start (or seperate start push button). And a seperate master switch for electronics. That would also provide some safety and a way to prevent unorthorised starting (which I believe is a requirement now). A toggle switch solution for mags, may still allow the engine to be started by hand proping even though the master is off. I could be wrong, but something else to think about.

 

Cheers

 

Baph

 

 

[Guest 4aplat]

Hi

 

I don't like the GA solution as it's not possible to make the engine turn without the mags (to increase the oil pressure when you change the oil or to test a cylinder compression)

 

in addition to this the GA is very heavy (my dash board is 2.5 kg lighter than it was before with the GA and other un-usefull instruments)

 

only 2 switches for the mag, one for the instruments, one for the pump, one for the radio/gps one for the flaps and the last one (near the throttle) to start the engine and that's all

 

MicheL

 

 

[dazza 38]

HI Guys, How about the toggle switches that have a Red locking guard. The guard has to be flipped up, before the toggle is moved up to the off position. They are used on some military aircraft.

 

 

[facthunter]

Guarded switches....that was my suggestion in post #4. Continuing on from that, I reckon the location in the Citabria is good. On a Panel above the door on the left side. No need to guard them when they are there. Surprising how often switches get bumped . The Skyfox was prone to it. You DO need to be able to "motor" your engine without having the Mags on at times. Nev. Keep thing as simple as possible. Nev

 

 

[Guest 4aplat]

HI Guys, How about the toggle switches that have a Red locking guard. The guard has to be flipped up, before the toggle is moved up to the off position. They are used on some military aircraft.

The red guards are not a good solution

 

they protect switches when the guards are closed but in case of emergency, if you need to switch the engine OFF --> KO !

 

One could say it's possible to mount them in the other way (guard open) but in this case it doesn't protect the switch ..........

 

MicheL

 

 

[Guest Maj Millard]

A lot of good discussion and suggestion on a subject that can easily ruin your day quickly.

 

Whenever I hop in a plane that has switch guards fitted, I think..what a great idea.

 

The early lightwings had them, and they still allowed the switches to be easily and quickly accessed.

 

My current aircraft has them ungarded, but they are high up on the left, and I haven't hit them yet. They would be safer with guards of course.

 

The guard suggested by Michel in post #6 is very effective, easy to make and not too bad to fit.

 

The red gaurded 'missile' switches are not suitable for IGN switches, and would make the chances of hitting them accidentially even greater. I do use one on my panel for the fuel transfer switch. When the red cover is up it does a great job of reminding me that the pump is on, as it takes 20 minutes to do the transfer.

 

I do believe IGN switches should be quickly accessed for good reason, as prev suggested.

 

I remember the early ul days when we only had one IGN switch....hit that accidentially and your going down, or pulling on a starter rope real hard !. A real good idea to fit guards if you don't already have them IMOP..............................................Maj...

 

 

 

 

[Spin]

I remember the early ul days when we only had one IGN switch....hit that accidentially and your going down, or pulling on a starter rope real hard !. A real good idea to fit guards if you don't already have them IMOP..............................................Maj...

Like the poor bloke who dumped his Volksplane into the trees a year or two back after knocking the magswitch - ouch! I have vivid memories of sitting in the back of a trike over a patch of unfriendly terrain, pilot and I taking turns to tug on the starter after a wee bit of mismanagement in switching fuel tanks - a bit of adrenalin helps but it still isn't too easy to achieve. We eventually resorted to my loosening my straps, hanging out of my seat to the left, trying to keep us on an even keel with one hand, whilst the man upfront tugged his heart out, swinging back into the space normally occupied by my head and shoulders.

 

 

[Guest Maj Millard]

Spin, The only thing better was when your out on a fly-out about to depart for home. All your mates are fired up and waiting in their aircraft, you give the start rope a pull,...and the damn rope breaks !!!!............Ah the good old days !!!????.................Maj...

 

(First photo :pull start handle lower-center of dash secured with velcro tab !)

 

 

 

 

 

[dazza 38]

HI Guys, How about the toggle switches that have a Red locking guard. The guard has to be flipped up, before the toggle is moved up to the off position. They are used on some military aircraft.

The guards im referring too are the ones that dont cover the whole toggle switch. It more like a flat plate, hinged at the top with a notch at the bottom where the notch connects to the base of the toggle switch preventing inadvertant movement.When wanting to raise the switch, just flick up the guard first.In a emergency, it isnt much slower than not having it

 

, milliseconds to flip. Eg- F111 Fuel Dump Switch.(the only difference is that the F111 has copper lockwire holding the guard down).

 

I wish i had a picture.Its hard to explain.

 

 

[Guest Maj Millard]

I'm with you Dazza,...................................Maj...

 

 

[Tomo]

My solution would be to place a guard plate under the switches but keep the 'down for off' orientation.

My thoughts also.

 

The Pietenpol I flew in the other day had a brilliant mag switch. (dual ig Ford Model A engine) Not sure if the switch would 'suit' a modern looking aircraft though...

 

 

[frankmcm]

Lots of useful advice coming through. Right now I'm in Florida for a few weeks. I see a couple of airshows locally, where I will be carefully scrutinising the cockpit arrangements of anything they let me close to.