Cessna Master Switch R & R

Ventucky Red

Ventucky Red

Pattern Altitude
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Jon
Does this require major open panel surgery, or is it held in place with a spring clip and can it be popped out? The second photo is the mount.

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Gary Ward said:
#1,
Remove cowl and disconnect battery.
Then remove pilots seat,
then...
Click to expand...

I was hoping not to hear that.... the pilot's seat that is.. :p

Yes, anytime I do anything electrical, I always disconnect the battery
 
Yup. Get that seat out. The job otherwise becomes really awkward for anyone who isn't a contortionist.

It's been a while since I changed a master switch, but IIRC you use a pick to release the small lock tabs on that little mounting plate and the switch comes out toward the firewall. Connect the new switch exactly as the old one, changing one wire at a time to prevent miswiring. Make sure the switch goes back in right side up, too, or the master/alternator stuff will be all wonky.

I find it helpful to take a photo with my phone of the wiring connections and switch orientation of stuff like this before I take anything apart.

The service manuals make no mention of switch removal.

Is changing that switch owner-maintenance stuff in the US?

The plastic landing light/nav light/pitot heat and other switches have barbed plastic tabs that have to be compressed just right so they'll let the switch move aft out of the panel (toward the seats). The double switches are a special pain. You need to fabricate an aluminum tool to compress them simultaneously, and even then you will raise your blood pressure somewhat.

While you're under there, see if you can determine the brand of the mag switch. It will be either Bendix or ACS, and both of those have separate and distinct ADs against them, and too many mechanics assume that it's a Bendix and do the annual Bendix test on it. I have found airplanes with 30+ years of that "Bendix ignition switch AD check carried out" in the logs, while the airplane had an ACS switch the whole time and was decades out of AD compliance.
 
Dan Thomas said:
Is changing that switch owner-maintenance stuff in the US?
Click to expand...
Depends on how far you stretch the Coleal memo, which established that the items in the preventative maintenance list were representative examples, not exhaustive. Closest item would be:

(16) Trouble shooting and repairing broken circuits in landing light wiring circuits.
 
Ed Haywood said:
Depends on how far you stretch the Coleal memo, which established that the items in the preventative maintenance list were representative examples, not exhaustive. Closest item would be:

(16) Trouble shooting and repairing broken circuits in landing light wiring circuits.
Click to expand...
OK. Thanks for that. In Canada, the "Elementary Maintenance" list is specifically declared to be exhaustive; that is, if it isn't listed, it is not an owner-maintenance item.
 
Ed Haywood said:
Depends on how far you stretch the Coleal memo, which established that the items in the preventative maintenance list were representative examples, not exhaustive.
Click to expand...
Technically is not stretching the Coleal LOI as it dealt with pilots checking tire pressure on a Part 135 jet. Its how you would “stretch” the long-established guidance mentioned in the LOI: take the Part 1 definition of preventive mx and apply it to the 31 categories listed in Appdx A(c). Same process has been used for determining what is a major alteration or repair as listed in Appdx A(a)&(b) as well.

So to use your item 16 above as an example, you could “stretch” that category to read as follows when you apply the Part 1 definition: Preventive maintenance means simple or minor preservation operations and the replacement of small standard parts not involving complex assembly operations. (16) Trouble shooting and repairing broken circuits in [any] wiring circuits.

So your reference to determine if it meets preventive mx is the Part 1 definition as applied to Appdx A(c)16 and not the Coleal LOI. Then you would use the proper manual reference to actually perform the mx and sign off the work. As long as you can shoe-horn the task into one of those 31 existing categories you're technically in the gray. But you can't create a new category.
 
Removing the pilot seat is not a big deal, in my experience. Putting it back in on a S model... make sure children are not in earshot unless you have a helper. The thicker upholstery in the S model (I presume T also) stops the seat just short of being free from the rail when pushed forward. A little pressure and wriggling will get it off. However, going back in requires extra effort to compress the foam against the side of the cabin at the front while the rollers/guides are positioned to engage the rail and the lock pins are retracted. Earlier models are supposedly less padded and much easier to replace. Definitely remove it as you will have much more space to lay on your back and not hire a Cirque du Soleil performer to help.
 
robin ardoin said:
Removing the pilot seat is not a big deal, in my experience. Putting it back in on a S model... make sure children are not in earshot unless you have a helper. The thicker upholstery in the S model (I presume T also) stops the seat just short of being free from the rail when pushed forward. A little pressure and wriggling will get it off. However, going back in requires extra effort to compress the foam against the side of the cabin at the front while the rollers/guides are positioned to engage the rail and the lock pins are retracted. Earlier models are supposedly less padded and much easier to replace. Definitely remove it as you will have much more space to lay on your back and not hire a Cirque du Soleil performer to help.
Click to expand...
Jack that seat all the way up with the vertical adjustment. That gets you more room. The front doorposts angle down and inward, so if the seat is low it will get fouled against the doorpost.

The older 182s were bad this way. Usually had to take the doorpost cover or kick panel off to get some room.
 
Just last week I replaced my avionics master switch. Wasn't too bad of a job. Took the seat out.
The old one was still working but was shooting sparks out of it during take off and landing. That got my attention as I was landing after dark and sparks shooting towards my leg.


Years ago I updated my ACS ignition switch and added the diode to the starter solenoid.
Yes having the seat adjusted up helps, as I fly it all the way down since I am tall. It's tight on my N model, but I have it down now from doing it many times.IMG_5033.jpeg
 
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The ignition switch was wrapped in this, you would have to open it up to see which switch is being used.
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Stay away from the prop because the mags are live when this switch is out. Pretty sure.
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Switch was working fine, I did the update from reading about it and wanted the diode on my starter solenoid. Kit cost 18 bucks.
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I think I remember that the instructions said to apply red paint markings to the screws to indicate it has been updated?

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