Receive the latest Hangar Talk postings daily. Your email address absolutely will not be provided to anyone.
Copper Line Revisited
I've read through the previous posts on the subject of copper lines work hardening but I need more specifics. Are the copper return lines on the bottom cylinders a potential failure item and should they be replace with something durable? Also, I have a one inch copper line at the oil cooler. Is this line suspect and should it be replaced with something like Stratoflex line? Finally, should all copper lines be replaced on the Jacobs engine and accessories even if they are in an ambient work environment? Caleb and Pete are your overhauled engines being installed with copper lines or have you gone to something twenty first century?
Jun 20, 2012
Jun 28, 2012
The copper scavange lines going from the lower rocker boxes to the oil pump mount into rubber hoses at all 3 outlets. As such, they have isolation from the stresses that would exist if they had flared ends hard mounted against fittings. The copper "J" tube that draws oil from the left side of the engine sump and into the 3/4" aft scavange inlet on the oil pump is hard mounted on sump end but slip-fit into a rubber hose coupling at the other end. This again helps defeat/ dampen the stressful effects of heat expansion and vibration. I'd be inclined to believe a failure of the "J" tube would be due more to over-tightening, or sheering due to not backing up the mating fitting during installation / removal than work-hardening. Certainly the vast majority of 195's still encorporate these copper lines.....
I've encountered 2 planes recently that had hard mounted metal lines feeding oil to the vacuum pump. Both were promptly replaced with OEM -2 rubber hoses. Not that the hoses will last forever either, but they are what Cessna installed to begin with! Not aware they've come out with a service bulletin recommending something different....
Post a Response