Piper J3

Piper J3

Well Known Member
I purchased my RV-12 from the original builder. I have checked all the SB’s for compliance. Service Bulletins for Fuel Tank, Landing Gear and Sensenich Prop Hub are not completed. I have Van’s parts for the Tank and Gear and this will be completed when weather permits.

I have a question about the Prop Hub. It is my understanding that only some of the 26505B hubs had a problem with blades loosing pitch setting over time. I have 80+ hours on my 12 and prop pitch seems to be set exactly correct. I indicate 130 mph TAS at 7500 MSL / 5500 rpm. Airplane climbs like a homesick angel. Prop & engine run extremely smooth with very little vibration.

The SB is not safety-of-flight and I don’t believe it is mandatory so my question is – can I continue to operate with this hub and just monitor performance? Are other RV-12 owner’s doing the same? I contacted Sensenich and they indicated I could get the hub exchanged at anytime in the future.

Love the airplane... :D
 
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Check prop blade angles.

Its good that you don't sense any vibration, but the better way to confirm the blades are pitched equivalently is to actually measure that with an electronic level and a device that helps you fit the level consistently on each blade (I think Van's sells an inexpensive one now, or you can fabricate your own) There are pictures on here of homemade ones that have worked very well.

The angle should be checked at least at annual inspection time, but isn't a bad idea to check them (and the torque on the prop bolts) more frequently.
 
I found that mine also fell within the SB. I emailed Sensenich in December to ask about it. Here is the reply I received:
Unless you have noticed any sort of blade de-pitch/vibration issue, you can keep flying the prop. If at any time you do notice these symptoms, all we need to do is have you send your hub to us and we already have replacement hubs on the shelf ready to go so it should only be a day or so turnaround.
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I haven't checked the pitch yet but will as soon as the plane finds its way back home. I was shopping around for a digital level or inclinometer, but found what looks like an alternate method that may be just as good. I'd be really interested to hear others' input on that method.

I don't really have a problem buying and using a digital level, but the claimed resolution and accuracy on all but the most expensive ones does not look terribly impressive to me. I also don't really trust claims like that from cheap electronics manufacturers. I haven't played with one to see if they're actually good enough for this or not, but I do know about how accurate my eyeball is in comparing lines on paper.
 
A call to Sensenich wouldn't hurt. I have found them very responsive to my questions in the past.
 
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