My partner is sitting in an AOPA maintenance seminar, and they are saying we must respect the calendar time requirement for a prop overhaul on our TB-10. It currently has 1700 hours left and is showing no issues, but will be up for OH on calendar time soon. I thought we could operate on condition, but this guy is saying the OH is required because of a reference in the limitations section of the AFM. Is this right?
First of all, that will depend on the prop. But the vast majority of props don‘t have any such airworthiness limitations.
Then it will depend on your maintenance regime/program.
On the first bit, this recent vid of Mike Busch is relevant.
My Harzell variable pitch props are now a year past calendar requirements having changed the maintenance program to allow for it. A reputable prop shop advised that all seals used in Harzells have a life of 10 years so I have gone for an 8 year overhaul rather than 6.
This is the service bulletin in question, and my prop is on pg 16:
https://hartzellprop.com/SERVICE-DOCUMENTS/SL/HC-SL-61-61Y.pdf
HC_SL_61_61Y_pdf
It shows a 72 month interval. How would I go about getting an approved extension?
Shanwick wrote:
My Harzell variable pitch props are now a year past calendar requirements having changed the maintenance program to allow for it. A reputable prop shop advised that all seals used in Harzells have a life of 10 years so I have gone for an 8 year overhaul rather than 6.
Did you have to get this approved by the CAA?
SBs should not be mandatory for private ops, in Europe, and definitely not on N-reg unless referenced in the MM airworthiness chapter.
A reputable prop shop advised that all seals used in Harzells have a life of 10 years
I am not disputing that the packaged seal may have a 10 year expiry date on it, but otherwise that “reputable shop” statement is BS 
It actually is referenced in the MM, which is why it’s an issue apparently. If you look at chapter 4, it’s right there.
dutch_flyer wrote:
chapter 4
Is that the airworthiness limitations chapter?
Airborne_Again wrote:
Is that the airworthiness limitations chapter?
That’s correct.
It says this:
A. HARTZELL propeller
Refer, either to HARTZELL Service Letter No. 61 (latest revision), or to Advisory Circular No. 20-37 (latest
edition) issued by FAA (US DEPARTMENT OF TRANSPORTATION, FEDERAL AVIATION
ADMINISTRATION), or to fascicle extract P-41-45 (latest edition) of GSAC (Groupement pour la Securite
de l’Aviation Civile, ex-BUREAU VERITAS, Aeronautics Division).
The one I have is BMM_020_04_R_pdf. I have just laboriously redacted the password-protected document which contained the name of the person who downloaded it from the US Socata group; the motive for securing it like that is just so bizzare… Fortunately the password was trivial to find with some free tools: wombat
I think if this went on the N-reg it would be regarded by the FAA as an illegal restrictive practice by the DGAC. The TB MM is full of stuff like that, though not in the AL section.
