Re: [COUPERS-TECH] Recon Crankshaft

[scott]

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Hydrogen embrittlement can occur during the chroming process. This is not an aero-urban legend - I wouldn't use the crank.

You should talk with a metalurgist to get the straight scoop.

 

Scott

----- Original Message -----

From: Anne and John

To: 'Ercoupers Tech'

Sent: Thursday, June 15, 2006 6:30 PM

Subject: [COUPERS-TECH] Recon Crankshaft

----[Please read http://ercoupers.com/disclaimer.htm before following any advice in this forum.]----

Does anyone in the group have any information on how hard chroming the journals on a Continental nitrided crankshaft will effect its longevity. I realise that this is not an acceptable procedure for certified aircraft engines, however, it is often used in the automotive industry to bring a damaged crank back to usable spec's.

 

 We are looking to move our 'Coupe into the Canadian Owner/Maintenance Category, which will allow us the freedom enjoyed by builders of homebuilt/experimental aircraft, and would like to install an 0-200 crank etc. into the C-85 case. However the crank in question came from a home built aircraft, ( a Cavalier with terminal wood rot ) and has since had the journals hard chromed. One aircraft mechanic has warned us that the chroming process will adversely affect the metallurgy, and will be prone to early failure. I am hoping that this is just an aeronautical urban legend, and save myself a couple of grand on another crank.

 

Any input, positive or negative, would be greatly appreciated.

 

John H

 

Flying off grass in Ontario.

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