I'm a mechanical engineer and a private pilot with a well-used and well-loved Cessna 210. A couple years ago, I started experiencing intermittent fuel supply problems. One of the possible causes my mechanic and I considered was a contaminated fuel nozzle.

To clean a fuel nozzle, most mechanics — and indeed, Continental Service Bulletin SID05-7 — recommend that you soak the nozzle in a solvent, such as MEK, Hoppe's #9, or lacquer thinner, and then blow it out with compressed air. However, not only does blowing with compressed air (at least with a blow gun) not do the job, in many cases it can have serious negative repercussions. Returning a clogged nozzle to service can put you at risk of a mid-flight partial engine failure, and even an off-field or forced landing.

The contaminants in my fuel nozzle did in fact survive several cleanings, and continued to cause problems. The fuel nozzle would work perfectly for a while, and then start exhibiting symptoms of clogging again. When I removed the nozzle, I could actually see — with the help of a magnifying glass — that there was something in it. The blockage disappeared when I blew compressed air into the nozzle, but then it came back!

Puzzled, I began to look at this issue more closely. My first step was to understand the inner workings of a fuel nozzle. That investigation led directly to the creation of NozzleFlush — a tool designed to do what compressed air alone simply cannot.