Another helpful link on the 340A this is an Aircraft Consumer article from 2011.
http://www.jtatwins.com/uploads/pdfs/Cessna%20340:340A.PDF
Perhaps the thread title needs to morph into the Cessna 321.5.
There is an excellent book on the 300 series twins I’ve read by William D Thompson. Wings for the world it was called. Gives a great background to the T303 and others. Wings for the World
I just sold a 58P Baron, that had good pressurisation, Garmin 430, WX radar, KFC200 AP, N reg with VAT receipt, low airframe time, 1400hr engines but recent shockload inspections for the price of C172P. I will buy another twin but only when I have a full time LAE working with me and we can do 3-4hrs a week with her. Until then a single is fine.
In case you haven’t seen it already, our previous thread on the 340 including lots of useful data from what_next:
The 340A has a cabin altitude of 7,500 at FL200 when new, thirty or forty years on my understanding is that to get the same cabin altitude you are probably at FL160-180
What is wrong with 10,000 cabin altitude?
Modern pressurised aircraft will start bleating through the CAS if the cabin reaches 10,000 feet. I am not sure why convention is to market the highest recommended cruise altitude as that which provides a 8,000 cabin altitude, perhaps a combination of comfort and safety margin? Presumably vintage systems have an annunciator bulb?
On turbocharged pistons how much power is lost to pressurisation? My impression is that rate of climb is quite low as cabin altitude approaches 10,000 feet, but that may be a design coincidence.
Hard IFR, as someone suggested is a 340 strength, in my view implies the ability to climb quickly to FL280 and above, and provide an 8,000 foot cabin. Struggling along at FL200 with not much rate of climb doesn’t strike me as weather topping capability.
The nice D reg 340A for €220k may indeed be a bargain if maintained to pristine standards. Am pretty sure it would take more than €200k to get an average 340A needing TLC to optimum standard.
Apart from the 340: Are there any 310 (non-turbo and turbo) or 303 operators around?
I’d love to hear their experience regarding maintenance, reliability and costs. Most data on the web refers to the US with the associated huge difference in basically everything from fuel prices to labour…
RobertL18C wrote:
I am not sure why convention is to market the highest recommended cruise altitude as that which provides a 8,000 cabin altitude,
Honestly, I have never come across that “8000ft” convention. Maybe that is a figure provided by manufacturers in their sales brochures, but I have never seen a sales brochure for a C340 (which will be a collectible by it’s own…).
RobertL18C wrote:
Modern pressurised aircraft will start bleating through the CAS if the cabin reaches 10,000 feet.
All Cessna piston twins have an (amber) annunciator light for cabin altitude in excess of 10,000ft. No aural warning.
RobertL18C wrote:
On turbocharged pistons how much power is lost to pressurisation?
Nothing. The turbo system is designed and adjusted for pressurisation on all the time. Your manifold pressures (which mainly determine the engine power) will not change by turning the pressurisation off, the wastegates will simply supply less exhaust stream to the turbos.
RobertL18C wrote:
Struggling along at FL200 with not much rate of climb doesn’t strike me as weather topping capability.
I don’t think anybody ever claimed that any piston twin (or any jet other than the Concorde) has “weather topping” capability. But at FL180 (which I would say is a “good” compromise for a pressurised piston twin) you have a lot more options, both weather and airspace-wise.
Nice article which has some comments on the T310 and the 340.
I know of very few pressurized pistons that can get to FL280 an still keep a “legal” cabin. The only one I can think of is, again, the upgraded Aerostar. The factory beefs up the structure somewhat with some internal stiffening and they increase the diff to 5.5psi. This in theory gives you a 12500ft cabin at FL280.
AdamFrisch wrote:
increase the diff to 5.5psi. This in theory gives you a 12500ft cabin at FL280.
5.5 psi delta p means about 8.5k at FL280. That is the delta p of the Meridian.
