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  #1  
Old 11-07-2019, 02:45 PM
JimRice JimRice is offline
 
Join Date: Aug 2014
Location: Collierville, TN
Posts: 98
Default Prop Bolts Tight in Crush Plates

I did not build my RV-4 to know the answer to the following.

I recently began working on my Condition Inspection. I noticed some corrosion on heads of the prop bolts which needed attention. I have the old 4" spool type prop extension with 3/8" prop/ext bolts and 7/16" ext/crankshaft bolts. Also, the installation has two front plates, one on either side of the front spinner bulkhead. The front has the groove into which the bolt head fit. The second is larger in diameter and thickness. (Photos below, though rear plate is hard to see.)

After removing the nuts from the prop bolts, the prop didn't want to budge. I attributed that to continued humid conditions in my hangar at the time. The bolts were very tight and next to impossible to move. I ended up using the old nuts threaded back on the bolts almost flush and then back them off against a a steel plate resting against the heads of the crank bolts. That pushed the entire prop and crush plates out from extension rather than just moving the bolts as I expected. At that point the prop was almost clear of the extension prop bushings. Rather than forcing anything, I called it a day. I went home and ordered a new set of prop bolts from Van's that evening.

I went back a few (dry) days later and was able to slowly work the prop loose and got it off okay. Even then the bolts were still extremely tight in the prop and didn't want to move. I took the prop home and kept it inside the house to help with any humidity issues. After a couple of days, I was able to tap the bolts out of the prop...though they were still tight in the two crush plates/spinner front bulkhead.

Once I had everything off the prop, I worked on getting the plates, which trap the front spinner bulkhead between them, off. I ended up putting penetrating oil on the bolts and was able to pull everything apart. Once apart, I was able to determine the bolts were extremely tight in the front plate, the one with the recess that traps the bolt heads so they don't rotate, and snug elsewhere, but not interference fit tight.

I'm a bit concerned about how difficult it was and that putting new bolts in will possible problems. I don't want to bugger up any threads and certainly don't want to have to hammer the heads.

All that said, should the bolts be that tight tight in the front plate? Should the plate be reamed?

My prop is a Props, Inc wood prop with a 4" thick hub. I've removed and installed several props over the years, both wood and metal, and have never had one this tight.

The plane has approximately 1050 total time engine/prop/airframe. From looking at the logs, I don't see anything indicated the prop/prop extension has ever been separated/removed since 1994. Due to the tightness, I was expecting some corrosion on the bolt barrells but found none, though the cad plating was pretty scuffed up by the time I got them out.

I'm glad I decided to pull the prop off and replace the bolts now.

See attached photos which will hopefully make my long-winded description more clear.


__________________
Jim Rice
Collierville, TN

1994 RV-4 N4WJ (Purchased/Flying)
1946 J-3 Cub N7155H (Restored/Flying)
1946 Globe Swift N3368K (Purchased Restored/Flying SOLD)
1987 Starduster Too SA-300 (Purchased/Flying/SOLD)
1994 V6STOL (Built w/dad/SOLD)

US Army Retired (still working to pay for flying)

When my ship comes in, I'll probably be at the airport.
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  #2  
Old 11-07-2019, 04:59 PM
jrs14855 jrs14855 is offline
 
Join Date: Apr 2008
Location: Lake Havasu City AZ
Posts: 2,279
Default Prop

Friction and the bushings hold the prop in place. The prop bolts and crush plates only provide clamping pressure. I would ream the prop and the crush plate .003 over the nominal bolt size. Do not ream the counterbore in the prop.
Bolts as tight as you describe prevent the proper installation torque on the bolts. Not applicable in your case because you are torqueing the nuts.
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  #3  
Old 11-07-2019, 08:06 PM
BH1166 BH1166 is offline
 
Join Date: Nov 2017
Location: Eatonton Georgia
Posts: 97
Default Same

Same exact stack as you eg: 4” spool spacer 4” wood prop hub ,but 800 hours. I purchased my 6A and at conditional, I look to upgrade, replace something I find no evidence in the logs ever being touched. February was new prop bolts, nuts and washers. Was a bear to deal with as yours. Bolts looked decent but coating gone. I found new 3/8 bolts slid in with just a bit if turning. Did not bore anything, just good cleaning. 1992 build, same Warnke prop.
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Butch
RV6A Purchased N72TX
2019 Dues Paid

Last edited by BH1166 : 11-07-2019 at 08:10 PM. Reason: Clarity
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  #4  
Old 11-07-2019, 09:53 PM
RotaVR RotaVR is offline
 
Join Date: Aug 2011
Location: LaCrosse, WI
Posts: 21
Default

Sounds like it’s been awhile since the prop was off. Might be a good time to consider a prop overhaul. Then you’ll know for sure what you’re flying behind.
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  #5  
Old 11-07-2019, 10:11 PM
PropMan PropMan is offline
 
Join Date: Dec 2008
Location: Donie,Texas
Posts: 163
Default

Odds are the prop hub has shrunk , (just enough to have the holes out of alignment with the crush plate and bulkheads) This is usually the 4 holes that do not line up with the blades. ream them out 1/16th inch over your bolt size and check fitment. You are welcome to call me and discuss.
713-417-2519

one more thought- if the bolts have corrosion on them, it will make a tight fit.
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Frank
RV6-N164FJ sold sadly
Legal Eagle w/Verner 3VW
Rans S7s
RV4- in progress

Last edited by PropMan : 11-07-2019 at 10:14 PM.
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  #6  
Old 11-08-2019, 03:34 PM
JimRice JimRice is offline
 
Join Date: Aug 2014
Location: Collierville, TN
Posts: 98
Default Re: Prop Bolts Tight in Crush Plates

Quote:
Originally Posted by PropMan View Post
Odds are the prop hub has shrunk , (just enough to have the holes out of alignment with the crush plate and bulkheads) This is usually the 4 holes that do not line up with the blades. ream them out 1/16th inch over your bolt size and check fitment. You are welcome to call me and discuss.
713-417-2519

one more thought- if the bolts have corrosion on them, it will make a tight fit.
Bolts were only tight in the front plate. I can insert and remove them in prop hub individually with only minor resistance. There is no corrosion on the shanks of the bolts, only on heads where exposed (inside spinner) though the cad plating is gaulded on the barrel. Once I had everything apart and could try each component individually, the front plate was the obvious restriction...holes are bright and shiney with no corrosion there either. I'm thinking the front plate needs reemed a tiny amount.
__________________
Jim Rice
Collierville, TN

1994 RV-4 N4WJ (Purchased/Flying)
1946 J-3 Cub N7155H (Restored/Flying)
1946 Globe Swift N3368K (Purchased Restored/Flying SOLD)
1987 Starduster Too SA-300 (Purchased/Flying/SOLD)
1994 V6STOL (Built w/dad/SOLD)

US Army Retired (still working to pay for flying)

When my ship comes in, I'll probably be at the airport.
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  #7  
Old 11-18-2019, 10:26 AM
JimRice JimRice is offline
 
Join Date: Aug 2014
Location: Collierville, TN
Posts: 98
Default Prop Reinstalled

Receive my new prop bolts/nuts/washers from Van's last week and got my prop reinstalled yesterday. New bolts went in with only slight hand pressure, through crush plate, front prop bulkhead and secondary crush plate. Everything torqued to spec and prop tracking was almost perfect at 1/32" differance.

It appears the cad plating on the old bolts had served it purpose as a sacrificial coating over the years and the resulting "corrosive gunk" had fill the 0.003 space in the aluminum plates. Once bolt were out holes in aluminum plates was bright and shiny. No reaming was required.

Not sure when the last time the prop was off the extension. It is much easier to remove the prop/extension from the crankshaft and leave the prop assembly intact, which is what I did last year when I replace starter ring (and belt since I had the prop off). It is entirely possible the prop has never been removed since installed on the extension in 1994... I know hit hasn't been in the five years I've owned and been maintaining this particular aircraft.

I believe it is something I will keep in mind for future reference and be more mindful here in SW TN's high humidity environment. It was also one of the wettest years on record this past year on top of the regularly high humidity. This is my fifth Condition Inspection prep I've done. It was the first time the prop bolt heads ever showed any signs of corrosion.

I'm looking everything over much more closely this year because of the above finding... I hope we are a bit dryer next year.
__________________
Jim Rice
Collierville, TN

1994 RV-4 N4WJ (Purchased/Flying)
1946 J-3 Cub N7155H (Restored/Flying)
1946 Globe Swift N3368K (Purchased Restored/Flying SOLD)
1987 Starduster Too SA-300 (Purchased/Flying/SOLD)
1994 V6STOL (Built w/dad/SOLD)

US Army Retired (still working to pay for flying)

When my ship comes in, I'll probably be at the airport.
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