Before removing any fuel cell, isolate the areas of possible leaks by opening the inspection plates and tracing the wetness or staining. Gravity causes fuel to run down the cavity floor, ribs and spars, so the leak may be far away from where the fuel exits the wing. It may be fuel from overfilling in the cavity or the next cell over leaking.
Check gaskets for tightness and make sure no gasket cement has been used.
Check all hose clamped connections for tightness, damage, and leaks.
Check filters, quantity transmitters, tubes and attachments for cracks or leaks.
Keep them topped off as much as possible.
Frequent use is good too because fuel sloshes.
Occasionally rock wings of hangared aircraft.
Alternate topping mains and auxs, if possible.
Low fuel is not good, empty fuel cells are bad.
Avoid auto fuel and additives as they deteriorate rubber.
Removed cells are to be placed in a bag and box to protect them from UV, ozone, heat and humidity.
Read the air-frame manual. These are only general suggestions to reduce unnecessary damage and ease a sometimes difficult job:
- After draining the fuel, loosen the clamps on the fuel and vent lines and allow the rubber to relax.
- Remove the filler, transmitter(s), tubing, fuel strainer(s), and drain valve. A hot, moist cloth can be applied to soften the nipples.
- Make sure the wing and fuel cell are thoroughly warm. Temperatures under 70F cause the rubber to be less flexible and harder to remove. Depending on your climate, you can use the sun to heat the wing.
- Most cells are removed through an inspection panel or an area around the filter. Open the inspection panels and undo the filler neck where it attaches to the wing. Inspect the gaskets for over torquing, elongated holes and gasket cement.
- Tape the edges of the openings to avoid abrasions and cuts to you and the cell.
- Reach in on the outer surfaces of the cell and undo bayonet clips, snaps, button slides, or lacing cord that hold the cell.
- Carefully fold and roll the cell into a tube shape to remove it through the opening.
- Once removed, wipe out any fuel residue, remove clips, cross vent tubes, quick drains, clamps and miscellaneous hardware.
- Leave the bolt rings in cell for inspection and testing.
- Do not oil the cell. Oiling is for long-term storage after repair. It’s like waxing before a paint job. It just adds more work, more time, and more cost. And in most cases, oiling will render the cell un-repairable.
- Fold loosely and box in a sturdy carton.
Read the air frame manual for exact procedures. These are suggestions:
- Inspect the cavity for debris, such as metal filings, hardware, tools or rags.
- Clean it thoroughly and re-tape rivet heads and sharp edges.
- You may want to check the venting system for restrictions and damage.
- Attach miscellaneous parts such as the clips and quick drain to cell if necessary.
- Fold and roll the cell into a tube as before and install through the taped opening.
- Work out snags before you tear the cell. Don’t use excessive force. Warmth is your friend.
- Once inside the cavity, unfold the cell, fit all corners, and smooth out any wrinkles.
- Fasten snaps, bayonet clips, button slides, and/or lacing cord that support the cell.
- Reconnect all fuel and vent lines. Then reinstall cover plates, transmitters, and fillers.
- When tightening clamps, do not over torque. Allow the rubber about an hour to relax, then re torque. Over-torquing will result in damage or leaks.
- Check for warped or deformed metal fixtures such as plates, pumps, transmitters or fillers and replace if necessary.
- Check bolts and screws for proper length so that they don’t bottom out when fully torqued.
- Check gasket and sealing surfaces that they are clean and dry. Do not use gasket cement or Fuelube.
- Install gasket to fuel cell surface (bold studs may be used to help to hold the gasket in place with proper clocking)
- Install fixture and tighten bolts or screws finger tight.
- Tighten bolts and screws in normal torquing pattern to specified torques.
- Allow several hours 0 preferably overnight 0 before retorquing.
- After retorque, safety wire as required