General Installation Tips

Question: What is the best way to drill the holes for the fuel line?

Answer: Many installers will fashion a drill bit on a long rod and drill the holes for the fuel line from the outboard edge of the wing with a second person using the inspection holes to guide the drill bit.

Question: Why do you show the fuel pump mounted at an angle?

Answer: This orientation will allow you to remove the pump filter for cleaning without removing the pump. The filter should be checked at every annual inspection or whenever you believe there is contamination in the fuel tanks.

Question: Why are there are two check valves installed for each pump assembly?

Answer: One check valve is installed to prevent the tip tanks from gravity feeding into the mains. The FAA had us add the second check valve to prevent a pilot from pushing fuel out of his main tank vent line should he try to transfer fuel into a full main tank. The FAA loves to take something that is simple and make it more complex. We generally feel that pilots are smarter than the FAA gives them credit for but added the second check valve anyway.

Question: Why don’t you give dimensions for locating the inspection panels?

Answer: This allows you the freedom to put them where they work best for you. Most of the panels provided are used to allow you to put the grommets in the holes drilled for the fuel line. Once that is done there really should not be a reason to use them again. If you do not need to add all the inspection covers you do not have to use them. For newer airplanes you may want to consider buying the Cessna flush mounted inspection covers instead of our surface mounted ones so that they match the existing ones. We do not provide the Cessna inspection covers because they are expensive and we are generally providing more than you would need for the newer airplanes.

Question: This is my first time installing the Flint tanks. Should I expect to do it in the time duration you call out on your website?

Answer: It is hard to say. We give a large range for installation time based on what installers have told us in the past. Airplanes with bladder main tanks generally take longer, hence the large range. A highly experienced installer once told us he thought a first time installer could easily spend 8 -10 hours going back and forth between the drawings and the actual work. Most first time installers tell us that by the time they get to the second wing they are going about twice as fast as the first.

Question: Where should I mount the fuel gauge(s)?

Answer: The drawings allow you the freedom to mount them where you want. They just need to be mounted in plain view of the pilot.

Question: Can I use a different fuel gauge than what your provide?

Answer: Yes, but it is a deviation from our STC and should be noted on the 337 or installed via a field approval. If the gauge you are using is STC’d a separate 337 can be filed instead. Our resistance fuel senders work on a range of, approximately, 32 ohms full and 248 ohms empty. If you are using a multi-function instrument you need to make sure that it has space available for the additional fuel tanks and that they can be marked to clearly show that they are for the auxiliary fuel tanks.

Question: If I have questions during the install can I call?

Answer: Yes! Please call with any questions you might have. We don’t just sell the best auxiliary fuel tanks for Cessna, we stand behind them and want to make sure we support the installer and final customer throughout their installation and use.

Question: My customer wants to know how long the fuel transfer should take.

Answer: Our 12V pumps transfer at a rate of about 45 gallons/hour. Our 24V pumps transfer at a rate of 30 gallons/hour. We generally recommend running the pumps a few minutes past the estimated transfer time to ensure you get all the useable fuel out of the tips. Many customers will lift the wing they are transferring fuel from a bit near the end of the transfer to maximize the amount of fuel transferred.

Internal Installation Tips

Question: What should I use to cut the rib at WS 190?

Answer: Most have found a small rotary saw, a 90 degree high speed drill, or a pin router works the best.

Question: This airplane has bladder main tanks and in the “flap tracks” there are existing large holes. Can I route the fuel line through those?

Answer: Yes, but you need to support the fuel line. If you cannot find grommets large enough contact us and we can provide them.

Question: This aircraft has bladder main tanks. Were do I locate the hole that penetrates through the fuselage.

Answer: One experienced installer drill from the inside of the cabin outwards using a “V” juncture of the structure as a guide. You can see a picture of this location here: Fuel Line Through Cabin.

Question: For bladder airplanes you have us tie into the fuel line at the aft door post. I’ve looked and there isn’t enough room to do that.

Answer: Most first time installers are intimidated by this. We can positively say there is enough room. If you look at the drawings it shows a dimension of 12″ with a +18″ tolerance down from where the fuel line inserts from the wing root into the fuselage. Move it down as far as you need to get clearance. Use the existing Adel clamp to secure the line and make sure the aileron cable is not rubbing against the fuel line.

Question: The aircraft I have has metal main tanks. I want to put the bulkhead fitting for the auxiliary fuel line on the top of the tank but it stands too high. What do I do?

Answer: Once you have the fitting mounted use a rubber mallet to lightly tap the fitting to indent the fuel tank to give room to reinstall the fuel tank cover. You don’t need much additional clearance to do this.

Question: In the installation pictures on your website it shows the bulkhead inserted without the additional hardware near the filler neck. How did he do that?

Answer: This installer fabricated a special wrench to allow him to access the nut in that location.

Question: I’ve tried to insert the tip tank into the wing but it doesn’t fit!

Answer: It will. They have been fitting since 1967. Some installers will drill out a few wing skin rivets to get some relief. Also, take some scrap aluminum sheeting to lay over the stringers so they don’t catch on the webbing of the tank (See Picture Here: Internal Tank Installation. Once the tanks are in pull out the aluminum sheeting. It does take a bit of muscle to get them in. As you push the tank in use a piece of wooden doweling inserted through the access ports in the area of the aileron (you will need to remove the aileron rod first) and lightly tap the tank against the forward spar. The tank should be flush against the forward spar and will only touch the rib at WS 172 at the rear corner of the tank. Shine a light down the forward spar to ensure it is flush against it before strapping the tank in place.

Question: How do you drill the hole for the quick drain valve location?

Answer: Before inserting the tank take a measurement of where the valve boss is on the tank. Once the tank is strapped in place drill a small hole and use a piece of safety wire to tap around to see if you are centered on the boss. Once you confirm the location you can then drill the final hole.

Question: Part of the filler neck scupper is falling on a stringer. What do I do?

Answer: You can trim the fiberglass scupper to get clearance from a stringer.

Question: The drawings call out for the use of a hot glue gun to fill the joint between the scupper and wing skin. What is this for?

Answer: This provides a backing for the PRC. You can use a fuel resistant caulking instead.

Extended Tip Tank Installation Tips

Question: The tips do not seem to match the wing profile. Am I doing something wrong?

Answer: You need to cut the leading edge of the Cessna back some. We show an angle cut but some installers will use a square cut. If this is not done you won’t be able to slide the tank tight against the leading edge and it will give the appearance of not matching the profile of the wing. This cut is required because the area of the tip tank where the navigation and strobe light wires route protrudes farther inboard, so relief in the wing skin is needed. If the tank does not appear to fit correct DO NOT DRILL AND MOUNT. Call for assistance.

Question: If the tank isn’t fitting correctly or giving me enough clearance at the aileron can I trim the tank?

Answer: You should never need to trim the tank. Please call us before doing so! We may ask you to provide some pictures of what you are encountering to be better able to advise you on how to proceed.

Question: I am not catching the stringers where the tip tanks mount onto the wing. Is that a problem?

Answer: On some aircraft the stringers do not go all the way out to the end of the closeout rib. If you cannot catch the stringers it is not a problem, but make sure you pick up the spar caps!

Question: Is it necessary to use a filler like RTV along the joint of the tip tanks and the main wing?

Answer: No. You may run into an area where there is a gap between the tip tank and the wing where a small amount of filler can be used for aesthetic reasons but there is no need to do this along the entire wing. We have seen pictures of installations where the installer has done this to “blend” the thickness of the tip tanks down to the wing skin and, in our opinion, this is not aesthetically pleasing. Our tips are much thicker than the stock tips, about 0.1375″, and fairly rigid where as the stock tip of a new Cessna 206H is about .080″ and flexible. There will be a difference between the look of the stock tips and those of the Flint tips. We feel that as long as the edge of the tip tank is painted the transition looks just fine.

Question: The drawings call out for a test flight to adjust the stall warning vane. What weight do we do the test at?

Answer: This should be done at the max gross weight of the modified aircraft. The plane should be loaded at the CG limit noted in the drawings.