DC 9s and Diesel Engines

Delta retired its last DC 9 from regular service yesterday. This was a machine that was first manufactured in 1965, McDonnell Douglas made about a thousand of them and this last one to be retired was put in service in 1978 when Jimmy Carter was President and interest rates were headed toward 20%.

The article I read online said Federal rules do not limit how many years an airplane can fly, just how many "takeoffs and landings." Again, the quality of journalism is lacking--the proper term is "cycles" and there are no Federal rules on how many cycles are allowed. It is much more complex than that and comes down to economics: older airplanes use more fuel, parts are expensive and hard to find and keeping them serviceable after their intended life becomes more expensive than the alternatives. Besides, the mechanics who are skilled at maintaining an airplane that is half a century old are either retired or dead.

Maybe the Feds should get more active in telling airlines how to run their business. I sincerely hope not as the parts that are currently the domain of the Federal government, like ATC, are woefully behind the times with old computer systems where upgrades are hampered by budget constraints.

I first encountered the concept of cycle limitations when we were looking at financing aircraft in the late 1980's. We eventually financed 757's (the model in my office) and 737's. About that time, the company also purchased a used corporate aircraft, a "Sabreliner" that was 1960's technology coupled with some stuff from the 1950's and I became interested in cycles. It was astounding to discover that there were DC 9s at that time with 30,000 cycles. Do the math, assume that an aircraft flies 4 legs per day, 330 days per year (even airplanes need days off) and you find that it takes 23 years to achieve 30,000 cycles. Most machines don't withstand that kind of use without failures, so the safety record of the airline industry is truly amazing, a combination of superb engineering and good maintenance programs.

Now, take a look at diesel engines. Unlike the aircraft industry that seems to stay ahead of the Feds, auto and truck engine makers do not seem to do anything but react. Diesel engines, in particular, have become more efficient and cleaner with the exception of the last few years when the Federal rules have caused "Rube Goldberg" solutions that reduce efficiency and introduce things like additives that have consequences no one knows yet.

And then there are the local limitations. One that I know of personally. The area occupied by Los Angeles and its neighboring cities has too many people! Wow, that was profound. In order to solve one of the problems of too many people, the South Coast Air Quality Management District decreed that no more diesel engines could be installed on public service vehicles (like utility trucks) if there was a gasoline or natural gas engine with similar power. This was about 5 years ago, so I don't know if they have overcome their idiocy or not, but the result was that certain utility trucks were equipped with gas or NG engines, replacing diesel technology that had been continuously improved for decades and that had natural characteristics suited to the job.

For instance, the workhorse of the utility industry is the "digger-derrick." It is the large truck that is used to dig holes and set poles and can lift a lineman up in a bucket to work on the lines. One of the reasons that the diesel is so well-adapted to this function involves the work that the truck does when it is not moving down a road. It pumps hydraulic fluid that powers the auger, the boom and other functions of the truck and these are irregular calls for power with long periods of idling. It gets really hot in parts of the Los Angeles Basin, and diesel engines use very little fuel and produce very little heat when idling. They also have a lot of torque. Gas and NG engines produce more heat and less torque. They are just not properly suited for the job, but since it was forced, they were installed.

And they soon fail. The attempt at "green" resulted in pollution as more engines had to be produced and refitted. Plus, the modern diesel engine produces so little particulate that it is a superior solution anyway.

January 1 is my "life insurance" birthday as I became 68.5 years old and life insurers now consider me to be 69. I wonder how many of my 30,000 cycles I have used up? Maybe I can get some spare parts and push for a few more, just so long as I am used and useful. Yes, my skin is like my shirt, it needs to be ironed before I go out, but maybe the engine is like the venerable diesel, suited to the task. I hope so.