Prop OH requirement - EASA-reg TB10

A complicated case, first time I have seen this in ALS of an aircraft.
I would try and find a way around it by referring to the Advisory Circular from the FAA instead of Hartzells own service letter. They write “or”, not and. The AC says that you are recommended to follow it, therefore not obliged to do so.

No matter what you, me or anyone else here think, the only person here who needs to interpret this correctly is the person reviewing your AMP…

When you check the service life of the engine you see that they are referring to its operating manual. AFAIK Lycoming never publish TBO times there but in a service letter.
So everyone would be convinced that you never need to overhaul the engine? Not so sure… :)

@Peter, yes, this kind of airworthiness limitation is typically stripped out of the MM by the FAA before they issue a US TC for a foreign aircraft. Sometimes the FAA review misses items, and it could potentially cause problems if an A&P IA were to notice it at annual inspection – but they usually don’t, and there is no approved maintenance plan on N-register aircraft that would cause them to be aware of it.

Unfortunately this scenario is not atypical for non-US built certified aircraft, even when they utilize US certified components that would almost never have any sort of similar limitation on a US built and certified airframe. It is one of the primary reasons that US buyers tend to be wary of foreign built certified airframes – Extra aircraft being an example of where profit for the OEM in repair is built into the maintenance manual via “mandatory” (MM limitations) parts replacement versus repair of components that could otherwise be repaired by several companies in the US. In that case it drives the insurance rates up too, although the typical wealthy Extra buyer has no idea why, maybe thinks it’s because his plane is extra special, and just pays the insurance bill regardless.

Re engines, my Lycoming is currently at 51 years since manufacture, never overhauled and working fine for now. I’m happy it wasn’t taken apart and reassembled four times before I bought the plane

For US N number, SB carry no weight unless listed in an AD or specified in an FAA approved maintenance manual, Limitations section.

When I was on G-reg, SBs were not mandatory either. The amusing difference is that MSBs (issued by Socata mostly) were covered by warranty whereas SBs were not, so Socata had a commercial incentive to issue MSBs after the warranty expired

In the end, as stated above, what matters is what your mechanic is willing to sign off. Which in turn takes us back to this, in most cases.

As I run my Hartzell prop for 25% of TBO in hours over a period of 10 years, keep the aircraft in a hangar and fly at least every two weeks, I have written into my SDMP a requirement to have the prop inspected to the LAA’s Minimum Inspection Program every 10 years (and it is a Part 23 aircraft). I have just had the first MIP done, the whole mechanism was stripped, inspected and the only parts that needed attention were a bearing and some seals. The UK prop shop who did the work were fantastic, peened and repainted the blades and their invoice was less than half that of a full Hartzell recommended overhaul.

I had to overhaul my prop here in Switzerland on the basis of a similar Service Bulletin. Also a Hartzell one. HC-C2YK-1

NCYankee wrote:

For US N number, SB carry no weight unless listed in an AD or specified in an FAA approved maintenance manual, Limitations section.

For EASA registered airplanes operated non-commercially and maintained under Part-ML, SB carry no weight unless listed in an AD or specified in an EASA approved maintenance manual, Limitations section.

dutch_flyer wrote:

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.

Look where? Can you post the MM please.