nope they don't

Here is a link that might be useful: mrtexas

several sites say the blooms are fragrant

http://www.backyardgardener.com/plantname/pda_3054.html

http://www.sunnygardens.com/garden_plants/poncirus/poncirus_2353.php

http://www.missouribotanicalgarden.org/gardens-gardening/your-garden/plant-finder/plant-details/kc/e790/poncirus-trifoliata.aspx

http://www.yale.edu/marshgardens/documents/070505.pdf

My flying dragon tree which is 10 years old in the ground does not have fragrant blossoms.

mrtexas,
I have found that real world experience often means little to academics/researchers... but I did find some researchers at Texas A&M Kingsville Citrus Research Center who work closely with growers and packers...AND seem willing to learn from real world experience.

i've never seen a trifoilate in bloom irl, so i shall defer to you

people at Edible Landscape forum was talking about flying dragon tree's flower in VA was fragrant. Here is the copy of the forum:

Posted by elder 6VA (My Page) on Fri, Sep 24, 04 at 21:49

Just have to get into the fray - P trifoliata originated in China, and was once grown in northern Europe where the rind from the fruit was candied and dried. This being the case assume it is very cold hardy. The colonists in America also grew P trifoliata as the fruit has a natural pectin which was used in making jellies, etc. In what form, and by what process I don't really know. There are actually old 'trees' growing in old town Alexandria, VA.
I have quite a stand of them (in northern VA), but have never tried eating or drinking any of their products. My trees reach a height of ten to twelve ft. They bloom early spring (the flowers on my trees being somewhat inconspicuous), have a strong scent and are used heavily by bees. Young plants are used in the citrus trade as rootstock for a variety of smaller citrus. Birds love making their nests in them, I have had as many as three nests in one tree the same spring: mockingbird, dove, and U/I. The thorns WILL puncture pneumatic tires, and the wood is extremely hard and heavy, but too small to be of much value. I would suggest that several trees planted under windows and pruned to a reasonable height would stop intruders quite readily. I have no doubt that they would serve well as a hedge plant if you are interested in keeping in any sort of large livestock......Elder

yup, only one post here by someone who actually has a mature tree in the ground

I have two mature flowering Poncirus and I can't smell any fragrance at all. But noses do vary! It's also possible that a dense group of flowering trees could all together produce a smell.
I haven't tried smelling Flying Dragon, but as it's just a varient form, I wouldn't expect any difference.

Thanks a bunch guys, yeah I will hold off then on one of these. I meant only if it had that intense fragrance of standard sour oranges and such, not if it has a barely traceable fragrance. what good is citrus without the fragrant blossoms? (or the fruit). Aesthetics? Blah.