Some considerations when you are really into it !!
On the American market there are a number of early DUKES for cheap money. These are pre-1975 machines and are called either Beech 60 or Beech A-60. They are offered between $ 80.000 and $ 120.000. Systems on these airplanes tend to be worn out and are very costly to replace. There is a very simple reason for that. Beechcraft sold its 1980 DUKE with good equipment and de-ice for around $ 640.000. If you calculate a 4 % annual price increase - which is not out of this world concerning the increased cost of labour and material as well as inflation - the 1996 DUKE would sell for about $1.3 Mio and plus sales tax. And there you are : you get a cheapy but the price you have to pay for the spares is calculated on a today basis. Someone who sells below say $ 100.000 knows this game, and knows how much he has to put into the aircraft to make it all working again.
DUKES are build almost to airline standards. So it is a long time before something really breaks. But if it does, be sure you have deep pockets.
Back to the early DUKES : there is nothing wrong with these airplanes but some of the systems are outdated and difficult to maintain : the pressure cabin control system for instance consists of a very peculiar controller, hard and expensive to get and the function is so-so. The autopilot is very often a H-14 pneumatic George that has to breath deeply to function properly. If it does for the moment, it won't do so for a long time. Always consider a replacement. If there is still the old avionic fitted, be prepared to replace it. No particular DUKE problem this rather a sign for the reliability of the system and its installation (airline standard, remember). After 25 years no system is up to date anymore. Some of the early DUKES were fitted with only 142 gal tanks. Forget them ! And don`t even think of upgrading the tanks to the 202 gal capacity. You could end up with a bill in the same amount you bought the airplane. The engines (Lycoming TIO-541) can be of an older version which results in smaller turbochargers and some other surprises
If you have to, go shopping for a decent Beech DUKE B-60. Roughly all airplanes build after 1975 are B-60. It is said that the production year 1975 was not the best Beech had and that there are a lot of squeaky airplanes from that year around. I myself cannot say if that is true, mine is from that production year and is as good as others. Anyway you will find airplanes that are worth looking at from $ 180.000 to ???. Here in Europe the price can go over DM 1 Mio. (app. $ 670.000) with EFIS installed and reasonably good engines.
Every hints and tips you find in various magazines concerning the acquisition of used airplanes is also true for the DUKE. I don't want to repeat them. What I will tell you are some things that are unique to the DUKE. The rest is routine. Just one common wisdom : if its the first DUKE you going to buy, go and get someone whose profession it is to look at and mend airplanes.Even better if his or her last contact with a DUKE is not five years ago changing a tire.
The first thing you have to look at when shopping for a DUKE is corrosion. This is something not easily detected from outside, especially when a new paintjob has been done. Two things can be of major concern. First a new paintjob has been done during the last couple of years. To get it done and over with someone forgot to either seal or later replace the eight breather valves in the belly of the airplane. These valves are responsible for letting all water out of the airplane when it is un-pressurized on the ground. You spray over them you seal them. Since the cabin of the DUKE is quite airtight, condensation and other water builds up in the belly and can't get out. There you have your first source for heavy corrosion. A friend of mine once flew a DUKE, that was making funny sounds. When he cut through the valves about 15 gal of water came out of the airplane. That is not 1.5 gal but 1 5 gal ! Those valves cost a dime, but it is tricky and therefore expensive to replace them. And : if you don't know you don't see from the outside.
The other thing on the topic of corrosion is the tail section. I tell you what : they made the whole tail from magnesium. Now you might remember from school that magnesium is highly corrosive and in some circumstances can light itself up when brought into contact with the oxygen in the air. Now don't run away fearing your DUKE in spe will incinerate the moment the ink is dry under your check. It is not that bad. But it is enough reason for concern. Once corrosion has started on the tail section and is not immediately treated properly you can forget it. So remove the tailcone and take a flashlight. If you are not allowed to by the seller, forget the deal. Open access holes in the horizontal stabilizers and look into them. Look for signs on the outside. Remember : the material for the tail section carries a price tag of over $100.000 sans installation. So you better take your time.
Engines and Turbochargers : Make sure both engines are Lycoming TIO-541-E1C4. Not so good if one or both carry the tag TIO-541-E1A4. Keep in mind that these engines are only used in the DUKE. No other aircraft carries these engines. The E1A4 is an older version that cannot be overhauled or remanufactured by Lycoming. Up to now you get these older versions exchanged into the newer E1C4 when you have them remanufactured. by Lycoming free of charge. But how long. The older version might have an other turbocharger then the new version; and the E1C4 version is much more solid then the old version. Look where the engines come from : are they overhauled by some fancy noname you are most likely in for trouble. Those power-plants are not very common on the market, so most of the overhaul shops just don't have the knowledge. Always a good sign is when they are Lycoming factory remanufactured. Best deal. Those engines have a bad reputation. Bullshit. They are fantastic and reliable powerplants when flown right. Remember : the DUKE can cover a temperature range of 60 deg C OAT in a matter of minutes. The engines are rated 380 hp all the way up. So you can ruin them quickly by pulling the wrong lever at the wrong time. I'd rather buy a lower priced one with engines near TBO then a midtime one that had it`s engines done by a noname. Further information on this subject in the maintenance section.
Avionics : To my opinion the DUKE was made for the KING Gold Crown avionics. Back-lit center panel does not work with Collins. A question of taste, but remember : Beechcraft installed Collins as standard equipment and charged you a very substantial extra on the KING Gold Crown.
De-Ice : the known-ice-certificate carries a lot of things to be installed and working. First there is this fabulous heated windshield. Gold plated, highly priced. Make sure it is working properly. You can feel it warming up in flight. Labor on replacing it is not substantial, the windshield itself is. The boots and the pneumatic system is another story. You can see what condition the boots are in, but then there is a so called ejector valve in the tail. It might stick. Try the boots a couple of times. If the pressure on the pressure gage drops considerably before building up, the DUKE needs either two new vacuum pumps or the ejector valve is about to quit. The boots on the DUKE are not cycled; they work or they don't. See maintenance section.
Landing gear : take an exact look at the up- and down-lock cables. Look at the entry step and at it's cables. A step that does not retract costs about 10 knots
Pressure cabin : check it working. If not working properly forget the deal. Any pressure differential below 4.0 psi in the appropriate level is a no go item. Don't get fooled by anyone saying it is probably only a loose wire. It is not. Something is really wrong and there are many components to check and replace very costly. If the differential pressure is near maximum 4.6 psi in climb and is decreasing by up to 0.5 psi in level flight with power reduced, the chances are good that the rubber landing gear seals are worn out. Parts are affordable, work is high.
BEECHCRAFT DUKE NET HOMEPAGE