SkyMaster Wing Mods

[Ernie Martin]

On your question on whether the auxiliary tanks have to be used all the way until they are empty, I know of no such requirement. If the plumbing of a 336 is similar to the early 337s, it is, however, a prudent move because if a main goes dry you can't get to whatever fuel remains in the auxiliary (for more see the Fuel Management page at www.skymasterus.com).

Ernie

[hharney]

In the C336 Service Manual it states that the auxiliary fuel tanks capacity is 19 gallons of which 18 gallons are usable. See the first attachment.

The main tank system (two interconnected tanks) have a capacity of 46.4 gallons each. If the C336 has 128 usable fuel then this would allow the mains to have 46 gallons usable each. Leaving 0.8 gallons unusable. See second attachment

Third attachment is the C336 fuel schematic.

The main tanks have an aft connection and a forward connection on the inboard main tank. The outboard main tank is interconnected to the inboard main by an upper and lower front connector and a lower aft connector. These connections are depicted on the schematic attached. Here is a photo of the tank http://www.337skymaster.com/messages...ead.php?t=2309


As pointed out on Ernie's site, when on extended flights the auxiliary fuel tanks should be use as soon as possible (60 minutes from departure) after mains have been used at least 1 hour. This is because the auxiliary tanks can not be used for landing. The electric fuel pumps will not provide fuel from the aux's if a engine driven pump fails and the aux's cannot crossfeed to opposite sides for front / rear engines. Therefore, I always use my aux tanks as soon as possible on long trips. Keep all the fuel you can in the mains for emergency issues that may arise.