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MZ 202 Alternator
#1
Last Sunday I lost my engine tach indication on climb out (I have a gyroplane) and then noticed a voltage drop from 13.8 to 12.6. I landed and checked alternator output and it was .117 volts. Just wondering if anyone else using this engine has had an alternator failure? I finally got the flywheel off and found the plate the lighting coil attaches to seperated from the lighting coil. I will try and post pic's.




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#2
Yep, looks mighty familiar. The mounting plate is weak, and in the case of our helicopters, (vertical mount) subject to breakage during a hard landing. Contact Leon, he will certainly send you another ASAP, for a price. Wink
Don't ask me how I know. You will also need to inspect your stator for broken magnets.
Skeeter
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#3
Leon has thickened the plate up to avoid this problem on the Mosquito.
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#4
Hopefully that will cure the problem! Looking at the cracked metal in seems to me that its metal fatique. Hard to believe a hard landing would cause that. My gyro has air shocks with a 12 inch travel, I hardly know when the mains touch. Here are a couple of pics showing the gear in action.


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#5
Skeeter, did you replace the rotor and magnets or just the stator? Trying to decide if I should do both. The magnets appear to be intact without cracks but not completely sure.
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#6
IMG_2600-1.jpg picture by albcnu

skeeter you crazy guy

skeetermag2-1.jpg picture by albcnu
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#7
I'm not familiar with this plate, but it looks like resonant vibration fracture.
Is there a way to upgrade my existing plate -- for example RTV silicon vibration dampers; rubber absorbers between the plate and block, reinforcing strips etc?

Hoyt Stearns
Scottsdale, Arizona US
http://HoytStearns.com

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#8
Hoyt A. Stearns Jr. - 6/27/2010 8:48 AM

I'm not familiar with this plate, but it looks like resonant vibration fracture.
Is there a way to upgrade my existing plate -- for example RTV silicon vibration dampers; rubber absorbers between the plate and block, reinforcing strips etc?

Hoyt Stearns
Scottsdale, Arizona US
http://HoytStearns.com


Nope! Just suck it up and replace it when it fails.
Have a great day,
Skeeter.
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#9
Hi All,
If you do not have the upgraded plate from Leon, get it. I know of about 2 or 3 of these plates that have cracked. I inspected mine as well with 53hrs on it. It is showing signs of cracking as well. These cracks are propagating in areas that are not stress related. I would have expected the cracks around the bolt holes or corners. Not the case. This is a cast part and with a cast part you have areas that are void. These are where the cracks are starting to form. Weakest link if you will. I did come up with a solution to prevent the plate from falling into the magnets of your flywheel. I mounted mine in red high temp RTV. This should keep the plate secured in the event of a total crack and also provide dampening from vibration. It also helps the lower crankshaft seal to stay sealed around the case. I'm having a new plate made of solid aluminum T6061. I haven't heard of any failures from the new thicker plate. Happy flying. Cam
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#10
Just an update, I received a new plate and coils today and will install this evening. The new plate according to Leon is machined from billet and not cast and it is thicker. Hopefully this will cure the problem. I will add a few pics later today.
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