Designed to provide a lot of performance for a comparably low price, the much-maligned Cheyenne still is a relative bargain for the kerosene crowd.
There are five basic Piper Cheyenne models. All share a common heritage: the basic PA-31 design originally introduced as the Navajo. There are two major branches to the design family. These are the PA-31T series, or Cheyenne/II, Cheyenne I/IA and Cheyenne IIXL (plus an unpressurized hybrid developed for the air taxi and commuter markets, the PA-31T3 or T-1040) and the PA-42 series, which consists of the T-tailed and longer-fuselage Cheyenne III/IIIA and Cheyenne IV/400LS.
Pratt & Whitney of Canada PT6 engines power all but the 400LS, which uses Garrett (now Allied Signal Engines) TPE-331s.
Piper management was slow to accept the turboprop engine; some members of the Piper family were said to be set against it. The lack of suitable piston engines, however, was a major factor in the failure of Pipers own Fat Albert, the Pocono. That, together with the obvious success of the Beech King Air and the troublesome big Lycomings on the P-Navajo, undoubtedly was a factor in the decision to develop a pressurized turboprop.
Whether internal disagreement affected development or not, the Cheyenne had a long gestation period. Other factors contributed to this, foremost among them a battle for control of the company that began in 1969 and that was not resolved until 1977 and the flood that devastated the Lock Haven plant.
Design work began in 1965 (the PA-31P pressurized Navajo was in development at the same time). Late in 1966 a Navajo was ferried to Edward J. Swearingens facility for installation of a pair of PT6A-6A engines. First flight of this proof-of-concept airplane occurred in the spring of 1967.
Major design revisions were made, and in October 1969 the prototype PA-31T-essentially a PA-31P with turboshaft engines-flew. The airplane failed to meet FAA stability requirements, so it was back to the drawing board for a fix. It sprouted the now-typical wing tip fuel tanks, PT6A-28 engines flat rated to 620 SHP and a redesigned flight control system that included a stability augmentation system (SAS) that became an item of major controversy and a blot on the reputation of the entire series.
The SAS is essentially an addition to the flight controls that is supposed to overcome the poor static stability of the original airplane. An angle-of-attack sensor is mounted on the nose, and is connected to a downspring. At high angles of attack, the vane causes the spring to pull the controls forward, thus providing artificial static stability. The tradeoff was poor dynamic stability. (More on this later.) The original system had some problems, but modifications over the years seem to have helped.
The SAS would not have been necessary were it not for the Cheyennes poor static longitudinal stability. This trait can be traced to the Cheyennes roots in the Navajo airframe. The Navajo is arguably one of the best cabin-class twins, but its airframe was designed for 300-HP piston engines, not turbines that are both far more powerful and much lighter. The extra power had a destabilizing effect, and the lower weight led to aft-cg problems. (It should be noted that the Cheyenne III, which is an entirely different airplane, does not share these troubles.)
Piper was never noted for sophisticated engineering. Designers there basically did whatever it took to accomplish something without a great deal of attention to whether it was the best way to achieve the objective.This attitude was reflected in basic systems and fabricating techniques as well as in cockpit organization and interior fittings. Quality and quality control were not characteristics widely associated with Piper products of the time.
The PA-31T finally was certified in May 1972. The next month, the flood hit. And while the first production airplane was completed a year later, the first customer delivery was not made until 1974.
J. Lynn Helms became the boss that same year. In 1975, he acknowledged many shortcomings and promised major improvements would take place in quality control and customer support.
He stuck to his word. Significant improvements were made throughout the product line in terms of maintainability, rational human factors-oriented redesign and in overall quality. While there still was much to be done, the improvements were credible and very apparent. But it was too late to start the Cheyenne from scratch.
The company painted a Cheyenne demonstrator in a blueprint format to point out all the technical advantages Piper marketing people perceived for the design. This was one of several attempts to overcome the poor image of Piper engineering and manufacture.
Whats in a name
Both in their design designations and marketing model names, there is a lot of confusion about what is what. Even the FAA admitted confusion, requesting distinguishing designations between the Cheyenne and Navajo (too many different PA-31s) for air traffic controllers and even issuing an AD to nail down the designation of the Cheyenne I.
Piper itself publicly confessed its confusion in a variety of ways. The last was when management decided the Cheyenne IV would be dubbed the 400LS but all other models would remain Cheyennes. Shortly thereafter, of course, all but the IIIA and IV were gone forever and the issue became moot for all but those odd creatures, the customers, many of whom suffer name confusion to this day. So here is a brief scorecard.
The original Cheyenne is designated PA-31T. The confusion started when Piper introduced a lower powered, lower cost turboprop and called it the Cheyenne I (PA-31T1). The Cheyenne became the Cheyenne II.
The Cheyenne I was certified in March, 1978. It is powered by PT6A-11 engines rated at 500 SHP. Physical dimensions are the same as the PA-31T except that the basic airplane wingspan is two feet shorter (40 feet, 8 inches versus 42 feet, 8 inches) because in standard form it does not have tip tanks (although most purchasers opted for them).
The I was developed to be the lowest cost turboprop in the market. Remote mounted avionics were considered mandatory in turbine powered airplanes. Piper used panel mounted King Silver Crown avionics in the I, a departure from tradition to achieve the price objective.
The Cheyenne IA was introduced in 1983. It has aerodynamically improved nacelles that increase performance at altitude. Tip tanks became standard. The interior was upgraded and the instrument panel was redesigned, including a lower glare shield to improve visibility.
The Cheyenne IIXL (PA-31T2) was certified in 1981. It is powered by PT6A-135s rated at the same 620 SHP as the Cheyenne II but features a stretched fuselage. Two feet were added forward of the wing leading edge. Maximum operating weight is 500 pounds higher than the Cheyenne II. An A version, with improved nacelles, was in development when Lock Haven was shut down.
Pressure differential is 5.5 psi for all three versions. Maximum operating altitude for the I and II was 29,000 feet, but in 1983 the II was approved for 31,000, as was the IIXL.
The PA-31T3 is a hybrid of the Navajo Chieftain (unpressurized) fuselage with the flying surfaces and engines of the Cheyenne I. Dubbed the T-1040, it was developed as part of Pipers air taxi/commuter marketing effort and certified in 1982.
A IA was the last airplane built at Pipers Lock Haven plant. It was completed in November. In December, the plant was shut. It also was the end of production of the PA-31T series, although production was planned to be restarted in Lakeland for the IA and IIXL.
Many elements of the first Cheyenne fit the Mickey Mouse appellation that was applied to all Piper airplanes. Electrical wiring, especially connectors and even some fuses, were a nightmare to troubleshoot because each one was a bit different and many junctions were in hard to reach parts of the airframe. This and other systems were rationalized with the 1978 model year. In that same year, the interior was improved. Insulation and trim was changed to increase finished interior dimensions.
Some pilots referred to the narrow windshield of the Cheyenne and P Navajo as a tank slit. In 1980 the windshield area was increased by 20 percent for both the I and II. Cockpit organization and cockpit lighting also were improved.
Interior appearance and quality were improved with time, especially in the last two or three years of production as Piper learned to deal with the upscale corporate market.
The PA-31T was produced from 1974 to 1983. A total of 526 aircraft were built. The -31T1 was in production from 1978 to 1984; 215 I and IAs were built. There were 82 -31T2s manufactured between 1981 and 1984 (although there are two listed as 1985 models, they were built the previous year). Only 24 -31T3 commuters were built in the roughly two year life span of the design.
Compared to the mainstay of the turboprop fleet, the King Air series, any of the Cheyenne series is a bargain.
With the I or IA, one gets relative simplicity and ease of operation. If maximum cabin space is an issue, the IIXL is the best bet.
When the IIXL was announced, Thomas Gillespie, then Pipers head of marketing, was asked if production of the II was going to end. He replied that there were enough pilots who wanted a hot rod to keep it in business.
That is a fair description of the original Cheyenne. A lot of early buyers liked the high climb rate and comparatively good short field performance in addition to its high cruise speeds. They put it into a lot of strips that couldnt accommodate other turboprops and a large number of piston twins.
Visibility from the cockpit is a real shortcoming until the 1980 model year. The PA-31T requires more of pilots than the -31T1 or -31T2 in terms of systems knowledge, planning and in-flight management. It also is a bit more involved to maintain.
This is because there are more systems, including the SAS. Many of the systems are not as well designed and organized as in later airplanes and because of the affects of age (not to mention abuse and neglect).
Earlier avionics and autopilots or flight control systems can present real headaches. And archaic autopilots can represent in-flight hazards if they are not meticulously maintained and rigged.
Generally speaking, operators of the original version should make a dedicated commitment to good initial and recurrent training, rigorous pre-purchase inspection and evaluation and make sure they find a very qualified maintenance technician and shop.
For a pilot with no turbine experience, the I or IA would be the best choice because it is the least demanding to operate. However, this doesnt mean it is simple. Even if your insurance company were willing to let you get away without top notch training, you should get it. Even if misuse or abuse of a system or poor procedures dont lead to an incident or accident, improper operation can easily lead to unserviceability and increased maintenance cost.
There is not a lot of competition to consider in this category. The 90 series King Airs and the Cessna 425 Conquest I are the only other similar airplanes in the PT6-powered category. Garrett TPE 331-engined airplanes, such as the Aero Commanders, Mitsubishi MU-2s or even Swearingen (Fairchild) Merlin II and III models are a totally different category and set of considerations.
The Cheyennes are a relative bargain in both initial price and operating costs. They should be in maintenance costs, as well, so long as they are properly operated and maintained.
No airplane in this category should be considered a weekend toy. Careless operation has the obvious consequences. Careless support can bite in terms of airworthiness, higher cost and accelerated loss of value.
All three models have large capacity nose baggage compartments (a maximum of 20 cubic feet with a 300 pound load limit, depending upon the model and the type of avionics installed) and another bay in the aft fuselage. Maximum area is 22 cubic feet; load limit is 200 pounds (interior furnishings can reduce both). Later models were offered with an optional cargo door to make it easier to load the after compartment.
The I is approved for a maximum of seven seats. Both the II and IIXL can carry eight. Typical configuration for the I and II is four facing chairs in the main cabin with a side-facing seat/potty against the starboard fuselage.
All three can carry a good payload and sufficient fuel for from 900 to 1,000 nm with reserves. Proper loading is a key issue in the operation of any of the PA-31T series, most especially with the original Cheyenne.
It has a wider cg range than the I or IIXL (138 inches aft limit compared to 136) and is far more sensitive in pitch (more on this below). The IIXL is the winner in terms of payload/range and loading envelope. All provide enough options to permit loading (or off-loading, as the case may be) to keep weight and balance within the limits.
While the basic nature of inertia and mass can make a Cheyenne a lumbering handful for pilots used to lighter airplanes, within their category they are responsive and nimble.
Operated within their limits, there are few peculiar characteristics other than the pitch sensitivity of the original Cheyenne.
While there are variations with equipment options, when lightly loaded cg is toward the forward limit and the airplanes are nose heavy. It is very difficult to keep the nose wheel off when landing in this condition. Trim must be run to fully nose up during the final approach and then conscious effort made to put in sufficient, gradual up elevator (gradual to keep from ballooning) to touch down on the main gear.
One of the most annoying characteristics of the Cheyenne is caused by the aileron/rudder interconnect. In ground handling and during cross-wind operations it is especially troublesome, since it fights the desired control inputs.
Gear and flap speeds are sufficiently high to fit in to a wide range of traffic situations. Maximum speed for extension of the first notch of flaps (15 degrees), or Vfe, is 181 KIAS. Full flap speed is 148. Gear extension speed is 153 KIAS (but Vlo-retract is 139).
The toughest aspect of maneuvering in the traffic pattern in pre-1980 Cheyennes is the restricted visibility. It takes particular attention during single pilot operations to keep everything in order and right side up while avoiding traffic.
As with any high performance airplane with many systems and basic all-weather capability, managing the Cheyenne is more taxing than maneuvering it. Once transition is complete, the basic task of flying is fairly simple so long as you keep everything within the envelope (although many pilots have commented on the pitch sensitivity of the PA-31T even with everything in bounds).
There is enough to manage in a Cheyenne even in good weather that it definitely is in the category of a check list airplane.
About that SAS
As noted above, Pipers artificial and marginal fix to the longitudinal instability of the original Cheyenne turned into a blot on the entire series. The available power of 620 SHP is too much for the configuration of the Cheyenne with loading toward the aft range.
Certification in the United Kingdom was not possible (and not even tried) because of pitch sensitivity and pitch force behavior and feel, which encouraged pilot-induced pitch oscillations rather than damping the tendency.
Many airplanes have artificial aids for undesirable or unacceptable handling characteristics. On the longitudinal axis, bobweights and downsprings are the most common. These introduce artificial pitch forces at the yoke to counteract PIO or over controlling tendencies.
The Piper PA-31T stability augmentation system (SAS) adds variable elevator force via a variable tension downspring. An angle of attack sensor on the right side of the nose measures and transmits angle of attack to a simple computer which commands a servo to vary downspring tension. The computer also determines stall margin, commands stall warning signals and provides input to a simple, cockpit mounted angle of attack indicator dubbed the stall margin indicator.
The system met the letter of FAA certification requirements in terms of achieving stick-free longitudinal stability but it did nothing for, and possibly aggravated, long-period phugoid divergence (in something approaching English, if pitch input moves the aircraft away from its trim airspeed, it tends to accelerate quickly in that direction, then recover abruptly [pull up or push over] with the divergence increasing with each cycle). Theres a loophole in the regulations, in that there is no requirement for long-period dynamic longitudinal stability, only one for static stability. So the SAS allowed the airplane to meet the letter of the law, but that didnt produce an airplane with desirable handling qualities.
But, what exactly was wrong with the original airplane? The FAA code as written when the Cheyenne was developed called only for positive static longitudinal stability. This means that, for example if an aircraft is trimmed to 100 knots, a positive pull on the yoke is needed to maintain, say, 90 knots. The greater the speed displacement, the heavier the pull. The rules require that the pull be roughly proportional to the speed displacement; i.e., a 20-knot displacement from trim speed will require twice as much control pressure as a 10-knot deflection. To the pilot, such an airplane will have a normal feel.
When the Cheyenne was first tested, it did not have the required traits in the climb configuration; little or no back pressure was needed to maintain 100 knots even when the aircraft was trimmed to 110. The potential danger is obvious.
The original version of the SAS addressed this problem, but the bugaboo of dynamic stability remained. As stated above, a normal phugoid will damp itself out eventually. But the Cheyennes character with the original SAS led to a wildly divergent oscillation, in the words of a former Piper test pilot.
The problem is this: At the top of a phugoid cycle, the angle of attack is high, and the SAS pulls forward on the yoke. This causes an unnaturally sharp pitchover and rapid speed buildup. This in turn causes a steep pull-up at the bottom of the oscillation, resulting in a steeper climb and lower speed at the top, which means a higher angle of attack, which means a sharper pull by the SAS…and so on.
A number of pilots have commented on the pitch sensitivity of the original Cheyenne during maximum power climb, with cg toward the aft limit and in approach mode.
The longitudinal stability characteristics and the SAS were fully covered in the November 1, 1981 issue of The Aviation Consumer. More recently, former Piper test pilot (and frequent Aviation Consumer contributor) William P. Kelly Jr. discussed the issue in a letter (February 1, 1988).
In that later issue, Kelly discusses a further change to the system Piper made with the 1980 model year: the addition of a bobweight to dampen long-period longitudinal oscillation tendencies. The bobweight was made available as a retrofit to earlier PA-31Ts (The modification, called the Dynamic Stability Improvement Kit is covered by Service Letter 977. In Kellys words: None of these planes should be running around without this modification….).
A further, operational change was mandated for the PA-31T when Piper applied to increase the maximum operating altitude from 29,000 to 31,000 feet. Maximum climb power was reduced and recommended climb speeds raised to keep the airplane further from the SAS operating speed range (nominally, 121 KIAS and slower).
For operators of the PA-31T, pitch instability should not be a concern if the airplane pitch system is modified to the latest specification (including the bobweight), the SAS is maintained properly, weight and balance limitations are observed and current limiting power settings and airspeeds are complied with.
Even though there is an emergency backup to the SAS (a compressed air cylinder that imposes maximum nose-down force on the downspring), SAS is a no-go item on the PA-31T.
There is no SAS or other device required on the I/IA or IIXL. The lower maximum power of the I together with a narrower cg range, climb power limits and the forward bias of loading equations in the IIXL because of the stretch forward of the leading edge as well as an aft cg limit that is also two inches forward of the limit in the original Cheyenne make longitudinal stability and pitch performance satisfactory without artificial aids.
Pilot and passenger comfort improved as the series was developed. Early versions tend to be dark and cramped. As interior improvements, including cockpit redesign and increased windshield area, were made, all occupants benefited.
Long-legged pilots are a bit jammed into the cockpit, especially in models with gussied-up interiors such as cabin dividers and refreshment centers which tend to impose on cockpit chair movement range most. The IIXL is best in terms of leg room for everyone.
All provide reasonable comfort for average and even slightly longer or wider people. The cabin is fine for three or four passengers even on longer flights, especially with the club seating arrangement.
Noise level is about average for a turboprop. So long as the propellers are balanced and the synchrophaser is in good trim (and the pilot knows how to use it correctly), in cruise the interior is quite comfortable.
As with all turboprops, minor variations-as little as ten to twenty-five RPM-in RPM from normal cruise settings can work wonders in sound level, sound quality and vibration. It pays to experiment (but dont judge the affects just by the pilots reaction. The difference between the left front seat and a cabin chair can be substantial, especially if propeller-induced vibration is being transmitted from the aft fuselage).
Steve Magginetti is service coordinator for Corporate Air Technology of San Jose, Cal. He writes that his facility currently supports about 20 Cheyennes along with a number of other turboprops.
Magginetti notes: …comparing the Cheyenne to other turboprops in its class (it) compares well…maintenance costs are equal or less than that of the King Air, Conquest or Fairchild Merlins.
Parts availability has had its good times and times that have been not so good, but I do not remember any time an aircraft was grounded more than a few days waiting for parts. Right now parts support is very good…
There have been more than enough lectures about the need to be very serious about all aspects of caring for and operating this type of airplane. Here is one more: if you dont have the time and money to spend on learning what is required and then doing it, stick to your local rent-a-wreck for your aviating needs. The Cheyenne and other sophisticated, high performance airplanes will each your lunch and/or your purse. Or both.
As with any design, there are specific, recommended or even mandatory maintenance procedures. Taking your Cheyenne to just any good technician could result in missing one or more procedures.
Magginetti mentions cabin heaters, torque indicating systems and the PA-31Ts SAS as systems that require higher than average attention.
The in-flight shut down and premature removal rates of the PWC PT6 engine family is impressive. But there have been a host of updates and there are a long list of recommended care and maintenance procedures that are key elements of keeping your powerplants up there with the fleet average.
Some changes, such as a retrofit that reduces temperatures during engine start-named (surprise) the Cool Start Kit-and procedures such as regular compressor washes can have benefits beyond making it to recommended hot section inspection (HSI) and TBO (3,500 hours for all three models).
They can significantly reduce the cost of a hot section inspection or overhaul by reducing the effects of wear and tear on very expensive engine components.
Pratt & Whitney and several of the companies that specialize in PT6 maintenance have field service reps who would be delighted to get you started on your support education. There is a lot to it.
There is a lot to the proper care of the rest of the airplane, too. It isnt any different from any other sophisticated collection of systems and sometimes conflicting elements.
We looked the records for a representative five-year period, during which a total of 187 service difficulty reports (SDRs) were submitted on the PA-31T series, including the PA-31T3/T-1040. There is no major pattern. Environmental systems, including the cabin blower, heater and air conditioning, fuel systems-including fuel line chafing, landing gear and horizontal stabilizer/elevator were the elements causing the most frequent reports.
Many of the problems are reflected in service letters, bulletins (and, frequently, remedial kits.
Most type-specific ADs apply to the original Cheyenne with the I/IA, not surprisingly, running second. Only three ADs apply specifically to the I and none to the IIXL, although most apply to all three. Most are not repetitive.
It is noteworthy that there have been few reported problems with corrosion. The most severe case was attributed to improper paint stripping. However, there have been a number of elevator spar problems attributed to dissimilar metals (aluminum and steel).
The two most notorious Cheyenne accidents were original PA-31Ts involving longitudinal control-the much maligned SAS system. Yet, in one the airplane was clearly out of weight and balance limits and in the other there is a suspicion that the airplane was improperly loaded. (Note that the longitudinal stability problem is at its worst at aft loadings, and if the range is exceeded all bets are, of course, off.)
A review of briefs of the 56 accident and incident reports a typical five-year period include eight fatal accidents, two of which were in commercial T-1040s. There is one accident that occurred to a PA-31T under similar circumstances to the two that called the SAS into question: loss of control during an instrument departure in fog.
The Cheyenne, according to the accident brief, hit the ground while in a vertical dive. Icing conditions existed.
Most of the other accidents can be related to pilot action or inaction (the largest single category is landing gear up with no mechanical malfunction).
In the worst accident in terms of loss of life, seven people were killed when an ATP took off in a IIXL and tried to scud run but hit the side of a mountain. The comments in the accident brief note that the regular pilot refused the trip because of the weather.
Most of the pilots involved in the reported accidents and incidents held ATP or commercial certificates; eight of the total held private licenses and one, a fatal accident, was flown by a student pilot.
There is little or nothing to attribute to the PA-31T design in these accidents. Most can be laid to insufficient knowledge of systems, lack of proficiency, failure to use check lists and other human performance issues.
Most modifications to the PA-31T series come under the general headings of upgrade and retrofit. The two most important areas are avionics and autopilot/flight control systems.
American Aviation, Inc. offers a retrofit cowl system for the PA-31T series (except the IA, which has the pitot cowl system as standard) that improves performance and reduces engine operating temperatures.
The company also makes what are called Speed Stacks, specially shaped exhaust stacks that are claimed to improve speed and reduce exhaust deposits on the aircraft. The McCauley Accessory Division of Cessna offers a propeller conversion kit that-according to the company-reduces interior noise and improves performance.
By the time the program ended, the Piper Cheyenne series offered good all-around performance, good use of interior space and competitive systems. The airframes are rugged. Earlier versions of the original Cheyenne have some marginal systems and marginal arrangements of the myriad bits and pieces combined with human factors oversights such as poor and poorly located systems controls and inadequate cockpit lighting.
However, the whole family lived up to the Piper reputation of offering a lot of airplane for the money. It still does.
My company has flown a 1983 Cheyenne I for two years now and we have over 900 hours on it. On the whole, we are pleased with it. Perhaps this is because we came out of a 602P Aerostar with a multiplicity of problems and had experienced every in-flight emergency possible with it.
With the Cheyenne, on the other hand, we have had no downtime for maintenance whatsoever, except for the regular scheduled inspections. We have had a couple of engine problems, but discussions with our maintenance base, Des Moines Flying Center, have convinced us that all is well.
Our problem is that the right engine from day one has periodically and suddenly lost two or three quarts of oil. No one seems to be able to explain the reason. The oil is going out the breather tube, and the evidence is all over the underside of the right wing. This is not a gradual loss, but a sudden and irregular one.
This same engine takes seven seconds to go from idle to full power. This means the pilot must either hold the brakes until full power is achieved, or duck-walk down the runway on takeoff. This is more a nuisance than a problem. One design problem needs a full explanation, however. That problem is the phugoid stability. I have never flown an aircraft that requires so much yoke movement to hand-fly above FL 230. It takes about four inches of yoke travel to keep the plane level at FL 270. If the altitude-hold isnt turned on or isnt functioning, we simply dont fly above 230.
In the summer, when the effective density altitude is higher, attempting to hand-fly at that altitude is simply impossible. When the altitude-hold is engaged, the trim wheel is in constant motion holding the aircraft level.
Below FL 180, the aircraft tends to become more stable, but the phugoid instability is still obvious, and with each oscillation it becomes worse. On this particular aircraft, the most stable ILS approaches are flown at 140 knots, in order to keep the phugoid from becoming a problem. At any speed less than 130 knots, the aircraft starts to oscillate. This presents no problem, but I can see how an inexperienced pilot could find himself a trifle overwhelmed by either the extra speed or the oscillations.
The pitch instability also becomes a problem in holding patterns at reduced airspeeds between 12,000 and 16,000 feet.
I cant give you a reason for the unstable phugoid, but only comment that it does exist and has to be dealt with by the pilot.
Weight and balance takes some careful managing. It tends to be tail-heavy. Therefore, every Cheyenne I or II pilot I know carries either 75 or 100 pounds of lead weights in the nose to keep the plane from sitting on its tailskid and to keep it within the legal center-of-gravity envelope.
Ground handling is easy and straightforward, but taxiing will result in two very bruised knees if any sharp turns are required. The yoke will beat your knees purple, especially in any sort of crosswind. Control authority is insufficient for a strong crosswind landing, so we learned to use differential power very early in our training on the Cheyenne.
One item that Piper should not have used was the Janitrol heater. It frequently and for no reason pops the circuit breaker, usually at FL 250 or higher, so that it becomes a trifle brisk in the cabin. The electric aux heat works fine, but cant be used if the de-ice equipment is on, because of the electrical overload. Of course, you usually need both at the same time. The average Janitrol event costs about $2,000, which includes a deep-cycle charging of the ni-cad batteries.
Passenger comfort is good in our aircraft. Pilot comfort, however, is less than satisfactory because it is cramped and the yoke constantly gets in the way of the pilots knees.
We are not well pleased with the parts availability. Des Moines Flying Service does an excellent lob getting parts from any source possible.
-Emmit G. Williams
Our company operated a Cheyenne II for almost three years, and I was principal pilot in the airplane for about 300 hours. The airplane is fast and dependable and has a somewhat undeserved bad reputation arising out of its short-coupled fuselage and somewhat poor stability. However, the plane can be flown correctly and safely, and is a fine performer.
The plane must be flown within its loading envelope or there can be big trouble for the occupants. The Cheyenne II came equipped with a total of eight seats, and in my opinion it should not have been equipped with the eighth-the rearmost seat. This is an invitation to disaster, because it can easily put weight too far aft. The eighth seat sits partly in front of the door and partly in the rear cabin baggage compartment.
In our case, we took this seat out, wrapped it up in plastic, and left it in the hangar during the entire period we owned the plane.
The much-maligned SAS system gave us no trouble whatsoever after we changed the SAS vane from an earlier type with a single heater to the newer type with two electric heaters. This vane on the earlier models tended to freeze up and sound a warning, which caused some pilots to try to disable the system.
Some people think the Cheyenne I is a better airplane because it has no SAS system. They are kidding themselves, since the reason theres no SAS is because the PT6A-11 engines are substantially downrated, and produce much less power. If a person wanted to do that in a Cheyenne II, he could simply self-limit the -28 engines to the 500-HP output of the -11. But then they would lose part of the reason for owning the II. Also, the IIs generally come equipped with far superior avionics, such as the King Gold Crown instead of the panel-mounted radios in the Cheyenne I. One of the most annoying features of the Cheyenne was the Janitrol combustion heater which, although thermostatically controlled, was either on or off. Frequently it would fail to light up during climbout or at cruising altitudes. As a result, the passengers either froze or cooked, and there never seemed to be a good fix for that.
One additional factor I believe to be absolutely necessary is that pilots flying the Cheyenne should attend the Flight Safety school on the Cheyenne on a recurrent basis. The instructors will put the pilot through aft-loading drills in the simulator, as well as many other things that are life-savers.
The Cheyenne II is a bit of a handful, and not one in which a low-time or untrained pilot moving up from piston engines should fool around without first-class training. A properly trained pilot will find it to be a very satisfactory airplane, except for the combustion heater problem.
-Frank G. Hathaway
Los Angeles, Calif.