N64GH

N64GH

Well Known Member
Patron
This year my A&P wanted to send my Hartzell constant speed prop in to be checked and install new seals (900+ hours and 14 years on it). It did not wriggle before and it did not wriggle when first installed our after test flight. Flew to Air Venture then the Florida Keys then back to California. 40 hours exactly. Sometime on the second half of the trip it started to wriggle. I am ashamed to say I do not reminder checking the prop after X51. The first preflight after the OSH/Keys trip the wriggle is obvious. Not only can I feel it I can see it wriggle. Called the prop shop described the problem they say it "should be ok". A few A&P's on the field looked they "think it is ok". I am concerned. Thinking about flying up to the prop shop and have them take a look. About 45 RV minutes away.

Comments, idea's, anything?
 
Last edited:
Probably worth the flight up to the shop.

Sounds like this is a great example of why Mike Busch recommends, "if it ain't broke, don't fix it."
 
Good idea to find someone who actually knows what the allowable tolerances are.
 
+1 on Paul.
It may not be a big deal, but if you don't know, find out.
Losing a prop blade is very high on the suckage scale. :eek:
 
Any excuse to fly

Jesse said:
Probably worth the flight up to the shop.

Sounds like this is a great example of why Mike Busch recommends, "if it ain't broke, don't fix it."
Click to expand...

Twist my arm I need to go fly, darn ;)
 
But hopefully you are flying it to a prop shop so they can tell you after a first hand look if it is ok or needs further inspection. Some movement in some propellers isn't uncommon but your prop shop has the manuals and the knowledge to advise.
 
MT - Mine Too!

FWIW -

I have a 3-blade MT, and after coming out of rebuild several years ago I noticed one blade had some "wiggle". Consulting with the installation/ operating manual, it was noted that up to 3mm tip movement (fore/aft) is acceptable. That is almost 1/8" - to me that felt like a lot! (Note: My blade movement was on the order of .050") I checked with MT-USA in Deland, FL and they confirmed that allowance. I asked how "looseness" got into the prop at rebuild, and they said it had to do with available thicknesses of shims that removed such movement - kind of like the Goldilocks theory, some are too thin, some are too thick - and one is "just right". Unfortunately for my prop, on one blade, there was no Goldilocks shim - so I was stuck with a slight movement. The prop performance was not comprised and I could not discern any operating changes while using it.

It has since been O/H again - this time no movement. That makes me a much happier camper, even though the factory says either way is acceptable.

YMMV

David Howe
 
Well that eases my concern a little. Still bugs me a little when before service it was rock solid now it wiggles. Actually your explanation seems like what the prop shop was trying to say only they were not as clear. Still planning on flying there tomorrow to have them take a look.

By the way how did you measure the fore and aft movement? I just held a ruler next to the prop. That seems to leave a lot of room for error holding ruler in one hand and wiggling prop in the other.

Thanks


HFS said:
FWIW -

I have a 3-blade MT, and after coming out of rebuild several years ago I noticed one blade had some "wiggle". Consulting with the installation/ operating manual, it was noted that up to 3mm tip movement (fore/aft) is acceptable. That is almost 1/8" - to me that felt like a lot! (Note: My blade movement was on the order of .050") I checked with MT-USA in Deland, FL and they confirmed that allowance. I asked how "looseness" got into the prop at rebuild, and they said it had to do with available thicknesses of shims that removed such movement - kind of like the Goldilocks theory, some are too thin, some are too thick - and one is "just right". Unfortunately for my prop, on one blade, there was no Goldilocks shim - so I was stuck with a slight movement. The prop performance was not comprised and I could not discern any operating changes while using it.

It has since been O/H again - this time no movement. That makes me a much happier camper, even though the factory says either way is acceptable.

YMMV

David Howe
Click to expand...
 
HC-C2YR-1BF/F7666A-4

Kahuna said:
Exactly what model prop is it?
Click to expand...
The work done was "Propeller disassembled/cleaned visually inspected all parts reassembled reshimmed LA'S.MFGS.MANUALS113B,202A guidelines functionally bench tested and angles set to mfgrs specs 11.0 degrees low pitch: 31.5 degrees high pitch drastically balanced following mfgs requirements."
 
I've found that props with loose blades won't take a good balance. They will drift on the computer. On a Hartzell there's a large clip that holds the blade in the hub, it's very unlikely a blade will come off. There was the case out in SoCAL where a prop shop was using illegal parts and a blade did depart a TravelAir, tore the engine off, crashed into a house and killed all on board. Needless to say every prop serviced by this shop was immediately AD'd. The pilot was the Cessna parts dealer at Cable airport, nice guy. Word was, the prop shop owner skipped the country.
 
FasGlas said:
I've found that props with loose blades won't take a good balance. They will drift on the computer. On a Hartzell there's a large clip that holds the blade in the hub, it's very unlikely a blade will come off. There was the case out in SoCAL where a prop shop was using illegal parts and a blade did depart a TravelAir, tore the engine off, crashed into a house and killed all on board. Needless to say every prop serviced by this shop was immediately AD'd. The pilot was the Cessna parts dealer at Cable airport, nice guy. Word was, the prop shop owner skipped the country.
Click to expand...

Cable (CCB) is home that is kind of the reason the wiggle bugs me.
 
FasGlas said:
I've found that props with loose blades won't take a good balance. They will drift on the computer. On a Hartzell there's a large clip that holds the blade in the hub, it's very unlikely a blade will come off. There was the case out in SoCAL where a prop shop was using illegal parts and a blade did depart a TravelAir, tore the engine off, crashed into a house and killed all on board. Needless to say every prop serviced by this shop was immediately AD'd. The pilot was the Cessna parts dealer at Cable airport, nice guy. Word was, the prop shop owner skipped the country.
Click to expand...

I had it balanced when it was reinstalled it would be interesting to see if it is still balanced. Flight to prop shop first though.
 
The Hartzell manual details limits for the blade to move fore/aft, radially and rotation.

There is a "set screw" (I do not understand the mechanics) in the Hartzell Hub that if improperly set, or comes loose, will give potentially a "lot of wiggle". When you enquire of the Hartzell prop shop they may well mention it. I would get their advice v the "wiggle" before deciding if it is flyable, should be fixed, or is OK to leave.
 
Just went through this. Thought the preload screw had backed out, but nope... It was tight. Prop disassembly adjustment and reseal (and $1000) and all is good.
 
End Play (leading edge to trailing edge): See Note below
Fore & Aft Movement (Face to camber): See Note below
In & Out: None
Radial Play (pitch change) ? 0.5 degree (1 degree total) measured at reference station
NOTE: Blades are intended to be tight in the propeller, however slight movement is acceptable if the blade returns to its original position when released.
Blades with excessive movement, or that do not return to their original position when released may indicate internal wear or damage which should
be referred to an appropriately licensed propeller repair facility.

This information can also be accessed here:

http://hartzellprop.com/wp-content/uploads/115N-0000-R20-AW.pdf

Please refer to Page 5-20.
 
Thanks

jnmeade said:
For general info, AC 20-37E
http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_20-37e.pdf
AIRCRAFT PROPELLER MAINTENANCE
Click to expand...

Thanks for the link. A quick read was helpful. The movement is unusual for my prop but is it unusual for that make and model. The prop shop by phone thinks not. I did see where they talk about blade to blade difference, which I definitely have. I did git an idea on how to measure the "wiggle" which I am off to the hanger to try. Any way I have mu original dilemma. This morning I am going to pull the spine again see if there is any grease after the additional 2 hours and 12 minutes flying. Try again to get an accurate measurement of the wiggle. Armed with that call the prop shop again see if they think it is OK to fly up there and have them take a look. I could be wrong but having them look at on the plane would be better? ANy way thanks for the link.
 
Return to original position?

Kevin Ryan said:
End Play (leading edge to trailing edge): See Note below
Fore & Aft Movement (Face to camber): See Note below
In & Out: None
Radial Play (pitch change) ? 0.5 degree (1 degree total) measured at reference station
NOTE: Blades are intended to be tight in the propeller, however slight movement is acceptable if the blade returns to its original position when released.
Blades with excessive movement, or that do not return to their original position when released may indicate internal wear or damage which should
be referred to an appropriately licensed propeller repair facility.

This information can also be accessed here:

http://hartzellprop.com/wp-content/uploads/115N-0000-R20-AW.pdf

Please refer to Page 5-20.
Click to expand...

OK will I will be checking that out today. I think it does but I was so shocked that it moved after 900 plus hours of it not moving and it not moving after the service I do not remember for sure.
 
You must log in or register to reply here.