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to the maintenance hangar with a committee of mechanics gathering around to speculate the diagnosis.
After some collective thought, it was decided that one of the hoses in the nose section related to the heater must have developed a leak. Unfortunately, this was located under the instrument panel, almost impossible to see or access. One of the junior mechanics was assigned the nasty job of crawling under the panel and disassembling a stack of things that were in the way. After about four hours it was apparent that a tear had occurred in the flexible hose just before it attached to the heater portion. The hose itself looked like it was installed at the factory 40 years ago and all dried out. It was decided the hose became cracked only after the other leaks had been repaired, which resulted in the cabin pressure climbing to a point the old hose couldn’t handle.
All hoses related to the system were then replaced, and I was again asked to test fly the airplane. I was cautioned that if the cabin failed to pressurize normally, the next thing would be to replace the controller itself, which would be very expensive. With some trepidation, I climbed the airplane through the previous 8,000-foot altitude and was relieved to see the cabin was still at sea level and the roaring leak noise was no longer present. I continued climbing until reaching the cabin’s maximal pressurization differential – also normal, indicating that the leaks were fixed.
Now, this kind of problem really does lead to questions about how long you should own a 40-year-old airplane ver- sus trading it in for a newer one...say something in the $1 million range.
Since I am already typed in the CJ, the jet was the first one to come to mind, with an Eclipse being a close second. But the problem is that these airplanes are really designed to fly long distances in the high flight levels. Just banging around down the west coast of Washington to California at 2,000 feet on a sunny day would not make sense, and that kind of flying is something I like to do recreationally. An- other problem with a jet is, if you fly it 120 hours per year at 400 knots, that is nearly 50,000 nautical miles. That is a lot of distance without any specific mission. Then there is the matter of the annual model-specific recurrent training in jets, which is expensive and also time consuming if just flying the aircraft for personal use. Insurance for single- pilot operations is also becoming a real problem for most light jets, in many cases resulting in just absurd costs for relatively poor coverage.
The next thought was, “How about a turboprop?” Prior to the C340, I owned a PT6-powered Cessna 425, so I have some experience with owning a twin-turboprop aircraft. But, I am not sure the notion of having twin engines in PT6-powered aircraft makes much sense anymore given the proven reli- ability of the engines. That logic leads me to think about a TBM or a Piper Meridian. The Piper Meridian does about 270 knots in the lower flight levels, but as it is derived from a piston-powered airplane, it is a little slow and short on fuel.
A TBM, on the other hand, was designed for turbine power from the start. The C-model carries a decent amount of weight and does about 300 knots on less than 50 gph in the flight levels. The cabin size is about the same as the 340,
and if you do the math, the miles per gallon is very close to the same (with the jet fuel being a bit cheaper). Further, there is no required annual training (something I am not opposed to but prefer to do on my schedule, not the FAA’s).
Now that I think a change from the C340 to a single-engine turbine such as the TBM might be a good idea, further ques- tions come up. One is the loss of flexibility when considering landing at nonpaved airports, something the RSTOL 340 with piston engines handles with ease. Next is the business of “capital cost.” I own the 340 outright and long ago depreci- ated the aircraft given its business use. My capital cost for that airplane is almost negligible.
However, if I spend $1 million to buy a TBM (even if us- ing my own money), that much cash should generate 8 to
The nose section just forward of the pressure bulkhead with the usual coverings removed. The black hoses are very expensive new replacements for ones that were dry and cracked.
September 2020 / TWIN & TURBINE • 19