by Marc Cook
You want to ditch the nose bag. You want to fly among the big iron where the air is smooth and the tailwinds tantalizingly strong. (Lets not think about the headwinds coming home, okay?) You want to make the most of your airplanes altitude performance in total comfort. You want pressurization.
Several manufacturers have given pressurization a go in the piston market, pumping up the cabins of singles and twins. Inherently conservative, the manufacturers based most of the early designs on non-pressurized models, a tactic thats good-because the airframe and engine combination are already well known-and bad-because a pressure vessel is ideally circular in cross section, something you wouldnt want for space reasons on a non-pumped model.
The range of choices in pressurized airplanes is not large, mainly because of limited market demand and the high cost of building them. If you can afford a twin, the universe of pressurized choices is larger but the costs are significantly higher, even for modest airplanes such as the Cessna 340. Well examine pressurized twins in a subsequent article; for now, well focus on two pumped-up singles, the Piper Malibu/Mirage series and Cessnas P-210, with an honorable mention of two other models, Mooney M22 and the Lancair IV-P homebuilt.
Of course, theres more to pressurizing an airplane than sealing up the fuselage like a giant ZipLoc bag and pumping in a bunch of air. (See the sidebar for an explanation.) For one thing, pressurization comes inexorably with turbocharging. There have been systems using engine-driven compressors-superchargers for the cabin-but all the modern models employ an air-bleed from the turbocharger system to provide cabin pressurization. (Turbines, in case youre curious, do the same thing, only taking bleed air from one of the high-pressure sections of the engine.)
Turbocharged engines, as a rule, consume more fuel and live shorter, more costly lives than similarly powered non-turbo models. On top of that, theres the maintenance issue; for many turbo applications just working on the engine is more difficult because of all the extra hardware.
Pressurized aircraft use turbo systems similar to (and in some cases the same as) their unpressurized brethren, so there shouldnt be much difference in the maintenance requirements or longevity, right? Not so fast.
The key difference is utilization. The typical non-pressurized, turbocharged airplane rarely goes above 10,000 feet unless theres a compelling reason to do so-weather, smooth air, a ripping tailwind-because of the inconvenience of donning an oxygen mask. But in a pressurized airplane, theres little incentive from the comfort standpoint to diddle around down low. Still you have to consider stage length and winds, among other factors, as you determine optimum altitude.
So as a generalization, pressurized airplanes are considerably more likely to be up in the flight levels on a regular basis. And that means to justify those long climbs, you really need to have some distance to cover and fairly often.
While the ride atop the weather is often sublime, it makes more work for the engine. As a rule, pressurized airplanes are heavier than their turbocharged counterparts and so have lesser climb performance. (This assumes the P-model doesnt pack significantly more horsepower, which is most often true.) Now you have a heavier airplane, struggling for longer climbs to higher altitudes where its asked to perk along sniffing very thin cooling air at reduced indicated airspeeds.
Whats more, because this engine will be in climb mode longer, you will have to carry more fuel- and P-models often come with additional capacity-to altitude, further hurting climb performance. Bottom line: Engines in P-model aircraft work hard and simply dont have as long a real-world TBO as similar non-turbo aircraft. Along with costlier maintenance, foreshortened TBOs represent the true incremental cost of pressurization.
Historically, pressurization systems have been reliable, although the word is filtering from the field that age is starting to take its toll on the hardware. Owners report relatively few problems with the basic system but more trouble keeping older door seals from leaking and hunting down other cabin leaks.
All cabins leak-there is no such thing as an airtight cabin-but the extent of the leaks might not become an issue until the pressurization system reaches its capacity and can no longer provide rated cabin differential at altitude. This is easy to check on a test flight.
Typically, the related environmental systems-air conditioning, in particular-give more trouble than the basic pressurization system. Owners regularly complain about inoperative air conditioning-a necessity in many parts of the country, particularly for low-altitude flights.
Pressurized aircraft are different from their turbocharged siblings by more than just the addition of pressurization hardware. P-models are more likely to have additional systems such as radar, de-icing equipment and other useful add-ons that need to be inspected, maintained or repaired periodically.
Windows are fantastically more expensive for a pressurized model and their replacement times can border on the excessive. In most cases, the turbo systems are more sophisticated-with high-end and therefore more complicated and expensive-to-overhaul controllers-no budget-minded fixed-wastegate systems here. Youll need to budget for the care and feeding of these systems and special parts.
While youre sharpening the budget pencil, remember that pressurized airplanes are likely to cost more to insure. A Cessna P210 is considerably harder on the insurance budget than a same-year T210, for example. One tip for the P210 guys is to remove one or two of the six seats and insure as a four- or five-passenger airplane. Supposedly, this can be less expensive but expect the numbers to vary widely from carrier to carrier.
How Do They Fly?
A pressurized airplane may be more complex and expensive to buy and maintain, but at least theyre less fun to fly. Actually, this observation is model-dependent. For example, a P210, as do all pressurized aircraft, has numerous seals around the control cables where they exit the pressure vessel. At altitude, the seals add friction to the control system, making an already heavy-handling airplane fly like a U-Haul trailer with wings.
Aircraft designed from the start to be pressurized are much better in this regard. (And, to be fair to the 210, the R models built in 1985 and 1986, are nice flying airplanes.) Whats more, converted designs kept their short wings, which are fine for low-altitude cruise but lose efficiency in the flight levels. Again, aircraft intended to regularly go high-the Malibu, for example-fly nicely in rare air. The bottom line on owning a pressurized airplane is this: itll cost you. Theres nothing free in aviation and the ability to travel among the puffy white ones mask-free is paid for in higher acquisition and upkeep costs.
Although you cant lay blame directly upon the shoulders of pressurization for these costs, its still true that you dont get a pumped cabin without the turbos and the capable systems attached to it.
A Singles Sampler
In the realm of piston twins, pressurization is almost a standard feature. And while the feature is just as desirable in a single, only three have made it to production. So far. Heres a closer look at your pressurized, single-engine options.
Cessna wowed the single-engine world with the P210, debuting in 1978. Although not the first pressurized single-Mooneys ill-fated M22 Mustang was-the P210 was by far the most successful of the period. Thats mainly because it was based on a tried-and-true airframe that had already garnered huge popularity as a turbocharged version. Cessna had lots of dealers and plenty of T210 owners looking for a step up the ladder that was an easier reach than a twin.
Beefing up the fuselage and adding the pressurization system from the Cessna P337 twin gave the P210 a 3.35 PSI cabin differential, enough for a 10,000-foot cabin at 20,000 feet. Not exactly airliner-quality atmosphere but enough to make flights from 14,000 feet to FL190 far more comfortable than in a T210.
Cessna built the P210 in what could be considered three generations. The 1978-to-1981 aircraft used a 285-HP Continental TSIO-520-P (rated at 310 HP for takeoff at a very noisy 2850 RPM) and had early trouble with the turbo and induction system. Cessna eventually updated the induction system on the early aircraft to restore altitude performance; its an update worth waiting for.
In addition, only the 1978 models had the clamshell main-gear doors. Cessna dropped the doors in 1979 and many 1978 models have been similarly modified by STC. Owners say the gear-door models are slightly faster and have marginally better climb. All these first-gen P210s have the capacity to run hot, so a thorough check of baffling and fuel-system calibration is in order.
Big changes came to the 1982 models, including an improved slope wastegate controller, simplified fuel system (now with a both position) that was less prone to vapor lock, improved cowl flaps that closed a bit tighter to help keep the engine warm on descent and a 200-hour-higher TBO (1600 hours) for the engine.
Dual vacuum pumps and alternators were made optional starting in 1982 as well. Although fundamentally unchanged, the P210 had been tweaked into an ever more impressive airplane, with many of the niggling problems finally ironed out.
Pipers Malibu arrived in 1984, which may in part explain why Cessna committed significant resources to updating the Centurion. Called the R model-available in normally aspirated, turbocharged and pressurized versions-it boasted more power from an intercooled TSIO-520, now up to 325 HP continuous.
The cowling was revised to improve cooling-air flow and to feed the new intercooler. Performance went up from a typical high-altitude cruise near 190 knots to a claimed 213 knots at 22,000 feet. Real-world cruise speeds for the pre-R models range from 165 to 185 knots, according to a recent survey of owners.
For the airframe came extended wingtips that helped house an additional 30 gallons of fuel, up from a marginal 90 to 120 gallons total, and improved high-altitude cruise. At the same time, Cessna fitted an entirely new horizontal tail that did away with the downsprings and bobweights, which were truly remnants of the Centurion growing, sometimes painfully, from a 260-HP, 2900-pound airplane.
The new tail made the R models handle with the kind of control harmony that makes Bonanza pilots so insufferable at cocktail parties. Overall, the P210 carries the Centurion tradition well, with good speed, high-altitude comfort and decent payload-typically in excess of 900 pounds. But this is a highly variable number according to equipment, say owners. Used values are higher than for a same-year T210, of course, ranging from a $20,000 premium to $38,000, depending upon the particular model year.
R models are comparatively rare and highly prized. Maintenance-wise, the P210 is more trouble than a T210 but, owners say, manageable in the face of the added comfort and capability pressurization provides.
Malibu owners have the kind of love/hate relationship with their airplanes normally reserved for hot-blooded spouses or generous (but bipolar) bosses.
When the Malibu works, all is right with the world-its fast, comfortable, capable and even handsome. Yet the model has put owners through the ringer for maintenance, and even a change of engine did little to alleviate significant (and often thrillingly expensive) problems. Indeed, many say the Mirages big Lycoming is more troublesome than the Continental it replaced.
Back in 1984, Piper launched the Malibu as the first designed-from-scratch pressurized single. It had all the hallmarks of a great design-a sleek cabin with near-cabin-class room, a long wing ideally suited for high-altitude flight and an unusually fuel-efficient engine that promised a lot of range on relatively little fuel. With a 5.5-PSI pressure differential, the cabin remains at 8000 feet right to the airplanes operational ceiling of 25,000 feet.
However, the original Malibu had a spate of engine problems and in-flight failures that caused Piper, in 1987, to ask owners to voluntarily ground their airplanes until the problems could be identified and fixed. Many Malibu owners say the engine gets a bad rap from pilots new to turbocharging, to say nothing of high-altitude pressurized flight, unknowingly treating it like a more durable, lower-output powerplant.
Even pilots used to high-strung turbo engines were caught off guard by the Continentals intended operations, which included lean-of-peak turbine-inlet temperatures (TIT) for cruise.
Some pilots thought this was just a save-fuel measure and opted to run richer. But because the Malibu didnt have cowl flaps, the lean-of-peak operation was necessary to contain cylinder-head temperatures. Fly the original Malibus engine as you would, say, a T210s, and youre in for big, expensive trouble.
Even if every Malibu owner began treating the engine with kid gloves-and had Continental got a handle on quality-control issues-the deal was done to put a Lycoming up front. Piper installed the TIO-540-AE2A starting in 1989, creating the Mirage.
The big Lyc is heavier, thirstier and not nearly as smooth as the Continental, but had a reputation for toughness that was, early on, validated in the Mirage. However, field experience has shown the Lycoming to be similarly hard on cylinders (valve guides, particularly) and its greater vibration leads to problems elsewhere, including the exhaust system and turbo components. Finally, the Lycoming is thirstier-it does make 40 HP more-reducing range compared to the Continental-powered models.
Owners say the Malibu/Mirage is a delightful airplane to fly and passengers praise the comfort of the cabin-although some say its too cold in the back, so bring blankets-and the relative quiet partly as a result of the baggage bay between the engine and cabin.
Typical full-fuel payload is around 920 pounds; good considering that youd be hauling 120 gallons of gas in the wings. Count on cruise speeds between 175 and 190 knots for the Continental, perhaps 3 to 5 knots more for the Lycoming-powered Mirage. Running lean of peak, the Continental will consume approximately 15 GPH at 75-percent power; the Lycoming, running rich of peak by decree, chomps down closer to 20 GPH.
By a large margin, the overlying issue with Malibu/Mirage owners is ongoing maintenance. For the design to be fast, it had to be aerodynamically efficient, which forced a tight engine bay-even more so for the Lycoming, which is a physically larger engine with a different accessory layout-and a general compacting of all systems. The only smart way to buy a Malibu or Mirage is to find a technician or shop intimately familiar with the breed and make him (or them) your best friend.
Appearing like a conventional M20 that was fed too many growth hormones, the M22 earns credit for being the first production pressurized single. And thats about where the accolades end. Mooney didnt find much of a market for the outsized single-it built a mere 29 between 1967 and 1970.
If you think its hard to get parts for regular Mooneys, you havent seen anything yet. In addition, the M22s Lycoming TIO-541 is a rare thing, whose overhaul costs are fully half of the value of a first-year Mustang. Unless youre out to collect unusual airplanes, we recommend a pass on this one.
Lancairs IV-P is a sleek, sophisticated and fast conveyance-a prime example of following experimental-category rules to the letter at the same time knocking the spirit of the rules with a carbon-fiber two-by-four.
Youll see the IV-P among the other aircraft for sale, often described as professionally built. (Hmmm. Is that legal?) Its experimental status highlights both the strengths and considerable weaknesses of the design. Without having to meet FAR Part 23 certification rules, the Lancair can and does have a small wing and a high stalling speed, which leads to excellent cruise performance but also cabin-twin-like approach speeds.
Its stall behavior has been called everything from benign to eye-opening, likely the result of variations among examples. Truly, no two Lancairs are exactly alike. Although likely to be at altitude, flying fast in potentially difficult weather, the Lancair carries no de-icing equipment and is not lightning-hardened. We hesitate to recommend purchasing a Lancair IV-P unless you really know what youre looking at or can hire someone intimately familiar with both the design specifically and methods of composite construction generally. Although a good bit of the hard work has been done at the Lancair factory, presumably with appropriate quality controls, theres a lot left to the individual builder.
Homebuilts as a rule dont have a stellar accident record, and with the Lancair youre not dealing with a 100-knot knockabout, but a 250-knot-plus, 350-HP pressurized traveler that deserves every bit of respect and demands pilot skills often beyond that youd need to fly a cabin-class twin.
In the end, its all about money. If pressurization is a must and you cant afford or dont want a twin, the most affordable and practical choice is the Cessna P210. As of spring 2004, used prices on these airplanes range from $176,000 for early models to $290,000 for a 1986 R-model.
That price range means theres some overlap with the early Continental-powered Malibus, which retail for as little as $285,000. But later model PA-46s are in the mid to high $300,000s. The bidding on a used Mirage starts at $485,000. Engine overhaul costs for the two Piper models are at least a third more than for the P210.
Operationally, the P210 enjoys an edge in dispatch reliability. Stories of high maintenance bills for the Mirage and Malibu are legion; less so for the P210. If you dont need or want the Pipers club cabin, the P210s cruise speed and payload is roughly comparable for less money. We think, however, that it should be considered as a four-seat airplane against the Malibu/Mirages six seats.
-Marc Cook is a freelance writer and editor. He lives in Long Beach, California.