sahrens

sahrens

Well Known Member
I have an opportunity to place an O-360 A3A on my RV-7. The engine has 600 hours on it since complete rebuild, 2700 total time. It suffered a prop strike and all the appropriate inspections were done. One interesting fact of the rebuild was the crank was replaced with a hollow crank instead of the solid crank of an A3A. Which would suggest it is usable for a CS prop.

I have looked at the logs; all the inspections and ADs have been complied with. I checked the crank serial number and engine serial number against MSB 569 and neither were part of the Lycoming AD. Compressions were in the mid 70s for all cylinders at the last annual in June.

Is there anything I am missing, or should be looking for? Can I put a CS prop on this engine?

Thank you for your time.
 
The A3A should have a hollow crank. (See Lycoming model codes.)

The CS or FP prop issue will depend on the plugs in the crankshaft in the front end.

I'd probably read through the logbook entry. Was it a repair or an overhaul? What does the parts list look like? When it was reassembled, what do the inspection documentation and forms 8130-3 look like? (Work on the top end? Was the case checked for cracks? Are the limits "new" or "service"? Etc.)

Dan
 
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A3A Engine Core

I have the same engine that is a core for a rebuild sitting in my hangar. The one I have can be and will be set up for Constant Speed prop. It has the necessary accessory case and crankcase that will allow conversion. There is a Lycoming Service Instruction that tells how to convert to or from Constant Speed and fixed pitch.
 
A4A

Around 1965 I was working for a Piper distributor in the NE. Our first Cherokee 180B had the A3A engine. The airplane had a disconcerting history of a significant loss of power on takeoff. This happened maybe once in every fifty takeoffs. The airplane made several trips to Lycoming at Williamsport where it stayed for several days at a time for testing. The final result was the solid front main crankshaft. Lycoming claimed there was localized heating that was causing the front main journal to grow and bind. I never bought into this theory but the engine worked fine with the new crank. So the A3A with the new crank became the A4A. I had the A4A on my Pitts and it had the port for the governor line.
 
Thanks

Now I have to go back and re-read the Lycoming information. I would have bet an A3A had a solid crank. After my reading mistake on the crankshaft, I thought it would be a good idea to re-read the engine log.

The crank was NOT replaced, rather align bored, ground to mains and rods, the camshaft was reground, connecting rods aligned and new superior millennium cylinder assemblies installed.

Thanks
 
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