<?xml version="1.0" encoding="US-ASCII"?>
<!-- Generated by DFIN XBRL Schema Document - http://www.dfinsolutions.com/ - on 30-06-2026 01:28:49 PM -->
<!-- Copyright(c) 2026 Donnelley Financial Solutions, Inc. All Rights Reserved. -->
<schema targetNamespace="http://www.ftportfolios.com/20260623" xmlns="http://www.w3.org/2001/XMLSchema" xmlns:ftsf="http://www.ftportfolios.com/20260623" xmlns:dei="http://xbrl.sec.gov/dei/2025" xmlns:srt-types="http://fasb.org/srt-types/2025" xmlns:deprecated="http://www.xbrl.org/2009/role/deprecated" xmlns:dtr="http://www.xbrl.org/2009/dtr" xmlns:oef="http://xbrl.sec.gov/oef/2025" xmlns:ref="http://www.xbrl.org/2006/ref" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xmlns:xl="http://www.xbrl.org/2003/XLink" xmlns:us-gaap="http://fasb.org/us-gaap/2025" xmlns:oef-pre="http://xbrl.sec.gov/oef-pre/2025" xmlns:oef-lab="http://xbrl.sec.gov/oef-lab/2025" xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:country="http://xbrl.sec.gov/country/2025" xmlns:us-roles="http://fasb.org/us-roles/2025" xmlns:enum2="http://xbrl.org/2020/extensible-enumerations-2.0" xmlns:us-types="http://fasb.org/us-types/2025" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:dtr-types="http://www.xbrl.org/dtr/type/2024-01-31" xmlns:oef-def="http://xbrl.sec.gov/oef-def/2025" xmlns:negated="http://www.xbrl.org/2009/role/negated" xmlns:xbrldi="http://xbrl.org/2006/xbrldi" xmlns:srt="http://fasb.org/srt/2025" xmlns:oef-sr="http://xbrl.sec.gov/oef-sr/2025" xmlns:srt-roles="http://fasb.org/srt-roles/2025" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xbrli="http://www.xbrl.org/2003/instance" xmlns:stpr="http://xbrl.sec.gov/stpr/2025" elementFormDefault="qualified">
	<import namespace="http://www.xbrl.org/2003/instance" schemaLocation="http://www.xbrl.org/2003/xbrl-instance-2003-12-31.xsd"/>
	<import namespace="http://www.xbrl.org/2003/linkbase" schemaLocation="http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd"/>
	<import namespace="http://xbrl.sec.gov/dei/2025" schemaLocation="https://xbrl.sec.gov/dei/2025/dei-2025.xsd"/>
	<import namespace="http://fasb.org/us-types/2025" schemaLocation="https://xbrl.fasb.org/us-gaap/2025/elts/us-types-2025.xsd"/>
	<import namespace="http://www.xbrl.org/dtr/type/2024-01-31" schemaLocation="https://www.xbrl.org/dtr/type/2024-01-31/types.xsd"/>   
	<import namespace="http://xbrl.sec.gov/country/2025" schemaLocation="https://xbrl.sec.gov/country/2025/country-2025.xsd"/>
	<import namespace="http://fasb.org/srt/2025" schemaLocation="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd"/>
	<import namespace="http://fasb.org/srt-types/2025" schemaLocation="https://xbrl.fasb.org/srt/2025/elts/srt-types-2025.xsd"/>
	<import namespace="http://xbrl.sec.gov/oef-sr/2025" schemaLocation="https://xbrl.sec.gov/oef/2025/oef-sr-2025.xsd"/>
	<import namespace="http://fasb.org/us-gaap/2025" schemaLocation="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd"/>
	<import namespace="http://fasb.org/us-roles/2025" schemaLocation="https://xbrl.fasb.org/us-gaap/2025/elts/us-roles-2025.xsd"/>
	<import namespace="http://fasb.org/srt-roles/2025" schemaLocation="https://xbrl.fasb.org/srt/2025/elts/srt-roles-2025.xsd"/>
	<annotation>
		<appinfo>
			<link:linkbase id="lnk">
				<link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member"/>
				<link:roleRef roleURI="http://xbrl.sec.gov/oef/role/ShareholderReport" xlink:type="simple" xlink:href="https://xbrl.sec.gov/oef/2025/oef-2025.xsd#ShareholderReport"/>
				<link:roleRef roleURI="http://xbrl.sec.gov/oef/role/ShareholderReportHoldingsDetails" xlink:type="simple" xlink:href="https://xbrl.sec.gov/oef/2025/oef-2025.xsd#ShareholderReportHoldingsDetails"/>
				<link:roleRef roleURI="http://xbrl.sec.gov/oef/role/ShareholderReportLineGraphDetails" xlink:type="simple" xlink:href="https://xbrl.sec.gov/oef/2025/oef-2025.xsd#ShareholderReportLineGraphDetails"/>
				<link:roleRef roleURI="http://xbrl.sec.gov/oef/role/ShareholderReportAverageAnnualReturnDetails" xlink:type="simple" xlink:href="https://xbrl.sec.gov/oef/2025/oef-2025.xsd#ShareholderReportAverageAnnualReturnDetails"/>
				<link:roleRef roleURI="http://xbrl.sec.gov/oef/role/ClassOnly" xlink:type="simple" xlink:href="https://xbrl.sec.gov/oef/2025/oef-2025.xsd#ClassOnly"/>
				<link:roleRef roleURI="http://fasb.org/us-gaap/role/eedm/ExtensibleEnumerationLists" xlink:type="simple" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-roles-2025.xsd#eedm"/>
				<link:roleRef roleURI="http://xbrl.sec.gov/oef/role/LargestHoldingOnly" xlink:type="simple" xlink:href="https://xbrl.sec.gov/oef/2025/oef-2025.xsd#LargestHoldingOnly"/>
				<link:roleRef roleURI="http://xbrl.sec.gov/oef/role/Other1CategoryOnly" xlink:type="simple" xlink:href="https://xbrl.sec.gov/oef/2025/oef-2025.xsd#Other1CategoryOnly"/>
				<link:roleRef roleURI="http://xbrl.sec.gov/oef/role/AdditionalIndexOnly" xlink:type="simple" xlink:href="https://xbrl.sec.gov/oef/2025/oef-2025.xsd#AdditionalIndexOnly"/>
				<link:roleRef roleURI="http://xbrl.sec.gov/oef/role/BroadBasedIndexOnly" xlink:type="simple" xlink:href="https://xbrl.sec.gov/oef/2025/oef-2025.xsd#BroadBasedIndexOnly"/>
				<link:roleRef roleURI="http://xbrl.sec.gov/oef/role/Other2CategoryOnly" xlink:type="simple" xlink:href="https://xbrl.sec.gov/oef/2025/oef-2025.xsd#Other2CategoryOnly"/>
				<link:roleRef roleURI="http://xbrl.sec.gov/oef/role/SalesLoadOnly" xlink:type="simple" xlink:href="https://xbrl.sec.gov/oef/2025/oef-2025.xsd#SalesLoadOnly"/>
				<link:roleRef roleURI="http://xbrl.sec.gov/oef/role/MaturityOnly" xlink:type="simple" xlink:href="https://xbrl.sec.gov/oef/2025/oef-2025.xsd#MaturityOnly"/>
				<link:roleRef roleURI="http://xbrl.sec.gov/oef/role/IndustrySectorOnly" xlink:type="simple" xlink:href="https://xbrl.sec.gov/oef/2025/oef-2025.xsd#IndustrySectorOnly"/>
				<link:roleRef roleURI="http://xbrl.sec.gov/oef/role/CreditQualityOnly" xlink:type="simple" xlink:href="https://xbrl.sec.gov/oef/2025/oef-2025.xsd#CreditQualityOnly"/>
				<link:roleRef roleURI="http://xbrl.sec.gov/oef/role/GeographicRegionOnly" xlink:type="simple" xlink:href="https://xbrl.sec.gov/oef/2025/oef-2025.xsd#GeographicRegionOnly"/>
				<link:presentationLink xlink:type="extended" xlink:role="http://xbrl.sec.gov/oef/role/ShareholderReport">              
					<link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/oef/2025/oef-2025.xsd#oef_ShareClassDomain" xlink:label="ShareClassDomain"/>
					<link:loc xlink:type="locator" xlink:href="#ftsf_C000092936Member" xlink:label="C000092936Member"/>
					<link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="ShareClassDomain" xlink:to="C000092936Member" order="2.0" />
					<link:loc xlink:type="locator" xlink:href="#ftsf_C000092935Member" xlink:label="C000092935Member"/>
					<link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="ShareClassDomain" xlink:to="C000092935Member" order="3.0" />
					<link:loc xlink:type="locator" xlink:href="#ftsf_C000092934Member" xlink:label="C000092934Member"/>
					<link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="ShareClassDomain" xlink:to="C000092934Member" order="4.0" />
					<link:loc xlink:type="locator" xlink:href="#ftsf_C000092933Member" xlink:label="C000092933Member"/>
					<link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="ShareClassDomain" xlink:to="C000092933Member" order="5.0" />
					<link:loc xlink:type="locator" xlink:href="#ftsf_C000092932Member" xlink:label="C000092932Member"/>
					<link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="ShareClassDomain" xlink:to="C000092932Member" order="6.0" />
					<link:loc xlink:type="locator" xlink:href="#ftsf_C000118178Member" xlink:label="C000118178Member"/>
					<link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="ShareClassDomain" xlink:to="C000118178Member" order="7.0" />
					<link:loc xlink:type="locator" xlink:href="#ftsf_C000121471Member" xlink:label="C000121471Member"/>
					<link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="ShareClassDomain" xlink:to="C000121471Member" order="8.0" />
					<link:loc xlink:type="locator" xlink:href="#ftsf_C000121472Member" xlink:label="C000121472Member"/>
					<link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="ShareClassDomain" xlink:to="C000121472Member" order="9.0" />
					<link:loc xlink:type="locator" xlink:href="#ftsf_C000232961Member" xlink:label="C000232961Member"/>
					<link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="ShareClassDomain" xlink:to="C000232961Member" order="10.0" />
					<link:loc xlink:type="locator" xlink:href="#ftsf_C000232962Member" xlink:label="C000232962Member"/>
					<link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="ShareClassDomain" xlink:to="C000232962Member" order="11.0" />
				</link:presentationLink>
				<link:presentationLink xlink:type="extended" xlink:role="http://xbrl.sec.gov/oef/role/ShareholderReportHoldingsDetails">               
					<link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/oef/2025/oef-2025.xsd#oef_ShareClassDomain" xlink:label="ShareClassDomain"/>
					<link:loc xlink:type="locator" xlink:href="#ftsf_C000092936Member" xlink:label="C000092936Member"/>
					<link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="ShareClassDomain" xlink:to="C000092936Member" order="2.0" />
					<link:loc xlink:type="locator" xlink:href="#ftsf_C000092935Member" xlink:label="C000092935Member"/>
					<link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="ShareClassDomain" xlink:to="C000092935Member" order="3.0" />
					<link:loc xlink:type="locator" xlink:href="#ftsf_C000092934Member" xlink:label="C000092934Member"/>
					<link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="ShareClassDomain" xlink:to="C000092934Member" order="4.0" />
					<link:loc xlink:type="locator" xlink:href="#ftsf_C000092933Member" xlink:label="C000092933Member"/>
					<link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="ShareClassDomain" xlink:to="C000092933Member" order="5.0" />
					<link:loc xlink:type="locator" xlink:href="#ftsf_C000092932Member" xlink:label="C000092932Member"/>
					<link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="ShareClassDomain" xlink:to="C000092932Member" order="6.0" />
					<link:loc xlink:type="locator" xlink:href="#ftsf_C000118178Member" xlink:label="C000118178Member"/>
					<link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="ShareClassDomain" xlink:to="C000118178Member" order="7.0" />
					<link:loc xlink:type="locator" xlink:href="#ftsf_C000121471Member" xlink:label="C000121471Member"/>
					<link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="ShareClassDomain" xlink:to="C000121471Member" order="8.0" />
					<link:loc xlink:type="locator" xlink:href="#ftsf_C000121472Member" xlink:label="C000121472Member"/>
					<link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="ShareClassDomain" xlink:to="C000121472Member" order="9.0" />
					<link:loc xlink:type="locator" xlink:href="#ftsf_C000232961Member" xlink:label="C000232961Member"/>
					<link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="ShareClassDomain" xlink:to="C000232961Member" order="10.0" />
					<link:loc xlink:type="locator" xlink:href="#ftsf_C000232962Member" xlink:label="C000232962Member"/>
					<link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="ShareClassDomain" xlink:to="C000232962Member" order="11.0" />   
					<link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InvestmentTypeCategorizationMember" xlink:label="InvestmentTypeCategorizationMember"/>
					<link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MoneyMarketFundsMember" xlink:label="MoneyMarketFundsMember"/>
					<link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="InvestmentTypeCategorizationMember" xlink:to="MoneyMarketFundsMember" order="2.0" />
					<link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockMember" xlink:label="CommonStockMember"/>
					<link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="InvestmentTypeCategorizationMember" xlink:to="CommonStockMember" order="3.0" />
					<link:loc xlink:type="locator" xlink:href="#ftsf_CorporateBondsAndNotesMember" xlink:label="CorporateBondsAndNotesMember"/>
					<link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="InvestmentTypeCategorizationMember" xlink:to="CorporateBondsAndNotesMember" order="4.0" />
					<link:loc xlink:type="locator" xlink:href="#ftsf_SeniorFloatingRateLoanInterestsMember" xlink:label="SeniorFloatingRateLoanInterestsMember"/>
					<link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="InvestmentTypeCategorizationMember" xlink:to="SeniorFloatingRateLoanInterestsMember" order="5.0" />
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					<link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="InvestmentTypeCategorizationMember" xlink:to="ForeignCorporateBondsAndNotesMember" order="6.0" />
					<link:loc xlink:type="locator" xlink:href="#ftsf_NetOtherAssetsAndLiabilitiesMember" xlink:label="NetOtherAssetsAndLiabilitiesMember"/>
					<link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="InvestmentTypeCategorizationMember" xlink:to="NetOtherAssetsAndLiabilitiesMember" order="7.0" />
					<link:loc xlink:type="locator" xlink:href="#ftsf_IndustrialDevelopmentBondMember" xlink:label="IndustrialDevelopmentBondMember"/>
					<link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="InvestmentTypeCategorizationMember" xlink:to="IndustrialDevelopmentBondMember" order="8.0" />
					<link:loc xlink:type="locator" xlink:href="#ftsf_ContinuingCareRetirementCommunitiesMember" xlink:label="ContinuingCareRetirementCommunitiesMember"/>
					<link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="InvestmentTypeCategorizationMember" xlink:to="ContinuingCareRetirementCommunitiesMember" order="9.0" />
					<link:loc xlink:type="locator" xlink:href="#ftsf_GovernmentObligationBondUnlimitedTaxMember" xlink:label="GovernmentObligationBondUnlimitedTaxMember"/>
					<link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="InvestmentTypeCategorizationMember" xlink:to="GovernmentObligationBondUnlimitedTaxMember" order="10.0" />
					<link:loc xlink:type="locator" xlink:href="#ftsf_CertificatesOfParticipationMember" xlink:label="CertificatesOfParticipationMember"/>
					<link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="InvestmentTypeCategorizationMember" xlink:to="CertificatesOfParticipationMember" order="11.0" />
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					<link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/oef/2025/oef-2025.xsd#oef_OtherCategory1Domain" xlink:label="OtherCategory1Domain"/>
					<link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/oef/2025/oef-2025.xsd#oef_OtherCategory2Domain" xlink:label="OtherCategory2Domain"/>
					<link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/oef/2025/oef-2025.xsd#oef_LargestHoldingsDomain" xlink:label="LargestHoldingsDomain"/>
					<link:loc xlink:type="locator" xlink:href="#ftsf_XcelEnergyInc625101585Member" xlink:label="XcelEnergyInc625101585Member"/>
					<link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="LargestHoldingsDomain" xlink:to="XcelEnergyInc625101585Member" order="2.0" />
					<link:loc xlink:type="locator" xlink:href="#ftsf_AmericanAgCreditCorp525Member" xlink:label="AmericanAgCreditCorp525Member"/>
					<link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="LargestHoldingsDomain" xlink:to="AmericanAgCreditCorp525Member" order="3.0" />
					<link:loc xlink:type="locator" xlink:href="#ftsf_BNPParibasSA850Member" xlink:label="BNPParibasSA850Member"/>
					<link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="LargestHoldingsDomain" xlink:to="BNPParibasSA850Member" order="4.0" />
					<link:loc xlink:type="locator" xlink:href="#ftsf_NextEraEnergyCapitalHoldingsIncSeriesU650060185Member" xlink:label="NextEraEnergyCapitalHoldingsIncSeriesU650060185Member"/>
					<link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="LargestHoldingsDomain" xlink:to="NextEraEnergyCapitalHoldingsIncSeriesU650060185Member" order="5.0" />
					<link:loc xlink:type="locator" xlink:href="#ftsf_HartfordInsuranceGroupTheInc604021247Member" xlink:label="HartfordInsuranceGroupTheInc604021247Member"/>
					<link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="LargestHoldingsDomain" xlink:to="HartfordInsuranceGroupTheInc604021247Member" order="6.0" />
					<link:loc xlink:type="locator" xlink:href="#ftsf_LandOLakesInc800Member" xlink:label="LandOLakesInc800Member"/>
					<link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="LargestHoldingsDomain" xlink:to="LandOLakesInc800Member" order="7.0" />
					<link:loc xlink:type="locator" xlink:href="#ftsf_CreditAgricoleSA713Member" xlink:label="CreditAgricoleSA713Member"/>
					<link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="LargestHoldingsDomain" xlink:to="CreditAgricoleSA713Member" order="8.0" />
					<link:loc xlink:type="locator" xlink:href="#ftsf_BarclaysPLC800Member" xlink:label="BarclaysPLC800Member"/>
					<link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="LargestHoldingsDomain" xlink:to="BarclaysPLC800Member" order="9.0" />
					<link:loc xlink:type="locator" xlink:href="#ftsf_WellsFargoAndCoSeriesL750Member" xlink:label="WellsFargoAndCoSeriesL750Member"/>
					<link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="LargestHoldingsDomain" xlink:to="WellsFargoAndCoSeriesL750Member" order="10.0" />
					<link:loc xlink:type="locator" xlink:href="#ftsf_BankOfAmericaCorp663Member" xlink:label="BankOfAmericaCorp663Member"/>
					<link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="LargestHoldingsDomain" xlink:to="BankOfAmericaCorp663Member" order="11.0" />
					<!--GeographicRegionDomain Only presentation and label linkbases-->			 
					<link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/oef/2025/oef-2025.xsd#oef_GeographicRegionDomain" xlink:label="GeographicRegionDomain"/>
					<!--IndustrySectorDomain Only presentation and label linkbases-->	
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					<link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="LargestHoldingsDomain" xlink:to="XcelEnergyInc625101585Member" order="1.0"/>
					<link:loc xlink:type="locator" xlink:href="#ftsf_AmericanAgCreditCorp525Member" xlink:label="AmericanAgCreditCorp525Member"/>
					<link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="LargestHoldingsDomain" xlink:to="AmericanAgCreditCorp525Member" order="2.0"/>
					<link:loc xlink:type="locator" xlink:href="#ftsf_BNPParibasSA850Member" xlink:label="BNPParibasSA850Member"/>
					<link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="LargestHoldingsDomain" xlink:to="BNPParibasSA850Member" order="3.0"/>
					<link:loc xlink:type="locator" xlink:href="#ftsf_NextEraEnergyCapitalHoldingsIncSeriesU650060185Member" xlink:label="NextEraEnergyCapitalHoldingsIncSeriesU650060185Member"/>
					<link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="LargestHoldingsDomain" xlink:to="NextEraEnergyCapitalHoldingsIncSeriesU650060185Member" order="4.0"/>
					<link:loc xlink:type="locator" xlink:href="#ftsf_HartfordInsuranceGroupTheInc604021247Member" xlink:label="HartfordInsuranceGroupTheInc604021247Member"/>
					<link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="LargestHoldingsDomain" xlink:to="HartfordInsuranceGroupTheInc604021247Member" order="5.0"/>
					<link:loc xlink:type="locator" xlink:href="#ftsf_LandOLakesInc800Member" xlink:label="LandOLakesInc800Member"/>
					<link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="LargestHoldingsDomain" xlink:to="LandOLakesInc800Member" order="6.0"/>
					<link:loc xlink:type="locator" xlink:href="#ftsf_CreditAgricoleSA713Member" xlink:label="CreditAgricoleSA713Member"/>
					<link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="LargestHoldingsDomain" xlink:to="CreditAgricoleSA713Member" order="7.0"/>
					<link:loc xlink:type="locator" xlink:href="#ftsf_BarclaysPLC800Member" xlink:label="BarclaysPLC800Member"/>
					<link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="LargestHoldingsDomain" xlink:to="BarclaysPLC800Member" order="8.0"/>
					<link:loc xlink:type="locator" xlink:href="#ftsf_WellsFargoAndCoSeriesL750Member" xlink:label="WellsFargoAndCoSeriesL750Member"/>
					<link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="LargestHoldingsDomain" xlink:to="WellsFargoAndCoSeriesL750Member" order="9.0"/>
					<link:loc xlink:type="locator" xlink:href="#ftsf_BankOfAmericaCorp663Member" xlink:label="BankOfAmericaCorp663Member"/>
					<link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="LargestHoldingsDomain" xlink:to="BankOfAmericaCorp663Member" order="10.0"/>
				</link:definitionLink>
				<link:definitionLink xlink:type="extended" xlink:role="http://xbrl.sec.gov/oef/role/SalesLoadOnly">
					<link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/oef/2025/oef-2025.xsd#oef_WithSalesLoadMember" xlink:label="WithSalesLoadMember"/>
				</link:definitionLink>
				<link:definitionLink xlink:type="extended" xlink:role="http://fasb.org/us-gaap/role/eedm/ExtensibleEnumerationLists">               
					<link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InvestmentTypeCategorizationMember" xlink:label="InvestmentTypeCategorizationMember"/>
					<link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MoneyMarketFundsMember" xlink:label="MoneyMarketFundsMember"/>
					<link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="InvestmentTypeCategorizationMember" xlink:to="MoneyMarketFundsMember" order="1.0"/>
					<link:loc xlink:type="locator" xlink:href="#ftsf_CorporateBondsAndNotesMember" xlink:label="CorporateBondsAndNotesMember"/>
					<link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="InvestmentTypeCategorizationMember" xlink:to="CorporateBondsAndNotesMember" order="2.0"/>
					<link:loc xlink:type="locator" xlink:href="#ftsf_SeniorFloatingRateLoanInterestsMember" xlink:label="SeniorFloatingRateLoanInterestsMember"/>
					<link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="InvestmentTypeCategorizationMember" xlink:to="SeniorFloatingRateLoanInterestsMember" order="3.0"/>
					<link:loc xlink:type="locator" xlink:href="#ftsf_ForeignCorporateBondsAndNotesMember" xlink:label="ForeignCorporateBondsAndNotesMember"/>
					<link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="InvestmentTypeCategorizationMember" xlink:to="ForeignCorporateBondsAndNotesMember" order="4.0"/>
					<link:loc xlink:type="locator" xlink:href="#ftsf_NetOtherAssetsAndLiabilitiesMember" xlink:label="NetOtherAssetsAndLiabilitiesMember"/>
					<link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="InvestmentTypeCategorizationMember" xlink:to="NetOtherAssetsAndLiabilitiesMember" order="5.0"/>
					<link:loc xlink:type="locator" xlink:href="#ftsf_IndustrialDevelopmentBondMember" xlink:label="IndustrialDevelopmentBondMember"/>
					<link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="InvestmentTypeCategorizationMember" xlink:to="IndustrialDevelopmentBondMember" order="6.0"/>
					<link:loc xlink:type="locator" xlink:href="#ftsf_ContinuingCareRetirementCommunitiesMember" xlink:label="ContinuingCareRetirementCommunitiesMember"/>
					<link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="InvestmentTypeCategorizationMember" xlink:to="ContinuingCareRetirementCommunitiesMember" order="7.0"/>
					<link:loc xlink:type="locator" xlink:href="#ftsf_GovernmentObligationBondUnlimitedTaxMember" xlink:label="GovernmentObligationBondUnlimitedTaxMember"/>
					<link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="InvestmentTypeCategorizationMember" xlink:to="GovernmentObligationBondUnlimitedTaxMember" order="8.0"/>
					<link:loc xlink:type="locator" xlink:href="#ftsf_CertificatesOfParticipationMember" xlink:label="CertificatesOfParticipationMember"/>
					<link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="InvestmentTypeCategorizationMember" xlink:to="CertificatesOfParticipationMember" order="9.0"/>
				</link:definitionLink>
				<link:definitionLink xlink:type="extended" xlink:role="http://xbrl.sec.gov/oef/role/BroadBasedIndexOnly">               
					<link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/oef/2025/oef-2025.xsd#oef_BroadBasedIndexDomain" xlink:label="BroadBasedIndexDomain"/>
				</link:definitionLink>
				<link:definitionLink xlink:type="extended" xlink:role="http://xbrl.sec.gov/oef/role/AdditionalIndexOnly">              
					<link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/oef/2025/oef-2025.xsd#oef_AdditionalIndexDomain" xlink:label="AdditionalIndexDomain"/>
				</link:definitionLink>
				<link:definitionLink xlink:type="extended" xlink:role="http://xbrl.sec.gov/oef/role/MaturityOnly">
					<link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/oef/2025/oef-2025.xsd#oef_MaturityDomain" xlink:label="MaturityDomain"/>
				</link:definitionLink>
				<link:definitionLink xlink:type="extended" xlink:role="http://xbrl.sec.gov/oef/role/IndustrySectorOnly">
					<link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/oef/2025/oef-2025.xsd#oef_IndustrySectorDomain" xlink:label="IndustrySectorDomain"/>
					<link:loc xlink:type="locator" xlink:href="#ftsf_GasMember" xlink:label="GasMember"/>
					<link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="IndustrySectorDomain" xlink:to="GasMember" order="1.0"/>
					<link:loc xlink:type="locator" xlink:href="#ftsf_InsuredMember" xlink:label="InsuredMember"/>
					<link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="IndustrySectorDomain" xlink:to="InsuredMember" order="2.0"/>
					<link:loc xlink:type="locator" xlink:href="#ftsf_AirportMember" xlink:label="AirportMember"/>
					<link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="IndustrySectorDomain" xlink:to="AirportMember" order="3.0"/>
					<link:loc xlink:type="locator" xlink:href="#ftsf_HospitalMember" xlink:label="HospitalMember"/>
					<link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="IndustrySectorDomain" xlink:to="HospitalMember" order="4.0"/>
				</link:definitionLink>
				<link:definitionLink xlink:type="extended" xlink:role="http://xbrl.sec.gov/oef/role/CreditQualityOnly">
					<link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/oef/2025/oef-2025.xsd#oef_CreditQualityDomain" xlink:label="CreditQualityDomain"/>
					<link:loc xlink:type="locator" xlink:href="#ftsf_NRMember" xlink:label="NRMember"/>
					<link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="CreditQualityDomain" xlink:to="NRMember" order="1.0"/>
					<link:loc xlink:type="locator" xlink:href="#ftsf_MoneyMarketFundsQualityMember" xlink:label="MoneyMarketFundsQualityMember"/>
					<link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="CreditQualityDomain" xlink:to="MoneyMarketFundsQualityMember" order="2.0"/>
				</link:definitionLink>
				<!--GeographicRegionOnly use only for STPR-->
				<link:definitionLink xlink:type="extended" xlink:role="http://xbrl.sec.gov/oef/role/GeographicRegionOnly">
					<link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/oef/2025/oef-2025.xsd#oef_GeographicRegionDomain" xlink:label="GeographicRegionDomain"/>
				</link:definitionLink>
				<link:labelLink xlink:type="extended" xlink:role="http://www.xbrl.org/2003/role/link">               
					<link:loc xlink:type="locator" xlink:href="#ftsf_XcelEnergyInc625101585Member" xlink:label="XcelEnergyInc625101585Member"/>
					<link:label xlink:type="resource" xlink:label="label_XcelEnergyInc625101585Member" xlink:role="http://www.xbrl.org/2003/role/label" xml:lang="en-US">Xcel Energy Inc 6 25 10 15 85 [Member]</link:label>
					<link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="XcelEnergyInc625101585Member" xlink:to="label_XcelEnergyInc625101585Member"/>
					<link:loc xlink:type="locator" xlink:href="#ftsf_AmericanAgCreditCorp525Member" xlink:label="AmericanAgCreditCorp525Member"/>
					<link:label xlink:type="resource" xlink:label="label_AmericanAgCreditCorp525Member" xlink:role="http://www.xbrl.org/2003/role/label" xml:lang="en-US">American AgCredit Corp 5 25 [Member]</link:label>
					<link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="AmericanAgCreditCorp525Member" xlink:to="label_AmericanAgCreditCorp525Member"/>
					<link:loc xlink:type="locator" xlink:href="#ftsf_BNPParibasSA850Member" xlink:label="BNPParibasSA850Member"/>
					<link:label xlink:type="resource" xlink:label="label_BNPParibasSA850Member" xlink:role="http://www.xbrl.org/2003/role/label" xml:lang="en-US">BNP Paribas S A 8 50 [Member]</link:label>
					<link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="BNPParibasSA850Member" xlink:to="label_BNPParibasSA850Member"/>
					<link:loc xlink:type="locator" xlink:href="#ftsf_NextEraEnergyCapitalHoldingsIncSeriesU650060185Member" xlink:label="NextEraEnergyCapitalHoldingsIncSeriesU650060185Member"/>
					<link:label xlink:type="resource" xlink:label="label_NextEraEnergyCapitalHoldingsIncSeriesU650060185Member" xlink:role="http://www.xbrl.org/2003/role/label" xml:lang="en-US">NextEra Energy Capital Holdings Inc Series U 6 50 06 01 85 [Member]</link:label>
					<link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="NextEraEnergyCapitalHoldingsIncSeriesU650060185Member" xlink:to="label_NextEraEnergyCapitalHoldingsIncSeriesU650060185Member"/>
					<link:loc xlink:type="locator" xlink:href="#ftsf_HartfordInsuranceGroupTheInc604021247Member" xlink:label="HartfordInsuranceGroupTheInc604021247Member"/>
					<link:label xlink:type="resource" xlink:label="label_HartfordInsuranceGroupTheInc604021247Member" xlink:role="http://www.xbrl.org/2003/role/label" xml:lang="en-US">Hartford Insurance Group The Inc 6 04 02 12 47 [Member]</link:label>
					<link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="HartfordInsuranceGroupTheInc604021247Member" xlink:to="label_HartfordInsuranceGroupTheInc604021247Member"/>
					<link:loc xlink:type="locator" xlink:href="#ftsf_LandOLakesInc800Member" xlink:label="LandOLakesInc800Member"/>
					<link:label xlink:type="resource" xlink:label="label_LandOLakesInc800Member" xlink:role="http://www.xbrl.org/2003/role/label" xml:lang="en-US">Land O Lakes Inc 8 00 [Member]</link:label>
					<link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="LandOLakesInc800Member" xlink:to="label_LandOLakesInc800Member"/>
					<link:loc xlink:type="locator" xlink:href="#ftsf_CreditAgricoleSA713Member" xlink:label="CreditAgricoleSA713Member"/>
					<link:label xlink:type="resource" xlink:label="label_CreditAgricoleSA713Member" xlink:role="http://www.xbrl.org/2003/role/label" xml:lang="en-US">Credit Agricole S A 7 13 [Member]</link:label>
					<link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="CreditAgricoleSA713Member" xlink:to="label_CreditAgricoleSA713Member"/>
					<link:loc xlink:type="locator" xlink:href="#ftsf_BarclaysPLC800Member" xlink:label="BarclaysPLC800Member"/>
					<link:label xlink:type="resource" xlink:label="label_BarclaysPLC800Member" xlink:role="http://www.xbrl.org/2003/role/label" xml:lang="en-US">Barclays PLC 8 00 [Member]</link:label>
					<link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="BarclaysPLC800Member" xlink:to="label_BarclaysPLC800Member"/>
					<link:loc xlink:type="locator" xlink:href="#ftsf_WellsFargoAndCoSeriesL750Member" xlink:label="WellsFargoAndCoSeriesL750Member"/>
					<link:label xlink:type="resource" xlink:label="label_WellsFargoAndCoSeriesL750Member" xlink:role="http://www.xbrl.org/2003/role/label" xml:lang="en-US">Wells Fargo And Co Series L 7 50 [Member]</link:label>
					<link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="WellsFargoAndCoSeriesL750Member" xlink:to="label_WellsFargoAndCoSeriesL750Member"/>
					<link:loc xlink:type="locator" xlink:href="#ftsf_BankOfAmericaCorp663Member" xlink:label="BankOfAmericaCorp663Member"/>
					<link:label xlink:type="resource" xlink:label="label_BankOfAmericaCorp663Member" xlink:role="http://www.xbrl.org/2003/role/label" xml:lang="en-US">Bank of America Corp 6 63 [Member]</link:label>
					<link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="BankOfAmericaCorp663Member" xlink:to="label_BankOfAmericaCorp663Member"/>
					<link:loc xlink:type="locator" xlink:href="#ftsf_C000092936Member" xlink:label="C000092936Member"/>
					<link:label xlink:type="resource" xlink:label="label_C000092936Member" xlink:role="http://www.xbrl.org/2003/role/label" xml:lang="en-US">C000092936 [Member]</link:label>
					<link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="C000092936Member" xlink:to="label_C000092936Member"/>
										<link:label xlink:type="resource" xlink:label="label_C000092936Member_2" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xml:lang="en-US">Class R3</link:label>
					<link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="C000092936Member" xlink:to="label_C000092936Member_2"/>
					<link:loc xlink:type="locator" xlink:href="#ftsf_C000092935Member" xlink:label="C000092935Member"/>
					<link:label xlink:type="resource" xlink:label="label_C000092935Member" xlink:role="http://www.xbrl.org/2003/role/label" xml:lang="en-US">C000092935 [Member]</link:label>
					<link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="C000092935Member" xlink:to="label_C000092935Member"/>
										<link:label xlink:type="resource" xlink:label="label_C000092935Member_2" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xml:lang="en-US">Class I</link:label>
					<link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="C000092935Member" xlink:to="label_C000092935Member_2"/>
					<link:loc xlink:type="locator" xlink:href="#ftsf_C000092934Member" xlink:label="C000092934Member"/>
					<link:label xlink:type="resource" xlink:label="label_C000092934Member" xlink:role="http://www.xbrl.org/2003/role/label" xml:lang="en-US">C000092934 [Member]</link:label>
					<link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="C000092934Member" xlink:to="label_C000092934Member"/>
										<link:label xlink:type="resource" xlink:label="label_C000092934Member_2" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xml:lang="en-US">Class F</link:label>
					<link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="C000092934Member" xlink:to="label_C000092934Member_2"/>
					<link:loc xlink:type="locator" xlink:href="#ftsf_C000092933Member" xlink:label="C000092933Member"/>
					<link:label xlink:type="resource" xlink:label="label_C000092933Member" xlink:role="http://www.xbrl.org/2003/role/label" xml:lang="en-US">C000092933 [Member]</link:label>
					<link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="C000092933Member" xlink:to="label_C000092933Member"/>
										<link:label xlink:type="resource" xlink:label="label_C000092933Member_2" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xml:lang="en-US">Class C</link:label>
					<link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="C000092933Member" xlink:to="label_C000092933Member_2"/>
					<link:loc xlink:type="locator" xlink:href="#ftsf_C000092932Member" xlink:label="C000092932Member"/>
					<link:label xlink:type="resource" xlink:label="label_C000092932Member" xlink:role="http://www.xbrl.org/2003/role/label" xml:lang="en-US">C000092932 [Member]</link:label>
					<link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="C000092932Member" xlink:to="label_C000092932Member"/>
										<link:label xlink:type="resource" xlink:label="label_C000092932Member_2" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xml:lang="en-US">Class A</link:label>
					<link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="C000092932Member" xlink:to="label_C000092932Member_2"/>
					<link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RealEstateSectorMember" xlink:label="RealEstateSectorMember"/>
					<link:label xlink:type="resource" xlink:label="label_RealEstateSectorMember" xlink:role="http://www.xbrl.org/2003/role/label" xml:lang="en-US">Real Estate Sector [Member]</link:label>
					<link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="RealEstateSectorMember" xlink:to="label_RealEstateSectorMember"/>
					<link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancialServicesSectorMember" xlink:label="FinancialServicesSectorMember"/>
					<link:label xlink:type="resource" xlink:label="label_FinancialServicesSectorMember" xlink:role="http://www.xbrl.org/2003/role/label" xml:lang="en-US">Financial Services Sector [Member]</link:label>
					<link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="FinancialServicesSectorMember" xlink:to="label_FinancialServicesSectorMember"/>
					<link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EnergySectorMember" xlink:label="EnergySectorMember"/>
					<link:label xlink:type="resource" xlink:label="label_EnergySectorMember" xlink:role="http://www.xbrl.org/2003/role/label" xml:lang="en-US">Energy Sector [Member]</link:label>
					<link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="EnergySectorMember" xlink:to="label_EnergySectorMember"/>
					<link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_StandardPoorsBBBRatingMember" xlink:label="StandardPoorsBBBRatingMember"/>
					<link:label xlink:type="resource" xlink:label="label_StandardPoorsBBBRatingMember" xlink:role="http://www.xbrl.org/2003/role/label" xml:lang="en-US">Standard &amp; Poor&apos;s, BBB Rating [Member]</link:label>
					<link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="StandardPoorsBBBRatingMember" xlink:to="label_StandardPoorsBBBRatingMember"/>
					<link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_StandardPoorsBBRatingMember" xlink:label="StandardPoorsBBRatingMember"/>
					<link:label xlink:type="resource" xlink:label="label_StandardPoorsBBRatingMember" xlink:role="http://www.xbrl.org/2003/role/label" xml:lang="en-US">Standard &amp; Poor&apos;s, BB Rating [Member]</link:label>
					<link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="StandardPoorsBBRatingMember" xlink:to="label_StandardPoorsBBRatingMember"/>
					<link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_StandardPoorsBRatingMember" xlink:label="StandardPoorsBRatingMember"/>
					<link:label xlink:type="resource" xlink:label="label_StandardPoorsBRatingMember" xlink:role="http://www.xbrl.org/2003/role/label" xml:lang="en-US">Standard &amp; Poor&apos;s, B Rating [Member]</link:label>
					<link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="StandardPoorsBRatingMember" xlink:to="label_StandardPoorsBRatingMember"/>
					<link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_StandardPoorsCCCRatingMember" xlink:label="StandardPoorsCCCRatingMember"/>
					<link:label xlink:type="resource" xlink:label="label_StandardPoorsCCCRatingMember" xlink:role="http://www.xbrl.org/2003/role/label" xml:lang="en-US">Standard &amp; Poor&apos;s, CCC Rating [Member]</link:label>
					<link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="StandardPoorsCCCRatingMember" xlink:to="label_StandardPoorsCCCRatingMember"/>
					<link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MoneyMarketFundsMember" xlink:label="MoneyMarketFundsMember"/>
					<link:label xlink:type="resource" xlink:label="label_MoneyMarketFundsMember" xlink:role="http://www.xbrl.org/2003/role/label" xml:lang="en-US">Money Market Funds [Member]</link:label>
					<link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="MoneyMarketFundsMember" xlink:to="label_MoneyMarketFundsMember"/>
					<link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockMember" xlink:label="CommonStockMember"/>
					<link:label xlink:type="resource" xlink:label="label_CommonStockMember" xlink:role="http://www.xbrl.org/2003/role/label" xml:lang="en-US">Common Stock [Member]</link:label>
					<link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="CommonStockMember" xlink:to="label_CommonStockMember"/>
					<link:loc xlink:type="locator" xlink:href="#ftsf_C000118178Member" xlink:label="C000118178Member"/>
					<link:label xlink:type="resource" xlink:label="label_C000118178Member" xlink:role="http://www.xbrl.org/2003/role/label" xml:lang="en-US">C000118178 [Member]</link:label>
					<link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="C000118178Member" xlink:to="label_C000118178Member"/>
					<link:loc xlink:type="locator" xlink:href="#ftsf_C000121471Member" xlink:label="C000121471Member"/>
					<link:label xlink:type="resource" xlink:label="label_C000121471Member" xlink:role="http://www.xbrl.org/2003/role/label" xml:lang="en-US">C000121471 [Member]</link:label>
					<link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="C000121471Member" xlink:to="label_C000121471Member"/>
					<link:loc xlink:type="locator" xlink:href="#ftsf_C000121472Member" xlink:label="C000121472Member"/>
					<link:label xlink:type="resource" xlink:label="label_C000121472Member" xlink:role="http://www.xbrl.org/2003/role/label" xml:lang="en-US">C000121472 [Member]</link:label>
					<link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="C000121472Member" xlink:to="label_C000121472Member"/>
					<link:loc xlink:type="locator" xlink:href="#ftsf_CorporateBondsAndNotesMember" xlink:label="CorporateBondsAndNotesMember"/>
					<link:label xlink:type="resource" xlink:label="label_CorporateBondsAndNotesMember" xlink:role="http://www.xbrl.org/2003/role/label" xml:lang="en-US">Corporate Bonds and Notes [Member]</link:label>
					<link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="CorporateBondsAndNotesMember" xlink:to="label_CorporateBondsAndNotesMember"/>
					<link:loc xlink:type="locator" xlink:href="#ftsf_SeniorFloatingRateLoanInterestsMember" xlink:label="SeniorFloatingRateLoanInterestsMember"/>
					<link:label xlink:type="resource" xlink:label="label_SeniorFloatingRateLoanInterestsMember" xlink:role="http://www.xbrl.org/2003/role/label" xml:lang="en-US">Senior Floating Rate Loan Interests [Member]</link:label>
					<link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="SeniorFloatingRateLoanInterestsMember" xlink:to="label_SeniorFloatingRateLoanInterestsMember"/>
					<link:loc xlink:type="locator" xlink:href="#ftsf_ForeignCorporateBondsAndNotesMember" xlink:label="ForeignCorporateBondsAndNotesMember"/>
					<link:label xlink:type="resource" xlink:label="label_ForeignCorporateBondsAndNotesMember" xlink:role="http://www.xbrl.org/2003/role/label" xml:lang="en-US">Foreign Corporate Bonds and Notes [Member]</link:label>
					<link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="ForeignCorporateBondsAndNotesMember" xlink:to="label_ForeignCorporateBondsAndNotesMember"/>
					<link:loc xlink:type="locator" xlink:href="#ftsf_NetOtherAssetsAndLiabilitiesMember" xlink:label="NetOtherAssetsAndLiabilitiesMember"/>
					<link:label xlink:type="resource" xlink:label="label_NetOtherAssetsAndLiabilitiesMember" xlink:role="http://www.xbrl.org/2003/role/label" xml:lang="en-US">Net Other Assets and Liabilities [Member]</link:label>
					<link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="NetOtherAssetsAndLiabilitiesMember" xlink:to="label_NetOtherAssetsAndLiabilitiesMember"/>
					<link:loc xlink:type="locator" xlink:href="#ftsf_NRMember" xlink:label="NRMember"/>
					<link:label xlink:type="resource" xlink:label="label_NRMember" xlink:role="http://www.xbrl.org/2003/role/label" xml:lang="en-US">NR [Member]</link:label>
					<link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="NRMember" xlink:to="label_NRMember"/>
					<link:loc xlink:type="locator" xlink:href="#ftsf_MoneyMarketFundsQualityMember" xlink:label="MoneyMarketFundsQualityMember"/>
					<link:label xlink:type="resource" xlink:label="label_MoneyMarketFundsQualityMember" xlink:role="http://www.xbrl.org/2003/role/label" xml:lang="en-US">Money Market Funds Quality [Member]</link:label>
					<link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="MoneyMarketFundsQualityMember" xlink:to="label_MoneyMarketFundsQualityMember"/>
					<link:loc xlink:type="locator" xlink:href="#ftsf_IndustrialDevelopmentBondMember" xlink:label="IndustrialDevelopmentBondMember"/>
					<link:label xlink:type="resource" xlink:label="label_IndustrialDevelopmentBondMember" xlink:role="http://www.xbrl.org/2003/role/label" xml:lang="en-US">Industrial Development Bond [Member]</link:label>
					<link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="IndustrialDevelopmentBondMember" xlink:to="label_IndustrialDevelopmentBondMember"/>
					<link:loc xlink:type="locator" xlink:href="#ftsf_ContinuingCareRetirementCommunitiesMember" xlink:label="ContinuingCareRetirementCommunitiesMember"/>
					<link:label xlink:type="resource" xlink:label="label_ContinuingCareRetirementCommunitiesMember" xlink:role="http://www.xbrl.org/2003/role/label" xml:lang="en-US">Continuing Care Retirement Communities [Member]</link:label>
					<link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="ContinuingCareRetirementCommunitiesMember" xlink:to="label_ContinuingCareRetirementCommunitiesMember"/>
					<link:loc xlink:type="locator" xlink:href="#ftsf_GovernmentObligationBondUnlimitedTaxMember" xlink:label="GovernmentObligationBondUnlimitedTaxMember"/>
					<link:label xlink:type="resource" xlink:label="label_GovernmentObligationBondUnlimitedTaxMember" xlink:role="http://www.xbrl.org/2003/role/label" xml:lang="en-US">Government Obligation Bond Unlimited Tax [Member]</link:label>
					<link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="GovernmentObligationBondUnlimitedTaxMember" xlink:to="label_GovernmentObligationBondUnlimitedTaxMember"/>
					<link:loc xlink:type="locator" xlink:href="#ftsf_GasMember" xlink:label="GasMember"/>
					<link:label xlink:type="resource" xlink:label="label_GasMember" xlink:role="http://www.xbrl.org/2003/role/label" xml:lang="en-US">Gas [Member]</link:label>
					<link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="GasMember" xlink:to="label_GasMember"/>
					<link:loc xlink:type="locator" xlink:href="#ftsf_CertificatesOfParticipationMember" xlink:label="CertificatesOfParticipationMember"/>
					<link:label xlink:type="resource" xlink:label="label_CertificatesOfParticipationMember" xlink:role="http://www.xbrl.org/2003/role/label" xml:lang="en-US">Certificates of Participation [Member]</link:label>
					<link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="CertificatesOfParticipationMember" xlink:to="label_CertificatesOfParticipationMember"/>
					<link:loc xlink:type="locator" xlink:href="#ftsf_InsuredMember" xlink:label="InsuredMember"/>
					<link:label xlink:type="resource" xlink:label="label_InsuredMember" xlink:role="http://www.xbrl.org/2003/role/label" xml:lang="en-US">Insured [Member]</link:label>
					<link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="InsuredMember" xlink:to="label_InsuredMember"/>
					<link:loc xlink:type="locator" xlink:href="#ftsf_AirportMember" xlink:label="AirportMember"/>
					<link:label xlink:type="resource" xlink:label="label_AirportMember" xlink:role="http://www.xbrl.org/2003/role/label" xml:lang="en-US">Airport [Member]</link:label>
					<link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="AirportMember" xlink:to="label_AirportMember"/>
					<link:loc xlink:type="locator" xlink:href="#ftsf_HospitalMember" xlink:label="HospitalMember"/>
					<link:label xlink:type="resource" xlink:label="label_HospitalMember" xlink:role="http://www.xbrl.org/2003/role/label" xml:lang="en-US">Hospital [Member]</link:label>
					<link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="HospitalMember" xlink:to="label_HospitalMember"/>
					<link:loc xlink:type="locator" xlink:href="#ftsf_C000232961Member" xlink:label="C000232961Member"/>
					<link:label xlink:type="resource" xlink:label="label_C000232961Member" xlink:role="http://www.xbrl.org/2003/role/label" xml:lang="en-US">C000232961 [Member]</link:label>
					<link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="C000232961Member" xlink:to="label_C000232961Member"/>
					<link:loc xlink:type="locator" xlink:href="#ftsf_C000232962Member" xlink:label="C000232962Member"/>
					<link:label xlink:type="resource" xlink:label="label_C000232962Member" xlink:role="http://www.xbrl.org/2003/role/label" xml:lang="en-US">C000232962 [Member]</link:label>
					<link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="C000232962Member" xlink:to="label_C000232962Member"/>
					<link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_StandardPoorsARatingMember" xlink:label="StandardPoorsARatingMember"/>
					<link:label xlink:type="resource" xlink:label="label_StandardPoorsARatingMember" xlink:role="http://www.xbrl.org/2003/role/label" xml:lang="en-US">Standard &amp; Poor&apos;s, A Rating [Member]</link:label>
					<link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="StandardPoorsARatingMember" xlink:to="label_StandardPoorsARatingMember"/>
					<link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_StandardPoorsAARatingMember" xlink:label="StandardPoorsAARatingMember"/>
					<link:label xlink:type="resource" xlink:label="label_StandardPoorsAARatingMember" xlink:role="http://www.xbrl.org/2003/role/label" xml:lang="en-US">Standard &amp; Poor&apos;s, AA Rating [Member]</link:label>
					<link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="StandardPoorsAARatingMember" xlink:to="label_StandardPoorsAARatingMember"/>
					<link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_StandardPoorsAAARatingMember" xlink:label="StandardPoorsAAARatingMember"/>
					<link:label xlink:type="resource" xlink:label="label_StandardPoorsAAARatingMember" xlink:role="http://www.xbrl.org/2003/role/label" xml:lang="en-US">Standard &amp; Poor&apos;s, AAA Rating [Member]</link:label>
					<link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="StandardPoorsAAARatingMember" xlink:to="label_StandardPoorsAAARatingMember"/>
					<link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InvestmentTypeAxis" xlink:label="InvestmentTypeAxis"/>
					<link:label xlink:type="resource" xlink:label="label_InvestmentTypeAxis" xlink:role="http://www.xbrl.org/2003/role/label" xml:lang="en-US">Investment Type [Axis]</link:label>
					<link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="InvestmentTypeAxis" xlink:to="label_InvestmentTypeAxis" priority="1"/>
					<link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetsNet" xlink:label="AssetsNet"/>
					<link:label xlink:type="resource" xlink:label="label_AssetsNet" xlink:role="http://www.xbrl.org/2003/role/label" xml:lang="en-US">Net Assets</link:label>
					<link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="AssetsNet" xlink:to="label_AssetsNet" priority="1"/>
					<link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InvestmentCompanyPortfolioTurnover" xlink:label="InvestmentCompanyPortfolioTurnover"/>
					<link:label xlink:type="resource" xlink:label="label_InvestmentCompanyPortfolioTurnover" xlink:role="http://www.xbrl.org/2003/role/label" xml:lang="en-US">Investment Company Portfolio Turnover</link:label>
					<link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="InvestmentCompanyPortfolioTurnover" xlink:to="label_InvestmentCompanyPortfolioTurnover" priority="1"/>                
					<link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_NoTradingSymbolFlag" xlink:label="dei_NoTradingSymbolFlag"/>
					<link:label xlink:type="resource" xlink:label="label_NoTradingSymbolFlag" xlink:role="http://www.xbrl.org/2003/role/label" xml:lang="en-US">No Trading Symbol Flag</link:label>
					<link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="dei_NoTradingSymbolFlag" xlink:to="label_NoTradingSymbolFlag" priority="1"/>		
				</link:labelLink>
			</link:linkbase>
		</appinfo>
	</annotation>   
	<element name="XcelEnergyInc625101585Member" id="ftsf_XcelEnergyInc625101585Member" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration"/>
	<element name="AmericanAgCreditCorp525Member" id="ftsf_AmericanAgCreditCorp525Member" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration"/>
	<element name="BNPParibasSA850Member" id="ftsf_BNPParibasSA850Member" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration"/>
	<element name="NextEraEnergyCapitalHoldingsIncSeriesU650060185Member" id="ftsf_NextEraEnergyCapitalHoldingsIncSeriesU650060185Member" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration"/>
	<element name="HartfordInsuranceGroupTheInc604021247Member" id="ftsf_HartfordInsuranceGroupTheInc604021247Member" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration"/>
	<element name="LandOLakesInc800Member" id="ftsf_LandOLakesInc800Member" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration"/>
	<element name="CreditAgricoleSA713Member" id="ftsf_CreditAgricoleSA713Member" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration"/>
	<element name="BarclaysPLC800Member" id="ftsf_BarclaysPLC800Member" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration"/>
	<element name="WellsFargoAndCoSeriesL750Member" id="ftsf_WellsFargoAndCoSeriesL750Member" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration"/>
	<element name="BankOfAmericaCorp663Member" id="ftsf_BankOfAmericaCorp663Member" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration"/>
	<element name="C000092936Member" id="ftsf_C000092936Member" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration"/>
	<element name="C000092935Member" id="ftsf_C000092935Member" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration"/>
	<element name="C000092934Member" id="ftsf_C000092934Member" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration"/>
	<element name="C000092933Member" id="ftsf_C000092933Member" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration"/>
	<element name="C000092932Member" id="ftsf_C000092932Member" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration"/>
	<element name="C000118178Member" id="ftsf_C000118178Member" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration"/>
	<element name="C000121471Member" id="ftsf_C000121471Member" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration"/>
	<element name="C000121472Member" id="ftsf_C000121472Member" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration"/>
	<element name="CorporateBondsAndNotesMember" id="ftsf_CorporateBondsAndNotesMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration"/>
	<element name="SeniorFloatingRateLoanInterestsMember" id="ftsf_SeniorFloatingRateLoanInterestsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration"/>
	<element name="ForeignCorporateBondsAndNotesMember" id="ftsf_ForeignCorporateBondsAndNotesMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration"/>
	<element name="NetOtherAssetsAndLiabilitiesMember" id="ftsf_NetOtherAssetsAndLiabilitiesMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration"/>
	<element name="NRMember" id="ftsf_NRMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration"/>
	<element name="MoneyMarketFundsQualityMember" id="ftsf_MoneyMarketFundsQualityMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration"/>
	<element name="IndustrialDevelopmentBondMember" id="ftsf_IndustrialDevelopmentBondMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration"/>
	<element name="ContinuingCareRetirementCommunitiesMember" id="ftsf_ContinuingCareRetirementCommunitiesMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration"/>
	<element name="GovernmentObligationBondUnlimitedTaxMember" id="ftsf_GovernmentObligationBondUnlimitedTaxMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration"/>
	<element name="GasMember" id="ftsf_GasMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration"/>
	<element name="CertificatesOfParticipationMember" id="ftsf_CertificatesOfParticipationMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration"/>
	<element name="InsuredMember" id="ftsf_InsuredMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration"/>
	<element name="AirportMember" id="ftsf_AirportMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration"/>
	<element name="HospitalMember" id="ftsf_HospitalMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration"/>
	<element name="C000232961Member" id="ftsf_C000232961Member" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration"/>
	<element name="C000232962Member" id="ftsf_C000232962Member" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration"/>
</schema>
