Using an electric deep fryer does the food need to be totally immersed?

Based on the comments, it sounds like your fryer has a fill line for just the oil, calibrated so that if you use that much oil then add a reasonably-sized turkey, you'll end up with the oil still safely below the top of the fryer. You'd never actually use 22 quarts of oil; then it'd be completely full of oil, on the verge of overflowing, with no room for food.

In that case, your chicken test doesn't really tell you very much. A turkey will fill the vessel more completely, so it may well take less oil to cover it. If you end up able to put your whole turkey in, and cover it with liquid, without getting dangerously close to the top of the pot, then you're okay. I would hope your fryer has another line closer to the top to tell you what a safe margin is there.

Do note that testing with wrapped birds also is misleading. That keeps the liquid from getting into the cavity, so it'll take less liquid to fill and cover that way.

And if the turkey is too big, then filling it to that 8 quart fill line then adding the turkey could cause it to overflow. So it really seems like you need to test with the turkey first (not wrapped!), to be sure it'll fit safely.

With all that said, supposing you do actually end up in the situation you mention in the question - not enough oil to cover the food - that's not good.

If your food is sticking out of the oil, it's not really cooking. It'll be in contact with hot air over the oil, but that's nowhere near actual hot oil.

Along with that, it'd indicate you've overfilled it, which is asking for trouble. The manual for your fryer almost certainly has some really strong warnings against that sort of thing. And even if the oil stops at the fill line, you have a huge turkey in there just waiting to shift or settle a bit, displace more oil, and push the oil above the max - it's still overfilled.

Doing something like that would make it really easy to splash hot oil out of the fryer, especially while you're putting the food in and getting that burst of boiling water and steam, which is incredibly dangerous. It's probably a fire hazard even with an electric fryer. And even without a fire, it's nothing you want splashing on you.

And in general, I'd strongly suggest you look at general safety guides before you attempt to deep fry a turkey, especially if you're not sure about part of the process.

Lots of discussion on this. (I have weighed in, too.) The type of unit the OP is refering to is designed for safe indoor turkey frying. As in the comments, the minimum amount of oil to be used is 4 quarts and the maximum amount is 8 quarts. With 2 gallons (8 quarts) of oil, a 12 pound turkey should fry okay in this unit.

I have a same or very similar unit with the same min and max fill amounts. Mine says it will take up to a 14 pound turkey. I have only fried 10 - 12 pound birds, but haven't had any problems.

All said, it should always be 'safety first' anytime someone is working with hot oil.

Last but not least, the reason the full capacity of the unit is listed (in this case 22 quarts) is because the unit can also be used for steaming and boiling foods.

Yes, the food needs to be immersed completely.

Also, frying needs certain temperatures. If the temperature drops too much when the turkey goes in, it'll not be a good thing. The fryer might struggle to get the temperature back up quick enough. Also the size of the turkey might make that the oil can't circulate freely enough, so you'll end up with colder areas within the oil.

Overfilling a deep fryer is a bad idea. Not only can you splash very hot oil everywhere, you will also overwhelm the fryer's heating element to where it can't keep the oil hot, and you'll get a lousy result. If you want to deep fry a whole turkey there is equipment for that, otherwise joint it and cook the pieces one or two at a time.

The problem with cooking whole is the height. Cooking whole the problem is packing factor. Is it an option to cut it in half and remove the legs? If you can cut it up you will get a lot more meat under the same amount of oil.

Yes the meat needs to be totally immersed.