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Skymaster Purchasing Information

This is the first archive special. Compiled by Ernie Martin, to whom I offer my grateful thanks, from messages posted on the message board in reply to questions posted by people who are looking to buy their first skymaster.

It is hoped that this section will help those people who want more information on the aircraft before deceiding if the skymaster is the right aircraft for them. Any further comments on this section would be most welcome on the message board.

----->The following was submitted by Paul Sharp.

There are several versions: Normally Aspirated, Turbo, Pressurized, O2A (military version). If you live in the East and don't fly much beyond the flatlands, a turbo model may simply be extra cost (to find, pay for, and maintain). For those of us in the west like myself who regularly fly IFR over mountains and at night, too, well I didn't even consider a non-turboed version. The turbo versions generally came with factory O2 systems, so they're ready for the higher altitudes. Another choice that can affect turbo or pressurized v. normally aspirated is getting above the weather. In that respect you may want turbos or pressurization no matter where you live. There is a large difference in service ceiling between turbo and pressurized versions. To the best of my knowledge, the pressurized versions are restricted to a certififed service ceiling of 20,000 feet. The turbo models range from 33,000 feet in the earlier ones like my 1967 T337B down to (I believe) 25,000 for the later models. On the other hand, if you want to fly higher in a turbo you have to wear a mask and deal with keeping your O2 tank(s) filled. With the pressurized models you don't need to wear a mask and you can get over "most" of the weather at 20,000 feet under normal conditions.

Another consideration is de-icing. The turbo and pressurized models are often deiced. Note, however, that none of the Skymasters are certified for "known" icing. As with other kinds of airplanes, if the A/C has been plumbed for but does not actually have deice boots installed it isn't too outrageous to have them added. If it isn't even plumbed then you're probably better off just finding one that already has boots.

Engine TBO (time between overhauls) is about 1400 hours; engines often run longer; lenders consider engine time strongly.

You can get a "centerline thrust" multi-engine pilot's license, but I got mine in "standard" twins so I'd have no restrictions.

Regarding operating costs, the main variable is maintenance, followed perhaps by insurance (mine is almost half the plane payment each month). On maintenance, if you buy one that's been kept up, maintenance is comparable to other twins; if not, it's $$$ time. The thing to watch for in Skymasters is that since they can be purchased cheaply, a number of people who have bought them over the years were not financially able to afford to maintain them right so they got run down; if you get one of these, you have a major expense getting them up to snuff and recurring costs thereafter. That's one of the reasons Skymasters have developed a reputation for costly maintenance, but the reputation is unwarranted if you buy one that's been properly maintained. The retractable gear needs thorough inspection and maintenance at annuals (and a close look from time to time otherwise). It's a complex gear system but works fine if maintained regularly and properly.

There's nothing wrong with a plane maintained economically, including work by a qualified owner, if the work has been done reliably. As with any model, make sure the maintenance is proper and per the book, and not the hairpin, home remedy variety.

I have figured my operating costs roughly, and find that if I double the hourly fuel costs it comes out about right. That doesn't count annuals, which are separate and can run from $2000 to whatever, depending on what's due or found to be in need.

Learn the alternative sources from which you can obtain parts because anytime you have to go to Cessna you can figure paying from 2 to 5 times (or more) the cost, and that's no exaggeration. Most of us have found alternatives for most parts, and do fairly well in that respect. Cessna is a good company and has an excellent multi-engine tech support department, but for some reason they seem to believe in highway robbery when it comes to parts (you wonder if you really bought a Beechcraft when you get a quote from them).

If you live where you have choices, try to find a shop that is familiar with the aircraft, or at least the engines (they're the same as on the Seneca II, for example), and get a good mechanic who's likely to be around for a while, and be shamelessly kind to him/them. It'll pay off. I've found shops with good people who'll work with me and let me do some of the easier things when I have time - supervising as I go and inspecting/signing off when properly finished - and they also let me track down parts, which enables me to shop around and find the best sources. Some shops don't like that, so you have to work the best deal you can find.

I recommend buying a service manual and parts manual from Cessna. For a while it appeared that they weren't available any more, but last I noticed there were comments here that they could still be purchased. I consider mine extremely helpful, not only to read up on things and learn about what the shop guys will allow me to help do, but to learn about the plane generally. It also allows me to not worry about dropping the aircraft off somewhere if I get stuck with a needed repair while on a trip. I know I can look things up, get part numbers, etc., and that I have a manual for the shop guys to look at.

Here are a couple of examples: Bungee in nosewheel steering broke. Cessna wanted $2300 for it. I got one (new surplus) for $350 from one of the other good supply sources. Big city (SL International) mechanics didn't want to repair an area on my de-ice boots, said they were old enough I should think about replacing them. Well, they are old, but I wasn't sure they needed to be replaced yet. Found another mechanic at an airport 1/2 hour away who had good experience with boots and did regular maintenance on them for other models. He inspected them, said he could repair a few small areas, possibly recoat, but in any event I should be able to get 5 - 10 more years from them. One shop away from home was checking the nosegear and thought they should dismantle and overhaul the whole thing to fix a small alignment problem. I read the service manual and noted the factory's recommendation (can't remember the details of the top of my head) that you had to remove the nosegear system only from one point down in a fairly simple operation to fix almost all nosegear problems - including the alignment thing they were talking about; I had it done by my home shop and saved a bundle the others would have charged to dismantle the whole complex nosegear system and overhaul it completely - which wasn't the proper answer to the needed repair as confirmed by my normal guys. Without the manuals I would have been dumb, fat, and poorer by probably somewhere around a $1000 or more.

For insurance, I suggest Skysmith International (800-743-1439) - best rates I've been able to find. For lenders, I found that they evaluate the plane's value - and especially engine time -- in connection with your loan application. My plane had been well-maintained but had one engine over TBO. It was running fine, but the lender would only lend $22K on it with the run-out engine. If I agreed to get the engine O/H'd as part of the purchase, they were willing to lend $55K. The O/H only cost $15K so you can see that there's a big consideration involved there. After you own it, if you are able to safely get more life beyond TBO, so much the better. But it's a big consideration when you buy.

I believe that all models are technically 6-seaters. In any event, as with most GA aircraft you can't load all 6 seats and luggage too, or you'll be over gross with any reasonable fuel load. In fact, you can't do that in a Skymaster at all since the "luggage" area is where the two back seats are! It's a small negative someone might bring up in reference to Skymasters, but since you can't have both it's moot to me. Also, bear in mind that the two rear seats are smaller or at least lower than the other four and are less comfortable for adults. I compromise by leaving the fifth seat in and the sixth one out, so that I can easily load baggage back there and/or a passenger if desired.

In practical terms, I don't consider the plane to be noisier than other twins. In my case I use an active noise-cancelling headset, so it simply doesn't matter; I also furnish headsets for all passengers. I guess if you got a DB meter there might be a slight difference between models, but average users of GA airplanes will find that they tend to be noisy - twins in particular - and you're crazy to fly in any of them without some kind of hearing protection.

Stay tuned to this website. There are a lot of owners, mechanics, and others who can give input, warning on certain things, and save you lots of time and money. It's a good, helpful group.

----->The following was submitted by J.R. Prukop.

You're already looking at the best website for information as to the pro's and con's of the different versions of the 337! There's a search engine for the message board located at the top and if you'll look back through previous posts you'll find a wealth of information that will help answer at least some of your questions, as well as in the message board archives listed down the left side of the webpage.

There are probably as many perspectives as there are choices when it comes to selecting the right Skymaster. But I believe the choices boil down to what kind of flying you'll be doing, how you'll utilize the airplane, and how much time and money you're willing to spend in terms of maintaining and tinkering, and that will ultimately be dictated by your own personal maintenance arrangements. I know some folks who own 185's that don't even change their own oil! On the 337 that's a cost consideration because you've got two engines, two filters and double the oil, and I prefer to do that job as it gives a moment of pause to look things over as part of my own preventive maintenance and care program. The Skymaster, not unlike many other planes, can be a time intensive project no matter what version or time in service.

Because of the locale where we are with mountainous terrain, it was natural to select the turbo version and the complimentary comfort package that goes with it: pressurization. So our choices were confined to the 1973 through 1980 model years. We then elected to go with a later model year to take advantage of certain refinements that Cessna did with the interior, i.e., the full floating rear seat that slides along rails mounted on the fuselage sides so as to take full advantage of the rear floor space. From 1973 through 1975 Cessna had an awkward fold-up arrangement with rails on the floor.

A big advantages of a pressurized Skymaster is noise, or the lack thereof. One remarkable thing about this aircraft is the fact that 'pressurizing' actually DECREASES the ambient noise level. The DB level is, in fact, LOWER than many single-engine airplanes (and, of course, substantially lower than most twins) because of pressure seals, double soundproofing, double pane windows, and due to the hollow rubber door seal that fills with pressurized air through small holes and compresses itself around the door opening. Note that I don't use fancy noise-cancelling headsets

Another advantage of the pressurized 337 - aside from the quiet comfort - is performance. Since you can get to a maximum certificated operating altitude of 20,000 feet, where you can operate the aircraft in thinner air (read: less drag) but with the turbo giving back the power you lose in the thinner air, the aircraft is FAST. In one of the articles written about the P337 by William D. Thompson, in his book "Cessna - Wings For The World II", he makes the claim: "To our pleasant surprise, this airplane was almost as fast at 24,000 feet as the much-more-expensive C-340." By the way, the difference in speed was roughly 23 knots - 228 for the C-340 and 205 for the C-P337 - and the difference in price was large - around $200,000 for the C-340 and $130,000 for the C-P337, both new in 1976 dollars. And, of course, since the C-340 is turning TSIO-520N engines that develop 310 bhp and the Cessna P337 is turning less expensive powerplants of 225 bhp, the pressurized Skymaster has considerably LOWER fuel flows. I'd rather give up the 23 knots difference, keep the $70,000 cash, keep the lower fuel bills, keep the lower engine-overhaul bills, take the safety of centerline thrust with no VMC, and still retain the stability and visibility of the Cessna "High-Wing" design.

Probably the best advice I could give you, is DON'T be in a hurry. You're dealing with a complex machine, and besides the logsbooks and published information for any one particular airplane for-sale, it is necessary to develop a keen sense of awareness of what and who you're dealing with. As one example, a recently advertised 1975 normally aspirated Skymaster with "FRESH" overhauled engines, something like 110 or 200 hours SMOH on each end, had a rear engine failure that resulted in a slam-dunk hard landing to the runway and because the rear prop was in the vertical position, it struck the pavement. In any event, when the engine was tore down it was discovered a non-VAR crankshaft was installed, and of course the AD requires that they be removed upon tear down (should have been done during overhaul when the cases were split). As a result Teledyne-Continental motors wouldn't accept the core engine as a credit on a reman or newly built engine ... the VAR cranks run about $2,100, and a core credit can amount to $8,000 or more, so as you can see this can get real expensive real quick. So a word to the wise, be slow and methodical ... and ask questions ... and just because its advertised with "FRESH" overhauled engines doesn't always mean what it says. By the way, I think if I were the owner of the airplane I just described, I'd be talking with a good attorney, because somebody messed up big-time ... it's called negligence and fraud.

In addition to this website, there's another good article on Skymasters (including tips for buyers) written/compiled by Scott Smith (SkySmith). Go to www.aero-news.net, click on "Previous ANN News Briefs", enter "Skymaster" in the Search box, then choose the 12/19/1999 article entitled "Cessna 337 Skymaster".

----->The following was submitted by GMAs.

Get the plane surveyed - no ifs ands or buts. Do it by someone who knows the Skymaster well (the ADs on the crankshaft, fuel strainers and mags) and who knows the difference between a thorough survey and an inspection. Check that the solenoids (master switch, landing gear, etc) have been changed. Fly the plane and check the avionics (including the autopilot) while you're at it.

----->The following was submitted by Ernie Martin.

If you look at the accident statistics of Skymasters, its record is comparable to other twins with retractable gear. You'd expect better, when you consider that the plane was designed to be very forgiving and easy to fly compared to a conventional twin (without the tendency to yaw over when you suffer a failed engine at takeoff). But it's precisely because of its apparent simplicity, some contend, that problems arise. Too many pilots think they can get in and fly, and you find, for example, an unusually large number of accidents due to simple fuel starvation because the pilot didn't check fuel or because he/she didn't know how the four tanks feed the engines. You see, because of its reputation as a bullet-proof aircraft, some pilots treat the 337 as if it was a simple single-engine aircraft. But it isn't. You don't just get in and fly. If you treat it for what it is - a complex, high-performance, retractable-gear, variable-speed-prop twin - and if you maintain it properly, and if you do thorough pre-flights, and if you stay proficient, then it is indeed a very safe aircraft.

One final point is yearly costs. Aside from interest, insurance, hangar/tie-down and fuel costs, which are fairly straight-forward to determine, what should you assume for maintenance costs (including engine/prop reserves and the cost of the annual inspection)? Paul Sharp (above) and others use an estimate that such costs are roughly equal to fuel costs (so an aircraft flown 150 hrs per year at 20 gal/hr and $2.50 per gallon, would have maintenance costs of about $7500). I use a different estimate: $30 per hour plus $5,000 per year (the basis for the $5,000 is that an aircraft will have maintenance costs even if it's not flown). For the 150-hour-per-year use we assumed here, my number is $9,500, a little higher than Paul's $7,500. But for 300-hour-per-year use, my number is $14,000 and his is $15,000. So take your pick, or choose in between the two numbers.