AD 76-07-12 Ignition Switch

[StinkBug]

I was going through my logbooks this evening getting ready for my checkride on friday and realized that I have a couple AD's that need to be addressed. I totally thought they were all due at annual, but apparently there are a couple 100hr ones. Oops. This one says that the pilot can perform the check, does that mean I can make the logbook entry to show compliance as well? It just so happens that I actually did a mag shut off check today before shutting down, so I know the switch is still working.

http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgAD.nsf/AOCADSearch/C14960A415D956BD86256E520053A53E?OpenDocument

The other AD is the landing gear lubrication one, which I'll run it by the shop for tomorrow hopefully. 

[Guest]

You are legal to sign off the AD in your airframe log book.  The check is being performed at the end of every flight by most pilots anyway.

Clarence

[Shadrach]

What do you mean Clarlence?

[Raptor05121]

I do not know what the AD is in reference to, but I think Clarence is referring to a hot mag check

[Mooneymite]

When my mag switch went bad, I could hold the key lightly either side of "OFF" and the engine would keep running.

I ordered the Bendix kit.  It was a simple fix.

[Shadrach]

I do not know what the AD is in reference to, but I think Clarence is referring to a hot mag check

That I understand.  It was the "end of every flight" part that I was curious about.  I kill the engine with the ignition key a few times a year, not at every shutdown.

[kortopates]

Before killing the engine with the Mixture, while idling at 1000rpm. we always flip the switch to Off just long enough to verify the engine will quit and then put it back to Both before it dies. Then kill it with mixture. It's part of our checklist and a best practice before I go out and risk pushing it back into the hangar or wherever parking may be not realizing I may have a hot prop without doing so.

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[Shadrach]

Before killing the engine with the Mixture, while idling at 1000rpm. we always flip the switch to Off just long enough to verify the engine will quit and then put it back to Both before it dies. Then kill it with mixture. It's part of our checklist and a best practice before I go out and risk pushing it back into the hangar or wherever parking may be not realizing I may have a hot prop without doing so.

 

 

 

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That reads like a great way to test the strength of the seams in the muffler 

[kortopates]

There are no seems just tubing. But why would you think that? It never dies, and never backfires or afterfires. Just a quick stumble.

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[Mooneymite]

That reads like a great way to test the strength of the seams in the muffler 

I do mine at low idle....750-800 RPM and have never had a backfire.

[Shadrach]

There are in fact seems in my muffler, I can't speak to the K model. I have always been admonished against reintroducing spark after killing the engine with the mag switch. Many years ago during a 1500 RPM run up, I clicked too far to the left and killed the mags for a split second. The resulting "report" got the attention of everyone within 500yds. I've been leery of "after fire" ever since!

Edited September 17, 2015 by Shadrach

[Guest]

Most pilots taught in recent times are taught to do a "live mag check" prior to killing the engine with the mixture control.  Only the really slow ones test the mufflers on flight school airplanes.

Clarence

[ryoder]

I have a new switch that gets rid of the AD.

But about the lubrication AD. Is that something a pilot can sign off? I did it at annual with my IA supervising and helping. He signed the annual.

[Guest]

I have a new switch that gets rid of the AD.

But about the lubrication AD. Is that something a pilot can sign off? I did it at annual with my IA supervising and helping. He signed the annual.

The lubrication AD is every 2000 hours, hardly a recurring AD at that interval.

Clarence

[jetdriven]

The lubrication AD I thought was due every 100 hours on pre-j models.  All the rod ends.

 

also the fuel injector lines must be signed off per the AD every annual and/or 100 hours.  

Edited September 18, 2015 by jetdriven

[StinkBug]

The lubrication AD on my plane is every 100hrs, and no the pilot can't sign it off. It also includes jacking up the plane and swinging the gear/checking preload. I did it today with my IA and it wasn't terribly hard, but not something I could have done without a set of jacks and a bit of his knowledge either. 

[ryoder]

I just removed panels and squeezed the grease gun to help him.  I'll do that next time too and time it with either an oil change or annual.  With all these mods and bad weather it's hard to get 100 hours.

[Guest]

I have a new switch that gets rid of the AD.

But about the lubrication AD. Is that something a pilot can sign off? I did it at annual with my IA supervising and helping. He signed the annual.

Sorry, I've mis read Ryan's post.  I thought he had installed an ACS Gerdes switch which does not have the "live mag" check each 100 hours, but does have a lubrication AD every 2000.

There are indeed several other recurring AD's due each 100 hours.

Clarence

[jlunseth]

I also do a quick mag check on shutdown every flight.  You don't dwell on the "Off" position, just a quick flick and a good ear will tell you if the switch is working.  I don't bother to check the idle speed, I am usually sitting on the tarmac ready to shut down so it is about 1200.

[kortopates]

There are in fact seems in my muffler, I can't speak to the K model. I have always been admonished against reintroducing spark after killing the engine with the mag switch. Many years ago during a 1500 RPM run up, I clicked too far to the left and killed the mags for a split second. The resulting "report" got the attention of everyone within 500yds. I've been leery of "after fire" ever since!

Thanks for clarifying. I understand your hesitancy now. But of course we don't actually kill the engine, just listen for the stumble and  always be very quick to turn back to both while listening. i.e. you don't really wait for the stumble as much as you listen to it as you manipulate the key to avoid taking too long. Granted backfire/afterfire is a small risk from being too slow about it, and although a hot prop should be an even smaller risk, its one risk I am more motivated to avoid by checking this.

Not sure when I started doing this. Long after my PPL training but before A&P school where we were all admonished about not doing this every time to be safe.

[jetdriven]

As long as long as it's below 1200 RPM (<1000 RPM preferrable) and you switch to "off" less than about 1-1.5 seconds it won't afterfire.  

[ryoder]

My flight school taught me to so this prior to every shut down.  I don't do it anymore now that I have the new switch without the AD.

[carusoam]

Ryan,

I think that is a final test of the mags more than a test of the switch, no?

if a mag were to fail during the flight, it may not be as noticeable...

it is better to have the heads-up before being dissapointed at the beginning of the next flight.

best regards,

-a-

Edited September 19, 2015 by carusoam

[jetdriven]

It's really more to test that the P-leads still ground the mags before handling a propeller such as pushing a plane into a hangar.  If the P-lead breaks the mag stays hot.  I've never found a broken P-lead but I've had 3 broken alternator field wires in 500 hours. 

[kortopates]

I've also never had a broken P-Lead but I have had an internally corroded Bendix switch that wasn't grounding the p-lead (and like Byron, a corroded field terminal that broke and even the big alternator output corroded and broke under the nut and broke during a 4.5 flight in Alaska that was mostly IMC - thank goodness for dual alternators!). The Bendix rebuild kit would have been perfect to fix it too, but at the time it was a 3-week wait to get one (I tried many sources) so I ended up buying the $500+ new Bendix switch.  AD or not, all switches are subject to the same issue over time.