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-   -   Counter/non-counter weighted engines? (https://vansairforce.net/community/showthread.php?t=119138)

PCHunt 11-18-2014 07:14 PM

YIKES!!

:eek::eek::eek:

Glad it turned out so well!

New name for your ride: "Gunslinger" :p

rhill 11-19-2014 02:45 AM

Quote:

Originally Posted by 6 Gun (Post 934483)
Well guess I win the prize for the only RV to sling a prop! I'm going to have to change the name of my plane (six gun) I was taking some acro from Patty after it happened and she said to call it (prop slinger) but I think I will call it 6 gun still. Anyway I went flying on a Thursday for a short flight and returned to land pulled power back in pattern to land and the plane sounded like it was running really rough landed done a run up everything checked good shut down and done a few things at the hangar.Another RV showed up and wanted to fly around a bit so off we went another run up all fine so off we go for a few minutes and we part company back to each others airport 3 miles out I pull power back to land I'm at 1200 agl and bam there goes my prop I think because I can't see out the windshield call my buddy and let him know I'm going to try to make it back to airport.Long story short landed with out a problem and shut down and still didn't believe prop was gone got out and looked and it wasn't there got down and kissed the ground and said thanks Lord for letting me live. 6 Gun had a io-360 angle valve with a Hartzell BA and a Sabra 2.5 spacer all of which was no longer there and the ringgear also gone.The engine we built did not have counter weights so when I had it yellow tagged I had new weights installed and crank balanced. 51 hours on the plane when it happened so far I have not been able to find the prop so I'm not a 100% sure what happened only that I have six broken bolts left of the assembly in the crank lugs.I'm pleased with the outcome because I lived to fly again and one day I'll get it put back together so 6 Gun will fly again.
Bob

WOW Bob, I'm glad you got down in one piece, Can you post some photos?Why couldn't you see? What happened to the counter weights? Was the cowl damaged when the prop assembly departed in flight?When was the Crank yellow tagged before or after the departure?Great job on making the airport.
RHill

6 Gun 11-19-2014 08:13 AM

prop
 
A few answers to questions the counter weights were installed at o/h 51 hrs TT on them the engine I purchased to o/h did not have them installed I wanted them installed because I was running high compression pistons .I used a SJ cowling so the spacer was needed with the Hartzell BA prop .The nose of the cowling was destroyed as the prop contacted the front of it and the ring gear came out the front and went under between the landing gear.Oil covered the windscreen so forward visablity was limited only able to see out side of Canopy .The spacer had its on set of bolts and the prop bolts into lugs built into the spacer the spacer bolts were broken off in the crank flange .A couple hrs before the prop departed I noticed a slight vibration in the wing tips on roll out after landing so I took the tailwheel off and checked it. On the flight before it came off when I pulled power back to land it sounded rough like fouled plugs so I done a run up after landing and checked good on the next flight the prop departed when I pulled back to idle to decend . It was talking to me before it happened I just did not know what it was saying.Why it happened I have a few ideas but I can't say for sure unless the prop is found.
Bob

flightlogic 11-19-2014 08:27 AM

add on topic drift
 
Just to drift a bit... my engine builder claims that the way most pilots are taught to cycle their prop during run up is hard on counterweights.
A DEEP, then repeated cycle of the prop is not good practice according to Jay. He has built overhauled engines most of his long career.
A quick pull of the prop control to hear a slight change, and you are done.
That and the advice to check mags before top of descent, are both counter to common CFI lore. But, they seem to be coming from those who have thought it through.

Walt 11-19-2014 11:38 AM

Quote:

Originally Posted by flightlogic (Post 934578)
Just to drift a bit... my engine builder claims that the way most pilots are taught to cycle their prop during run up is hard on counterweights.
A DEEP, then repeated cycle of the prop is not good practice according to Jay. He has built overhauled engines most of his long career.
A quick pull of the prop control to hear a slight change, and you are done.
That and the advice to check mags before top of descent, are both counter to common CFI lore. But, they seem to be coming from those who have thought it through.

To add to that unless you are in an unfamiliar aircraft, troubleshooting, have had the prop off or something similar I recommend folks don't cycle the prop at all, serves no real purpose and is hard on the engine.

Canadian_JOY 11-19-2014 03:17 PM

What would the prop cycling recommendation be for a new build with a new engine and new prop? (in this case, Lycoming factory O-360-A1F6 counterweighted engine, Hartzell C/S compact hub prop with 7666 blades)

Walt 11-19-2014 04:00 PM

Quote:

Originally Posted by Canadian_JOY (Post 934675)
What would the prop cycling recommendation be for a new build with a new engine and new prop? (in this case, Lycoming factory O-360-A1F6 counterweighted engine, Hartzell C/S compact hub prop with 7666 blades)

My opinion, cycle it a couple of times just to be sure it's working and to bleed some of the air out, 100 rpm drop is enough. It will probably still surge on TO so throttle up slowly (which is also good practice), rapid throttle movement is hard on the engine even without counter weights.

Back to the prop exiting the aircraft, great job flying the aircraft!!!! You are certainly a very lucky guy. This is one reason I like to stay away from "non-standard" installations, no desire to be a test pilot. A sabre prop extension with a CS just looks like trouble to me. If you need the extension the Hartzell extended hub would be the "preferred" way to go.

BillL 11-19-2014 04:25 PM

Quote:

Originally Posted by 6 Gun (Post 934576)
A few answers to questions the counter weights were installed at o/h 51 hrs TT on them the engine I purchased to o/h did not have them installed I wanted them installed because I was running high compression pistons .I used a SJ cowling so the spacer was needed with the Hartzell BA prop .The nose of the cowling was destroyed as the prop contacted the front of it and the ring gear came out the front and went under between the landing gear.Oil covered the windscreen so forward visablity was limited only able to see out side of Canopy .The spacer had its on set of bolts and the prop bolts into lugs built into the spacer the spacer bolts were broken off in the crank flange .A couple hrs before the prop departed I noticed a slight vibration in the wing tips on roll out after landing so I took the tailwheel off and checked it. On the flight before it came off when I pulled power back to land it sounded rough like fouled plugs so I done a run up after landing and checked good on the next flight the prop departed when I pulled back to idle to decend . It was talking to me before it happened I just did not know what it was saying.Why it happened I have a few ideas but I can't say for sure unless the prop is found.
Bob

I hope you will come back and start a new thread with your information. Some pictures of the failed parts would be helpful. It will get lost in this thread and is possibly off topic.

I have the Hartzell composite prop + the 2.5" Saber space (not flying yet). I have mine hand tight on the crank and it would be easy to forget to torque the bolts. One indicator of torsional slippage on the crank flange would be fretting between the aluminum hub and the steel crank. In determining the safety of this extension, I was referenced the many many extensions used with heavier props, longer extensions and high g loading in aerobatic and racing applications. I have not been on VAF forever, but this is the first failure noted on this extension.

Sharing your experience would be greatly appreciated.


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