R-755-9

[rslakey]

Good day all,
I am in the process of addressing several issues on an R-755-9 radial that is mounted on an engine stand. The engine mount, as best I can tell, was designed for this engine--there are no identifying numbers on it, but it looks like mounts used on R-755-9s I have found on YouTube. However, the mount I have has worn out isolators. I found a reference to the original mount, apparently made by Lord, with a part number of RL-15-E or RL-15-F. I can't seem to locate any of those. Anyone have any ideas?

The mount I have is a ring mount, and the isolator fits entirely inside the mount, from what I can tell. I have attached a few photos for clarity.

roger

 

[rslakey]

Oh, I should also ask if anyone has the Handbook of Service Instructions for the R-755-9.

 

[FLYBOYJ]

RL-15-1-ACP Engine Mount Bushing FAA-PMA Approved

Vintage, NOS, AS-Removed, and Airworthy Warbird and Aircraft parts from Aircorps Depot RL-15-1-ACP Engine Mount Bushing FAA,PMA Approved

www.aircorpsdepot.com

You also might try Barry Controls who has many Lord PMA approvals

https://hutchinsonai.com/wp-content/uploads/2020/05/Barry-Controls-2011-compressed.pdf

 

[swampyankee]

Lord is still in business. You could ask them

 

[rslakey]

RL-15-1-ACP Engine Mount Bushing FAA-PMA Approved

Vintage, NOS, AS-Removed, and Airworthy Warbird and Aircraft parts from Aircorps Depot RL-15-1-ACP Engine Mount Bushing FAA,PMA Approved

www.aircorpsdepot.com

You also might try Barry Controls who has many Lord PMA approvals

https://hutchinsonai.com/wp-content/uploads/2020/05/Barry-Controls-2011-compressed.pdf

Excellent! Thanks for the tip! I haven't had success with Lord calling me back. I will definitely try Barry Controls!

 

[MiTasol]

Manual

 

[rslakey]

Manual

Thanks MiTasol! Thank you!!!!

 

[BobB]

That looks like you probably have a Cessna UC-78 mount. RL15E was designed in 1946 for Jacobs installation on Cessna 195 and RL15F was for Continental W-670. They used RL15-37 & RL15-45 dynafocals respectively which are like RL15-1 except offset. I'm pretty sure that the Lord dynafocals won't fit a UC-78 mount but I never bothered to check measurements because it doesn't matter if only used for storage. Are you planning to run the engine on this mount?

 

[rslakey]

Yes, we do plan to run the engine on the stand, so having some sort of isolator is important, but it will be a permanent run stand engine, so we have some liberty in what will work. The mount is secured between pieces of "L" angle bracketry, so the receiving side can be modified if needed; I am assuming the mount side has the isolators pressed in. So really, I think the most important dimension is the press fit into the mount, as I can widen the engine stand support if needed. Based on your info, looks like the RL-15-E is the mount needed. Does that make sense?

 

[BobB]

Yes, we do plan to run the engine on the stand, so having some sort of isolator is important, but it will be a permanent run stand engine, so we have some liberty in what will work. The mount is secured between pieces of "L" angle bracketry, so the receiving side can be modified if needed; I am assuming the mount side has the isolators pressed in. So really, I think the most important dimension is the press fit into the mount, as I can widen the engine stand support if needed. Based on your info, looks like the RL-15-E is the mount needed. Does that make sense?

No, the RL-15 is the worst thing possible because it won't fit and is very expensive. It is possible that original UC-78 mount isolators are still available. Check with Air Repair and Radial Engines Ltd; they both have websites.

 

[rslakey]

Got it! I will scope out the UC-78 option. Thank you!!! We did access the lower left mount isolator this morning. It was all but gone, leaving only the outer bushing, which we were not able to remove by heating and tapping out. See two recent photos. Any ideas on how to remove the outer bushing? (Note: we thought about simply leaving that bushing in place and pressing in a new isolator with a smaller outside diameter, but the inside diameter of the outer bushing is oblong, with a difference of 0.030 inches between minor and major diameter.)

 

[BobB]

Got it! I will scope out the UC-78 option. Thank you!!! We did access the lower left mount isolator this morning. It was all but gone, leaving only the outer bushing, which we were not able to remove by heating and tapping out. See two recent photos. Any ideas on how to remove the outer bushing? (Note: we thought about simply leaving that bushing in place and pressing in a new isolator with a smaller outside diameter, but the inside diameter of the outer bushing is oblong, with a difference of 0.030 inches between minor and major diameter.)

That may be rusted in place. If making a better pressing tool doesn't work, there's always the option of reaming it out to a thin shell that can be collapsed. You could also try dry ice on the bushing after heating the mount bracket. Where are you located?

 

[rslakey]

We are located in Irving, TX--Mid-cities area between Dallas and Fort Worth.

 

[SaparotRob]

This Forum is amazing.

 

[MiTasol]

Bobs got the right idea but I would use a CO2 fire extinguisher firing down a press tool fractionally smaller than the bush OD plus a funnel to concentrate it on the bush so that there is minimal waste of the cooling effect. A good squirt followed by a hard wack on the press tool.