f14av8r

f14av8r

Well Known Member
Normally, I move my plane around by the tailwheel with a tow bar. This weekend, I was visiting my brother and mostly moved it around by the prop. I was surprised to find that I have some play, fore and aft, in the crankshaft. I've searched and read about this extensively already (VAF and elsewhere) so I know some play is normal. But, it sure makes me nervous!

I get an audible and tactile "thump" when I push / pull on the prop. So, my first question is - is that normal?

Second question, I read a lot about endplay limits and such but it's not clear to me exactly how to measure the end play (case to starter gear?) and I definitely don't know what excess endplay means to me as an operator. Does too much (whatever that is) mean I"m grounded? Or, do I just check for leaks more carefully? Any help / advice will be much appreciated

RV-4, O360-A1A Carb, 1600 hours SMOH (2nd), Hartzell CS/Blended.
Thanks in advance!
Randy
 
f14av8r said:
I get an audible and tactile "thump" when I push / pull on the prop. So, my first question is - is that normal?

Second question, I read a lot about endplay limits and such but it's not clear to me exactly how to measure the end play (case to starter gear?) and I definitely don't know what excess endplay means to me as an operator. Does too much (whatever that is) mean I"m grounded? Or, do I just check for leaks more carefully? Any help / advice will be much appreciated
Click to expand...

Yes, it is normal.

I don't remember what the spec is but the allowable is quite high.

If you are concerned though, the best thing is to measure it and compare to the limit. Any means of measuring the actual fore/aft will give you the value you need.
 
In fact, if you DON"T get the end play, stop and investigate. Could be a failing engine, with metal filling the gap. One of my pre-flight items is to listen and feel for the clunk.
 
The end play is relatively small, as mentioned above, however, the feeling when you move the plane via the prop "feels" like it is much greater. It is measured with a dial micrometer firmly attached to the engine case. While it may not be good for the prop, I do not believe that it hurts to pull or push on the crank flange. Remember that the prop is generating 100's of lb's of thrust that is opposed by that internal flange. the key is to gradually apply any force.

Larry
 
Measured the Play

I measured the crank play today. I was glad to find it is .019 inches, well below the service limit of .026 inches.
Randy
 
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