R11SOW27Mar2013.pdf

DISTRIBUTION STATEMENT A. Approved for public release: Distribution is unlimited.

27 Mar 2013

Statement of Work (SOW) for

Truck, Tank, Aircraft Refueling, 6000 Gallon, A/S32R-11

Prepared by

AFLCMC SUPPORT EQUIPMENT AND VEHICLE ENGINEERING DIVISION

235 BYRON STREET, SUITE 19A

ROBINS AFB GA 31098-1813

THIS PAGE HAS BEEN INTENTIONALLY LEFT BLANK

TABLE OF CONTENTS

1. SCOPE

2. APPLICABLE DOCUMENTS

2.1 Government documents

2.1.1 Specifications, standards, and handbooks

2.1.2 Other Government documents, drawings, and publications

2.2 Order of precedence

3. REQUIREMENTS

3.1 Program management

3.1.1 Program manager

3.1.2 Plant access

3.2 Program reviews

3.2.1 Post-award orientation conference (PAOC)

3.2.2 Technical reviews

3.2.2.1 Design reviews

3.2.2.1.1 Design review location and schedule

3.2.2.1.2 Design review content

3.2.2.2 Test readiness review

3.2.2.3 Technical review data package

3.2.3 Program management review support

3.2.4 Conference room

3.2.5 Meeting agendas

3.2.6 Meeting minutes

3.3 Systems engineering

3.3.1 Environment, Safety, and Occupational Health (ESOH)

3.3.2 Reliability and maintainability

3.3.2.1 Reliability

3.3.2.1.1 Basic reliability model

3.3.2.1.2 Basic reliability prediction

3.3.2.1.3 Failure Modes, Effects, and Criticality Analysis (FMECA)

3.3.2.2 Maintainability

3.3.2.2.1 Corrective maintenance prediction

3.3.2.2.2 Reliability-Centered Maintenance (RCM) analysis

3.4 Logistics

3.4.1 Technical Order (TO) requirements

3.4.1.1 Technical Manual schedule and status report

3.4.1.2 TO verification

3.4.2 Training/familiarization

3.5 Testing and evaluation

3.5.1 Design analysis

3.5.2 First production test

3.5.2.1 First production test procedures

3.5.2.2 First production testing

3.5.2.3 First production test daily situation reports (SITREPs)

3.5.2.4 First production test report

3.5.3 User operation test

3.5.3.1 User operation test acceptance…………………………………………………...11

3.5.4 Restoration

3.5.5 Disposition

3.5.6 Production acceptance procedure and report

3.6 Configuration management and control

3.6.1 Configuration requirements

3.6.1.1 Baselines

3.6.1.1.1 Functional baseline

3.6.1.1.2 Allocated baseline

3.6.1.1.3 Product baseline

3.6.2 Production release

3.6.3 Engineering Change Proposals (ECPs)

3.6.4 Request for Deviation (RFD)

3.6.5 Service Bulletin…………………………….………………………………………13

3.6.6 Shipment of refuelers………………………………………………………………13

3.6.7 USAF Registration Numbers………………………………………………………14

1. SCOPE

This document defines the tasks associated with the procurement of the aircraft refueling truck as described by MIL-PRF-32080E and is to be used in conjunction with the specification.

2. APPLICABLE DOCUMENTS

The following documents are applicable to the SOW to the extent specified herein.

2.1 Government documents.

2.1.1 Specifications, standards, and handbooks. The following specifications, standards, and handbooks of the exact revision listed below form a part of this SOW to the extent specified herein.

DEPARTMENT OF DEFENSE SPECIFICATIONS

MIL-PRF-49506 Logistics Management Information MIL-PRF-32080E Truck, Tank, Aircraft Refueling, 6,000 Gallon, A/S32R-11

DEPARTMENT OF DEFENSE STANDARDS

MIL-STD-882E Standard Practice for System Safety

DEPARTMENT OF DEFENSE HANDBOOKS

MIL-HDBK- 217F(2) Reliability Prediction of Electronic Equipment MIL-HDBK- 470A Designing and Developing Maintainable Products and Systems MIL-HDBK-1568 Material and Processes for Corrosion Prevention and

Control in Aerospace Weapons Systems

2.1.2 Other Government documents, drawings, and publications.

DEPARTMENT OF DEFENSE MANUALS

TM 86-01N Air Force Technical Manual Contract Requirements

DATA ITEM DESCRIPTIONS (DIDs)

DI-SAFT-80101B System Safety Hazard Analysis Report DI-MGMT-80227 Contractor's Progress, Status and Management Report DI-MISC-80508B Technical Report/Study Services (Design Analysis) DI-MISC-80508B Technical Report/Study Services (Technical Review

Data Package)

DI-MISC-80508B Technical Report/Study Services (Service Bulletin) DI-NDTI-80603A First Production Test Procedure DI-CMAN-80639C Engineering Change Proposal (ECP) DI-CMAN-80640C Request for Deviation (RFD) DI-CMAN-80642C Notice of Revision (NOR) DI-NDTI-80809B Test/Inspection Report DI-CMAN-81218 Product Base Line Index (PBLI) DI-ADMN-81249A Conference Agenda DI-ADMN-81250A Conference Minutes DI-SESS-81526B/T Instructional Media Package DI-SAFT-81626 System Safety Program Plan

(Unless otherwise indicated, copies of the above specifications, standards, and handbooks are available from the Standardization Document Order Desk, 700 Robbins Avenue, Building 4D, Philadelphia PA 19111-5094.)

2.2 Order of precedence. In the event of a conflict between the text of this document and the references cited herein, the text of this document takes precedence. Nothing in this document, however, supersedes applicable laws and regulations unless a specific exemption has been obtained.

3. REQUIREMENTS

3.1 Program management.

3.1.1 Program manager. The contractor shall identify to the Government and maintain a single point of contact (Program Manager) for all matters under this contract. The contractor shall also ensure that all program management personnel assigned to the program shall be available, as required, to meet program objectives.

3.1.2 Plant access. The contractor shall arrange for full access to applicable contractor facilities and offices by Government representatives conducting any business, making observations, or performing inspections required by public law or by this contract.

3.2 Program reviews.

3.2.1 Post-award orientation conference (PAOC). The Government will convene a PAOC with the contractor at Warner Robins Air Force Base, Warner Robins, Georgia not later than 30 days after contract award. The Procuring Contracting Officer (PCO) will coordinate the actual date, time, and location of the conference with the contractor. The Government will be responsible for the minutes of the PAOC.

3.2.2 Technical reviews.

3.2.2.1 Design reviews.

3.2.2.1.1 Design review location and schedule. The contractor shall conduct a preliminary design review (PDR) 90 days after the contract is awarded. The contractor shall conduct a critical design review (CDR) 180 days after the contract is awarded. The PDR design review shall be held at Warner Robins Air Force Base, Warner Robins, Georgia. The CDR design review shall be held at a location that is mutually agreeable to both parties. The PCO will coordinate the actual date, time, and location of the reviews with the contractor.

3.2.2.1.2 Design review content. The PDR and CDR shall include formal technical reviews of the proposed design; program risks shall be reviewed on a technical and schedule basis. Each review shall include, but is not limited to, preliminary calculations; any necessary design studies or analyses including the design analysis as required in 3.5.1; preliminary drawings, including equipment layout drawings (packaging), proprietary or restricted design processes, components, and information; electrical and mechanical design; environmental control; thermal design aspects; software design; training materials; lists of materials, parts, and processes; human engineering elements; corrosion control; maintainability; production capability and manufacturing; and quality considerations. Final drawings, final calculations, and any mockups or any assemblies shall be made available for the Government review as well. The contractor shall brief all system safety risks and status at all program and technical design reviews. All applicable comments from the PDR shall be incorporated into the CDR design documentation.

3.2.2.2 Test readiness review (TRR). A test readiness review (TRR) shall be conducted 14 days prior to the start of the first production test. The TRR shall be conducted via teleconference call between the two parties. The TRR shall assess test objectives, test methods and procedures, scope of tests, and determine if required test resources have been properly identified and coordinated to support planned tests.

3.2.2.3 Technical review data package. A formal design data package of the PDR, CDR, and TRR shall be provided. Each data package shall be provided not later than 14 days after each review and shall be submitted in written format to the Government. The Government shall have 30 days after receipt of each design data package for approval/disapproval. The contractor shall have 10 days after receipt of the Government comments for resubmittal of the design data package. The Government shall have 14 days after receipt of contractor’s resubmission for approval/disapproval. All materials presented at the PDR and CDR design reviews shall be included in the package that is presented to the Government 14 days prior to the TRR.

The contractor shall prepare all necessary detailed status reports for the technical review meetings, conference agendas, and conference minutes. The contractor shall prepare formal documentation of the PDR, CDR, and TRR (DI-ADMN-81250A, Conference Minutes, DI-MISC-80508B, Technical Report/Study Services).

3.2.3 Program management review support. The contractor shall participate in and support all reviews, audits, and meetings as requested by the PCO or the Program Manager. Program Management Reviews shall be conducted quarterly or as required at a mutually agreeable location or via teleconferences.

3.2.4 Conference room. The contractor shall provide a conference room suitable for meetings of up to 10 Government representatives, plus contractor personnel, in support of scheduled meetings at the contractor’s facility.

3.2.5 Meeting agendas. The contractor shall publish an agenda for all meetings and conferences specified in 3.2.2 and 3.2.3. The contractor shall request from the Government any items or issues to be discussed or presented at the meetings, and shall include such items in the agenda.

Agendas shall be submitted not less than 14 days prior to any meeting. (DI-ADMN-81249A, Conference Agenda)

3.2.6 Meeting minutes. The contractor shall provide a written record of the discussions, decisions and action items identified at each meeting. Minutes shall be provided no later than 10 days after the meeting. Minutes shall include presentation material. The Government shall have 10 days after receipt of contractor submission for approval/disapproval of minutes. The contractor shall have 5 days after receipt of the Government comments to resubmit the minutes for final approval. The Government shall have 10 days after receipt of contractor resubmission for approval/disapproval of minutes. Final Distribution of meeting minutes shall occur 5 days after Government approval. (DI-ADMN-81250, Conference Minutes)

3.3 Systems engineering.

3.3.1 Environment, Safety, and Occupational Health (ESOH). The contractor shall establish, conduct, document, and maintain a system safety program in accordance with MIL-STD-882E.

The contractor shall document their approach for analyzing, eliminating, or minimizing hazards during all phases of the program. The contractor shall initiate changes in the system design based on safety analysis results such that the associated risk is reduced to a level acceptable to the Government. The design of the aircraft refueling truck shall not contain any system safety (to include environment and occupational health) mishap risk categories greater than medium as defined in TABLE III and TABLE V of MIL-STD-882E. The System Safety Program Plan (SSPP) shall be provided 14 days prior to the PDR. A System Safety Hazard Analysis (SSHA) shall be conducted by the contractor in order to demonstrate compliance with the identified mishap risk requirements of the aircraft refueling truck. The initial SSHA shall be provided 14 days prior to the CDR; updated versions of the SSHA shall be provided 14 days prior to the TRR and 14 days prior to the first production test report. The Government will have 30 days after receipt of the SSPP and SSHA report for approval/disapproval. The contractor shall have 10 days after receipt of the Government comments to resubmit the report. The Government shall have 14 days after receipt of contractor resubmission for approval/disapproval. The contractor shall manage Hazardous Materials (HAZMAT), including those embedded in the system or used during operation or maintenance, as an element of the Systems Engineering process. The contractor shall list any HAZMAT, as defined in FED-STD-313D (Material Safety Data, Transportation Data and Disposal Data for Hazardous Materials Furnished to Government Activities), to be delivered under this contract, including locations, quantities, and special handling and disposal procedures. The use of Hexavalent Chromium is prohibited. The system shall not generate or use Class I or Class II Ozone Depleting Substances during operation or disposal.

(DI-SAFT-81626, System Safety Program Plan; DI-SAFT-80101, System Safety Hazard Analysis Report).

3.3.2 Reliability and maintainability.

3.3.2.1 Reliability.

3.3.2.1.1 Basic reliability model. The contractor shall develop and maintain a basic reliability model for the system in accordance with A.4.1 of the specification. The basic reliability model shall be documented in the design analysis (see 3.5.1) and reviewed at the design reviews.

3.3.2.1.2 Basic reliability prediction. The contractor shall prepare and maintain a basic reliability prediction for the system in accordance with A.4.2 of the specification; it shall be based upon the associated basic reliability model (see 3.3.2.1.1). The basic reliability prediction shall be documented in the design analysis (see 3.5.1) and reviewed at the design reviews.

3.3.2.1.3 Failure Modes, Effects, and Criticality Analysis (FMECA). The contractor shall prepare and maintain a FMECA for the system in accordance with A.4.3 of the specification; it shall be based upon the associated basic reliability model (see 3.3.2.1.1). The FMECA shall be documented in the design analysis (see 3.5.1) and reviewed at the design reviews.

3.3.2.2 Maintainability.

3.3.2.2.1 Corrective maintenance prediction. The contractor shall prepare and maintain a corrective maintainability prediction for mean time to repair (MTTR) in accordance with A.4.5 of the specification. The model and failure rate data shall be consistent with that of the basic reliability prediction (see 3.3.2.1.2). The corrective maintenance prediction shall be documented in the design analysis (see 3.5.1) and reviewed at the design reviews.

3.3.2.2.2 Reliability-centered maintenance (RCM) analysis. The contractor shall perform RCM analysis in accordance with A.4.4 of the specification in order to develop preventive maintenance tasks and intervals. The RCM analysis and the preventive maintenance tasks and intervals shall be documented in the design analysis (see 3.5.1) and reviewed at the design reviews.

3.4 Logistics.

3.4.1 Technical order (TO) requirements. The contractor shall develop and deliver technical manuals in accordance with TM 86-01N, Air Force Technical Manual Contract Requirements.

3.4.1.1 Technical manual schedule and status report. The Technical Manual schedule and status report shall be in accordance with TM-86-01.

3.4.1.2 TO verification. Technical order verification shall be in accordance with TM 86-01N at the contractor’s facility and shall occur in conjunction with the First Production Test.

3.4.2 Training/familiarization. The contractor shall provide with each truck, a product training/familiarization DVD or CD, otherwise known as an Instructional Media Package (IMP) that verbally and visually provides all information for the servicing operation and routine maintenance of the truck and its components, using manuals as a baseline. The instructional media package shall be due 60 days before the beginning the production of hardware. The Government shall have 30 days after receipt of DVD(s) for approval/disapproval. The contractor shall have 10 days after receipt of the Government comments to resubmit the DVD(s). The Government shall have 14 days after receipt of contractor resubmission for approval/disapproval.

Final distribution of the Instructional Media Package shall occur 5 days after Government approval. (DI-SESS-81526B/T)

3.5 Testing and evaluation.

3.5.1 Design analysis. A design analysis of the system and each subsystem shall be performed to verify compliance with this SOW and each applicable requirement of the specification. The initial design analysis shall be due 14 days prior to the PDR. The initial design analysis shall include, but is not limited to, a basic reliability model (see 3.3.2.1.1) and prediction (see 3.3.2.1.2); a FMECA (see 3.3.2.1.3); a corrective maintenance prediction (see 3.3.2.2.1); an RCM analysis and preventive maintenance tasks and intervals (see 3.3.2.2.2); an electrostatic discharge analysis (see 4.6.2.4 of the specification); a service life analysis (see 4.6.5 of the specification); a surface transportability analysis (see 4.6.8.1 of the specification); an air transportability analysis (see 4.6.8.2 of the specification); and a tie down provision analysis (see

4.6.8.2 of the specification). (Note that the system safety hazard analysis is addressed in 3.3.1.2) Updated versions of the design analysis shall be provided 14 days prior to the CDR, 14 days prior to the TRR, and 14 days prior to the First Production Test Report (FPTR) (DI-MISC-80508B, Technical Report/Study Services).

3.5.2 First production test.

3.5.2.1 First production test procedures. The contractor shall develop detailed first production test procedures (FPTP), which shall address all requirements identified in the specification and this SOW. The FPTP shall include data record sheets, charts, graphs, identification of test instruments by manufacturer, model number, and serial number. The test procedures shall be submitted 30 days after the PDR. The Government shall have 45 days after receipt of the FPTP to review and approve/disapprove the FPTP. Any subsequent submissions by the contractor shall not be later than 21 days after receipt of Government comments. (DI-NDTI-80603A, Test Procedure)

3.5.2.2 First production testing. After Government approval of the first production test procedures, the contractor shall schedule the testing to be conducted. If shipping is required to move the item(s) to and from a test site away from the contractor’s facility, the contractor shall be responsible for all costs associated with the shipment. The contractor shall notify the Government of the date, time, and location of first production testing 21 days prior to the start of testing. The test shall be witnessed by one or more Government representatives from the program office. First production approval shall be contingent upon approval of the user operational test (see 3.5.3).

3.5.2.3 First production test daily situation reports (SITREPs). Throughout the first production test, the contractor shall submit a daily situation report (SITREP) that shall cover all monitored daily test activities. Examples are:

a. Test logs.

b. Observed data to include: observations, comments, anomalous conditions, or other items completed for each first production unit.

c. Recorded data as applicable to the type of equipment.

d. Records of preventive maintenance activities performed.

e. Total number of failures occurred daily and corrective resolution implemented.

(DI-MGMT-80227, Contractor's Progress, Status and Management Report)

3.5.2.4 First production test report. The contractor shall submit a FPTR for approval not later than 30 days after completion of the first production test. The Government shall have 45 days after receipt of FPTR for approval/disapproval. Subsequent submission of the FPTR by the contractor shall not be later than 21 days after receipt of government comments. The Government shall have 14 days after receipt of contractor resubmission for approval/disapproval.

The First production test approval shall be contingent on successful completion of the user operational test. (DI-NDTI-80809B, Test/Inspection Report)

3.5.3 User operational test. After completion of first production test and first production test report review, the first production aircraft refueling truck shall be shipped to Seymour Johnson Air Force Base, North Carolina, for the user operational test. The contractor shall be responsible for all costs associated with shipping the first production unit to the test location. The contractor shall be on site at Seymour Johnson the first day of the user operation test and shall provide instructional hands on training to familiarize the operator with the functions of the truck and how to properly conduct servicing operations. The hands on training shall include demonstrations performed by the contractor that will illustrate servicing operations and proper operation of the controls. A morning session and afternoon session shall be conducted in order to account for any overlapping shifts. Air Force operators will utilize the truck in a very intense functional capacity on a daily basis for a period of 30 days. Mission operations shall be conducted in accordance with 4.3 of the specification. The contractor shall provide a spare parts kit with the item shipped containing all items required to conduct scheduled maintenance during the user operational test as well as common repair parts predicted to be needed during the test.

Contractor’s support shall be available at all times during the test not later than 48 hours of notification including weekends (excluding official Government holidays). The test base shall provide weekly status updates to the Government program office. The status updates shall include a detailed log (excerpt from the control log) of all refuel/defuel/bottom load fills/hydrant servicing operations, inspection forms, maintenance occurrences, Quality Control (QC) sample results, recommended areas for improvement, and user feedback.

3.5.3.1 User operation test acceptance. User operation test approval shall be granted by the Government and defined as no major component failure or a deficiency that would require a design change of any major component or system. If there are any major discrepancies or design changes to any major component or system, a first production test of the major component or system impacted by the change shall be performed. During this period, the user operation test shall be stopped and shall resume once the major component or system has passed the portion of the first production test applicable to the deficiency.

3.5.4 Restoration. After successful completion of the user operational test and first production acceptance, the first production aircraft refueling truck shall be shipped, not later than 30 days, to the contractor’s facility for restoration. The contractor shall be responsible for any repairs that may be necessary to restore the aircraft refueling truck to a serviceable, “like new” condition while retaining configuration integrity. The contractor shall be responsible for all costs associated with shipping of the first production aircraft refueling truck to the contractor's facility for restoration.

3.5.5 Disposition. The first production aircraft refueling truck shall be retained at the contractor’s facility, to serve as a manufacturing standard, until the last shipment.

3.5.6 Production acceptance procedure. The contractor shall test each production aircraft refueling truck in accordance with 4.6 of the specification as applicable to production models only.

3.6 Configuration management and control.

3.6.1 Configuration requirements.

3.6.1.1 Baselines.

3.6.1.1.1 Functional baseline. The functional baseline is the specification.

3.6.1.1.2 Allocated baseline. All of the documents used to produce and define the accepted CDR configuration shall constitute the allocated baseline.

3.6.1.1.3 Product baseline index. The Product Baseline Index Report shall be due 21 days after the approval of the First Production Test Report. The Government will have 30 days after receipt of the data for approval/disapproval. The contractor shall have 10 days after receipt of the Government comments to resubmit the data. The Government shall have 14 days after receipt of contractor resubmission for approval/disapproval. Any subsequent changes shall be provided within 5 days after change approval. All of the documents used to produce and define the accepted first production aircraft refueling truck shall be identified in the Product Base Line Index (PBLI). The list shall identify the applicable version number as required.

(DI-CMAN-81218, Product Base Line Index (PBLI))

3.6.2 Production release. Production release is acknowledgment by the procuring activity that the contractor has satisfied all requirements to proceed with delivery of hardware to be furnished under the contract. The contractor assumes all risks in initiating production before the first production test report has been delivered and approved by the procuring activity.

3.6.3 Engineering change proposals (ECPs). Notwithstanding any other provision in the contract, no contractor or subcontractor's change in design, fabrication, assembly, part, material, process, or source of supply shall be made after production release unless such change is submitted in writing by ECP and approved by the procuring activity. The Government shall have 2 days after receipt of contractor submitted ECP for approval/disapproval. Subsequent submissions by the contractor shall be due not later than 10 days after receipt of Government comments. Any request for change shall be accompanied by complete documentation supporting the need for the change. A Notice of Revision (NOR) shall be submitted with each ECP. The Government shall have 2 days after receipt of contractor submitted NOR for approval/disapproval. Subsequent submissions by the contractor shall be due not later than 10 days after receipt of Government comments. (DI-CMAN-80639C, Engineering Change Proposal (ECP); DI-CMAN-80642C, Notice of Revision).

3.6.4 Request for deviation (RFD). The contractor shall prepare an RFD whenever a departure from the contractually-specified base line is proposed for a specific number of units or for a specific time. The Government shall have 2 days after receipt of contractor submitted RFD for approval/disapproval. Subsequent submissions by the contractor shall be due not later than 10 days after receipt of Government comments. (DI-CMAN-80640C, Request for Deviation).

3.6.5 Service bulletin. The contractor shall prepare service bulletins as required to notify the Government of new maintenance problems and/or procedures to be implemented on the contractor’s equipment prior to issuance of permanent changes to the technical manuals. The service bulletins shall also identify any potential safety hazards previously identified.

(DI-MISC-80508B, Technical Report/Study Services)

3.6.6 Shipment of refuelers. All refuelers must be prepared for over-the-road shipping and comply with the U.S. Department of Transportation, Code of Federal Regulations (CFR), Part 172, Title 49, Transportation, PART 172—HAZARDOUS MATERIALS TABLE, SPECIAL

PROVISIONS, HAZARDOUS MATERIALS COMMUNICATIONS, EMERGENCY

RESPONSE INFORMATION, TRAINING REQUIREMENTS, AND SECURITY PLANS.

In addition to complying with U.S. Department of Transportation, Code of Federal Regulations, 49 CFR Part 172, for over-the-road shipping, all refuelers with destinations outside the 48 contiguous United States of America (OCONUS) must also conform to the most current International Maritime Dangerous Goods Code (IMDGC), Volume 2. This includes preparation of refuelers for shipping to OCONUS locations, inspection of refuelers for compliance with the IMDGC, Volume 2, and completion of and endorsement of the International Maritime Organization’s “IMO Dangerous Goods Declaration”, by personnel certified in accordance with the U.S. Department of Transportation, Code of Federal Regulations, 49 CFR Part 172, Subpart H.

http://ecfr.gpoaccess.gov/cgi/t/text/text-idx?c=ecfr&tpl=/ecfrbrowse/Title49/49cfr172_main_02.tpl

Costs associated with preparation, compliance, and certification for shipping will be included in the cost of the refueler.

3.6.7 USAF Registration Numbers. Contractor will request Air Force registration numbers no later than 90 days and at least 60 days prior to delivery of vehicles. "US Air Force", "Vehicle Registration Number" and "For Official Use Only" are not required on the side or the rear of the vehicle. However, the vehicle registration numbers and contract numbers are still required on the vehicle data plate IAW MIL-STD-1223. Also, vehicle registration numbers and contract number must be shown on the DD250.

http://ecfr.gpoaccess.gov/cgi/t/text/text-idx?c=ecfr&tpl=/ecfrbrowse/Title49/49cfr172_main_02.tpl http://ecfr.gpoaccess.gov/cgi/t/text/text-idx?c=ecfr&tpl=/ecfrbrowse/Title49/49cfr172_main_02.tpl