Zerk fitting in prop failed

While flying Friday, that I thought was oil quickly began spreading over my canopy. It turned out to be #5 grease from my prop hub.

After a safe landing, I removed the spinner and found grease had squirted out of one of the 4 zerk fittings.

The prop and assembly is about 15 months old, and has ~125 hrs on it.

Question 1; Has anyone ever heard of this before?

Second point, I was very saddened to see 2/4 forward spinner flange bolts had failed by stripping out the threads. (see pic).

Question 2; Has anyone else experienced this?



http://imgur.com/delete/RHCXF2weHpi7pLZ

I'd suggest that you might have a heck of a vibration going on, or a misaligned spinner - or something putting stress on that prop and spinner.

What ?Paul said. Also, those are shallow, blind holes in the prop dome. Not something to drill into casually. You can go right through it and really have a leak. I'd say its prop shop time.

Zerk

Are you saying that the little spring loaded ball in the Zerk fitting was not sealing and allowing grease to be slung out? I have seen minor seepage from this location before. Vibration theory has some merit especially if there are other indicators in that area like cracked baffles or cowling wear. Are the threaded parts of the bolts still in the holes?

Don B

RV 9 Rebuild in Progress

Ground it

Something very serious is going on, and I would ground it until you locate the source of the problem. Two safety wired bolts pulling out together by stripping the threads is almost uneard of, and should have really caused a noticiable vibration when they came out and flew to the side of the spinner.

Vic

On easy; one not so easy - MAYBE!

You can replace the zerk with an identical part from any local supplier. You will know quickly if it is sub-standard. Piece o cake.

The stripped holes in the dome are another problem, at a much higher level. Best you talk to Hartzell to see if there is a fix, but there might not be one.

Then you have to figure out why those holes stripped in the first place....

BTW Hartzell spinners use a slip-over fwd bulkhead (glued into the spinner dome), and do not use those 4 holes...well, at least the ones I use are built that way...maybe you can avoid the stripped hole dilemma?

Good luck!

Carry on!
Mark

Did you find the missing two bolts inside the spinner when you removed it?

If not, might it have been assembled without them?

Just looking at possibilities.

PCHunt said:

Did you find the missing two bolts inside the spinner when you removed it?

If not, might it have been assembled without them?

Just looking at possibilities.

Click to expand...

Yes,
they were still safety wired together.
The original bolts were cut off too short to have enough thread contact.
There were standard washers (not star washers).
Also replaced the motor mounts, which may have been a vibration cause?

Daddyman
happy to donate to VAF

daddyman said:

Yes,
they were still safety wired together.
The original bolts were cut off too short to have enough thread contact.
There were standard washers (not star washers).
Also replaced the motor mounts, which may have been a vibration cause?

Daddyman
happy to donate to VAF

Click to expand...

I would remove the other two bolts and check their length.
And you don't need lockwashers; that's what the safety wire is for.

PS On the failed bolts, was the safety wire in the proper direction? It's not unheard of for people to get it backwards.

What size are the 2 remaining bolts? Should AN4H-4A

What type / how many washers under them? Should be 3 AN960-416.

Vans do not tend to supply the AN4H-3A type bolts, but maybe you could use these and reduce washers accordingly.

If you mismatch the bolt length v number of washers, then either inadequate threads will be engaged, or you will screw the bolt in too far and punch through the base of the dome, or strip the threads. Either outcome is not good

As others say, suspect prop to shop will be 1st step - ensuring it is correctly refitted is next. NB put some torque seal on the dome / prop junction and ask prop shop to ensure prop comes back with dome aligned in same way, else you will have more fun and games refitting the spinner

Zerk

I installed 4 studs with Red Loctite in the prop dome , the front spinner bulkhead is now installed with nylock nuts . The shallow depth of the hole in the aluminum dome looks easily damaged with the wrong length bolt .
I have seen them with Helicoils installed , might be an option .

update

daddyman said:

While flying Friday, that I thought was oil quickly began spreading over my canopy. It turned out to be #5 grease from my prop hub.

After a safe landing, I removed the spinner and found grease had squirted out of one of the 4 zerk fittings.

The prop and assembly is about 15 months old, and has ~125 hrs on it.

Question 1; Has anyone ever heard of this before?

Second point, I was very saddened to see 2/4 forward spinner flange bolts had failed by stripping out the threads. (see pic).

Question 2; Has anyone else experienced this?

http://imgur.com/delete/RHCXF2weHpi7pLZ

Click to expand...

Got it back together and tested, then test hop.
All well in my RV world.
Daddyman
Thanks