The Beech 60-series Duke is one of those airplanes that sometimes gets a bad reputation from folks who just don’t understand it. Yes, it can be a real handful on the maintenance floor if the previous owner didn’t give it the attention it demands. Yes, its turbocharged Lycoming TIO-541 engines are somewhat unusual and early variants had a short TBO, and even shorter in the hands of pilots who don’t know how to treat them.
But the Dukes-especially later B60 models-can be good airplanes that serve serious owner-flown missions with a high level of styling, signature Beechcraft fit, finish and handling, plus decent performance. Still, like any high-end pressurized cabin-class piston twin, be prepared to write hefty checks when it comes to maintaining one, and bring your A-game when flying it.
History
With a 14-year production run, the Duke dates back to 1966 and generally competes with Piper’s P-Navajo and of course the Cessna 414 and 421 pressurized twins. The Duke was advanced in its day thanks to manufacturing processes and materials, and that included skin bonding, honeycomb panels and chemical milling, plus magnesium was used in the empennage. The landing gear is classic Beech, however, being essentially identical to the smaller Baron’s.
Beech didn’t change the Duke much over the years, although there were three models to include the straight 60 (sold in 1968 and 1969), the A60 (1970 to 1973) and the B60, introduced in late 1973 with airframe number 247. The fuel capacity was bumped up from 202 to 232 gallons in 1976. All told, 596 Dukes were built.
The model progression represents steady refinement, but the airplane’s configuration remained basically unchanged. In 1971, the Model A60 was introduced with a modest increase in gross weight (up 50 pounds from 6725 to 6775), but useful load and performance dropped a bit. According to book figures, the straight 60 is a much better short-field performer than the A60. However, Duke owners tell us those early figures were extremely optimistic, and that the A60 is only slightly inferior in takeoff and landing performance to its predecessor.
One difference among the three models concerns the exhaust stacks. The original 60 had the shortest stacks, and suffered from flap corrosion due to the impingement of exhaust gases. The A60 had longer stacks, but corrosion was still a problem. The B60 has the longest.
All Dukes are powered by 380-HP Lycoming TIO-541 engines. The slightly unusual powerplant has the turbocharger designed in as an integral component, rather than added on as an accessory. Early models installed on the 60 and A60 were maintenance headaches and had 1200-hour TBOs. But the engines have been upgraded over the years and now have a 1600-hour TBO; it’s unlikely that many of the 1200-hour engines are still in service. Several Duke owners, in fact, tell us they’ve gone we’ll past that figure by operating the engines properly and, in particular, ensuring that they are properly warmed up and cooled down to avoid shock cooling. It’s advice worth taking, given the number of cylinder problems we’ve heard about.
Performance
The Duke travels at a good clip but guzzles fuel. At 24,000 feet, max cruise is about 220 knots (250 MPH) at 65-70 percent power. Fuel consumption is about 40 GPH. One Duke owner told us he flight plans 52 gallons the first hour, 43 gallons for every hour thereafter and uses 68 percent power. In contrast, at 55 percent power, fuel consumption drops to about 30 GPH, but speed falls to about 185 knots.
The Duke edges out other pressurized twins in performance, with one exception, the pressurized Aerostars, which fly 10-15 knots faster on about 25 percent less fuel. Using high power settings for speed has a price, though: One owner called the cabin noise level “unbearable” at 75 percent power. Bring along your best ANR headsets, and consider modern interior upgrades.
Although the Duke’s range is rather limited-its standard fuel tanks hold just 142 gallons-most have optional long-range fuel tanks that hold from 202 to 232 gallons, depending on the model. Top off the optional tanks and you can boost up the manifold pressure and make a four-hour, 900-NM trip with IFR reserves. At reduced power and full fuel, you can fly the Duke 1000 NM, which is average for its class.
The Duke wasn’t designed for short runways. Most owners say they won’t even think about using anything with less than 3000 feet. One owner, though, says he regularly flies his Duke out of a 2650-foot runway in Pennsylvania.
This compels us to repeat an old but true story about how motorcycle daredevil Evel Knievel once ordered the pilot of his Duke to land on a drag strip. The Duke ended up with its snout through a truck trailer Knievel used as a dressing room. Another limitation of the Duke is that its initial climb on takeoff is rather lethargic until it reaches about 500 feet, according to some owners.
Climb performance is important for a pressurized airplane designed to cruise above 20,000 feet. Here, the Duke turns in respectable performance once it gets going. A climb to 24,000 feet, at full gross on a warm day, takes just 28 minutes, reports one corporate owner. Others say the airplane climbs 700 to 1000 FPM, depending on weight.
The addition of intercoolers improves climb performance and offers other benefits, though some say they think the benefits of intercoolers are dubious. At any rate, the Duke’s climb performance (once it settles into the climb) is generally considered superior to any other owner-flown pressurized twin-except, again, for the pressurized Aerostars.
Single-engine performance is about average for this class of airplane. In other words, you’ll be mumbling curses and prayers when an engine quits, even under ideal conditions. Expect a climb, at full gross weight and sea level, of 307 FPM (this assumes a perfectly running airplane flown with flawless technique).
Service ceiling with one dead engine is 15,100 feet. Some pilots say that intercoolers improve single-engine performance. The addition of vortex generators goes a long way toward improving single-engine performance. As always, we heartily recommend VGs on any twin. They’re a simple mod that really works, in our opinion.
Loading
As you might expect, the Duke is not a six-person airplane with full fuel, but it still beats anything in its class in terms of useful load and range. Late-model Dukes generally have a useful load of better than 2000 pounds, even when carrying full equipment. Earlier models, which tend to have less equipment and weigh several hundred pounds less, do even better: Some straight 60 and A60 models have useful loads approaching 2300 pounds. Such figures compare favorably with the cabin-class Cessna 421, which has seven seats to fill compared to the Duke’s six.
One drawback is the Duke’s healthy rate of fuel consumption, which translates into a smaller payload. Compared to other pressurized twins, the Duke uses a few hundred more pounds of fuel on a long trip. Still, the Duke shines in one respect: It can carry full fuel and two to four people. But there are variations in load-carrying capabilities.
One corporate owner of a lavishly equipped Duke reports that he makes three-hour, 600-mile trips with six people and 136 gallons of fuel. In contrast, a private owner, whose Duke has optional fuel tanks, says he’s at gross with full fuel, 100 pounds of baggage and two people.
The Duke’s single baggage compartment is located in the nose and can carry up to 500 pounds. According to one owner, this makes it easy to get the Duke out of its forward CG limits but difficult to get out of its aft limits. Another says he finds the airplane’s weight and balance characteristics benign-that is, hard to get out of CG in any manner.
Comfort, Handling
Owners give the Duke decent marks for overall passenger comfort. Its cabin pressure differential is 4.7, so at 24,000 feet the Duke has a cabin altitude of 10,000 feet, which is superior to most six-seat pressurized twins. On the downside, the Duke is similar to Bonanzas and Barons in that it has a tapering cabin. Two adults in the back seats will travel elbow to elbow. In 1974, though, the B60 model’s side panels and ducting were reworked to offer a bit more lateral cabin room. More recent models come with redesigned seats that increase the amount of aisle space by a few inches.
If you’re on the hefty side, it may be a tight squeeze entering the Duke’s cockpit. As for the cockpit layout, it’s user friendly: All the necessary controls, switches and avionics are within easy reach and view of the pilot, except for the circuit breakers. They’re a far reach on the far right of the copilot’s panel.
Cockpit visibility, though, is barely adequate. To see over the glareshield, a pilot of average height might be tempted to pull the seat forward; however, the seat will also automatically move up, which may put the pilot’s head next to the headliner.
We like that the power controls and gear and flap levers have been placed in the standard order (they’re reversed in earlier Barons). The flap system also is straightforward, with just three lever positions: up, approach and land. Maximum gear-extension speed is a phenomenal 175 knots. Also, dual control wheels are standard equipment, and the cowl flaps are electrically operated. A glance out the window will confirm whether they’re working.
Owners report the ride will be comfortable and fairly quiet, except during climbs or power settings above 2500 RPM. While most concur that the cabin is noisy at cruise and takeoff power, one owner reports the rear cabin seats are about as quiet as a King Air’s, but that the heater is inadequate in wintertime or at high altitudes, unless the cabin is filled with bodies.
In Beechcraft tradition, pilots compliment the Duke’s handling characteristics. Its controls have a solid (some say heavy) yet responsive feel, which is not surprising, since the Duke is the heaviest of all six-passenger airplanes. One owner, praising the Duke as a rock-solid IFR platform, said, “ILS and LPV approaches are like a railroad track.” Predictable and docile, the Duke trims up we’ll and holds its airspeed, and pitch changes are minimal when the flaps or gear are extended.
One pilot, though, said the Duke’s controls were too heavy for him, and that he prefers lighter and more responsive inputs. In turbulence, one pilot says the Duke is a “bear to fly” without a yaw damper, while another says adroit foot-work can be substituted for a yaw damper.
Feeding It
It should be no surprise that pressurized twins with amenities such as air conditioning typically cost a small fortune to maintain, but the Duke seems to be in a class of its own. Over the years we’ve heard Duke owners complain about mechanics automatically jacking up their prices for a Duke because it’s a Beechcraft at the top of the food chain.
While maintenance shops won’t feel sorry for you when you roll up to the hangar in a Duke, most satisfied owners correctly point out that the key to keeping bills down, and ensuring that the Duke’s engines reach TBO, is to properly operate and maintain the airplane. And woe to those who got a “good buy” on a used Duke that was not properly operated or maintained. It can be an expensive mistake.
To help reduce such costs, though, many owners stress that it’s important to find a shop that is familiar with the Duke, rather than letting a mechanic who has never worked on the airplane learn at your expense.
The Duke Flyers Association, which was formed in 1988, can help in this area. On a brighter side, buyers will be glad to know that parts availability has not been a problem.
Don’t even consider a pre-1976 Duke unless you’re sure its 380-HP Lycoming TIO-541 engines have received the appropriate upkeep. A pair costs some $110,000 to overhaul, which underscores the need for prudence in this area. As for other engine problems, here are some major ones that we’ve identified through owner complaints and service reports over the years:
• Cylinders and pistons. Until 1974, the TBO of the TIO-541 was only 1200 hours, primarily because of cylinder woes, with cracking around the exhaust ports the major problem. Since then, engines built or overhauled with improved pistons and cylinders have had a TBO of 1600 hours. One factor in cylinder failures was improper pilot technique in warming up and cooling down the engines; if temperature changes were too abrupt, cylinder stress would result. (Incidentally, a check of SDRs revealed numerous cylinder problems.) Still, Dukes built in 1976 and later (serial number 804 and up) have the upgraded engines. They have a 1600-hour TBO, and owners report operating them for 1600 and even 2000 hours.
• Turbochargers. The 60, A60 and 1974 B60 models had cast-iron turbo housings that tended to crack from the heat. This was no small problem in flight, since a turbocharger failure in a pressurized airplane can lead to partial or total cabin depressurization. However, the cracking problems stopped in 1974, when stainless steel blowers were fitted. By now, almost all cast-iron turbo housings have been replaced with the stainless steel ones; however, a few old ones remain, so be sure you’re not getting one of them-especially when sourcing the airplane outside of the U.S. If you are, make sure you get a price reduction.
During a demonstration ride, be sure to check for manifold pressure drift. Mixture control cables also have had their share of problems. Be sure to see that you’re getting the upgraded versions, since replacing mixture control cables costs several thousand dollars.
• Crankcases. Through 1977, Dukes had a high incidence of crankcase cracks (which goes to show, at least, that Continental isn’t the only company to have crankcase cracking problems). The Duke’s crankcases were beefed up in 1988, starting with engine serial number 78.
Other Service Items
Dukes came with jet-style nickel cadmium (nicad) batteries. You’d think that this would give a high degree of dependability and wear. But the battery is improperly cooled, and it can be destroyed by a slight improper adjustment of the voltage regulator. Average life is just two years or less. That may seem like a decent enough battery life, but not when the battery costs thousands. Fortunately, later model Dukes have lead-acid batteries. Beech has stopped offering lead-acid conversion kits, but you could probably have a Beech dealer install one. Our suggestion is that you try and buy a Duke with lead-acid batteries.
The Duke’s heated windshield drew various complaints: delamination and static discharges that pitted the plastic. We’ve heard of delamination problems on earlier Dukes but not later models. Some speculate that St. Elmo’s fire might be caused by not having the static discharge lines attached to the ailerons. (Incidentally, we didn’t find any SDRs pertaining to windshields.)
Other reports point to various problems with the exhaust. The Model 60, in particular, had short exhaust stacks that lead to flap corrosion. The condition of the exhaust pipes also should be checked at the rear by the slip joints; they came off and triggered a fire in one case.
Various magneto, landing gear, drive train and wheel problems also were mentioned in SDRs and owners’ reports, so make sure these items receive a thorough going over on a prepurchase inspection.
After receiving two reports of partial outboard elevator separations in Dukes, Beech issued mandatory service bulletins in 1989 to check the airplanes’ horizontal stabilizers and elevator hinge attachment areas. The bulletin affects certain Duke 60, A60 and B60 series models. Beech said an inspection should take two techs 12 hours to perform. Inspections were to be performed as soon as possible, but no later than the next 50 hours.
The Duke is subject to relatively few ADs, considering the complexity of the aircraft. The various spar cracking ADs that have affected Bonanzas and Barons in recent years don’t apply to the Duke, fortunately. Aside from various shotgun ADs, the only really important ones in the past 20-odd years have been 85-22-5, which dealt with Inconel bolts in the wing attach fittings, and 80-4-7, which called for inspections of the wing outer attach fittings.
Major Mods
When searching the market you’ll find the Rocket Engineering Royal Turbine mod, which is a B60 converted with two PT6A-35 engines rated at 525 HP each. Max cruise is 290 knots at FL270. With a 45-minute reserve up high, range is about 1000 miles and endurance about 3.5 hours. Gross weight is 7050 pounds, max landing weight is 6775 pounds and the published empty weight is 4650 pounds. With a total of 260 gallons aboard, 658 pounds can be carried in the cabin. While a well-cared-for late-model piston Duke with low-time engines might sell for $250,000, we spotted a couple of turbine Dukes in the $700,000 range. There aren’t many conversions out there-under 25 as far as we know.
There are plenty (207) of “Grand Dukes” modded with BLR Aerospace (www.blraerospace.com) winglets and over 160 with aft body strakes. The company also has a VG kit-a popular mod for the Duke. The winglets are compatible with aircraft serial numbers P-247 and on. The early 60 and A60 models have different tips that aren’t compatible.
The VG kit is $3950 and install time is eight hours. Aft body strakes are $5750 and take 16 hours (plus paint work) to install. The winglets are $17,950, plus 30 hours of instalation for dry tips and 40 hours for wet tips. BLR’s Nick Dean said all Dukes up to serial number P-364 were 202-gallon aircraft; P-365 and on are all 232-gallon Dukes, although you will find a few earlier ones that were either retrofitted with the later Beech wet tips or that have an STC that BLR did for wet tips. The company made 30 ship sets of these back in the 1990s and sold all of them.
A Grand Duke fully modded has lower stall speeds-78 knots compared to 82 knots on a stock airplane in the clean configuration, and 70 knots compared to 76 knots on a stock airplane in the dirty configuration. The short-field approach speed is drastically lowered to 77 knots with a BLR-modded Duke, compared to 99 knots for a stock airplane, according to the BLR. You’ll see better climb, too, when equipped-nearly 350 FPM better when both engines are making best power. The new gross takeoff weight of a fully equipped Grand Duke is 7000 pounds, compared to 6775 on a stock airplane.
To help with slam-dunk descents while still being kind to those finicky Lycoming engines, PowerPac Spoilers (www.powerpacspoilers.com) offers aftermarket “jet type” hydraulic spoiler kits for the Duke. The kit is $7495 and the idea is to deploy them at any speed (up to Vne) for rapid descent rates without the need to pull the power off.
Beech Duke Accidents: Engines
After reviewing the 100 most recent Beech Model 60 accidents, we were impressed by the tiny number of runway loss of control (RLOC) accidents-three-puzzled by the number of fuel-related accidents-14-and concerned that the majority of accidents following an engine power loss involved a fatal loss of control.
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The Beech Duke has, in our opinion, impeccable ground handling, as reflected by the miniscule number of RLOC accidents, but its single-engine handling requires pilots to bring their A-games. Unfortunately, our examination of accident reports reflected that a lot of pilots didn’t give the airplane the respect it demands and several brought on an engine stoppage by failing to maintain their machines or buy fuel.
Of the 27 engine/mechanical accidents, lack of, or improper, maintenance accounted for over half. One owner put unapproved parts into both turbos, regularly subjected them to high turbine inlet temperatures and then had them both give up the ghost on the same flight.
When an engine does cease reciprocating, the Duke has the highest rudder force at Vmc, 150 pounds-the max allowed by the regs-of any piston twin. The high rate of loss of control accidents following engine stoppage causes us to strongly encourage owners to take regular recurrent training.
We also suggest carefully screening flight instructors. One fatal accident occurred because the instructor insisted on practicing stalls with a recovery technique involving differential power. The day before the fatal accident that technique caused the airplane to enter a spin, from which the new owner was able to recover. Not content, the next day’s radar data indicate that the instructor did it to the owner again, at 1200 feet AGL.
Another CFI yanked a throttle to idle shortly after takeoff while the speed was below Vmc. The owner survived the crash. We can’t help but wonder why he had lifted off below Vmc.
Lack of maintenance led to seven events in which the gear wouldn’t extend as we’ll as seven damaged airplanes because one or both brakes didn’t work on rollout.
No one has ever accused the Duke of being a short-field airplane. Eight pilots went off the end of a runway, usually due to coming down final too hot and/or touching down we’ll down the runway. Landing downwind wasn’t the best decision one pilot ever made. He left skid marks from the displaced threshold to the end of the 2500-foot runway.
With both engines running, the Duke has a deserved reputation for excellent inflight handling. Only five pilots lost control in IMC, and it generally took thunderstorms to do it. One pilot lost it at FL270 in a boomer, recovered at 14,500 feet and landed with major structural damage. Another spun his iced-up Duke, recovered and landed, also with major structural damage.
We were stunned by the events starting with a shop removing a homemade autopilot system from a Duke during its annual. The owner then had work stopped before the shop could finish the annual, took the airplane to his hangar and reinstalled the autopilot. On the next takeoff the airplane rolled inverted at 50 feet and crashed.
Pro Feedback
The Duke is not only the sexiest plane on the ramp, it is also a true thoroughbred. The airframe is as solid and sturdy as they come and the engines can be remarkably reliable if operated and cared for properly. After 20 years of working on nothing but Dukes, it’s rare to see engines removed at TBO. The norm for us and the industry is more like 1900 to 2000 hours, and they are usually still running strong. If not for a self-inflicted lifter issue that has been solved by an aftermarket carbide lifter STC, this engine is bulletproof. I once ran across a Duke owner who had 3200 hours on his engines and was still running them. As for the airframe, one of our customers lost control at 28,000 feet in his turbine Duke. ATC had him clocked in a 6000 FPM descent and he managed to recover from a spin at 10,000 feet and landed the plane. It was bent, but intact. The FAA told him if he had been in anything but a Beechcraft he would be dead. The owner repaired the plane and it is still flying today.
After buying my first Duke in 2000 and getting involved with the Duke Flyers Association (www.dukeflyers.org, 419-755-1223 or 419-529-3822), I quickly learned that the largest disparity to Duke ownership is the ability to find a qualified shop to maintain it. So in 2001 Royal Air started an aircraft maintenance operation that centered around Duke maintenance to provide maintenance for our Part 135 charter operation. A few years later we opened our doors to the public. After many years and many annuals the typical cost to annual a Duke that is flown regularly at our shop runs between $6000 and $12,000. When we are not performing annuals for others we will take an airframe and refurbish it to like-new condition.
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The Duke is the ultimate pilot’s aircraft. Upgrading to a Duke is like trading in your Buick for a Porsche. It has a solid feel, but is also nimble and maneuverable with excellent slow-flight characteristics. With the Boundary Layer VG kit, the VMC is reduced to essentially the stall speed, dramatically increasing safety margins during engine-out scenarios, or to aid in getting in and out of short fields. Yes-I said it-in and out of short fields. The biggest myth I hear is that the Duke is a runway hog.
I have known people over the years who have flown their Dukes in and out of fields as short as 2500 feet. My first instructor, and Duke expert, was a man named Dale Lockhart. Dale knew the Duke backward and forward and he provided training for all our pilots for many years. After listening to runway hog accusations by new recruits, Dale would bet them lunch that he could demonstrate a 500-foot takeoff and landing. He never lost that bet.
If one gets proper training and has a capable shop to service the plane I can just about guarantee a pleasurable experience owning and flying a Duke. Many of our customers are longtime owners, and 15 to 30 years is not uncommon. These owners will tell a completely different story from the one passed around mostly by people who have never owned a Duke.
As I learned more and more about this aircraft a disparity emerged. My initial reaction after buying my first Duke was that it was the best-kept secret in aviation. Much of the public’s perception was quite different. It was important for me to understand why and do my part to rectify this. I learned everything I could about this aircraft. To me it is a superbly engineered and constructed airplane that pushes the boundaries of performance, safety and comfort. It is, after all, a Beechcraft. The Duke was spawned from 1960s technology and as of today there has not been another production piston twin that can do what the Duke does well. So, after buying or selling over 60 of these planes and listening to hundreds of prospective customers I feel I can at least talk intelligently about some of the sources of the disparity.
I know of hundreds of longtime Duke owners who will tell you wonderful things about their experiences (if asked). Unfortunately there are quite a number of unhappy Duke owners who gladly tell anyone and everyone who will listen about their negative experiences.
The tragedy comes in when you understand that it is not the aircraft’s fault so much as it is pilot error, in that a good aircraft becomes a bad aircraft when it is neglected, mistreated or owned by someone who really can’t afford the plane. Eventually this becomes a problem aircraft only to get sold under market price to someone who did not know what he was getting into. As a result, this problem Duke keeps getting passed around from person to person with stories abounding from the bad experiences.
I liken the Duke to a vintage Porsche. To fly one is like trading in your Buick for a sporty hot rod. A vintage Porsche should be maintained by a seasoned Porsche mechanic, but is truly a joy to own and drive if it is within your budget. A problem Porsche offered at an attractive price does no service to the unsuspecting buyer who always wanted to own one but never thought he could afford to buy one. The takeaway is to do your homework, buy a good Duke and steer clear of the “bargains.” The Duke Flyers Association is a great resource to anyone looking to learn more about this aircraft.
I have heard many nightmare stories, but I have also owned and flown one specific Duke for 15 years. It was literally one of the most reliable Dukes I have ever owned. I attribute this to buying a good one and flying the plane regularly and correctly. We have many customers who will tell a similar story about their experiences. The typical Duke flies an average of only 40 hours per year (that’s an average of once per month). That makes it hard to keep “sit-itis” from taking its toll. The planes that we see that are in the best shape are the ones that are flown regularly and log more than 150 hours per year.
Beechcraft chose to make Duke tails out of magnesium to save weight. Over the years it has become obvious that aluminum would have been a better choice. If not treated correctly by the paint shop, filiform corrosion will start, in time requiring an eventual repaint of the tail. On average, we see from five to 15 years for this corrosion to germinate and surface. It is a slow-moving corrosion and would only render the tail unrepairable if allowed to expand untreated for many years.
Throughout my flying career I have flown several Beech products up to and including the King Air 200, which is an excellent choice if your budget permits. But after years of flying both the King Air and the Duke I can still say without any doubt that nothing can touch the Duke dollar-for-dollar or pound-for-pound in the overall value of what you get for your money. That’s why I fly Dukes. You can contact us at www.royalairinc.com for advice about owning this awesome aircraft.
Glenn Adams
via email
