"The Meridian now can compete favorably in altitude with the TBM, fly 3,000 feet higher than the JetProp piston to PT6 conversion, and cruise at 280 knots using 260 PPH of fuel."


https://www.businesswire.com/news/home/ ... Turboprops

Is this true? Any idea how much $$$????

Guessing a solid two commas.

T

The STC is a little over $11k. The 280kts isn't accurate. At least not at the published power settings.

Funny how many planes are advertised to go
* This far
* This fast
* This altitude

* just not at the same time

My plane will do 272kts but probably not to TBO :-)

Chip-

The Meridian can do 280 KTAS if you fly it by ITT, or simply use the M600 power tables.. The engine in the M600 is identical to the M500, they just unlock 100 more horsepower with some airframe mods. Since the M500 will record an exceedance above 1313 torque you would really be looking at about 270 knots burning 250 pph at FL300 on an ISA day flying ITT and torque limits. If you fly the normal cruise power tables with a Hartzell 5-blade prop you would see 260 KTAS burning 222 pph, and would be certainly babying the engine. Now the M600 can certainly run neck in neck with a TBM700, if you run it by ITT

M600 POH shows 276 knots as the fastest published TAS -- that's at FL300 at ISA-15 at "max cruise" which is "Not recommended by Pratt and Whitney Canada".

Luckily, though, the required torque setting of 1553lbs (100%, essentially) will be unattainable, even at ISA-15. You will temp out first.

Piper is testing at least two M600s with PT6A-52s upfront, though (well, one, right now, since one of them had an engine fire in flight). You might be able to see 280kts in the real world in one of those:

https://registry.faa.gov/aircraftinquir ... t=403MM%20
https://registry.faa.gov/aircraftinquir ... rtxt=524LT

The extra 2,000 feet that the RVSM cert gets you is mostly about range, not speed. At ISA temps, the M600 uses 1lb of fuel per nautical mile. At FL300, you're still doing basically the same TAS, but your fuel specifics are about 8% better -- 1.08 nm per lb.

The downside is your cabin is going to be north of 10,000 feet. Fatiguing for a long flight.

Our current M600 is a solid 7+ knots above book, as was our last one. I have heard this from some other owners. I think the fastest we have personally pushed our bird was 282 KTAS. But we see 270+ not too uncommonly when light at normal power settings. I flight plan 265 which is the real average in a mix of hot/heavy cool/light missions.

Mine is also faster than book, but I've never seen 280, except going downhill.

Agreed that 270-something is easily doable when light.

To be really competitive, the pressurization needs to be beefed up to maintain a cabin altitude < 10,000 ft at higher levels.

Not sure if the existing airframe structure can support such a modification.

Here is 277 at mid weight and ISA+7. Could definitely get 280 on this day by bumping the ITT up the ITT limits, which are 800, but Pratt recommends running torque settings like the Meridian. We run torque minus about 20-50 ft. lbs. we want to have a nice hot section and OH.

Is there an evidence running the meridian by torque extends its life?

Or better yet, why does anyone run a pt6 so far below the max temp settings? It is not disallowed? Given the overhaul limits do not change based on how you run it, seems like running it at 100% temp all the time would make no difference in long term reliability.

Torque vs temp in the Meridian has usually been framed as a question of cost at HSI and OH. I don't think anyone really believes that a first-run -42 run routinely at 775C (25 degrees off redline) isn't going to make it to TBO.

Only Pratt or a large fleet operator like FedEx can probably answer that question with any certainty. You'd need to factor the higher speed, which drives down depreciation and non-engine related maintenance costs, against the increased fuel burn and the impact on engine maintenance, if any.

For years, PWC swore up and down that terrible things [tm] would happen if you ran a Meridian/M500 above the recommended torque schedule.

Then Piper shipped the M600 and the recommended cruise torque settings in the high 20s are higher than the recommended settings for the Meridian/M500, despite the fact that it's the same engine, intake, etc.

Personally, I fly my M600 to the recommended book torque settings, since I know it's not my terminal aircraft and when I sell it, I don't want a prospective buyer to dig into the G3000 logs and see that I was running the engine hard. But if that wasn't a concern, I wouldn't have any qualms about running to the max cruise table, which will usually temp or Ng you out up high.

The engine guru from Daher answers that question by saying it makes no difference, except for how much money you want to spend at HOT or OH.

The effects of running above the recommended torque settings is a debate even among P&WC engineering support staff. There are some that believe the higher temps help against sulfidation without having other negative impacts on the engine and overhaul costs. I've personally come to the conclusion that running the PT6-42A at temps up to around 740-750* will have little to no effect on overhaul costs and may reduce sulfidation. It's worth mentioning that running the recommended torque values in the POH yield this temperature under many conditions.