CESSNA 340 / 340A
The pressurized, twin-engine, 6 place Cessna was certified in October of 1971. This aircraft had (2) 285 turbocharged Continental engines. The C340A came along in November of 1975 with two 310 HP Continentals. The C340A had a maximum of 5990# takeoff and landing weight.
QUIRKS
Probably the weakest part of the airplane is the landing gear system. Be sure that this system is looked over by someone very acquainted with the Twin Cessna landing gear.
I’ve noticed that the emergency gear extension system does not work on some aircraft I have conducted training in.
The second item is the fuel system, especially if you have the wing locker tank on the left side only. Let’s say you have the 31.5 gallon aux tanks and you take off with full fuel. You need to fly for 1 ½ hours prior to switching to the aux tanks. The excess fuel that the engines do not use is returned to the main (tip) tank so that the fuel level in this tank increases the longer the aux tanks are selected. Once the aux tanks are nearly empty you switch back to the main (tip) tanks. When the left tip tank gets low enough on fuel you can then turn on the wing locker fuel pump which pumps its fuel to the left tip tank. This causes the left wing to become heavier than the right wing and so you need to crossfeed fuel from the left tip tank to the right engine and the excess fuel goes to the right tip tank! Another thing, you can’t crossfeed fuel from one aux tank to the other engine, so that it is imperative to empty the aux tanks as soon as possible so that in the event of an engine failure you have access to all the remaining fuel. Any time you switch from using fuel from the aux tank to the tip, or the tip tank to the aux, you need to enrichen the mixture momentarily and then re-lean as the head pressure is different between aux and tip tanks. In the twin Cessna’s with tip tanks, they found that if you were low on fuel and in a fairly steep nose down attitude the fuel pump could not pick up that last ~ 5 gallons of fuel from the front of the tank. The solution was to put a transfer tube at the front of the tip tank - and have a constant running electric fuel pump draw fuel from that area and put it next to the fuel pump. The operation of these pumps should be checked during preflight – just turn the battery master switch on and go out and listen to these “ticker” pumps (located at the rear of each tank) operate. If no noise – no go. They are required to be operating to fly.
Another item that can be confusing is the nomenclature. The main (tip) tank pumps are called aux pumps, the pumps downstream of the auxiliary tanks are called in-line pumps and the pumps transferring fuel from the wing locker tanks are called transfer pumps. The pumps located at the rear of the tip tanks are also called transfer pumps. Tell the line crew to add fuel to the “Tip” Tanks – not the main tanks as they may believe that the aux tanks are the Main tanks.
Why would some Twin Cessnas have a wing locker fuel tank only on one side? There is a good reason. We’ll discuss that during ground school.
Fuel selector – The fuel selectors can leak. Even if you have the fuel selector in the proper detent, fuel can drain from the tip tank to the aux tank if the aux tank is not full.
Exhaust – the exhaust system needs to be inspected for deterioration, cracks etc.
Wing spar – fortunately at least for now, the wing spar AD does not apply to Twin Cessnas with Tip tanks.
Be cautious of engine cases & cylinders cracking. Be very gentle with power changes. We’ll discuss how to reduce the chance of crankcase or cylinder cracking.
You may find that you need to burn more fuel during cruise than recommended by Cessna unless you have a RAM converted Twin-Cessna and use their power/altitude/fuel flow recommendations.
MY OPINION
RAM Aircraft, LP of Waco, TX has done wonderful things to Twin Cessnas. For example, they can upgrade the C340A to 335 HP engines and add VGs. The takeoff weight increases to 6390 for both the 340 & 340A. How about 225 TAS at FL 230 at 70% power! A well maintained C340 converted by RAM to the VII mod would be a great airplane to own! Ram Aircraft has taken the stock 340, which didn’t have much useful load, and made it into a significant airplane. Why do you think Aerostar Aircraft Corporation had to certify the 702P with the extra ~500# load carrying capability? They did it to compete with the C340 RAM VII. The shop maintaining the 340 would have to know the airplane well for me to think seriously about purchasing this aircraft. Another option would be a thorough pre-purchase inspection by someone who knows the aircraft extremely well who could determine the value of the airplane and indicate how much money I’d have to put into it to bring it up to my standards. The Cessna 340, although a cabin class aircraft with its airstair door and aisle is a little cramped getting into – at least into the cockpit with one person already in his seat. If you wanted a wider cabin you might consider the C414 or C414A. The C421C is able to carry more and is larger still but that is a significant step upward.
OBSERVATION – Building the C340 was discontinued in about 1977. You may find one with a data plate later than 1977 but I’m quite sure it was built prior to 1978 with the data plate not being put on until the aircraft was sold. The FAA mandated that aircraft with engines powered by AvGas, as compared to Jet fuel, could not have fuel in the wings closer than ~18” from the tips. Therefore the C310 was discontinued and the Crusader came along. The Cessna 414 was discontinued and the C414A took its place etc, etc.