Piper Aircraft’s M-Class of single-engine airframes is a series that is based on the company’s PA-46 type. Specifically, the M350, M500 and M600—the current production variant of the latter being marketed the M600/SLS—are based on PA-46-350P, PA-46-500TP and PA-46-600TP, respectively, variants that were first certified by the FAA on Aug. 30, 1988, Sept. 27, 2000, and June 16, 2016.
The differences between those types include the equipped engine, with the M350 powered by a Textron Lycoming direct-drive turbocharged engine, and the M500 and M600 both certified to be equipped with a variant of Pratt & Whitney Canada’s PT6A turboprop engine.
All three of the PA-46 variants that are marketed as M-Class airframes are certified to seat up to six persons—including the pilot—with the M500 and M600/SLS’s cabins promoted as having a length of 12 ft. 3 in., width of 4 ft. 1 in. and height of 3 ft. 11 in., as well as volume of 165 ft.3 In addition to that space in the cabin, 20 ft.3 of internal baggage space is available on M500 and M600 that can accommodate up to 100 lb.
Another distinction between the M350, M500 and M600 is the Garmin avionics systems that each is equipped with. Both the M350 and M500 feature Garmin’s G1000 NXi integrated flight deck, which incorporates the company’s GFC 700 automatic flight control system (AFCS). According to Piper, however, the installation on the M500 is differentiated from that on the M350 by the fact that the former’s GFC 700 has an “enhanced AFCS.”
Differences in the operating limitations of the PA-46 variants that serve as the basis for the M350, M500 and M600 also exist, with the former airframe limited to a maximum operating altitude of 25,000 ft., a limitation that increases to 30,000 ft. on the latter two variants.
The airspeed limitations of the M-Class include M350’s never-exceed speed (VNE) of 198 kt. indicated airspeed (KIAS), as well as the M500 and M600’s respective maximum operating limit speeds (VMO) of 188 KIAS and 250 kt. calibrated airspeed (KCAS). Supplementing that VMO speed, the M600 is also limited to a maximum operating Mach limit of 0.55 Mach.
He adds that the increased redline enables him to descend without pulling back the power, affording more operational flexibility when arriving at airports used by jetliners.
Operators say the Meridian is easy to fly, very reliable and relatively economical to operate. They also say the aircraft pushes its 188 KIAS red line when the aircraft is at max cruise at altitude and that the 127 KIAS maneuvering speed is a severe limitation when encountering turbulence. Other pressurized single-engine turboprops are clean-sheet designs, not adaptations of piston engine aircraft. As a result, they have 160+ KIAS maneuvering speeds. But they also cost $1 million to $2 million more.
“Piper has gone out of its way to talk with customers. It’s completely different from the M500, but it’s still simple, it’s efficient. This is the most serious [single-engine] airplane that Piper has ever built,” says Lance Boxer, who flies s.n. 48.