Mag test.

[Blue Max]

I was taught during my training to do a mag test.
You run the engine to about 4000 revolutions and test the mags by switching the toggle switches on and of and listen ( and look)for a drop in revolutions of about 180 revolutions.
lekker.!!
That is what I am doing to make sure the engine will be running on both mags in working condition.
Off lately I came to the understanding that some okes do a test by running the engine at 6000 reffs before take-off for 3 to 4 minutes.!. Because, they say that when you take off, the engine is going to run at, at least at 6000 reffs and therefor you have to make sure it is O K to get you to take-of without a problem.
Jislaaik ouens weet julle hoe klink n engine teen 6000 reffs vir 3 min terwyl dit op die grond staan en jy die boer se bome hier agter jou wegwaai en jy gevaar loop om n klip in die prop op te tel.?
Help n biekie met hierdie ene.?

[KFA]

Het hulle al gesien hoe lyk 'n prop wat teen daai revs op een plek maal. Sandblasted. Hy kan sommer reguit paintshop toe.... Het hulle ook gesien hoe buig die goose nek daar voor by die wiel as jy hom so vashou? Dit is sommer nonsens. Die vervaardiger skryf voor hoe jy dit moet doen en dit is dit.

[Bundy]

Dis n klomp kak...and downright dangerous. Have a chat to your tjommies Oom Paul definately not how it should be done.

The Cart is not designed to be stationary at near to full RPM! The danger of a runaway trike is also present here!

I do my Mag check at 3600rpm and I try and do it over grass or paving if possible. (Depends where you are)

Some guys only check their mags before the first takeoff of the day...I check mine before every TO...and again before I do my final shut down.

[nicow]

Doen jou mag check tussen 3200 en 3800 revs.3600 is fine

[Andre morne]

Al waneer ek my trike vir vir 3min opi grond vol revs laat hardloop is waneer ek hom kla gediens het om te kyk of als reg is

[Alkemac]

Under CFI at Panorama, we used to run full tilt for 10 seconds at the power block, and then do a mag test at idle speed.

Also at switch off, we used to do a mag test at idle speed.

[mulderpm]

Oom Paula, I know of a few pilots who do this test and they have had instances where the engine fails during this test. Ask Flo.

I don't do this test because I believe it is dangerous, bad for the airframe and propeller and the chances of the engine failing in this minute or so in comparrison to the whole flight does not prove anything. Also the manufaturer does not specify a test like this.

I rev the engine up to +-3000 rpm and then switch off the mags one by one listening to the drop in rpm. My tachometer shows a drop of about 150 rpm but because you are short circuiting one of the coils I don't think it is accurate under these conditions. Rotax specifies a max drop of 300 rpm.

[bobthebuilder]

Take a look at this, it clears some misconceptions regarding mag checks.

http://www.caa.govt.nz/Publications/... ... rApr08.pdf

[Duck Rogers]

Dis n klomp kak...

[Louis Cole]

Ek stem saam met Bundy. Dit is 'n sommer 'n klomp kak. Om vir 4 min. jou vliegtuig teen vol rewolusies te hardloop net om jou "mags" te toets is malligheid en net ou Dowwe Dolla sou 'n "power check" met 'n rpm toets verwar. Ek het gevind dat elke skool sy eie "pre-flight" roetine ontwikkel wat soms baie vanmekaar verskil. By Centurion Flight Centre byvoorbeeld leer Flo as deel van jou opleiding onder andere twee spesifiek afsonderlike "pre-flight" toetse nl. 'n "magneto"-toets en 'n "power check".

- Die "magneto" toets vereis dat jy voor elke vlug die rewolusies tot 3000 rpm opstoot, die magnetos afsonderlik afskakel en kyk vir 'n daling in die rpm van nie meer as 300 rpm nie en dan albei gelyktydig af te skakel en dan weer aan te skakel.

- Die "power check" vereis dat jy jou vliegtuig weg van ander vliegtuie, voertuie of mense teen 'n voorwerp maak staan en dan stadig jou vliegtuig se rewolusies op te stoot na volkrag vir sowat 'n minuut ( die tyd wat dit jou kan neem om op te styg en dan stadig weer van die krag af te kom.

Ek het ook al die twyfelagtige voorreg gehad om saam met ouens te vlieg wat feitlik geen "pre-flights" doen nie selfs nie op kritieke toetse soos vir water in die petrol en verkoeler, rpm magneto toets, water temperatuur ens. wat alles uiteindelik bydra tot enjin problem en hopelik op die grond.

[Bundy]

Ek het ook al die twyfelagtige voorreg gehad om saam met ouens te vlieg wat feitlik geen "pre-flights" doen nie

Tick...tock. (See newsletter issue 4)

Guys like that will learn the hard way sooner or later...if they survive of course.

The pre flight is definately taught differently depending on the ATO, but as long as it covers all the necessary and is done in the same way everytime it is not a problem I think?

[Blue Max]

Die manne wie my opleiding gegee het, het my niks van 'power test' geleer nie.
En beslis nie teen 'full power' vir n minuut nie.!Ek vermoed daar moet n goeie rede daarvoor wees en na my mening is dit sekerlik dat dit nie goed is vir die engine om in n stilstaande posisie die lug te staan en maal teen 6000 + reffs nie.
Dink aan n motorvoertuig wat jy vir n minuut teen full power staan en reff versus n voeruig wat beweeg teen top spoed.
Ek sal nie my aerietjie aan so n toets onderwerp nie.! Want daar is n verskil tussen full reffs stilstaande en full reffs in beweging. Punt.

[KlapperKnop]

RhinoPark taught me to be aware of an engine out after take off at all times. I was only taught of mag test and no power test.

[Morph]

What does a mag-drop test prove?

Normal operation both mags are on, and both plugs per piston is firing, engine is running smoothly

switch A off, half the plugs are now firing, causing the rpm to drop slightly and engine run rough. The engine is running on Mag B

Switch A back on and Switch B off. You are now running on Mag A.

If both switches cause a drop in RPM then the mags are working fine

There are only two error options

1. No drop in rpm, engine running nice and smooth, i.e. both mag A and B are running. Switch A causes a rpm drop as expected, but Switch B doesn't alter the RPM at all. The earth lead to switch B and Mag B is missing. Under normal operation switching the switches off effectively shorts the mag to earth. You will probably find that the engine won't die when you switch both switches off, it will just run roughly, and you will have to use the choke to flood it to get the engine to stop. Why, because Switch B is not shorting out Mag B? This is dangerous and must be fixed quickly, why.... because MAG B is hot and even a simple movement of the prop by a kid, or you during preflight etc, could cause it to fire, and then you have an unmanned aircraft and seriously injured people? I would remove the plug leads until you can get this fixed.

2. One switch works perfectly, the other causes the engine to die. When you start the engine is running rough. In this case you have a faulty Mag. If Switch A causes the engine to die it means that Mag B is faulty, and vice verse

Now why would running at 6000 rpm help you? You really just need to run at a high enough rpm so that you can hear the difference in rpm, at idling the engine is running too rough to tell accurately.

I also suggest if you spend 5 minutes running your engine at full tilt on the brakes, you are going to have very unhappy neighbors, especially from the dust and stone storm caused, as well as the noise. The only time you need to go to full power is on takeoff.

Once you have done all your checks, enter and line up with the runway, apply full power, check you are getting full power, and if not abort the takeoff

[Grumpy]

Nice explanation Greg !!