The constitutional amendment to authorize a political subdivision of this state to extend the number of days that aircraft parts that are exempt from ad valorem taxation due to their location in this state for a temporary period may be located in this state for purposes of qualifying for the tax exemption.”
This relates to the "freeport exemption" which seems to allow for products that are sent to a manufacturing facility in order to be assembled and ultimately exported to be exempt from property tax evaluations. It is intended to enhance the export industry in the state.
Some pros and cons lifted from another site:
Proposition 3: HJR 133 by Harper-Brown
The Texas Constitution currently allows for what is known as the “Freeport Exemption.” This exemption allows for goods and tangible property to be exempt from property taxes if the property is used for manufacturing purposes, the property is transported from out of state, and the property is then transported outside of the state within 175 days. In other words, if the goods are a stored in a pass-through facility, the goods are tax exempt. This constitutional amendment extends the 175 day Freeport exemption to 730 days for aircraft parts before the parts must be transported outside of the state.
Supporters Say:
Companies that ship aircraft parts currently utilize the Freeport exemption. However, aircraft parts frequently sit on shelves for longer than 175 days and after the 175 days, they are subject to property taxes. Extending the days aircraft parts may sit on the shelves of warehouses and distribution centers from ½ a year to 2 years before being subject to property taxes will allow additional distribution centers for aircraft parts to develop in Texas around our airports. This growth in distribution centers and warehouses will provide additional economic development which would offset any potential revenue decline.
Opponents Say:
The legislature should not single out specific industries for tax breaks without considering other types of pass-through distribution centers or warehouses that were excluded by this law. The legislature should instead eliminate the property tax on tangible property and inventory which will then produce even more economic development.
And click here for more detail from the Texas Legislative Council.