The Cessna 310
A Real Twin
By: Jerry Temple
Phone: (972) 712-7302      Fax: (972) 712-7303

Some aircraft by either their name or their image have evolved into representing much more than just themselves.  Say “puddle jumper” and many see a Piper Cub.  Say “Piper Cub” and many simply think of all single engine airplanes.  The terms “Lear Jet” and “Business Jet” are the same to millions.  And, when the term “light Twin” is used throughout the world, the Cessna 310 rushes into the minds of many.

In my library, I have copes of numerous articles that have bee written about the 310 since its mid-fifties introduction.  In preparing for this article I reviewed articles I’ve written – Tips for Buying a 310 COO 11/95, and the four part series in the 1999 Oct, Nov, Dec and the January 2000 Cessna Owner’s Magazine.

Rather than simply “dusting off” these previous efforts at talking twin Cessna, I reviewed in my head the thousands of conversations, letters, faxes and emails I’ve had about the Cessna 310.  So here is a 2005 Cessna 310 status report.

The short nose 310’s, which includes all models through 1970-74 310Q are often referred to as “short nose models”.  The 310R, manufactured from 1975-81 is the long nose model.  Turbo-charging, as an option, was introduced with the 1969 T310P.  All turbo 310’s, from ’69 through the ’81 are powered by the Continental TSIO-520-B or BB producing 285 HP.  The TBO is 1400 hours.  The normally aspirated models through the ’74 310Q have the 260 HP Continental IO-470 with its 1500-hour TBO.  The normally aspirated R model is powered by the 285 horsepower IO-520-M or MB with a 1700 hour TBO.

Colemill Enterprises of Nashville modifies various Cessna, Beech and Piper aircraft.  Colemill’s primary 310 modifications are exchanging on the short nose models (up through the ’74 310Q) the 260 HP IO-470 with the 285 HP IO-520.  Thus, the short nose models are given the R model’s engine.  However, Colemill “tweaks” the engines to produce 300 HP for five minutes, thus providing the extra punch for take-off and initial climb.  It’s called the Executive 600 (300 HP + 300 HP). To give the 310R more performance the 285 HP IO-520 is replaced by the 300 HP IO-550.  Referred to as the Bearcat, this 600 horsepower combo provides the pilot not needing, or wanting, turbo-charging with added power for take-off and climb.  Because of the Bearcat’s performance gains, short nose 310 owners also wanted the IO-550 power plant.  When these are installed on the short nose models, it’s called the Executive II.  310 weights are not changed by the Colemill conversions.

RAM Aircraft of Waco, Texas offers two modifications to the turbo-charged 310s.  The RAM Series I Conversion ups the horsepower to 300 HP per side.  The RAM Series IV increases the horsepower to 325 HP per side.  This is the same engine set up as RAM offers on the 340A and 414/414A.

The 310 is a real twin.  Load it with people and baggage and there is still room for the fuel needed to go somewhere.  Beginning with the ’64 310I, there are wing locker storage areas and the long nose 310R (’75-’81) has the 32” nose extension, which provides the space for 350 Lbs. less installed Avionics.  In addition, the Aft Cabin plus the “Hat Shelf” provides in cabin storage.  With the easy removal of the aft two seats (#’s 5 & 6) a huge cargo hold is created.

One feature of the 310’s that is always enjoyed is its wide cabin.  In many competitive twins the front seat occupants will touch shoulders.  Even with average size people the cockpit will be cozy.  With a later model 310, the crew will have a wider cabin.

A common customer question is “What is a 310R II or T310R II?”  It was simply a marketing package.  A grouping of certain popular options rather than each being an individual item on the price list.  It usually meant certain Cessna 400 Series avionics and some popular equipment/accessories.  It means nothing today when purchasing a used airplane and, in fact, it’s doubtful any 310’s with a II package today still exist as equipped when new.  It is similar to what one may hear about autos “”it has the XL package”.   The Roman numeral II meant zero to the engineering department or the FAA

Depending on age and upgrades over the years, 310’s will likely have the Cessna 400A or 400B autopilot or be equipped with a Century, King or STEC autopilot.  Many will also have a flight director..  If equipped with a 400A or 400B, there is absolutely no reason these autopilots should not operate correctly.  Parts are available.

For pilots purchasing their first twin a 310 provides great fun and great preparation.  If a goal is a pressurized twin Cessna, such as the 340 or a 400 Series 414/414A or a 421B/C, 310 time creates a simple transition to the Cessna cabin class pressurized twins.  In addition, 310 experience is viewed by insurance underwriters as a plus when considering pressurized twin insurance.

Formal 310 training is offered by various simulator-based schools i.e. Flight Safety, SimCom, RTC, and there are several “in aircraft” trainers with insurance approved courses.

I urge 310 and all twin Cessna owners to avoid the instructor or school with “it’s just another twin” attitude.  I also advise 310 buyers and owners to not just accept the pilot experience of an airline captain or ex-military pilot who flew 310s a long time ago.  There is too much at stake not to invest in training from instructors and schools with current proficiency and knowledge.

The same with maintenance.  A comprehensive pre-purchase inspection from a true Cessna Specialist is a critical step in the purchase of a 310.  Additionally, a specialist should also perform major maintenance.  A local shop, which conducts maintenance of several lines of aircraft, can conduct minor maintenance.  However, annual inspections and major modifications should be the sole job of a specialist.  The consequences of not doing this could fill every page of this magazine.

The three most common 310 related questions I am asked are about the exhaust system, the landing gear and fuel systems.  A recent fourth question is about the lower wing spar cap.

My answers:  The Exhaust AD issued in 1975 and changed in Jan. 2000 applies to the turbo-charged 1969 T310P – 1980 T310R.  It does not affect the normally aspirated models.  It’s a good AD and today, in 2005, is no big deal.  There’s a visual inspection every 50 hours.  That’s easy to combine with an oil change.  Some additional items like the removal and inspection of the exhaust pipe are done at an annual.  All components are inspected at an engine exchange, but most owners would logically replace these with new exhaust components when installing a new engine.  Again, the Exhaust AD “is no big deal”.

If one must find a weak spot on 310s it’s the landing gear.  There’s a lot of pushing and pulling going on.  But, two rules will prevent most problems.  The gear needs to be rigged once a year.  Some shops and mechanics tend to want to avoid rigging.  Why?  It is a big job.  One man all day, or a couple of people for eight hours.  And that labor adds up.  But it is inexpensive when compared with the consequences of poor landing gear upkeep.  The second rule regarding twin Cessna landing gear is  – no heavy braking when turning.  Pilots that have been checked out by me hear my voice in their sleep stating, “Brake-straight, brake straight.  No turning”.

The fuel system is not too complex.  Give me a cross country with a new owner on a delivery flight and he’ll be able to teach the fuel system when we land.  The tip tanks are the Mains. They hold 50 gallons.  We always take off and land on the Mains.  When?  Always!!  We then fly for either 60 or 90 minutes (depending on the size of the auxiliary tanks).  We then switch to the in-wing auxiliary tanks and use up the 40 or 63 gallons they hold.  We then switch back to the Mains

Some models will have a Nacelle or Wing Locker Tank installed directly behind the engine compartment.  There may be one or two installed, a left and a right.  On the days we select to carry fuel in the Nacelle tanks, we fly for 60 minutes and then transfer the Nacelle fuel to the Main tank on that respective side.  If an aircraft has two Nacelle tanks, all is always equal and balanced.  However, if only one Nacelle tank is installed, we do crossfeed for a few minutes to keep the load balanced.  It’s ten times more difficult to write about this procedure than to actually do.  Again, one cross-country eliminates all questions.

There has been much publicity and discussion regarding the lower Wing Spar Caps for the last three years.  There is an AD for the Wet Wing 402C and 414A.  There are Service Bulletins for other models.  These are not Airworthiness Directives.  As of this article’s publication, there is no wind spar AD for any 300 Series twin Cessna nor for every 400 Series model.

Cessna has issued Service Bulletin MEB05-5.  Not all 310s are affected.  The SB subject, the installation of a Wing Spar Strap is not required until a 310 has 11,000 hours.  With the many 310s having 4-5000 hours total time, and that total time accumulated in a period of 25-30 years, most 310 buyers need not worry about this modification.

Because of the long production run of the Cessna 310, there’s today a 310 for every twin pilot’s situation and budget.  From well-maintained 175-180 KT mid-sixty’s units to 210 KT RAM I and IV converted Turbo R’s.  From old avionics with “manual situational awareness” to new glass panels with “press a button and know everything”.

The Oct – Dec ’99 and Jan 2000 articles written for Cessna Owner can be seen at  See Temple’s Tips #14 –17.

I fly all twin Cessnas from an older 310 to late model 421C.  I enjoy flying them and respect them.  Their soundness has forgiven the mistakes of many a pilot and mechanic.  However, whenever I’m flying a 310 (all models) or whenever I look over from my right seat to a new proud owner in his left seat, one thought always comes to mind.  “This is fun”.