Finishing Touches Placed On Aircraft Specialty Fuel Lines

Today was a mixed bag of firewall forward work activities, most notably placing the finishing touches on the Aircraft Specialty Teflon fuel line instillation. Even though the fuel lines were installed, they were not yet secured to the carburetor flange bolts. Also, the rubber hose that connects the balance tube to the right intake manifold was damaged during removal of the fuel clamp block (which after removing all the banjo fittings serves no useful purpose), so a new piece of hose was cut and installed.

New piece of fuel hose to replace the piece of hose that was damaged during removal of the no longer necessary fuel clamp block (pictured in the Jan 25, 2016 posting). The end of the hose attaches to where the blue tape is protecting the port from debris.


The clamp was installed on the hose making sure the tang for installing the vibration dampening spring was positioned correctly.

Using a spring hook tool to reattach the spring from the carburetor onto the tang.

To prevent the Teflon hoses from chafing or the balance tube from being damaged by the fuel marshal, a piece of rubber hose was slit and placed over the balance tube so the fuel marshal/fuel lines can be secured directly to the balance tube.

The space between my fingers is where a piece of slit fuel line was placed over the balance tube to prevent it from being damaged by the fuel marshal when it is wire tied onto the balance tube.

Fuel marshal is now secured onto the balance tube with wire ties.

Now with the final positioning for the fuel marshal determined, attention was given to reinstalling the hose clamps on the intake manifold flanges used to secure the fuel line to each carburetor.

Both green fuel line hose clamps reinstalled onto the flanges on the intake manifold and the fuel marshal secured onto the balance tube with wire ties.

Of note: The bottom two Teflon hoses on the right in the above photo still need to be secured with Adel clamps … but first a small mounting bracket needs to be made … a rainy day project.


In doing a little more research on the torque values for the 37 degree fittings, it appears that because the new fittings are steel on steel, a higher torque value of 100 inch pounds is recommended … so the torque of all the 1/4" steel to steel fittings was increased to 100 inch pounds.


Continuing on with closing out the tasks in Section 46, the last task in the section is to remove the banjo fitting on the oil return port and install a straight adapter for flair fittings.

This banjo fitting (on the oil return port) needs to be removed and replaced with a straight adapter for flair fittings.

The Banjo fitting seen in the previous photo was replaced by this straight fitting.