Piper 400LS

thrust reversers on the front of the en- gines also results in better landing per- AOPA PILOT • 41 formance on contaminated runways. One trade-off in addition to lower sex appeal is higher noise and vibration. Piper began design studies on the 400LS in 1979 with the objective of combining aerodynamics, power and propulsion on the 400LS to add near-jet in-flight per- formance to better fuel specifics and lower perceived noise levels than exist- ing turboprops. The program was an- nounced in September 1982; the proto- type made its first flight in February 1983. A second test airplane was added to the program that June, and certifica- tion was obtained in July 1984. The good old-fashioned way to in- crease performance is to hang a bigger engine on an airplane. This works to a certain extent, but any design exercise is a critical evaluation and series of com- promises of many factors. In fact, the biggest improvement gained by power increases on most aircraft is in climb and altitude performance. At higher speeds, such things as increased drag become limiting factors to performance. The airframe is based on the Chey- enne III; certification was by amend- ment to the Ill's approval (model des- ignations are PA-42-720 for the IlIA and PA-42-1000 for the 400LS) under FAR Part 23, although Piper points out that many of the certification and structural criteria were accomplished to FAR Part 25 standards. Icing system certification is under Part 25; the new, dual-bus elec- trical system is based on Part 25 require- ments. The company has been perform- ing continuing fatigue tests, which had reached 75,OaO hours last spring, on a complete airframe to substantiate struc- tural integrity. Skins are thicker to carry the higher pressurization (7.7 pounds per square inch) and to permit flush riveting throughout the airframe. Flush riveting results in smoother airflow and reduced drag. Computer-aided design was em- ployed to optimize the shape of the in- board wing section. The fuel system is different, in part because of the different configuration of the Pratt and Whitney PT6 and Garrett TPE331 engines that power the IlIA and 400LS, respectively. The IIlA incorpo- rates a bladder fuel cell in each nacelle. Both use tip tanks, but the 400LS carries fuel in wet outer-wing tanks and in bladder fuel cells in the leading edge of the inboard wings; fuel capacity is slightly higher (3,765 pounds versus 3,899 pounds, respectively). The environmental control system was changed, principally because of the different characteristics of the Garrett All of the amellities expected ill a corporate trallsport call be specified for the 400LS, from ilz-flight telepholles alld elltertaillmellt cellters to beverage service. Ample baggage space alld a cargo door are also available. 42· OCTOBER 1986 PIPER400lS The 400L5 can fly jet profiles while keeping passengers comfortable. engines. Low and high pressure bleed air is drawn from different points on the powerplants; the low pressure port sup- plies sufficient bleed air at lower alti- tudes (nominally below 19,000 feet). The two sources are blended from there up. The air is conditioned through an environmental control unit. This system requires that an engine be run to provide cabin cooling or heating on the ground. Most of the other systems of the two models are the same. The hydraulic sys- tem and landing gear have been modi- fied to handle the higher weights of the 400LS. Many small refinements have been made, as well. For instance, the main landing gear doors are canted, a modification that aids in gear retraction but also has resulted in decreased drag with the gear extended. The 400LS is the first design to use the Garrett TPE331-14 engine. It produces 1,645 shaft horsepower (shp) and is flat rated at 1,000 shp in this application, which enables rated power to be pulled up to 20,000 feet in standard atmo- spheric condition (the gear box is rated at 1,250 shp). In this installation, the en- gines are counter-rotating: clockwise on the left engine and counter-clockwise on the right. Although designated as a TPE331, the engine is quite different from others in the series. It is a modular design, which permits extensive work, such as hot-section inspection or gear- box overhaul, without removing it from the wing. Maximum propeller rpm is 1,540. Pilots used to other engines in the series will be envious, since the concern with uneven shaft cooling after shut- down does not exist in the Dash 14. Garrett claims a 10-percent improve- ment in fuel efficiency over earlier ver- sions and fixed hourly cost for both scheduled and unscheduled mainte- nance with its Maintenance Service Pro- gram (MSP). There are two micropro- cessor-based Integrated Engine Computers (lEC) on each powerplant that provide torque indication to the cockpit, calculated exhaust gas tempera- ture and torque limits, self-diagnostic capabilities and engine performance data storage for automated trend moni- toring. Each powerplant also features a Many prospects consider the cabin too narrow (right), Piper has cOlltracted with well-known industrial designer Ben Isaacman to make better use of available space. Mock-up is shown above. Standard interior, shown at left, includes seven chairs, with the forward four in a club arrangement. Seats are comfortable, and noise level is comparably low. Compare aisle width to new design at far left. AOPA PILOT • 43 negative torque sensing system (NTS) that will move the propeller toward the feathered, or high-pitch, position if a loss of power is sensed. Engine power is translated into mo- tive power by large, four-blade, ad- vanced-airfoil, composite Dowty Roto] propellers. Many advantages are claimed for the propellers, including lighter weight, corrosion and fatigue re- sistance, greater damage tolerance and the ability to tailor the activity of each blade along it>length and chord to mini- mize vibration and maximize perfor- mance. Each blade consists of carbon fi- ber spars over a foam core, bonded lightning conductors and a reinforced leading edge to minimize erosion. Deic- ing is provided by conventional e]ectri- cally heated elements. Computer-aided design was also em- ployed in the nacelle design to minimize drag and improve airflow. The straight- through design of the engine results in exhaust being routed out the aft end of the nacelle, over the wing. There is a slight amount of residua] thrust. The spinners are an area-rule design that re- duces drag at the junctions of the pro- peller shanks and hubs. We waited quite awhile to fly the 400LS after its introduction, in part be- cause we wanted the opportunity to fly a variety of missions-short dashes and ]ong-haul-to see how flexible an air- plane it is. Since the emphasis was on all-out performance, we also wanted the 44 • OCTOBER 1986 PIPER 400LS opportunity to sample flight profiles that considered the passengers in back. We missed severa] opportunities for ]ong- distance positioning flights because of schedule conflicts and finally settled for a trip to Piper's Vero Beach, Florida, base, where the 400LS and other Chey- enne lines were being relocated after the decision to close the Lake]and, Florida, manufacturing facility. Over a period of two days, we flew with Douglas H. Smith of Piper, then later flew the same airplane, the 29th 400LS, N4ll91, for a photographic ses- sion out of Frederick, Mary]and. The longest trip we flew was just over 300 nautical miles, but in a series of five flights with 10 takeoffs and landings, we sampled cruise altitudes ranging from 12,000 feet to FL410 and made several quick turnarounds that would be typical of many corporate operations. The pas- senger load varied from none to four, and takeoff weights ranged from 12,000 pounds down to just under 9,500 pounds. We operated from non-con- trolled airports and TCA-bound high- density ones and flew a variety of preci- sion, non-precision and visual approaches. We also flew some of the maximum-performance profiles that so much has been made of. One of the rea] tests of the airplane, which is in the category for which I like to get some good systems and opera- tiona] training before flying, was that I got into the airplane and started to oper- ate it (under Smith's careful eye and tu- te]age, of course), and instead of going out to try some of the rudiments-a typical training profile-we flew a mis- sion, including a couple of high-ATC- workload and traffic encounters. That speaks well for the airplane and its cockpit and systems design. The panel is jet simple, focused on flying, managing power, communicating and navigating. System annunciators are mounted just below the glare shield. There are just two pairs of levers on the quadrant: power levers that also control propeller blade angle in the beta (re- verse) and ground idle modes, and com- bined fuel/propeller or rpm levers. Trim controls are lower on the quadrant, and, in most installations, principal flight control system or autopilot controls and long-range navigation controls are mounted below and behind them. There are two overhead switch panels that contain most of the electrical, engine, ice protection, lighting and avionics con- trols. These are mostly color-coded push-on/off buttons (green is for go). There are many procedures and sys- tems checks, of course, and the check list is detailed. There are many systems to learn with respect to normal and emer- gency operations. Proper training is, as always, essential, but pilots accustomed to turbine airplanes will find the 400LS an easy aircraft to learn. The airplane has a stick pusher that is activated if speed is reduced to 77 knots (stall speed clean at gross weight is 93 KIAS). One system that I expected to find as a go/no-go item because of the massive tail and power/propeller com- bination is not: a yaw damper. One was installed and is a useful aid in turbulent air, but it is not required. The airplane is equipped with a three- tube Collins electronic flight instrument system (EFIS) and the Collins digital APS-65 flight control that includes air- speed and vertical speed hold modes and half-bank and soft-ride modes to add to passenger comfort at high alti- tudes and in rough air. Collins Pro Line II avionics constitute one of the two standard packages (the other is a Bendix/King package). Bendix/King EFIS is another option. King's digital KFC 400 flight control system has just been certificated in the 400LS, so cus- tomers now have a choice of either the Collins or King digital system as part of the basic equipped price of the airplane. PIPER 400LS Radar and known-icing equipment are also included. Interior cabin space is a frequent criti- cism of the Cheyenne series, and Piper has contracted with Isaacman Associates to redesign the interior for greater actual and apparent space. A mock-up is shown on page 43; Piper hopes to dis- play the finished product this month. Operation on the ground and in flight is crisp, effective and without tricks or traps. Control pressures are fairly heavy, as they should be for an aircraft of this size and weight and considering the range of dense to thin air in which it operates. Handling at altitude, by the way, is solid. The 400LS will go right up to FL410 (ATC willing) and is easy to hand-fly there. Its climb performance, as a matter of fact, is better than several jets, even above 35,000 feet. I stalled it at 41,000 feet, which seems odd at best: I did it as a demonstration of the spread between cruise and stall speeds and as a further sampling of its handling qualities at altitude. In most flights, I stuck to a maximum deck angle of 10 degrees up and down, using attitudes that would not alarm the average passenger. Even with this tem- perate profile, performance is competi- tive with the fanjets. We did not even bother with maximum cruise power, se- lecting long-range cruise, which pro- duces low cabin noise levels. Passengers remarked that they could easily hear the conversation in the cockpit. We encountered a good bit of turbu- lence and some shear during a couple of approaches. The 400LS handled it well, and I found during landings at lighter weights that it has a tendency to float, just like a Cherokee. Piper has achieved its design goals with the airplane. It is unquestionably the highest-performing turboprop around and can chase the jets while burning 30- to 35-percent less fuel. The greatest shortcoming we saw during our brief time with it is its payload with maximum fuel. As N41191 is equipped, which includes 675 pounds of options, payload is only 363 pounds. However, with maximum payload of 2,048 pounds, 41191can still fly a trip of more than 1,100 nm with IFR reserves. That makes it very competitive with other turboprop and turbofan aircraft in typi- cal corporate operations. Piper is far from achieving its market- ing goals, however. No turboprop is selling very well these days, and there are a great many bargains to be had. But the 400LS was to establish a new bench- mark that would bring both turboprop and jet customers into the new propel- ler-driven niche that, for the moment, does not seem to exist. Whether it is a strategic marketing er- ror or the fact that other airplanes are too entrenched, squeezing the 400LS from both sides, or whether it does represent a new part of the market, only time- and a lot of sales calls-will tell. 0 , I '. Recommended TBO Propellers Piper PA-42-1000 400LS Base price $2,731,250 Price as tested $2,681,605 AOPA Pilot Operations/Equipment Category:' All-weather $2,731,250 to $2,975,000 (est.) Length Height Wingspan Wing area Wing loading Power loading Seats Cabin length Cabin width Cabin height Max ramp weight Max takeoff weight Max landing weight Max zero luel weight Oil capacity •.. r 170 KIAS 170 KIAS 194 KIAS 167 KIAS 170 KIAS Landing distance over 50-It obst 2,310 It Landing distance, ground roll 1,100 It Limiting and Recommended Airspeeds Vmca (min control w lone engine inop) 99 KIAS Vx (best angle 01 climb) 115 KIAS Vy (best rate 01 climb) 138 KIAS Vyse (best single-engine rate 01 climb) 125 KIAS Va (design maneuvering) 187 KIAS Vie (max flap extended) 10° 30° VIe (max gear extended) Vlo (max gear operating) extension retraction Vmo (max operating) to 27, I 00 It 244 KIAS at 41,000 It 177 KIAS Vr (rotation) 105 KIAS Vs I (stall, clean) 93 KIAS Vso (stall in landing config) 84 KIAS All specificatiolls are based 011 mallufacturer's calcula- tiolls. All performallce figures are based 011 stmldard day, stalldard atmosphere, at sea level alld gross weight, ulliess otherwise 1I0ted. 'Operatiolls/Equipmellt Categories are defilled ill JUlie Pilot, p. 103. The prices reflect the costs for equipmellt recommellded to operate ill the listed categories. Baggage capacity Max operating altitude Single-engine service ceiling Std empty weight 7,2771b Empty weight, as tested 7,952 Ib Max uselulload 4,858 Ib Uselulload, as tested 4,1831b Max payload w /Iull luel 1,0381b Payload w /Iull lueL as tested 363 Ib Fuel capacity, std 3,900 Ib (3,820 Ib usable) 582 gal (570 gal usable) II qt, lelt engine 12 ql. right engine lorward: 300 Ib, 17 cu It alt: 300 Ib, 31 cu It Performance Takeoff distance, ground roll 1,500 It Takeoff distance over 50-It obst 2,150 It Accelerate/stop distance 3,260 It Max demonstrated crosswind component 18 kt Rate 01 climb, sea level 3,250 Ipm Single-engine ROC. sea level 1,0001pm Cruise speed/endurance w/45-min rsv (total luel consumption) @ max cruise, 24,000 It, 11,000 Ib 349 KTAS/ 3.5 hr (939 pph/140 gph) @ long-range cruise, 41,000 It 297 KTAS/7.5 hr (448 pph/67 gph) 41,000 It 28,000 It Specifications 2 Garrett TPE331-14 single fixed-shalt 1,000 shp each (flat-rated) 3,000 hr 2 Dowty Rotol lour-blade lull-Ieathering, reversible 106-in diameter 43 It 5 in 17 It 47 It 8 in 293 sq It 41.12Ib/sq It 6.03 Ib/hp 8-9 18 It 2 in 4 It 3 in 4 It 8 in 12,135Ib 12,0501b 1l,100lb 10,000 Ib Powerplants 46· OCTOBER 1986