Two engines are better than one


With regard to Richard Greene’s comment about why he decided to purchase the single engine D-JET (Why I decided to buy a D-JET, Nov. 3 issue), I would like to point out that I have personally deflated the Mean Time Between Failure (MTBF) specs for turbine engines over the last 31 years. I had five turbine engine failures with causal factors of maintenance error (2), ice ingestion (FOD)(1), bleed air fitting part fatigue (1) and, my personal favorite, design error (1). All of those factors were attributable to human error of some sort. The most frightening failure was in the single engine TA-4J Skyhawk attributable to a droop cam design in the primary fuel control. Fortunately, I didn’t need the rocket- powered ejection system as the backup manual fuel control system worked to restore thrust. My most recent failure was in the Boeing 757 just last month! That was a “piece of cake” shutdown and divert.

Therefore, if I were in the market for my own personal jet, I’d go double engine, even if I needed to seek out a partner or two to help fund it. If I win the lottery, you can find me looking at the Adam A700, Cessna Mustang or Eclipse.

You may also want to take a look at the location of the engine, and judge for yourself how well the aircraft may be able to withstand the worst possible in-flight failure mode of the turbine engine, which is uncontained turbine section parts separation. The engine manufacturers spent countless hours developing the engine parts and designs to prevent this horrible scenario, but it still happens on rare occasions.

You’re calling the risk on purchasing a single vs. a twin jet.

Good luck and happy flying.


Aircraft Mishap Investigation Instructor

Naval Aviation Safety School (1990-1993)

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