Cessna 337 Skymaster

Kit Facts

Type External tip tank
Added fuel total 39 gallons (19.5 per tank/side)
Useable fuel total 38.6 gallons (19.3 per tank/side)
Net added span 52 inches
Gross weight increase Total of 4,630 (if gross weight is 4,700, it will stay the same)
Dry weight 46.3 lbs
Installation time 55-65 hours (with previous installation experience)
For aircraft subject to AD2011-15-11 add 30 – 35 hours.
Need to be painted Yes
STC and models covered
  • SA5090NM : 337, 337A, 337B, 337C, 337D, 337E, 337F, 337G, 337H, M337B, P337H, T337E, T337F, T337G, T337H, T337H-SP, A23EU, F337E, FT337E, FT337F, F337F, F337G, FT337GP, F337H, FT337HP
Flight manual supplement & ICA
Airworthiness Directive
Limits At weights between 4330 lbs. and 4630 lbs. there must be at least 12 US gallons of fuel in each wing tip tank.
Kit price $13,184.00
For aircraft subject to AD 2011-15-11 add $2,100.00

We’ve been selling extended tip tanks for the Skymaster since 1989. They carry 39 gallons total, 38.6 usable. They are fiberglass tanks that bolt onto the end of the wing and replace the factory tip. New holes are drilled in the wing skin and our tank/tip is bolted in place. The overall span is increased by 54 inches which results in a better climb and above 10,000 feet, we usually get reports of an additional 3 or 4 kts in cruise speed. The tank has it’s own filler cap and quick drain valve. We ship the tanks in gray primer so they must be painted to match the wing.

For tank installation the close-out rib is removed and if you have strobes, the transformer is re-located to the inboard side of the rib.

The next step is to run the fuel line inboard to the part of the wing where the strut attaches. The transfer pump is mounted here along with two check valves. The fuel line is then run inboard to the main tank. For rubber cell mains, the fuel enters through a tee fitting in the door post into the fuel line that runs from the mains down to the engine. For metal main tanks, a bulk head fitting is installed in the side or top of the main tank.

Gauge(s) and lighted rocker switches are then mounted on the panel, pedestal or over the doors. Apply the placards, fill out the 337 and you’re finished.

The kit is quite complete including tanks, caps, mounting and plumbing hardware, transfer pumps, check valves, fuel line, wire, switches, gauges, fuses, installation drawings and STC. You supply some PRC sealant if your main tanks are metal.

Local installers complete the job in 55 – 65 hours but if you have someone do it that has never done one before it will probably take longer. If the aircraft is subject to AD 2011-15-11 you can expect to add an additional 30-35 hours labor. It’s not an exotic installation but, done right, it takes some time. 2011-15-11