Mike Busch Maintenance Forums

[Aaron Novak]

Couple questions I would ask on the cam above would be:

1-Where is this aircraft flown and stored? Climate plays a big role here.

2-What fuel was used? MoGas or AvGas?

Unfortunately in the picture above, someone has "polished" the lobe and journal to "pretty it up" , so much of the information is not present. Also to answer a question, the nose of the cam in not loaded as highly as the flank, and so where we see the pitting ( not convinced its spalling ), is in the highest loaded area. The journal corrosion, and the note of corrosion on the other steel components leads one to believe there was something in the operation of the engine that led to moisture/acids in the oil attacking the parts.

[1TJ]

Couple questions I would ask on the cam above would be:

1-Where is this aircraft flown and stored? Climate plays a big role here.

South Africa - Flown mutiple times per week.

2-What fuel was used? MoGas or AvGas?

Avgas

Unfortunately in the picture above, someone has "polished" the lobe and journal to "pretty it up" , so much of the information is not present. Also to answer a question, the nose of the cam in not loaded as highly as the flank, and so where we see the pitting ( not convinced its spalling ), is in the highest loaded area. The journal corrosion, and the note of corrosion on the other steel components leads one to believe there was something in the operation of the engine that led to moisture/acids in the oil attacking the parts.

There was no polishing done to this cam. It had rust that started the spalling process as we have observed over the past 20 years.

The only question I have is what is responsible for the rusting in the first place. My guess is that the engine sat unused at some point. Probably when it was waiting to be installed.

Ed

Edward Kollin
Tehcnical Director
Aircraft Specialties Lubricants

[Aaron Novak]

Hi Ed,
Thanks for the answers. Any engine, aviation or not is subject to corrosion from storage. However having it to such an extensive degree on a surface thats sheilded by a bearing is fairly abnormal. Any chance that there is are oil samples as well? Fuel samples either?

[f_lunn@yahoo.com]

Now you know two! I change oil ( and filter) every 3-4 months, regardless of flight time. I also fly my plane for 35-45 minutes at least every 3 weeks, if for some unfortunate reason I have not been able to fly it more often.