Take it from me Choppie - the fuel system on a 135 is/was a doddle. Now would you like to talk about the 101 or S3 or CH47 fuel systems perhaps?
The Chinook was simple enough....cannot speak to the other two....but compared to the Bell 412 which is the Standard for which complicated fuel systems are measured....is a real pain in the butt.
How many different fuel quantity numbers did one have to memorize depending upon the various failures?