DC-8 EPR/RAT gauge

[Jess-8]

Hi all

I'm currently making a custom panel for the DC-8 in FS9.
I now stumbled upon the EPR/RAT gauge (see image below).
I know that when you select the 3-Engines option the gauge flips to show the values for 3-Engines operation but what do those yellow lines mean on the gauge? I don't think they indicate the altitude as different altitudes have completely different values (following the operating manual of the DC-8).
Could someone explain me what those yellow lines and numbers mean and how the gauge handles different altitudes for the TO and MCT EPR value?
Thx

http://img823.imageshack.us/img823/1512/eprgauge.jpg

Regards

Jess

[oceancrosser]

Hmmm, its been 30 years since I flew the Diesel 8, and we did not have this unit in any of ours. This appears to be a calculator, to calculate EPR from RAT (the F/E did those calculations). I am not sure about the yellow lines, they appear to be a way to correct EPR setting based on a something, perhaps ANTI-ICE on?
Which series DC-8 are you basing this on?

[Jess-8]

thx for the reply.
This gauge is used on 9G-MKG, a DC-8-62F. Must say that the inboard engines are JT3D-3B and outboard JT3D-7

[Jess-8]

Mystery solved :D

According to a couple DC-8 study guides, the yellow numerals are pressure altitude engine pressure ratio limitation numerals. Example would be, on the left hand scale, the yellow "4" is pressure altitude 4,000 ft. and the EPR limit is approximately 2.07