prop seal question

[rbridges]

On 10/15/2017 at 12:35 AM, Shadrach said:

Andy, you should stop doing that unless you're working on a steel hunbbed machine (I know of no light singles that use a steel hub). Hartzle has a service bulletin about it. AMT magazine did an article on it as well.

Aluminum hub Hartzells do not have an inner seal on the bearing race. You may get away with servicing the hub as you've described once maybe even twice, but it will fill the hub with grease. When it gets full enough, the next time the prop is cycled the piston will push the grease out the through the only path available...past the blade shank seals. Once they've herniated the prop must be opened and resealed.

From Hartzell manual 202A volume 11:

2 In-service lubrication: Using a hand      operated grease gun, apply approved grease to each lubrication fitting until grease emerges from the removed lube fitting hole in a steady flow or until a maximum of 1 fl. oz (30 ml) of grease has been applied, whichever comes first. 

This is the front half of a Hartzell aluminum hub (3 blade). One can see that there is nothing to stop grease from filling the cylinder. There is a grove for the outer seal, a bearing race and that's it.

This is a pic of my prop.  They said mine has a fitting that you remove to allow grease to escape.  

 

 

[Shadrach]

13 hours ago, rbridges said:

This is a pic of my prop.  They said mine has a fitting that you remove to allow grease to escape.  

 

 

They all have that fitting. It does not prevent over servicing. Make sure that whomever is maintaining your aircraft follows Hartzell's maintenance instructions.

Edited October 28, 2017 by Shadrach