Tip 14 – Tips For Buying a Cessna 310
Part I: How They Come in 1999
By: Jerry Temple
Phone: (972) 712-7302      Fax: (972) 712-7303

As published in Cessna Owners Magazine Oct 1999

When I accepted the task of writing an article about the Cessna 310, the featured aircraft in this issue, my first thought was to review an article I wrote about 31O’s in the November 1995 issue of this publication. Titled, Tips for Buying a 310, the article was a general review of 310 models with comments on systems, options and training.

After rereading the text. I saw few, if any, changes I’d make. Why not just reprint it. Like an FAA physical no changes. The fact is that if in 1995 you write about an airplane made from 1955 – 1981, you’ll need to think of another approach for an article about the same airplane in 1999. After all the past hasn’t suddenly changed.

Therefore, the purpose of this article, the first in a three part series, is to address many of the questions prospective 310 buyers have, and to provide buyers with a sense of what they can expect to see if shopping for a 310. This article will not address detailed data. i.e. aircraft dimensions, fuel flows, range, ceilings, handling, etc.

This article will also be limited to 1962 to 1981 31O’s. The older 31O’s represent a small segment of the marketplace and an area where I rarely operate. This implies no negative reflection on a neat 1960 31OD.

In addition to my November ’95 Tips there have been other informative articles about the 310 in Cessna Owner Magazine. See Still Handsome After All Those Years in March ’95 and Twin Peeks, also in November ’95.

Additional articles about 310’s can be found in past issues of other aviation magazines and the Aviation Consumer. Reprints of previous Cessna Owner Magazine articles and most others can be purchased from the respective publishers.

Part Two: OK I Want One and Part Three: Go For It will be published in upcoming issues of Cessna Owner Magazine. Part Two will address certain critical subjects such as insurance, financing, missing logbooks and damage history.

These are subjects that must be looked into before buying a Trade-A-Plane. Part Three will outline the steps of the acquisition process and provide information on training, maintenance and owner support.


Cessna 31OG-R

One way of grouping 310 models is the 1962-74 short nose canted-tank models and the 1975-81 long nose R model. Each year from ’62 through ’69 had a different model number. The Q was the first model built for more than a year. Within the Q’s there is a division: the ’70 and ’71 without the rear Omni-Vision window and the ’72 – ’74 with the window. If your budget has you considering an early Q, you should also be looking at ’68Ns and ’69Ps. They’re very similar to an early Q. In 1975 Cessna added 32″ to the nose thus giving the R model a 21 cubic inch baggage compartment. This obviously appeals to Part 135 operators.

The normally aspirated short nose models are powered by versions of the popular Continental 10-470 (D,U,V,VO) all producing 260HP. The normally aspirated R model is powered by the 285 horsepower Continental IO520M and later by an improved MB.

Optional turbo charging began with the 1969 T310P. All Turbo 31OP’s, T310Q’s, and T31OR’s are powered by the TSIO-520B or BB which produces 285HP. The two primary 310 modifications are engine upgrades by Colemill Enterprises and RAM Aircraft.

Colemill has long offered its Executive 600 (3OOx2) for the 31OF-Q which replaces the IO470s (260 hp) with the IO520 (300 hp). And Colemill offers the Bearcat mod for the R model where the IO520 (285 hp) is exchanged for the IO550 (300 hp). Both have been very popular. Colemill now offers the IO550E (300 hp) in the short nose models, and most short nose 310 owners select it – it’s called the Executive II.

RAM’s specialty is upgrading the TSIO520. Their Series IV, VI, and VII mods for the Cessna 340,414 and 414A are excellent. A key element to these mods are useful load increases. The Turbo 310 P, Q or R, have never been weak haulers, nor weak performers. Therefore, modifying engines for turbocharged 31Os has never been a big portion of RAM’s business. RAM does offer a 300HP (Series I) and a 325 hp (Series IV) for all Turbo 31O’s.


The Fuel System

The fuel system in all Tip-Tank twin Cessnas is the same with small exceptions. The capacities vary between twin Cessna models and between 310 models. These capacities are simply the result of model differences and original specifications.

All 31O’s carry 50 gallons in the Tip Tanks, which are the main tanks. Early 31O’s have a 15-gallon auxiliary (AUX) tank in each wing. Beginning in 1967 the AUX tanks have a capacity of 20 gallons each. So far that’s a total usable of 130 to 140 gallons. In 1973 the AUX tank grew to 31.5 gallons, with the total usable thus becoming 163 gallons. Some 310’s have what was an optional 20-gallon Nacelle or “wing-locker” tank. It is located just aft of the firewall. A 310 can have one or two of these “Wing-Locker Tanks.” With one, usable fuel is 183 gallons. With two, it’s 203 gallons. So the fuel capacity numbers of significance are 130, 140, 163, 183 and 203.

Occasionally you will see numbers other than these. First, it may simply be someone stating total capacity rather than the customary usable. Or 31Os and other twin Cessnas may have after market fuel tanks installed. Tom’s Aircraft in Long Beach, CA distributes an 18.5 gallon tank. These can be installed where the factory puts its 20 gallon Nacelle tanks. Like with factory original tanks a 310 could have one or two of these 18.5 gallon tanks. Additionally, Tom’s tanks can be installed in the aft portion of either wing locker where baggage is usually stored. Thus, depending on how the aircraft was manufactured. one to four of Tom’s 18.5 gallon tanks could be in a 310 or can be added.


STOL (Short Take-Off & Landing) Kit

Sierra Industries in Uvalde, TX owns the STC to what was known as Robertson STOL System. Sierra marketed the kit as the R/STOL System. The system greatly reduces take-off and landing distance and reduces stall speeds and VMC. Sierra still supports these systems with parts but has not installed a kit in many years. The price for an installed 310 Kit in 1990 was $19,900. Almost certainly over $25K if made today. An occasional R model with a Robertson kit will be for sale.


Vortex Generators

Vortex generators are not only a plus and a must. First VG’s are not a STOL System. Do not purchase an aircraft with VG’s or install them to get into or out of a small strip. Yes, takeoff and landing distances are reduced as a result of lower approach/landing and lift-off speeds. And yes, brake wear may be reduced as a result of lower landing speeds. But that is not what Vortex Generators are about. The bottom line is that VG’s reduce VMC making a twin safer. They allow a twin in a single-engine emergency to get slower before directional control is lost. All of this translates to precious extra seconds during which time a proficient pilot can hopefully be making the right decisions.

I would not own any twin Cessna (or any other aircraft STC’D for VG’s) without them. In addition to the added safety provided by VG’s. Vortex Generator manufacturers also offer increased Gross Weight/Useful Loads for certain models. Therefore, if a 310 now has VG’s, confirm if it has any increased Gross Weight/Useful Load, or ask the various manufacturers about weight changes for any model you’re considering purchasing. VG’s can be installed in one day. Their cost is between $1,800-2,500 depending on the kit you chose.



There are two STC’D systems for Spoilers or Speed Brakes. PowerPak employs panels that pop out of the wings and the Precise System stows a “cartridge” in the aft portion of the Nacelle (wing locker area) which opens to extend panels. Few 310’s are spoiler equipped. Like many modifications if its already there – great. If not, you need to seriously evaluate cost versus benefit. I doubt if normally aspirated 310’s need spoilers. They would be nice to have on a T31O, but only if you regularity operate in the mid to high teens. Managing descents is just not that difficult for a disciplined pilot.



A significant portion of the 310 fleet has been modified with Cleveland Wheels and Brakes. If an aircraft did not have them it would be wise to make this change at the next annual.


Air Conditioning

Few 310’s have air conditioning, especially older units. The typical factory unit in an R model is installed behind the right engine with the cooling vents housed on the “hat shelf” behind seats 5 & 6. With factory air, you cannot have both the air conditioner and a right side factory Nacelle fuel tank. A popular after market system is the Keith System, commonly referred to as JBAir. The Keith System is a quality unit. It is electrically powered so it is possible to have a ground power cart hooked to a 310 and be pre-cooling the aircraft. The factory unit requires the right engine to be running. A new Keith air conditioner for a 310 costs $12,000 and takes a week to install. Great to have on the ground and at lower altitudes – especially in the hot climates.



Normally aspirated IO-470 powered 310’s (short nose) have two bladed McCauley or Hartzell props. On certain models a three bladed McCauley was an option. All turbo 310’s come with 3 bladed McCauley props. RAM mods are offered with three bladed McCauley or Hartzell Q-Tip propellers. Both McCauley and Hartzell today offer STC’d propeller conversions. Early 310’swith two blade Hartzells, are effected by AD 97-10-02. All three bladed McCauleys are effected by AD 95-24-05 R1. This late 1995 AD is why you see so many twin Cessnas with low time props.


Anti Ice/DeIce

310’s come with not Anti-Ice or DeIce equipment or with combinations of Heated Propellers, DeIce Boots, Alcohol Windshields or a Heated Windshield. Older units usually have zero equipment or just hot props. A popular and efficient combination is what is referred to as Full DeIce. This consists of Hot Props, Boots and an Alcohol Windshield. The older I get the more I like this setup. Beginning in 1977 a Certified for Flight Into Known Icing option was offered. In simple terms, the key difference between Known Ice and Full DeIce is the electric heat strip (Hot Plate) that mounts on the pilot’s windshield. It is an expensive item to replace, somewhere between $8,000 – $10,000. Few can be repaired. For an airplane to be Known Ice “legal” every component of the Known Ice Kit must be working. An after-market Hot Plate is being advertised. Though it can be added, it does not make the aircraft, even a 1977 or newer, Known Ice Certified. As I wrote in the November 1995 Tips, I have never seen a 310 field certified for Known Ice. Forget it. Save you money. If you need Known Ice, purchase a 1977 – 1981 R model with the factory install kit.


Avionics – Part A

Few 310’s will today have Cessna 300 Series Avionics. Some will have 400 Series Avionics with various models of 400 Nav/Coms. This is important since there is a wide range of quality and features in various 400 Nav/Coms. Also, both Narco and Michels have direct replacement for certain Cessna Nav/Coms. Many 310’s will have King Silver Crown Nav/Coms and DME, but will have a Cessna R446 ADF and RT459 Transponder.

Some aircraft no longer have an ADF. Owners are freeing up space for other equipment. Depending on age, a 310 might have a straight Cessna 400 autopilot or a Cessna 400A or 400B. Other popular units installed over the years were the Bendix 810, Century III and King KFC200. Many 310’s simply have an autopilot with a DG or HSI. Others will have an HSI and a Flight Director. For new autopilot installations most buyers choose King or STEC. Two thoughts on Cessna 400A and 400B autopilots. First, they have served me well for 25 years. And secondly, if your shop hints that they can- not fix Cessna radios, question them. There are thousands of Cessna Avionics equipped airplanes with someone taking good care of them. For autopilot problems, Autopilots Central in Tulsa has an excellent reputation. Older and problem autopilots are sent to them from all over the world.


Avionics – Part B

The differences in what I’ll call optional Avionics i.e., GPS, GEMS, weather avoidance are significant. I’ll use the words “few” “many” and “most” to try to give the reader an undefined feel for quantity.

Most 31Os will have some type of Loran or GPS unit panel installed. The Lorans vary from very old and very basic to the once popular Northstar M1 to the once state of the art King KLN88. Many 31Os will have GPS installed. The differences in GPS receivers i.e., VFR, IFR Enroute, IFR Approach is vast. Some GPS units have moving maps and some can interface with fuel flow computers such as the Shadin Digi-Flow. Many 31Os come with a complex GPS and many aircraft will have a dedicated moving map.

Most aircraft will have an intercom. Installations range from 2 to 6 place. Many may have a BOSE or Telex interface. These allow headsets with Active Noise Reduction and to be powered by the aircraft’s electrical system instead of a battery pack. Do not expect headsets to be a part of a sale, unless they are listed on the specification list.

Most 31Os will have a Horizontal Situation Indicator (HSI) as the pilots primary directional instrument. A few, likely older models, will have a regular Directional Gyro (DG). Many may have a DG on the right side panel.

While on the subject of the right panel, many 310s, especially Qs and Rs, will have various co-pilot instruments. This will vary from just a DG and altimeter to a full set of flight instruments.

Many 31Os will have Strikefinders and many will have various models of Stormscopes. The Bendix RDR160 in both monochrome and color was factory installed in many R models. The King/Narco KWX56 color radar is also in many aircraft. If it’s an old unit like an earlv RCA, then repairs are not realistic. Parts are simply not available.

If you want to add radar in most short nose 31Os you’ll likely need to add a Norton Nose Kit. It adds a porpoise like nose that gets the aircraft mistaken for an R model. Archie Tramell still teaches an excellent radar course and sells his training videos. I would highly recommend this course for radar owners. Very precise Graphic Engine Monitors (GEMS) are both popular and beneficial. Manv 310s will have a GEM. New panels built around a modern radar. GPS and moving map. All are a great investment.



Expect a wide range of conditions. Many units may have original paint to units that have been painted 2-3 times. The price guide books, such as the Aircraft Digest (Blue Book) and Vref usually describe a base aircraft with a condition “7” paint quality. To aid in defining a “7” a rating, outline is given. However, this is a good case of where obtaining professional advice is valuable. A pro will give you a judgment based upon how a particular aircraft stacks up against others of its kind. Often a long time owner will describe his “family member” as an “8” when it is in fact a “5” when parked next to two dozen typical 31Os. (Comments regarding repainting an aircraft will be in Part 3 – Go For It.)



Like paint, expect a wide range of interior conditions. From original interiors to interiors with various areas that have been redone. As with paint, the price guides describe a base aircraft with a condition “7” interior. Again, a professional representing the seller, or the buyer can be of valuable support.

All right, now you’ve done what you believe is a great deal of homework and now you’re ready to purchase a 310. Sorry, but you are not quite ready. Several important subjects must be thoroughly looked into and understood before starting to accumulate spec lists and photos. Part Two of this series – OK – I Want One will address insurance, financing, availability and the subjects of damage history and missing logbooks. Now you will he prepared to shop.

Part Three – Go For It will review the steps of the acquisition process, i.e., offers, deposits, escrow, contracts, test flight, inspection, FAA documents and delivery. Part Three will also address training facilities, maintenance and owner support.


A Lasting Thought

One last thought regarding obtaining help in the sale or purchase of a 310 or other twin Cessna. It is likely that as you read this article you have a lawyer and an accountant. You almost certainly have a dentist and physicians with various specialties. And, you may have a landscape specialist for your home and other skilled professionals who all have one basic purpose – to keep you, your family and business out of trouble. Few people would argue over the value of having such professional support. Final thought: The purchase or sale of a twin Cessna has evolved into a complex business transaction requiring the full time effort of an aviation professional. It’s resource management.