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- May 21, 2020
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I pulled my Sensenich wooden prop off of my 1946 J3 Cub to have my prop hub inspected (magnetic particle) due to some surface corrosion and to have it cadmium plated. Aircraft Specialties Services did the mag particle inspection, resurfaced the crush plate and cadmium plated the whole assembly. I ordered all new bolts, washers, castle nuts and cotterpins and bushings. I am ready to reinstall the prop, but for the life of me, I can’t find any written torque value for the prop hub nut for my A-65 tapered shaft. I have checked several forums as well, but have found nothing definitive. Anyone? Bueller? Bueller?
Also, the key that goes in the key way…does it have to be perfectly centered or go in a certain way?
Additionally, what about indexing the prop with the engine. Before I removed the prop, I made a mark for the #1 Cylinder at TDC on the side of the crankcase as well as the prop and prop hub (see pics). The slot in the shade and the hub pin are at the 10 o’clock position as viewed standing in the front looking at the engine, but the prop blades are about at the 2 and 8 o’clock position looking aft toward the engine. The key way is approximately at the 4 o’clock position (see pic). I am not sure if the prop was correctly indexed to the engine from the previous owner considering that the when he restored the aircraft ten years ago, he also used nylon lock nuts instead of the AN Castle nuts with cotterkeys to secure the prop to the hub. I had to replace several automotive parts with PMA approved parts on this certificated Aircraft as well, so…about that…
After I installed the prop and hub (oops!), I realized that the Sensenich installation instructions mentioned putting the engine at top dead center on the number one cylinder and indexing It with the #1 prop blade at the 10 o’clock position. Is that from my point of view facing the aircraft or sitting in the cockpit looking forward? Is the purpose of this for balance or for hand propping or what? I don’t recall the Blades Being numbered, so how do I know which one is the number one Blade?
Am I overthink this? I don’t want my prop to come off or be out of balance with the crankshaft. Help
Also, the key that goes in the key way…does it have to be perfectly centered or go in a certain way?
Additionally, what about indexing the prop with the engine. Before I removed the prop, I made a mark for the #1 Cylinder at TDC on the side of the crankcase as well as the prop and prop hub (see pics). The slot in the shade and the hub pin are at the 10 o’clock position as viewed standing in the front looking at the engine, but the prop blades are about at the 2 and 8 o’clock position looking aft toward the engine. The key way is approximately at the 4 o’clock position (see pic). I am not sure if the prop was correctly indexed to the engine from the previous owner considering that the when he restored the aircraft ten years ago, he also used nylon lock nuts instead of the AN Castle nuts with cotterkeys to secure the prop to the hub. I had to replace several automotive parts with PMA approved parts on this certificated Aircraft as well, so…about that…
After I installed the prop and hub (oops!), I realized that the Sensenich installation instructions mentioned putting the engine at top dead center on the number one cylinder and indexing It with the #1 prop blade at the 10 o’clock position. Is that from my point of view facing the aircraft or sitting in the cockpit looking forward? Is the purpose of this for balance or for hand propping or what? I don’t recall the Blades Being numbered, so how do I know which one is the number one Blade?
Am I overthink this? I don’t want my prop to come off or be out of balance with the crankshaft. Help
