6 yrs
RV-6 0-360 A1A C/S prop new from Vans in 1994.
Always hangared, appeared in perfect shape.
At 7 yrs and 300 hrs TT I asked Hartzel rep at Oshkosh about the 6 yr thing.
They stand by it, for liability reasons but said the main reason for looking inside the hub is for corrosion. aparently, some air carriers, especially ones based in the western states with drier air and flying lots of time quickly document the good condition at OH and get a wavier from the FAA to push the requirements longer.
That said, I postponed the OH on my -6, and at 9 yrs and 450 hrs, I started getting a very light spray of tiny dots on the windshield, so small I didn't even think it was anything wrong with the plane, hindsight is really something!
a few flying hours later, while wiping the plane down after a local flight, the tiny dots were larger and on the cowling around the air intakes and it was obvious something was amiss. Off with the spinner and I found a glob of grease that had built up inside the spinner at the seal failure point and was slowly working its way out the joint between the spinner and backplate.
The OH shop (1800.00) said an internal oil seal had failed and put oil in the grease cavity and pushed the grease out.
I'm glad it happened on a local flight and not in the middle of a multi-day xcountry as the decision to continue flight would have been a hard one based on stories I've read about pilots losing forward visability from oil on the canopy. After the investigation, again with hindsight, I'd flown it for several hours with the leak without knowing it, so maybe it would have been ok for a few more, but I'm sure I'd have made the right decision and grounded the plane until I could get it fixed.
So, past the 6 yrs recomendation, its a guess and should be considered preventative maintenance. BTW, there wasn't any corrosion in my hub, so my decision to continue flying past 6yrs, based on low time and always being hangared was the right one, who knew a seal would fail.
Now that you are aware of Hartzel recomendation, ask around, like you are doing here, of the "certified' planes. My hangar mate just bought a 182, and while shopping, found lots of planes that hadn't complied with it, with varying opinions from the owners.
I will most likely go past 6 yrs again, but will watch the prop area closer!!
but then again, in 6 yrs, I'll be wiser and richer, so maybe I will have it OH'd.
or most likely a take apart and re-seal job, as we don't actually have to have them OH'd.
Just my 2 cents.
Bob Martin
RV-6 N94TB
Louisa VA