As most of our Sierra and Duchess drivers know, we are facing a new AD (AD 2006-18-15) from Hartzell, on the constant-speed props. Older Sierras and the A23-24 Supers, with the McCauley CSP, are not affected by this AD. Here is the FAA link.I have developed a growing dislike for Hartzell over the way they have handled a string of hub and other prop ADs over the years. I won’t go into all the gory details, but they have consistently tried to coerce people away from the 2-blade props and into the 3-blade props. They are now on their third iteration of the 2-blade hub (basic, A-suffix, and now B-suffix). Part of my concern is that the original hub AD started out this same way. There was a requirement to inspect the front hub-half with a magnifying glass. Then the back half began cracking, in certain applications, and replacement was required. Now there has been a blade separation on a plane in our class, as opposed to ‘just’ the agplanes, acro folks, and higher-horsepower applications. This makes me wonder whether newer hubs will hold up any better, in the long run. It also makes me wonder whether the ECI is adequate, as the more severe applications resulted in these same hubs cracking where it went undetected (in the back half). And having said all of this in my preamble, I do need to emphasize that this AD is nothing to sneeze at. Losing a prop blade will certainly ruin your day, and probably the short remainder of your life. While there have been fortunate exceptions, in most cases the imbalance is so severe that the engine and mount depart the plane, with the resulting loss of control.

I have been assured by a prop shop I work with that both the A-hub and the B-hub props are excluded from the AD. Only the original ‘plain hub’ props have to be recurrently-inspected or upgraded. If you look at the serial number stamp on your hub, if there is an A or a B after the SN, you are already in compliance.

If (as is most likely) you are not in compliance, you must:

  • Have the Eddy Current Inspection done on the front half of your prop hub.
  • Or have the A-suffix hub installed.
  • Or have the B-suffix hub installed.
  • Do one of the above within 50 flight hours after September 25, 2006.

Comments and complications:

  • The ECI can be done on the plane. Pricing is ranging from $150-$250 (so far).
  • You need to locate an on-airport shop, or a shop that will bring their gear to you.
  • You’ll need to verify that you will be able to remove and reinstall the spinner, unless the shop includes someone who holds an A&P license. These shops are held to very strict rules by the FAA. They can’t R&R the spinner (or prop) without an A&P license. But they usually won’t care if you do it (with or without an A&P license).
  • If you elect to have the hub replaced, to terminate the repetitive AD, be sure you know your prop’s legal status. If a prop shop disassembles a prop that is out of hours or calendar time limits, they cannot legally reassemble it unless everything is within limits and a full overhaul is complied with. This also opens the risk of discovering an out-of limits blade, or the like.
  • Most shops should be willing to do on-aircraft ECI, regardless of the prop’s overhaul status.
  • Make sure you don’t wind up with an A-suffix hub with an unknown history. It will not be legal to install one which was removed from a plane subject to an earlier hub AD. My advice would be to buy only a B-suffix hub, if you do replace it.
  • Hartzell has extended the discount offer (for the B-suffix hubs) to September 2007.
  • I have to believe that a plane and prop will have a somewhat lower resale value, if the hub has not been replaced and the ECI remains an annual requirement. Partially due to the added inconvenience, unless you happen to be co-located with a prop shop that can do the ECI.
  • Oceanside Propeller Service, located just West of the Titusville Space Coast Regional (KTIX) airport, will do on-aircraft inspections at the Titusville airport, for $150. You will need to do your own spinner R&R. Daniel, 321-453-7707.

Thank you for adding to the resources available for your Fellow BAC Members.