Continued Air Worthiness
Tips for Trouble Free Operation
Flight Manual Supplements
Purchasing Used Flint Tanks

Continued Air Worthiness
The following recommended maintenance should be performed in conjunction with Cessna’s maintenance procedures.

1. Pre-flight check:

a. Visually check entire aux fuel system for leaks.
b. Drain fuel sample fro aux tanks and check for contamination.
c. Visually check wing to aux tank mounting screws.
d. Inspect tanks for damage such as impact or abrasion.
e. Turn on power and check fuel gauges for correct reading.                                          f. Check fuel cap o-rings for signs of wear and replace as necessary.

2. Periodic maintenance (100 hour check) all of the above plus:

a. Ensure that all placards are in place per installation drawings.
b. Clean aux tank fuel pump screen.
c. Torque pump mounting bolts to 50 to 70 inch pounds.
d. Check fuel line mounts and connections for tightness.
e. Inspect all electrical connections for chaffing and correct mounting.
f. Inspect tip tank nav lights for correct operation, proper sealing , signs of chaffing on  wires and secure connections (see installation drawings for sealing information).
g. Torque tank mounting bolts to 10-12 inch lbs (extended tips).
h. Confirm proper operation of fuel indicators and transfer pumps.

Tips for Trouble Free Operation

  • Keep the tanks full when on the ground to prevent condensation from getting into the fuel or corroding the senders and pumps..
  • Use a countdown timer when transferring fuel to know when to turn the pumps off.
  • Follow the Flight Manual Supplement.

We have been building tanks since 1967 with very few problems. Here are the few we have run into:

Gauge doesn’t work: Generally, it’s not the gauge. Most often it’s the fuel level sending unit located in the tank itself. If the tanks aren’t kept full (see tips), condensation can form. Not only does this introduce moisture into the tank which is hard on the senders. We changed our senders to a “marine” type about 1998 but even these can only tolerate so much moisture. You may have the older metal type anyway. To determine if the problem is with the gauge or the sender swap the leads to the two gauges to see if the problem travels with the wire. If it does, it’s the sender. If it doesn’t, we have gauges in stock. We’ll need to know how many gallons your tanks hold and the voltage of your system when you order. If it’s the sender, we also stock those. We need to know the model airplane when ordering. By the way, it’s very difficult to change the sender without removing the tank but sometimes it can be done. Usually it’s easier to remove the tank.

Gravity transfer: This is the fuel moving from the aux tanks to your main tanks when the plane is parked. You have a check valve problem. It’s easily cured. Some small bit of debris under the ball in the check valve that is preventing the valve from closing. The check valve can be opened and cleaned, use Avgas or Jet A to clean the balls. Do not compress or extend the spring in the valve and put a small amount of oil on the o-ring when reassembling the valve. If you did determine the ball was fouled by debris it would be good to check the aux tanks to make sure the source of the debris is eliminated. This would also be a good time to check the pump filter.

Electrical noise: If you hear noise in the headphones when the transfer pump is running, you have electrical noise. This is generally caused by a bad ground somewhere. The problem is, where? It can be almost anywhere, at the battery, the pump itself or in the radio. If you look and can’t find a loose ground, we have a solution. We offer a noise supression kit. It consists of a special capacitor which is installed on the power lead to the pump and shielding for the wire from the capacitor to the pump. We always have them in stock.

Leaks: We don’t have many leaks but they sometimes do happen. Especially when the tanks get above 25 years old. Some leaks are simple like a leak at the quick drain or the cap which only requires an o-ring change. We stock them. Others are more difficult like fuel getting into the tube that runs through the leading edge of the tank. This fuel would appear at either the nav light dry bay or the inboard, forward corner of the tank. We generally recommend sending the tanks to us if the leak is not caused by a damaged o-ring.

Rebuild information
If you have a problem with the integrity of your tank, we may be able to rebuild them to factory specifications. This is not to be confused with a repair, which we are not certified to do. Since we are rebuilding the tank and not repairing it we do have to fix any area of the tank that is not up to spec.

Rebuilds are can be a complicated process with many factors involved. But we will work with you to help solve your problem.

  • Before we put any labor into a tank we always give it a good visual inspection first. This allows us to give you an idea of what may be involved before we begin the rebuild. Pictures from our customers can sometimes help us determine an issue before the tank is sent to us. But, having the tank in hand for inspection is preferable, pictures can be deceiving. Pictures can be of benefit to us in determining the approximate age of our extended tips.
  • All rebuilds require a pressure test. This test uncovers damage that a visual inspection alone cannot do. Please call for current pricing for this test. You should understand the a pressure test can cause an area to leak that may not have been leaking before the test. While this is not common, we want you to understand the risk. After the pressure test we will work up a quote that will include all necessary repairs. Though rare we sometimes discover other issues once we open the tanks to proceed with the work. Should a customer wish not to proceed prior to the commencement of the rebuild they are only out the cost of the pressure check. We will ship the tanks back to you if you wish (shipping charges apply) or with your consent we will destroy them. We do not rebuild tanks for resale.
  • We can only rebuild a tank to a revision level that we still have drawings for. We have drawings for most of our tanks but since some of our STCs go back to the 1960s our records aren’t complete. Also, certain parts, namely the fuel caps, are no longer available. If you do not have the cap or adapter we may not be able to rebuild the tank to that revision level.
  • It may be necessary to alter the tank (eg. remove paint, drill a seized screw, etc) to determine if and how the tank can be rebuilt. We are not responsible for returning the tank to it’s original condition (aka. the status before any alterations).
  • We reserve the right to refuse to rebuild any tanks for any reason.
  • Other unforeseen issues may arise during the process.

The following are the steps for a rebuild:

  • Contact us regarding the rebuild of your tank and let us know what you are shipping to us.
  • Ship us your tank, your contact information, as well as an explanation of the problem.
  • We will do a visual inspection to determine if the tank can be rebuilt. If they cannot be rebuilt, we will contact you.
  • We will perform a pressure test to confirm what is needed for your rebuild.
  • We will contact you with an estimate to rebuild your tank. At this point you can choose to have them rebuilt, shipped back to you, or destroyed.
  • You send payment for the rebuild.
  • Once payment is received the rebuild will commence.
  • After the tanks have been opened there is a possibility that other problems may be found. These problems must be repaired before the tanks are certified. We will contact you with a estimate to rebuild the new damaged area.
  • When your rebuild is complete, a second (no charge to customer) pressure test is done to test integrity of tank.
  • Your tank will be shipped back to you (If tank(s) are not shipped in a container that is in re-usable condition for return shipping, a packaging fee will be added to your invoice).
  • Invoices must be paid in full before tanks will be returned.

Flight Manual Supplements
Current Flight manual supplements can be found online. Simply go to the “Kits” section and select your aircraft model. Your FMS should be linked to on that page. Note: Some early aircraft may not have a FMS and all information is communicated to the pilot through the use of placards. Check your STC to see if you have all the placards you need.

Purchasing Used Flint Tanks
Occasionally we run across people who have purchased a used set of Flint tanks. We do recommend one be careful when going this route as an old set with problems can quickly approach the cost of a new set.

We do stock most of the parts that you may need to have a complete kit should you have just the tanks and a few of the components. Before calling please look over these parts of your tip tank system:

  • Do you have a STC and permission statement?
    • The FAA requires you to keep a copy in the aircraft and it must carry the aircraft ‘s serial number and registered owner’s information.
  • Do you have installation drawings for the install process or to verify the tanks were installed properly?
    • If you are doing an install on a new aircraft you may need new or different fittings. You can determine what you will need by checking the installation drawings to the parts you have. If you do find you need something or have a question please feel free to contact us .
  • Look the tanks over very carefully for any blue stains that may indicate a leak.
  • Inspect the mounting holes for any elongation. The edge distance of these holes is very important.
    • For example, a 206F, G or H model, distance from the center of these holes to the edge of our tank must be .75 inches, plus or minus .25 inches
    • Other models can have different measurements, please contact us for your specific model.
    • Please note that mounting tanks with preexisting mounting holes is more time consuming than mounting a new, undrilled set.
  • Which fuel cap do you have?
    • You can see the various caps here we’ve shipped over the years in the pictures section of the website. Many caps are no longer available from the manufacturer.
  • Inspect the check valves. They should be our newer brass version or they must be replaced.
    • The older aluminum check valves have been known to spring pinhole leaks.
  • Inspect the pumps. Run them for a few seconds on the bench before installing them. Remove the bottom of the pump and clean the basket screen and look for rust.
  • Remove the sending units and check for the presence of rust and ensure free movement. When in doubt choose to replace the senders before mounting the tips. You have ready access to the senders at this time.

Again, use caution when going with the “used tank” route, you don’t know where they’ve been or what they’ve been through. What may save you a little money up front may become less attractive economically should you have problems later on.