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

Jack and board, I'm doing some research on M600's and there's some
very helpful posts on this board. But I thought I read somewhere
that the new nose gear enhancements were on the 2019 models
forward. But if it's 198 and up, it looks like that takes us up to
2022 and beyond.

Can someone please clarify? Also, if anyone knows, how much and
how long does it take to get it done if I do buy an earlier model without
the enhancements.

PS:

I owned a 2001 Meridian right when it came out - in one of the landings
I almost went off the runway (to the right) and it was the most out of
control that I've ever felt in an airplane - but it was for a very brief period of
time. I was new to the plane (had lots of time before that in A36s, Barons,
etc) and I was landing at night. Being new (maybe 60 hours at this point?)
and at night, I landed a little hot but nothing too bad. I was thrilled to have
thrust reverse and I used it a little aggressively / right after the nosewheel
touched the ground - which I quickly learned not to do anymore. Right after
entering reverse, the plane veered sharply to the right and I was very close to
going off the runway at about 60 knots or so. Luckily, I undid what I just did
(put the power back to idle / beta) and the plane immediately righted itself. The
bottom line is that it was scary and it should not have happened regardless
of when I went into reverse - I think that planes should handle that. There
were other less alarming incidents with that nosewheel and we had it
beefed up after the STC (I believe) and it worked better but it was never
perfect. I always treated the nosewheel touchdown with care and alertness.

I loved the airplane, but not the nosewheel. And now that the M600 holds
90 more gallons, a higher useful load and has a much higher Vmo, I think
that Piper did what needed to be done to make a very nice flying airplane
even better - as long as the nosewheel does not cause any more problems -
which we all know it did just a couple of years ago. I understand that's partially
due to tire pressure - but Piper needs a more robust design. And as long
as the enhancements fix the problem, that'll be great because, other than that,
it's a great plane.

Any input would be helpful.

The new nose gear is definitely better. Never had any problem with the older ones, but less forgiving of sloppy landings. I think mainly over control. I liken it to the steering on a 70's cadillac, smooth, but sloppy (PC12) and a more modern sports car (M600). On the PC12, turning is a suggestion. Put a lot of pressure on the pedals and the nose will slowly start moving in the desired direction. In the M600, gentle pressure will turn the nose wheel pretty instantaneously, and actually moving the rudder pedals will turn the plane aggressively, little to no self centering. You get used to it, and gently under-correct if anything, until tracking straight. Interesting with the new design, the wheel wants to stay centered (a lot of self centering force), so takes a lot of rudder pressure to turn the nose, more like what you would be used to in a heavier nose steerable aircraft. I have landed the new gear well beyond the max demonstrated x-wind of 17 knots, and seems to do OK. Not a wobble in many landings that I can recall.

The new gear is retrofittable to all years of the M600. Piper used to offer the part at cost ?10K, not sure what it is now. Don't think the labor is too much. Would definatale recommend it, if not financially constrained.

Chuck, thanks for your input.

So, does the beefed-up nose gear become standard from 2022 forward - or is it 2019 forward?

Come to think of it, I would think 2022 because I think several of the runway excursions
came after 2019:

http://www.kathrynsreport.com/2021/02/n ... board.html

Thanks.

Don't quote me with authority, but I think some of the notable enhancements

SN 81, G3000 upgraded to the NG version. Better screens, better speed and some minor hardware upgrades and some other options. GDL 60 with automatic database updates, remote monitoring. GWX8000 radar. System 7 operating system, that has too numerous to count G3000 goodies. Like 3D safe-taxi, glide range rings, performance profiles that download winds aloft so fuel over destination is pretty accurate as winds change by altitude and routing, not just current burn and speed etc.

SN 81 the new Woodward FCU. 100 degree cooler starts, less maintenance.

SN 100 Autothrottles, Autoland, HALO.

SN 198, new Nose Gear (retrofittable to all M600's)

Pretty much every year saw incremental improvements in some aspect other than fit/finish/options/accessories, so every year is a little better than the prior up to the last which was SN 281 iirc before switching to the M700. They upgrade as much as Cirrus, just don't advertise it. Some of the notables are coversion to USB-c's at all stations, retaining the 110V front and back power outlets (nice for starlink), shrinking the O2 cabinet so the co-pilot seat goes back as far as the pilot seat now, decreasing the pedestal size to improve ingress/egress, relocating all the headset locations for a cleaner cabin, Lemo's all stations, touch to light cabin lighting, Lee Coolview windows, that cut solar glare like 90%, on and on. My 2019 is a dinosaur now . Some of the newer models have gotten rid of recurring inspections, and the wing life limits are different. I am 99.5% certain that the legacy birds will get the full 10,000 hour life limit after speaking with many in the engineering and c-suites at Piper, but require some ongoing surveillance and a minor wing mod. Keen interest to me, since we are the highest or one of the highest hour birds flying right now.

Doug re your Meridian I can address that. It’s a maintenance and tire pressure issue that most mechanics do not understand. An airplane like the TBM has a lot of positive caster. That means looking from the side it slopes back with the bottom forward. That angle gives you stability whether it’s an airplane or car. The system can be designed as stable with positive or negative (sloped to rear) if intended that way. If the landing gear is vertical (zero caster) it is not stable.

The angle is adjustable. The PA46 has limited travel for nose gear extension. If you adjust it for 3 degrees positive the system is very stable but when the gear retracts the doors will not fully close the tire is in the way. A larger tire makes is worse. In the opposite direction you have plenty of clearance for retraction but you are at zero or maybe 1 degree negative. That is not stable.

The next factor is strut length. Setting the nose strut to the max permitted enhances stability. A soft nose strut reduces caster and therefore not stable. Same applies to tire pressure. With a low nose strut and low tire you can be unstable even if the gear itself is adjusted correctly.

The main landing gear is just the opposite. Putting the main struts at the upper limit tips the nose down therefore unstable.

The perfect setup is nose gear where the nose doors can barely close and rest on the tire, nose strut high limit, main struts at low limit, tires at recommended pressure or even a bit more. All these things can stack up. If you airplane is at the opposite it can be a handful.

The M600 came along with slightly more weight distribution on the nose with the same mechanism. Combine that with an airplane where everything is at the bad end of limits and you will be unhappy. An M600 with the original gear with everything on the good end of the limits is no problem which is why most of them did not depart the runway.

The new design gives you more caster and also stronger for less flex.

Chuck, thanks for the helpful information.

One additional thing that I remember reading about the G3000 NG (serial # 81
forward in the M600) is that it adds the chime that goes off 1,000' before leveling
off in either a climb or descent. I think that's really important and even the older
G3000s in the M2 had that feature - I flew a 2015 model with that feature and it
was nice to have.

Also, when you're talking about "legacy" M600's that still need wing spar inspections,
how far back does that go? I definitely wouldn't want to buy one with that issue.

2019 forward seems to be the target for me because I want the more modern
G3000s so it's easier to update databases, has safe taxi, better radar, etc. The
database updates in the 2015 M2 was a pain - it was a fair amount trickier than
my 2000 G58 Baron that had Garmin 530's and 430's - database updates were
a piece of cake. Garmin shouldn't have gone backwards like that after 15 years.
Other than that, I love the G3000 platform.

Don, thanks for all of the helpful information about the Meridan / M600 nosewheel
issues!