<?xml version="1.0" encoding="utf-8"?><!DOCTYPE Zthes SYSTEM "http://zthes.z3950.org/xml/zthes-05.dtd">  <Zthes><term><termId>31348922</termId><termName>fixed-pitch propellers</termName><termType>PT</termType><termNote><![CDATA[ The simplest of propeller designs, associated with light, piston engine aircraft. The angle of attack of fixed pitch propellers is set at installation and cannot be changed during aircraft operation. ]]></termNote><termCreatedDate>2026-03-30 20:42:13</termCreatedDate><relation><relationType>UF</relationType><termId>31348923</termId><termName>fixed-pitch propeller</termName><termType>ND</termType></relation><relation><relationType>BT</relationType><termId>31348920</termId><termName>aircraft propellers</termName><termType>PT</termType></relation></term>  </Zthes>