Piper PA-23 Kit - 720P

Piper PA-23 Series

For years the FAA has tried to resolve the sometimes-exaggerated issue of trapped water in the Piper PA-23 series fuel system. Many believe, as we do, that maintenance of the gaskets and cap seals in addition to proper sumping eliminates the main source of these problems. The safety record of these aircraft shows that, if properly maintained, there really isn't a problem. HOWEVER: it is proven trapped water can and does occur at altitudes other than level or near level. This concerns the rulemakers and so there is a Notice of Proposed Rule Making for a possible Airworthiness Directive requiring corrective action. Two solutions have been offered.

Piper Valve


First a return of a rescinded AD with a slight twist. AD 90-23-18 R1 originally called for cementing a rubber wedge inside the inboard aft corner of each fuel cell. The result was a corner that trapped more water than a normal one. This time the wedge is to be installed outside the cell in the same corner. There are two basic problems with this. The wedge displaces some of the space for the fuel cell creating a wrinkle in the vertical edge of the corner. Chaffing and flexing will result in leaks down the road. The other problem is that it still doesn't get the water out of the system at the normal collecting point.

Piper Valve

The second solution would be to install a nipple and flush drain valve at the low point. Almost all other aircraft have this feature and it works! Both solutions require the cell to be removed or nearly so for installation. The proposed costs are nearly the same. So if you were required to comply, which one would you prefer?

We acquired this STC for installing drain valves in 1998 and have upgraded it to use our popular stainless steel valve. Now you can purchase the STC kit and have the fuel cell modified or replaced all at one facility

Benefits include:

Stainless steel construction

FAA approvals
TSO - C76b
STC - SA01110CH

STC eligibility listings below

Improved sumping
A drain valve is installed at the low point in the inboard aft corner of the fuel cell allowing for a more thorough sump.

Clean Look
A large stainless steel washer supports the installation and protects the wing skin.

Simple maintenance
Once installed, you can; drain the cell, clean the valve, or change the standard o-ring without removing the valve and disturbing the fuel cell.

Recommended by
Owners, Piper & Apache Associations, IA & A&P’s

Piper PA-23 Photos


The fuel cell is removed and the bottom inboard aft attach point is removed from the fuel cell. Then a rubber drain nipple is vulcanized into the same location on the fuel cell. The wing is then modified by drilling out the four rivets that hold the corresponding attach bracket to the lower wing skin in a diagonal pattern. The bracket is removed and discarded. Next the center of the hole where the valve will pass through the skin is located by marking crossing lines from one rivet hole to the other. The valve hole and a small hole adjacent to it are drilled. A rivnut and fillister screw are installed in the small hole. The fuel cell with the valve hose clamped in place is inserted into the cavity. The valve drops through the valve hole and is secured with a rubber spacer, stainless steel washer, drilled check nut and safety wired to the fillister head screw.


Approved Model List

Models Serial Numbers
PA-23-150 23-1 thru 23-1182 (except 23-1177)
-160 23-1177, 23-1183 thru 23-2046
-235 27-505 thru 27-622
-250 27-1 thru 4916,
27-7304917 thru 27-7554168
27-7654001 and up
-250E 27-1 thru 4916,
27-7304917 thru 27-7554168



Eagle Fuel Cells-ETC, Inc. | 617 Skylane Taxiway | Eagle River, WI 54521 USA
T: 715.479.6149 | F: 715.479.6344 | E: info@eaglefuelcells.com

Copyright © 2017 - Eagle Fuel Cells-ETC Inc.