The General Electric CF34 high-bypass turbofan (used primarily on the Bombardier CRJ and Embraer E-Jet regional jets), unlike the vast majority of jet engines (both civil and military), is not certified to burn so-called “wide-cut” fuels (gasoline-kerosene blends, nowadays used mainly in cold-weather operations), such as Jet B1 and (formerly) JP-3 - only “narrow-cut” fuels (straight kerosenes), such as Jet A-1,2 Jet A, JP-5, and (formerly) JP-1. In contrast, CF34s in military service (known to the military as the TF34, and used mainly on the A-10 ground-attack aircraft) do just fine with wide-cut fuels (an absolute necessity back when aircraft so engined entered military service, as the go-to military jet fuel back then was JP-4, aka Jet B with the military’s stamp of approval).

This is a bit surprising, as:

  • it renders CF34-equipped aircraft unable to operate in very cold places (wide-cut fuels, having much lower freezing points and viscosities than the straight kerosenes, remain useable down to much lower temperatures than their narrow-cut ilk), and
  • there doesn’t seem to be any obvious technical reason for such a restriction, seeing how, as mentioned above, military CF34s are perfectly happy to run on wide-cut fuel.

Is there some critical difference between the military and civilian versions of the CF34 that renders wide-cut fuels compatible with the former but not the latter (maybe a gasket somewhere in the civilian CF34 that’s dissolved by the gasoline in wide-cut fuels?), or did General Electric simply not bother to certify the civilian version for use with wide-cut fuels?

1: Formerly also often known as “JP-4”.

2: Also often known as “JP-8”.

  • 1
    $\begingroup$ What is your source for saying it's not certified for wide-cut fuels? $\endgroup$ – fooot Jun 30 at 5:48

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