Flight Test: Piper M600

Would the M600 prove too sim­i­lar to the M500? Not a bit of it! With im­prove­ments in­clud­ing 100 more horses, masses more fuel, a new wing, greater load, and fab­u­lous avion­ics, this is def­i­nitely a step up

Pilot - - CONTENTS - By Dave­un­win

Wih more horses, way more fuel and ex­cel­lent avion­ics, the M600 is a very dif­fer­ent beast to the M500

Imust ad­mit that I ap­proached this flight test with some trep­i­da­tion. Hav­ing been the first jour­nal­ist to fly the M500, I was a lit­tle wor­ried that the 600 might be a bit too sim­i­lar to jus­tify a full flight test re­port. It is still a PA-46 af­ter all, and shares the same Type Cer­tifi­cate as the Ma­trix, Merid­ian and Mi­rage. How­ever, when I ex­press my con­cern to Piper’s Thomas Nielsen as we walk out on a late spring day at Ox­fordLon­don air­port, he soon puts my mind at ease. “I don’t think you need to worry about that,” he grins “this is a very dif­fer­ent ma­chine!” As we draw closer, I can see sev­eral dif­fer­ences al­ready. For ex­am­ple, even though the 2017 brochure clearly shows a four-blade pro­pel­ler, this air­craft has a five-blade Hartzell ‘Scim­i­tar’ unit. “That’s cor­rect,” con­firms Thomas, “Piper is con­stantly re­fin­ing and im­prov­ing the de­sign−the Hartzell five-blade com­pos­ite prop was cer­ti­fied in March. It just gets bet­ter and bet­ter.” The en­gine is the same as the M500’s, a Pratt & Whit­ney Canada PT6A-42A, but it’s now flat-rated to 600shp (100shp more than the M500).

This is still 250shp less than it is ca­pa­ble of at sea level, en­sur­ing it can pro­duce its full rated power right up to around 23,000 feet.

A neat touch is the sight tube for check­ing the oil quan­tity. The PT-6 is renowned for con­sum­ing very lit­tle oil, and Thomas jokes that most of the oil used is that wiped off the dip­stick.

A clever fea­ture of both the 500 and 600 is an in­trigu­ing door be­hind the NACA ducts in the lower half of the cowl, which Thomas ex­plains func­tions as an in­er­tial sep­a­ra­tor. On some PT-6 in­stal­la­tions the in­er­tial sep­a­ra­tor is man­u­ally se­lected from the cock­pit but this is a much sim­pler in­stal­la­tion. The two wing tanks have a com­bined ca­pac­ity of 984 litres, which is a huge (more than 50%) in­crease on the 644 car­ried by the M500. Al­though from a dis­tance the 600 does look a lot like the 500, I start to re­alise it is a very dif­fer­ent− and much more ca­pa­ble−ma­chine.

The wing has changed sig­nif­i­cantly. In fact, it’s a clean-sheet de­sign, with more area than the M500’s, new sin­gle-slot­ted flaps and re­designed ailerons. It’s also con­sid­er­ably stronger, al­low­ing an in­crease in the Vmo from 188 to 250kt, and can carry an ex­tra 454kg. Thomas is ex­tremely knowl­edge­able about the M600, and ex­plains that the in­board spars are ma­chined while the in­board skins are ‘chem-milled’. More ob­vi­ous im­prove­ments are that the Garmin GWX weather radar is faired into the star­board wing’s lead­ing edge (on the 500 it’s car­ried in a pod be­neath the wing), and that the wingtips are stylishly up­swept. As you’d ex­pect, in­creas­ing the max­i­mum weight by twenty per cent ob­vi­ously re­quired the wide-track but rel­a­tively short wheel­base un­der­car­riage to be tweaked, and the main legs have been moved slightly aft. The nose­wheel strut re­tracts aft and car­ries a large LED land­ing light (from S/N36 on­wards there will be a land­ing light on each of the main legs, which re­tract

in­wards). Pow­er­ful LED nav­i­ga­tion lights are mounted just in­board of each wingtip.

The FIKI (Flight Into Known Ic­ing) pack­age con­sists of pneu­matic rub­ber boots on the lead­ing edges of the wings, fin and tailplane; de-ice for the prop and a heated pi­lot’s wind­screen. Down at the tail I am in­trigued by what ap­pears to be a tiny stub wing pro­trud­ing from the fuse­lage just in front of the tailplane. Ap­par­ently, this di­rects a flow of air onto the rud­der to aid in spin re­cov­ery. Thomas en­cour­ages me to move the el­e­va­tor, which is in­cred­i­bly heavy (more on that sub­ject later).

By now I’m ea­ger to hop into the pi­lot’s seat and start the en­gine, but Thomas in­sists that I take a good look at the cabin first. Ac­cess to it is via a clamshell door on the port side aft of the wing (the lower half also func­tions as an airstair) and I see straight­away that a lot of thought has gone into styling and pas­sen­ger com­fort. The test air­craft’s in­te­rior fea­tures Piper’s EXP (Ex­pres­sion pack­age), which can be cus­tomised in myr­iad ways. There are

plenty of USB ports for pas­sen­gers to charge their de­vices, and they can make phone calls or send and re­ceive texts and emails through the G3000 via the Irid­ium GSR 56 sys­tem. The black leather seats with red stitch­ing nicely com­ple­ment the car­bon fi­bre ta­ble and side pan­els. It’s all ex­tremely smart. One fea­ture I greatly ap­pre­ci­ate−as I be­come both older and fat­ter−is that the front seat­backs fold flat so ac­cess to the pi­lot’s seat is bet­ter than on some larger air­craft I’ve flown.

Thus far I hadn’t been able to fault any as­pect of the air­craft, so I was both dis­ap­pointed (and slightly re­lieved) when I fi­nally found some­thing to com­plain about! The pi­lot’s re­straint sys­tem is only a three-point in­er­tia reel ar­range­ment, and when you’re zip­ping along at 300mph and sud­denly run into un­ex­pected tur­bu­lence it sim­ply isn’t ad­e­quate. There’s a good rea­son why Boe­ing and Air­bus put four-point har­nesses into the pi­lots’ seats of their air­craft.

Stay­ing with air­lin­ers, if it weren’t for the five-blade prop out­side the wind­shield you’d swear you were in a 400-seat jet­liner. The avion­ics pack­age is Garmin’s in­cred­i­ble G3000, and the in­stru­ment panel is filled with two twelve-inch PFDS, a cen­trally lo­cated twelve-inch MFD and an Aspen Avion­ics EFD-1000 ‘Evo­lu­tion’ standby in­stru­ment to the left of the pi­lot’s PFD.

The al­phanu­meric key­pad fit­ted to the 500 has been deleted, and ev­ery­thing is now done via the dual GTC 570 dig­i­tal touch­screens be­low the MFD. The in­ter­face is very in­tu­itive (the screens ac­tu­ally re­sem­ble smart­phone screens), and when I re­mark to Thomas that I’d once had dif­fi­culty op­er­at­ing a touch­screen in tur­bu­lence, he points to the small bar be­neath the GTC 570s, which you can use to hook your thumb around. Be­neath the GTC 570s there’s a small pedestal with the un­der­car­riage se­lec­tor to its left and the flap switch on the right.

The pedestal car­ries the big sil­ver T-han­dled power con­trol and red-topped fuel con­di­tion lever (which strongly re­sem­bles a mix­ture con­trol), el­e­va­tor trim wheel, rocker switch for rud­der trim, fric­tion lock and emer­gency fuel con­trol. There is no prop lever as the prop is au­to­mat­i­cally gov­erned at 2,000rpm, while lift­ing the power con­trol up and back over a gate se­lects ‘Beta’ (which flat­tens the prop pitch, pro­duc­ing less thrust so you don’t have to ride the brakes) and then ‘re­verse’. Most of the elec­tri­cal switches are in a neat over­head panel, which make an al­ready un­clut­tered in­stru­ment panel even clearer.

I turn on the bat­tery and Thomas in­tro­duces me to the G3000. I’ve al­ways thought the G1000 to be a fan­tas­tic piece of kit but the G3000 has taken the sci­ence of avion­ics to an­other level en­tirely. It has all the fea­tures we’ve be­come used to over the years, but ac­cess­ing them has be­come even eas­ier due to the shal­low menu struc­ture. As with all things dig­i­tal, you do

need to sit down with the book to get the best out of it, but it is quite in­tu­itive. It’s also ex­traor­di­nar­ily pow­er­ful.

Two fea­tures I re­ally like are that the screens of the PFD and MFD can be split 60/40, mean­ing (for ex­am­ple) that you can bring up an ap­proach plate while re­tain­ing your es­sen­tial flight in­for­ma­tion; and that, as well as dis­play­ing the fre­quency se­lected on the COM, it also shows the name of the sta­tion. This must be a tremen­dous as­set, par­tic­u­larly when deal­ing with con­trollers whose ac­cents can be some­what dif­fi­cult to in­ter­pret (or if you’ve sim­ply for­got­ten whether the last per­son you spoke to was Ap­proach or Tower!) I also like the ‘En­hanced Map HSI’, which al­lows ad­di­tional in­for­ma­tion (such as ter­rain, airspace or weather radar) to be over­laid on the HSI dis­play. By en­abling even more in­for­ma­tion to be dis­played within the pi­lot’s pri­mary in­stru­ment scan, sit­u­a­tional aware­ness is taken to a new level.

And speak­ing of level, the 600 re­tains the same pro­tec­tions pro­vided by the GFC 700 au­topi­lot’s en­hanced au­to­matic flight con­trol sys­tem (see ‘ESP and USP’ be­low) and also in­cor­po­rates a hy­poxia recog­ni­tion sys­tem with in­te­grated au­to­matic de­scent mode. A full ex­pla­na­tion of this very clever sys­tem is be­yond the scope of this ar­ti­cle but, ba­si­cally, if the au­topi­lot is en­gaged above 14,900ft, and there’s a loss of cabin pres­sure and no in­ter­ac­tion de­tected from the pi­lot within a spe­cific time frame, the sys­tem is­sues mul­ti­ple prompts. If these prompts are ig­nored the sys­tem as­sumes the pi­lot has be­come in­ca­pac­i­tated and the air­craft au­to­mat­i­cally de­scends to be­low 12,500ft. The G3000 re­ally is a fully in­te­grated dig­i­tal avion­ics suite that in­cor­po­rates ev­ery as­pect of op­er­at­ing a sin­gle en­gine tur­bo­prop. Even the pres­suri­sa­tion sys­tem is fully au­to­matic.

Easy to op­er­ate

Start­ing the en­gine con­firmed that Piper’s engi­neers have done a great job of mak­ing the 600 very easy to op­er­ate. There are no fuel valves in the cock­pit−both tanks are per­ma­nently on and feed si­mul­ta­ne­ously; the big red han­dle at the base of the pedestal is the emer­gency shut-off. To start, sim­ply press and hold the start but­ton for one sec­ond, and when the Ng sta­bilises at around 15% move the fuel con­di­tion lever to run and then mon­i­tor the in­ter-tur­bine tem­per­a­ture (ITT) gauge; the tem­per­a­ture sta­bilises well be­low the red limit. Af­ter just a cou­ple more post-start checks we’re ready to roll.

Even with the power lever on the idle stop the 600 wants to taxi faster than I do, so to avoid con­stantly rid­ing the brakes I pull the power lever back into Beta. With ev­ery­thing checked−there re­ally isn’t that much to do−and trims and flaps set, I line up, stand on the brakes and bring the power up to 1,500ft-lb on the torque gauge. (Per­son­ally, I’d pre­fer the power was pre­sented as a per­cent­age. Dur­ing the two weeks prior to fly­ing the M600 I’d flown singles and twins, pis­tons and tur­bines, nose­wheels and tail­drag­gers, glid­ers and mo­tor­glid­ers−so I need ev­ery­thing as sim­ple as pos­si­ble! But, to be fair, if you only flew 600s I’m sure you’d soon learn the num­bers, and Thomas later ex­plained that us­ing torque in foot-pounds al­lows the power to be set more ac­cu­rately at sea level.)

As men­tioned ear­lier, al­though the 600 is 454kg heav­ier than the 500, it does have 100 more horses. To­day, with only

Thomas and me on board, and around half fuel, we’re pos­si­bly lighter than a fully laden 500 but still have the ex­tra ponies at our dis­posal! Am­bi­ent con­di­tions are close to ISA (air­port el­e­va­tion is only 270ft, with an OAT of 17°C) and there’s a slight cross­wind from star­board. The en­gine al­most groans as the big prop bites into the air, and the 85kt Vr doesn’t take long to at­tain. In fact, the take­off con­ver­sa­tion is ba­si­cally very short: “air­speed alive, Vr, pos­i­tive rate−gear up, flaps up”. The POH claims barely 800 me­tres is needed to clear a 50ft ob­sta­cle at MTOW and I can well be­lieve it.

The Ox­ford con­troller ini­tially keeps us at 2,000ft, and I’m pretty busy with power and trim un­til we’re cleared to climb up to our op­er­at­ing al­ti­tude of 10,000ft. Of course, in the real world of com­pli­cated airspace, lots of traf­fic and in­clement weather I’d sim­ply have en­gaged the au­topi­lot at 500ft, but where’s the fun in that?

Hav­ing been cleared to climb I ease the power lever for­ward, then re­mem­ber the elec­tric rud­der trim. With 600shp ro­tat­ing five big blades at 2,000rpm there’s no short­age of P-fac­tor, pre­ces­sion and torque, and when­ever ei­ther the air­speed or power changes the rud­der trim needs a cou­ple of clicks to keep the pedal forces neu­tral and the slip in­di­ca­tor cen­tred (al­though I do feel the Garmin’s slip in­di­ca­tor is overly sen­si­tive). As we climb I try a few turns and sense al­most im­me­di­ately that the han­dling seems slightly heav­ier than the 500 (al­though with some air­flow over the el­e­va­tor now it was much lighter), and that it also seems con­sid­er­ably more sta­ble. Both of those traits are def­i­nite im­prove­ments (it is af­ter all, a trav­el­ling aero­plane) while the over­all con­trol har­mony and re­la­tion­ship be­tween con­trol and sta­bil­ity are ex­actly how they should be for an air­craft of this class. Piper has built a lot of aero­planes over the last eighty years, and it shows. Slow­ing down for a look at the stall is in­ter­est­ing. Of course there are both

The ex­tra horses have greatly im­proved both the rate of climb and cruise speed

au­di­ble and vis­ual stall warn­ings, but you may re­call that I found the el­e­va­tor to be very heavy on the ground? Well, as the IAS dips be­low about 65kt it gets re­ally heavy. You can’t trim the forces out−it is an ex­cel­lent nat­u­ral warn­ing that you’re sim­ply fly­ing too slowly. Due to time con­straints I don’t get a chance to ex­am­ine the cruise per­for­mance at the op­ti­mum op­er­at­ing al­ti­tudes (typ­i­cally around FL250 to FL280). Al­though it has a ser­vice ceil­ing of 30,000ft it is NON-RVSM, and there­fore cer­ti­fied up to FL280.

Thomas had flown it over from Florida, and as­sured me that the ex­tra horses have greatly im­proved both the rate of climb and max­i­mum cruise speed, while the new wing has en­hanced per­for­mance at al­ti­tude. Dur­ing the trip from Vero Beach he’d typ­i­cally cruised at 28,000ft and 182kt IAS, for a TAS of 270 while con­sum­ing around 153 lit/hr of fuel. One of the ma­jor dif­fer­ences be­tween the 500 and 600 is that the fuel tanks are ap­prox­i­mately fifty per cent big­ger. Of course, if you fill the tanks you can’t fill the seats, (op­er­at­ing any tur­bine-pow­ered air­craft re­quires a com­pro­mise) but if you do fill the tanks the range is al­most 1,500nm, in­clud­ing IFR re­serves. Usu­ally I’d make an ob­ser­va­tion here about the en­durance (over seven hours) be­ing but­tock and blad­der-bust­ing, but the seats are very com­fort­able− al­though a head­rest for the pi­lot wouldn’t go amiss−and a ‘uni­sex’ re­lief tube is pro­vided!

A more rep­re­sen­ta­tive ‘mis­sion pro­file’ is that it can eas­ily carry about 500kg (four adults and lots of lug­gage) over 800nm. How­ever, the great strength of op­er­at­ing such a well-equipped tur­bo­prop is the ease with which you can make the best use of the up­per winds. The G3000 can even man­age the de­scent−a use­ful as­set when you’re fly­ing sin­gle pi­lot at 28,000ft with a ground­speed of 300kt and ap­proach­ing a busy TMA. The cabin pres­suri­sa­tion runs at 5.6psi, which equates to a cabin al­ti­tude of ap­prox­i­mately 10,000ft when the air­craft is at its cer­ti­fied op­er­at­ing ceil­ing of FL280. You don’t even have to worry about your pas­sen­gers’ ears should you have to ex­pe­dite your de­scent−the dig­i­tal pres­suri­sa­tion sys­tem con­trols the cabin pres­sure so smoothly they won’t even no­tice, as I found out when Thomas told me to try an emer­gency de­scent from

10,000ft to 4,000ft. I pulled the power back to flight idle (which es­sen­tially turns the prop into a gi­ant disc air­brake) and pushed the yoke for­ward. This pro­duces a very high de­scent rate, while the much higher Vmo en­sures I don’t over­speed the air­frame. High or low, fast or slow−this re­ally is a very flex­i­ble fly­ing ma­chine.

Once level at 4,000ft the con­troller gives us radar vec­tors back (in­ci­den­tally, who­ever re­named Kidling­ton ‘Ox­ford-Lon­don’ ei­ther has a fine sense of hu­mour or a poor sense of di­rec­tion, but I di­gress). The sky isn’t that busy, but if it were the op­tional GTS 855 TCAS with ADS-B in and out would be much ap­pre­ci­ated. The big screen of the G3000’s PFD makes the ap­proach very easy to fly, and if I wasn’t quite sure where the run­way was I could clearly see it, as the syn­thetic vi­sion is over­laid on the PFD. Thomas rec­om­mends set­ting 400ft-lb of torque at the top of the glides­lope and, with the un­der­car­riage down and the first stage of flap, it re­ally does feel as if we’re on rails as we start the long slide down the in­vis­i­ble slope to the wait­ing run­way at 120kt.

As we draw nearer the long cowl­ing slightly im­pedes my view of the run­way but full flap pitches the nose down a bit, im­prov­ing the view and re­duc­ing the speed to 95. Eas­ing the power lever back as we cross the fence the speed starts to wash off, but we still float in ground ef­fect be­fore the mains set­tle gen­tly onto the run­way with the typ­i­cal ‘chirp-chirp’ of rub­ber ac­cel­er­at­ing from zero to 80kt in a in­stant. Lower the nose­wheel, then pull the power lever into re­verse−the en­gine roars, the air­speed col­lapses and within sec­onds I can­cel re­verse to avoid erod­ing the prop. An ex­cel­lent fea­ture is that, had I made a com­plete mess of the ap­proach in hard IMC, all I would need do is hit the TOGA but­ton on the power lever, as the en­hanced AFCS can fly cou­pled go-arounds. Ba­si­cally, the au­topi­lot lev­els the wings and pitches the nose up nine de­grees, and if the pub­lished missed ap­proach pro­ce­dure is loaded and ac­tive all the pi­lot has to do is push the NAV but­ton on the au­topi­lot con­troller and it will fly the en­tire missed ap­proach. It re­ally is quite in­cred­i­ble just how ca­pa­ble the au­to­mat­ics are.

A hugely im­pres­sive ma­chine

I was hugely im­pressed by the M600. Piper has re­ally thought about how it can ease the pas­sage of a PPL/IR tran­si­tion­ing from an Ar­row or Co­manche onto their first tur­bine. It has range, power and speed, cou­pled to some of the most ad­vanced avion­ics in civil avi­a­tion, and yet is not ac­tu­ally that dif­fi­cult to fly. If only I were rich...

Five-blader in­creases ground clear­ance, wide-track un­der­car­riage makes for sta­ble han­dling on the deck

Seats fold for eas­ier ac­cess, but it’s still some­thing of a scam­ble to get into or out of the cock­pit

Above: over­head panel and trio of G3000 screens make for a 21st cen­tury air­liner-style cock­pit, yet the de­gree of au­to­ma­tion — in­clud­ing pres­suri­sa­tion con­trol — reduces the pi­lot work­load to an as­ton­ish­ing de­gree

Above: a per­fect view, even in the murk — G3000 syn­thetic vi­sion dis­play; dual GTC 750 in­ter­face

Test air­craft’s muted cabin hues per­haps re­flect Euro­pean tastes — other colour and trim op­tions are avail­able

Right: pro­duc­tion mod­els will carry LED land­ing lights on main legs. Nose­wheel (far right) re­tracts aft

Clamshell door wel­comes you aboard but is the sole ac­cess to cabin and cock­pit In­set right: vane at root of tailplane di­rects air flow over rud­der to aid spin re­cov­ery. Weather radar pod (far right) is now set in wing lead­ing edge

Five-blade pro­pel­ler makes the best of the ex­tra power, clever in­take de­sign gives au­to­matic in­er­tial sep­a­ra­tion

Above: tur­bine oil sight gauge re­places the dip­stick

Brochure shot: as our flight test makes clear, the M600 has great in­ner beauty un­der­pin­ning its good looks

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