In personal discussion with someone in Piper, they already have fatigue testing far beyond the current life limit, but as testing is ongoing, there is no reason to up the limits until some airframes get near, so they don’t have to keep updating the numbers. There is also a fix for the legacy wings to address the concern that limited wing life. I was assured they were going to get at least the promised 10,000 hours. We have one of the higher time birds, 1600 hours on our 2019, so may be one of the ones that push Piper.

The typical fatigue testing requires multiple lifetimes on a single article, which then is reduced to the allowed life time based on statistical analysis. I think it is usually about 3:1, so if they are shooting for a 10,000 hour life, the article must be cycled for 30,000. This is often an accelerated fatigue spectrum, so the equivalent of a 1 hour flight may actually only take a few minutes, but then there will also be outlier events (2-3 G pulls or the like that don't routinely happen in normal usage) that are interspersed.

There are of course issues that arise, and fixes done on the article, and such things that can skew the results for affected parts.

Where I used to work, we typically could get to at least 10,000 hour life (about 30,000 equivalent flight hours) in about the same time as the flight test program, so on first delivery we could offer that much life. The structural test articles were among the first built, and often were in testing before the prototype flew.

It is good Piper thinks they will get more life with the additional testing and fixes, but it will have to be validated by that testing, and things don't always go as planned. To me the most concerning part is they already once had to reduce the life limit based on additional test results; that implies they encountered something that affected previously validated testing, which is not per any engineer's plan....

For all involved, I do hope they have an economical path to a longer life for the airframe.

Phil

Wow! Exactly what I was looking for, thank you Jack!

There is a key difference between ch 4 (life limits) and ch 5 (inspection program).

An owner is required to use the most up to date version of ch 4. This means if there is a revision, it immediately applies to you. No way out of it. So part life limits could change at any time a new revision of ch4 is released. The content of ch4 is FAA approved, the OEM can't publish a new ch4 revision until the FAA says so.

A PA46 turbine does NOT have to be maintained under an inspection program in ch5. That only applies to multiengine turbines per 91.409(e). It doesn't matter if the PA46 AMM has a ch5 program, or if it was revised, the plane can be maintained using the annual inspection.

For multiengine turbines, they must select an inspection program, and once selected, that locks in that revision of ch5 (if they are using the OEM inspection program). The OEM can change ch5 *without* FAA approval, they simply publish new stuff. But an owner who has selected a prior revision is not obligated to use the new revision, they can stay on the old one for as long as they own the airplane.

This all came to a head when Cessna decided to drastically change the Conquest inspection program to add SIDs which ratcheted up the inspection burden significantly. The adding of the SIDs did not require FAA approval. An opinion from the FAA chief counsel said Cessna had no ability to force current owners to use the new program as this would be a violation of the Administrative Procedures Act (APA) since Cessna doesn't have the power to "make rule", only the FAA had that power.

There may still be Conquest owners out there operating on the pre SID revision (rev 15 I think). Under current rules, each new owner has to select a THEN current inspection program, so new revisions do catch planes when they are sold. This is stupid and I consider it to still be a violation of the APA since the OEM still made rule, it just didn't apply immediately, and the APA has no such time limit on rule impacts.

The requirements in ch4, however, do apply and they can have a huge impact on airframe life.

There's no logical reason an METP and SETP should have radically different inspection rules, but they do. 91.409(e) does not apply to SETP.

Mike C.

Sounds like a great Corner Post lawsuit opportunity.

RAS

Thanks for all the great info everyone! I'm convinced So, in the market for an M600. Ideally a 2018-2019 model year. Feel free to ping me with any specific leads!
Darren