Amend the Keffer amendment to HB 3540 by adding the following 
SECTION, appropriately numbered, to read as follows:
	SECTION___.  Section 21.05, Tax Code, is amended by amending 
Subsection (e) and adding Subsection (f) to read as follows:
	(e)  For purposes of this subchapter, a commercial aircraft 
shall mean an instrumentality of air commerce that is:
		(1)  primarily engaged in the transportation of cargo, 
passengers, or equipment, for others for consideration, at least 
50% of the time;
		(2)  economically employed when it is moving from point 
to point as a means of transportation for a fee, flat rate or 
expense charge; and
		(3)  operated or managed by, a certificated air carrier. 
A certificated air carrier is one engaged in interstate or 
intrastate commerce under Part 121 or 135 authority of the U.S. 
Department of Transportation or Federal Aviation Administration.