Propeller Malfunction

[jpusser]

I had quite an interesting experience while flying today.  I had been up site seeing for about an hour.  When I returned to the airport, I crossed over midfield and abeam the numbers on downwind I heard a loud bang followed by intense vibration.  I immediately pull the mixture and landed without incident.  I was sure a rod had broke, but I couldn't find anything wrong with engine after getting it in the hanger.  I finally found that the prop didn't look normal.  The blades appeared to have different pitches, and there was a dent in the spinner where one of the blades had rotated to far.  After removing the spinner I found I was able to rotate one of the blades 360 degrees.  So the vibration was a miss match of pitches on the blades and the loud bang was something in the hub.  The propeller is a  hartzell on my 62 C model.  It was overhauled 4 years and 226 hours ago with the updated hub.  I plan on calling the shop who overhauled it, but wanted to get everyone's thoughts first.  The prop is suppose to be good for 60 months or 2000 hours.  I know crap happens but I have never heard of a propeller malfunction like this.

[carusoam]

Jpusser,

 

Additions to the thought process....

 

Interesting situation,  did the bang happen anytime before, during or after your gumps check?

 

I suppose you recently went from cruise rpm and light load while descending, to a high rpm setting while slowing down in the pattern.

 

Certainly not a failure i am familiar with, but sounds like the blade angle actuator let go on one blade.

 

No oil loss?  (from the governor system) 

 

Any hub grease on the blades? (lost seal, grease runs out)

 

Best regards,

 

-a-

[N33GG]

Be glad the blades stayed attached to the hub.  It could have been a lot worse.  Glad you are OK. 

[KSMooniac]

Yikes!  That sounds terrible, and yes, you are very fortunate the blades stayed in the hub!  This is the kind of failure that needs to be reported to the FAA as well.

[fantom]

Very unusual, you're quite fortunate. I would at least remove the spinner and take a look.

Ditto on notifying the FAA.

[sleepingsquirrel]

Although it may be prudent to report this occurrence, I don't think it's required. A propeller blade seperation or a piece thereof is a required report. Needs a through inspection though.

[Lionudakis]

I'd still report it.

I had an issue with an Aztec I was annualing, removed one propeller for inspection by a shop, the damage was minor and repairable, but he noticed something fishy with the blade shape, and the hubs were overdrilled for an AD. I took him the other and it was worse. Turns out the blades were counterfeit (cut down 50 year old counterweited blades, with weights cut off) and a lot of parts were sub standard, worn etc, and the hubs were both scrapped. That shop got to provide 2 new props, but our shop said not if, but when they would have come apart. All paperwork was in order, and nothing I could detect during annaul inspection.  Pretty bad for 100+ hr time since overhaul propellers, with new blades installed.  

My point is,  Aviation or not. Theres shady faa certified repair stations out there and bad parts. It might warrant an airworthiness directive, or shop checked on for qc. There might be others.