In the mid-1960s,Piper, noting the success of Beech’s King Air, decided to explore the possibility of producing its own twin turboprop. The manufacturer hired legendary aircraft designer Ed Swearingen to retrofit a Piper PA–31P pressurized Navajo with 550-shaft-horsepower Pratt & Whitney Canada PT6A-20 turboprops. After a successful first flight in April 1967 and further tests indicated that the Pratt powerplant and Piper airframe were a good match, the PA–31T Cheyenne was launched.
The Cheyenne was a simple and reliable entry-level turboprop that was more affordable and faster than the King Air 90. However, the Cheyenne’s smaller cabin could only accommodate two pilots and four passengers—plus a fifth passenger if the belted potty seat were used. Baggage space was limited, but the airplane could operate from relatively short runways and be flown by a single pilot.
The initial production model of the Cheyenne was powered by two 620-shaft-horsepower Pratt & Whitney Canada PT6A-28 turboprops and included 30-gallon wingtip fuel tanks. Dual King Gold Crown avionics were standard. The Cheyenne first flew in October 1969 and was certificated in May 1972. Cheyenne deliveries began in 1974.
When Piper introduced the lower-powered and less expensive Cheyenne I in 1978, the manufacturer renamed its original twin turboprop the Cheyenne II. Essentially the only difference between the original Cheyenne and the Cheyenne II were some cabin configuration changes. The stretched PA–31T2 Cheyenne IIXL, which had a two-foot-longer fuselage than the original Cheyenne, entered production in 1981. The IIXL has an extra cabin window on the left side, a nearly 500-pound higher max takeoff weight, and is powered by more powerful 750-shaft-horsepower PT6A-135s. Besides offering more interior room, the IIXL’s longer fuselage eliminated the need for the stability augmentation system.
Over the years, many enhancements for the Cheyenne II have been developed, with the most notable being Blackhawk Modifications, Inc.’s XP engine upgrade, which involves replacing the Cheyenne’s original engines with new 750-shaft-horsepower PT6A-135A turboprop engines. The simple bolt-on upgrade enables operators to cruise approximately 20 knots faster.
The PT6A-135A engine was also the cornerstone of the Super Cheyenne conversion, which was offered by T-G Aviation of Hamilton, Ontario, Canada. Some Cheyenne operators have also boosted the speed of their airplanes by fitting them with cowl/ram air and exhaust stack aftermarket kits.
In addition, numerous panel upgrades have been developed for the Cheyenne II, including installation of lighter, more capable new-generation avionics from Aspen, Cobham (Chelton and S-TEC), and Garmin.
Piper built a total of 526 original Cheyennes and Cheyenne IIs, and 228 remain on the FAA registry, according to Vref. Prices range from $310,000 for a 1974 model to $520,000 for a 1983 model. Of the 81 Cheyenne IIXLs produced, 46 remain on the FAA registry. Prices range from $620,000 for a 1981 model to $680,000 for a 1984 model.
Engines | Two Pratt & Whitney PT6A-28s, rated at 620 shp Seats | Seats: Up to 8 (including two pilots) Max takeoff weight | 9,000 lb Max cruise speed | 277 kt Takeoff distance (over 50 ft obstacle) | 1,980 ft Range | 1,195 nm Wingspan | 42 ft, 8 in Length | 34 ft, 8 in Height | 12 ft, 9 in
Engines | Two Pratt & Whitney PT6A-135s, rated at 750 shp Seats | Seats: Up to 8 (including two pilots) Max takeoff weight | 9,474 lb Max cruise speed | 273 kt Takeoff distance | 2,042 ft Range | 1,060 nm Wingspan | 42 ft, 8 in Length | 36 ft, 8 in Height | 12 ft, 9 in
A new P&WC-produced video helps aircraft mechanics by breaking down engine rigging into simple, repeatable steps. Airtime spoke to the two men behind this handy PT6A resource to learn more.
THE IMPORTANCE OF WELL-RIGGED ENGINES
Jan Hawranke, Externals, Controls & Nacelles (ECN) Program Leader for PT6A engines, remembers exactly when he started to worry that the art of engine rigging was in danger of disappearing.
During the course of one year, an aircraft OEM sent back a dozen fuel control units that appeared to be faulty and couldn’t be matched to each other on a twin-engine aircraft. This was a significant concern, since engines must be rigged exactly the same way to perform in harmony.
Jan didn’t understand why the units were being returned, though, since they were in perfectly good condition. That’s when the “aha” moment hit him: the real issue was that the OEM’s mechanics didn’t have the information they needed to rig the fuel control units properly.
Rigging—the process of hooking up engines to an aircraft’s body—is an integral part of the engine’s installation process. It has to be done with the utmost care each time an engine is installed, Jan explained to Airtime.
On an aircraft with two engines, if both are not rigged exactly the same way, one might produce more power than the other. The pilot will then have to compensate by adjusting the power lever positions. It would be like driving a car with brakes that pull the car to one side, requiring the driver to turn the wheel to keep the vehicle straight.
Rigging information is available in aircraft maintenance manuals (AMMs), but it’s a complex process that cannot fully be captured in a written document or reviewed at a glance.
“There’s an art to good rigging,” says Jan. “A lot of it comes down to the mechanic’s feel and experience. The fuel control units being returned were a red flag to us that something was changing.”
A lot of the veteran mechanics who mastered rigging 20 or 30 years ago are retiring now. The know-how that existed years ago, the unwritten details that make for good rigging, are being lost. We realized it was important to pass that knowledge on to younger mechanics.
– JAN HAWRANKE
A VIDEO THAT MAKES MECHANICS’ WORK EASIER
While the airframer is ultimately responsible for providing rigging information, P&WC has always worked closely with OEMs to develop clear and thorough explanations. Indeed, two decades ago, Jan worked on a video designed to complement the information found in AMMs with tips on the rigging process.
For various reasons, he was never satisfied with the original video, which was now out of date anyway. He decided it was time for take two. Jan turned to a master of the rigging craft, P&WC veteran Rob Winchcomb, to star in a new rigging video.
You want both engines to behave the same way all the time, especially when landing, which is one of the most stressful moments of a flight. It’s a handling issue. Well-rigged engines make the pilot’s workload easier by ensuring that the response from each engine is identical whenever the levers are operated.
– ROB WINCHCOMB, PT6A CUSTOMER MANAGER
THE FUNDAMENTAL RULE OF RIGGING
The pair spent two weeks in Australia with a local production crew to create the video. To make it as authentic and useful as possible, it features in-service PT6A-powered aircraft, generously made available by Australia’s Royal Flying Doctor Service.
The video provides detailed instructions on every aspect of rigging, such as the differences between fine and coarse adjustment of the serrated washer, or how to match the travel of propeller levers. As Rob emphasizes, no matter what action is being performed, the number-one rule of rigging remains the same: whatever you do physically to one engine, do exactly the same thing to the other one.
As mentioned in the video, it’s also a good idea to have two people in the cockpit when performing this complex job, with one operating the engine and the other following the instructions and writing down the results. The more efficient you are, the less fuel you will burn during the final checks in the engine run bay.
P&WC will eventually release two different versions of the video for two different fuel control unit models, starting with the first one below. Click on the links to watch:
The PT6A-140AG engine sets the benchmark for performance and fuel efficiency for the agricultural segment, delivering 15 percent more power and five percent better specific fuel consumption (SFC) than other engines in its class.
The C-12 Huron is a military version of an executive passenger and transport aircraft based on the Beech Model 200 Super King Air. It is primarily used by the US Air Force, US Navy, US Army and US Marine Corps for several functions, including range clearance, embassy support, medical evacuation, VIP transport, passenger and light cargo transport. The C-12 took its maiden flight on 27 October 1972 and entered service with the US Army in 1974.
The hulks of seven DC-3 fuselages are parked alongside Basler Turbo Conversions’ 75,000-square-foot facility in Oshkosh, Wisconsin. Three more DC-3s sit inside, disemboweled, bracketed by yellow scaffolding in a main hangar that looks like a surgical theater. With them, a shiny white and blue BT-67, a “Basler-ized” DC-3, awaits its new owner. Fly-away price: about $4 million.
Since 1990 Basler has given new life to dozens of DC-3s. (In the 33 years prior to that, Basler Flight Service had reworked more than a hundred DC-3s, modifying interiors, restoring airframes, and overhauling engines.) Basler installs Pratt & Whitney Canada PT6A-67R turboprop engines and Hartzell five-blade metal propellers in place of the piston engines and props that powered the original aircraft. The company increases the DC-3’s volume 35 percent by inserting a 40-inch plug in the fuselage forward of the wing and moving the cabin bulkhead forward five feet. A BT-67 boasts 45 more mph of cruise speed and almost 4,000 more pounds of useful load than the original DC-3.
The aircraft’s notoriously temperamental 14-cylinder piston radial engines have always been seen as its weakest feature, so hanging turbines on DC-3s is not a new idea. The British tried it at the end of the 1940s using Armstrong-Siddeley Mamba and Rolls-Royce Dart turboprop engines. The engines helped, but the unpressurized aircraft couldn’t be flown at an altitude that would use the engines to their best advantage, and the project was quickly dropped. The idea was resurrected in the 1960s: In California, a few “Super Turbo Threes” were made and sold, but that project also fizzled. A Taiwanese venture failed as well.
One of the most interesting turbo conversions was done by aviation legend Jack Conroy in the 1960s. His modified DC-3 initially featured three Dart engines, two on the wings and one stuffed in the nose. He sold the airplane to the Specialized Aircraft Corporation, which replaced the engines with Pratt & Whitney models. DC-3 experts then trace the Tri-Turbo to Santa Barbara Polair, Inc., which leased it to the U.S. Navy as a ski-equipped arctic research aircraft. Some have suggested it flew missions for the CIA. The late Warren Basler bought the aircraft in 1992 from a salvage yard in Tucson. It was so distinctive that Basler insisted it be preserved as an important part of the DC-3’s history, and today it sits in Oshkosh, stripped and weathered, awaiting rebirth.
The latest in the PA-46 line of aircraft that includes the -310P Malibu, -350P Malibu Mirage and -500TP Malibu Meridian, the M600 continues Piper’s success with high performance singles.
During a demonstration tour of the M600 in Australia, Australian Flying was fortunate enough to have the opportunity to fly the demonstration aircraft when it visited Archerfield.
The demonstration flight included a flight to the Darling Downs and back at 10,000 feet while truing out at a respectable 240KTAS. This flight ably exhibited the M600’s ability to be used as an executive transport aircraft or family high performance touring aircraft seating six adults in comfort.
Looking it over
This particular aircraft had been fitted with the optional five-bladed composite propeller, which provided smooth performance with a marginal increase in thrust and therefore performance over the standard four-bladed Hartzell propeller. That extra blade also means a slightly smaller diameter and therefore increased ground clearance.
This was the first striking feature I noticed as I walked up to the aircraft outside Archerfield’s Jet Base hangar. With the PA-46’s long nose accommodating the 600 horsepower flat rated PT6A-42A, the aircraft looks similar to the older models until you look much closer.
The M600 has a totally new designed wing from previous PA-46 models that results in reduced drag while being able to carry a total of 996 litres of Jet A-1 in two internal wing tanks.
Each wing leading edge is equipped with pneumatic boots for de-icing and along with a small LED light on the fuselage side below each cockpit window to enable the pilot to observe if any ice is present at night. The vertical tail and horizontal tailplane are also similarly equipped with leading edge boots.
Entry into the Piper M600’s cabin is via a single two-section door located at the rear left side of the cabin. The bottom section when lowered, houses the stairs for boarding while the locking mechanism is in the top sill. Integral within this lower door are the air ducts to aft cabin.
Once inside, the rear of the M600’s cabin has four seats in pairs facing each other just aft of the main spar that protrudes slightly on the floor.
All rear cabin seats have access to emergency oxygen masks, which are housed in a drawer under each seat. They are the airliner style nose and mouth mask. The two front seats have EROS quick-donning masks located in their boxes behind each seat facing inwards towards the access-way into the cockpit.
Moving forward into the cockpit is not without some difficulty. For the larger pilots amongst us, the cabin ceiling is quite low and after bending over and then lifting one foot over the main spar, you are able to slide forward into the cockpit seats. Once seated the flight deck is very comfortable with all controls falling easily to view and hand without effort without any extended reaching. Similarly, the view over the long nose is not limiting for all operations.
Above the windscreen is located the main switch panel with mainly electrical, avionic master and other systems switches nearest to the command pilot on the left side. This may pose problems for those pilots using multi-focal glasses looking upwards.
The five screens of the Garmin G3000 GNSS/SBAS Avionic System dominate the main area of the panel. The visible components of the Garmin G3000 system comprise three main display screens and two GTC 570 Touchscreen Controllers. The three main screens display most of the information required for IFR flight with the two outboard screens primarily displaying the Primary Flight Display (PFD) information using vertical tape displays of airspeed, altitude and VSI with a full 360 compass rose at the bottom.
The centre Multi Function Display (MFD) screen shows the engine indications vertically on the left with the moving map on the major area of the display. Alongside these primary engine indications are the ancillary indictors for cabin pressure, electrical loads, pitch trim, flap and landing gear.
The MFD also displays the Electronic Flight Bag using the appropriate Jeppesen charts. Below the centre MFD screen, are the twin touch-screen controllers. Each screen allows the pilot to enter the required frequencies on either of the twin VHF radios, transponder codes, navigation waypoints as part of a flight plan, control the charts selected on the MFD, allows the selection of various aircraft systems displays, accesses satellite weather information as well as planning aircraft performance. They truly are the control heart of the aircraft.
Outboard to the left of the pilot’s PFD is the Aspen Avionics standby instruments. This consists of a single flat panel colour display of attitude and heading with tape airspeed and altitude indications.
Situated below these display controllers are the engine controls consisting of the power lever, condition lever and the manual pitch trim wheel. To my liking, the power lever is mounted a little too low and sits just slightly lower than the height of the front seat bases. This posed a slight problem later during the flight.
Located either side of the centre touch-screen controllers are the landing gear switch to the left and the three-position (up, t/o and lnd) flap switch to the right. Outboard on the left, are the various engine bleed air controls and the air-conditioning. The various Auto-flight mode controls are located above the centre MFD. These control the heading bug, navigation course (CRS) selector, flight director On/Off, altitude selector, yaw damper and vertical speed selector (V/S).
Flying the beast
Our flight was planned to depart YBAF on an IFR flight plan at 10,000 feet for a short flight up to Warwick on the southern Darling Downs and back to Archerfield.
After checking that all the electrical and bleed controls were selected appropriate for an engine start, annunciator lights checked, the battery voltage was checked sufficient for an internal power start. After checking that the fuel pumps were selected on MAN, L and R fuel pump messages showed on, the ignition switch selected to man and the prop area was clear, a start cycle was commenced.
Selecting the start mode to auto, lifting the cover and pushing start there was an immediate whirring sound and the Ng % began to increase quite quickly. As it passed 13%, fuel is introduced to the engine by advancing the Condition Lever to run. The main limitation that we were looking for on the start, was a maximum of 1000°C, which is limited for just five seconds. The only other limit that needs to be observed is that the starter has disengaged above 56% Ng.
While waiting for the obligatory warm up and checking of engine parameters, the avionics were selected on and the relevant weight and fuel data were entered or confirmed from fuel onboard and the flight plan route entered into the G3000, we were virtually now ready for taxy.
Of course the most important item for flight in this type of aircraft around SE QLD, making sure the air conditioning was selected on. Immediately cooling air was felt coming from the air outlets making for a comfortable flying environment.
Taxying the M600 required little extra power with our light weight, and the M600 quickly accelerated to a comfortable taxying speed. With the reversing propeller, taxy speed was easily controlled not by riding the wheel brakes, but by pulling the power lever back to the Beta position: zero pitch.
This is achieved by pulling the power lever slightly up and aft of the idle detent. Only momentary selections were required to control the speed before returning the power lever back to idle as we taxied out to Archerfield’s Runway 10.
Having a turbine power unit doesn’t negate the requirement for a propeller check. After entering the run-up bay and parking the brakes, the power lever was advanced to 1900 RPM for a propeller governor check followed by a reverse and Beta lock-out test.
After all the other normal pre-take-off actions, we were now to ready to move to the holding point, obtain our airways clearance and aviate.
With the flaps set to the T/O position, the power lever was advanced to around 1500 psi TRQ and the M600 accelerated rapidly towards an initial rotate speed of 85 KIAS. I found maintaining the centerline relatively easy with the powerful rudder design of the aircraft and direct nose-wheel steering at lower speeds.
The back pressure required at lift-off was a little higher than I expected, but provided positive response.
Initial obstacle clearance climb out speed of 95 KIAS is quickly achieved and after the gear and flaps had been retracted and the circuit area cleared, I accelerated the aircraft to a cruise climb speed of 145 KIAS at 1500 fpm. Best rate of climb is achieved at 122 KIAS.
During the climb, we only needed to monitor the engine’s limits in Torque, ITT and Ng. The pressurization was being looked after for us automatically as we climbed towards our cruising level of 10,000 feet.
United Technologies Corporation’s (UTX – Free Report) business subsidiary, Pratt & Whitney Canada, recently secured an approval from Transport Canada to augment cycle limits on its premium PT6A-140, -140A and -140AG engines. This approval to increase cycle limits will aid it in extending the life of Low Cycle Fatigue (LCF) parts like compressor, power turbine disks and impeller.