2017 AF Corrosion Conference

Transcription

1 2017 AF Corrosion Conference Corrosion in the Aircraft Structural Integrity Program (ASIP) 7 June 2017 Chuck Babish AFLCMC/EZ DSN: charles.babish@us.af.mil DISTRIBUTION A. Cleared for Public Release, Distribution Unlimited

2 Outline ASIP Introduction Corrosion Requirements in ASIP Corrosion Metrics in ASIP Reviews Corrosion R&D Needs Other CP&C Needs 2

3 Why Does USAF Have ASIP? Established on 12 June 1958 to control structural fatigue in response to four B-47 aircraft losses in one month Aircraft Date Failure Location Number of Flight Hours Cause of Failure B-47B 13-Mar-58 Center Wing, BL 45 2,077 Fatigue TB 47B 13-Mar-58 Center Wing, BL 35 2,419 Fatigue B-47E 21-Mar-58 Disintegration 1,129 Fatigue B-47E 10-Apr-58 Wing to Fuse Fitting, FS 515 1,265 Fatigue B-47E 15-Apr-58 Disintegration 1,419 Overload 3

4 Why Damage Tolerance Philosophy in ASIP? F-111 loss on 22 December 1969 and F-5 loss on 20 April 1970 demonstrated ASIP fatigue controls not effective F-111 structural failure due to fatigue cracking from a manufacturing defect (design unable to tolerate damage) Defect 4

5 USAF Destroyed Aircraft Rate 1.E-03 Aircraft Safety Record Since ASIP Damage Tolerance Implemented USAF Destroyed Aircraft Rate (Annual Rate for All Causes, Cumulative Rate for Structural Failures) 1.E-04 All Causes Except Combat Structures 1.E-05 1.E-06 1.E-07 1.E-08 5

6 ASIP Policy (1 of 2) AFPD 63-1, Acquisition and Life Cycle Management 3.6 The Air Force shall apply integrity programs to weapon systems. AFI , Acquisition and Life Cycle Management For each Aircraft Mission Design Series (MDS) the Air Force acquires, uses, or leases, the PM shall establish an (ASIP) IAW AFI , Corrosion prevention and control (CPC) is an important element of product and system integrity. The PM shall integrate CPC with program integrity efforts Each ASIP shall be developed, documented, approved, and executed according to MIL-STD-1530, Aircraft Structural Integrity Program (ASIP). 6

7 ASIP Policy (2 of 2) AFI , 3.1. The PM shall establish an ASIP for each Mission Design Series (MDS) the Air Force acquires, uses, or leases For each aircraft MDS developed or modified by the Air Force, the ASIP shall comply with MIL-STD-1530, DoD Standard Practice for (ASIP) Obtain PEO approval for the ASIP Master Plan before the System Requirements Review (SRR) For aircraft that are to be modified, fly new missions, or whose operation will extend past the aircraft s certified design service life, develop a revised ASIP Master Plan and obtain PEO approval of the revised plan before modifications are executed, regular flights begin under the new mission, or commencing operations beyond the previously certified service life. MIL-STD-1530D, With Change 1 published 13 October

8 ASIP Framework Established in MIL-STD-1530 Task I, Design Information Task II, Design Analyses & Development Tests Task III, Full- Scale Testing Task IV, Certification & Force Management Development Task V, Force Management Execution 8

9 Corrosion Requirements in ASIP: A Continual Evolution (1 of 4) Pre-STD phase: focus on fatigue, strength, & flutter HQ USAF Message, 19 November 1958 (ASIP official start) ASD-TN , September 1961 ASD-TR-66-57, January 1968 MIL-STD-1530, 1 September 1972 Structural durability requires that the areas of the structure that could be susceptible to fatigue, corrosion, or other crack initiation mechanisms Complete corrosion-control requirements for all fracture and fatigue critical parts that meets the strength, corrosion, and service life requirements MIL-STD-1530A, 11 December 1975 The corrosion prevention and control plan shall be in accordance with MIL-STD

10 Corrosion Requirements in ASIP: A Continual Evolution (2 of 4) MIL-STD-1530B, 20 February 2004 Corrosion prevention shall also be a primary consideration in the development and implementation of the durability and damage tolerance control process and the fleet management process. An appropriate tracking methodology shall be developed and implemented to monitor and assess corrosion potential and other environmentally-driven structural or critical coating degradation modes. Appendix B: Inspections of individual air vehicles shall be accomplished to ascertain the condition of the airframes with respect to corrosion. Emphasis shall be placed on corrosion detection through nondestructive inspections and prevention. For those areas found to be corroded, the preferred approach is to eliminate the corrosion by removing it or replacing the structural elements in question. This may not be feasible in rare cases because of near-term operational requirements. In these cases, an assessment shall be accomplished to determine the change in the inspection program that will account for the influence of corrosion on structural integrity. 10

11 Corrosion Requirements in ASIP: A Continual Evolution (3 of 4) MIL-STD-1530C, 1 November 2005 A Corrosion Prevention and Control Program shall be established for the aircraft structure. The program shall establish a Corrosion Prevention Advisory Board (CPAB) responsible for establishment and oversight of the execution of the program.. A Corrosion Prevention and Control Plan shall be prepared and corrosion prevention and control processes shall be used Evaluation of corrosion susceptibility Corrosion assessment Corrosion tests Corrosion assessment updates 11

12 Corrosion Requirements in ASIP: A Continual Evolution (4 of 4) MIL-STD-1530D Change 1, 13 October 2016 Task I Task II Task III Task IV Task V Design Information 1. ASIP Master Plan 2. Design Service Life & Design Usage 3. Structural Design Criteria 4. Durability & Damage Tolerance Control Design Analyses & Development Testing 1. Materials and Structural Allowables 2. Loads Analysis 3. Design Loads/Environment Spectra Full-Scale Testing Certification & Force Management Development Force Management Execution 1. Static Tests 1. Structural Certification 1.L/ESS Execution 2. First Flight Verification Ground Tests 3. Flight Tests 4. Stress and Strength Analysis 4. Durability Tests 5. Corrosion Prevention & Control 5. Durability Analysis 5. Damage Tolerance Tests 6. Nondestructive Inspection 6. Damage Tolerance Analysis 6. Climatic Tests 7. Selection of Materials, Processes, Joining Methods & Structural Concepts 7. Corrosion Assessment 7. Interpretation & Evaluation of Test Findings 2. Strength Summary & Operating 2. IAT Execution Restrictions (SSOR) 3. Force Structural Maintenance 3. DADTA Updates Plan (FSMP) 4. Loads/ Environment Spectra Survey (L/ESS) System 4. L/ESS and IAT System Updates Development 5. Individual Aircraft Tracking (IAT) 5. NDI Updates System Development 6. Force Management Database 6. Structural Risk Analysis Development Updates 7. Technical Orders 7. CPC Plan & Corrosion Assessment Updates 8. Sonic Fatigue Analysis 8. Resolution of Test Findings 8. Analytical Condition Inspection 9. Vibration Analysis 9. FSMP Updates 10. Aeroelastic and Aeroservoelastic Analysis 10. Technical Orders Updates 11. Mass Properties Analysis 11. Repairs 12. Survivability Analysis 12. Structural Maintenance Database Execution 13. Design Development Tests 13. Structural Certification Updates 14. Structural Risk Analysis 14. Economic Service Life Analysis Updates 15. Economic Service Life Analysis 15. Others as Required 12

13 Corrosion Metrics in ASIP Reviews Corrosion Prevention & Control Criteria for Compliance Metric Green Yellow Red Corrosion Manager 1. Assigned & adequately trained (e.g. DAU CLM 038, CLE 070, etc.). 2. Full-time job for the a/c weapon system; or if part-time, have sufficient time to execute CP&C. Both 1 of 2 0 of 2 Corrosion Prevention & 1. CP&C Plan is approved by AF CPCO, it's current (within 5 years) and it's executed as written. Control Plan 2. It drives all aspects of aircraft program planning, funding & scheduling related to CP&C Both 1 of 2 0 of 2 Corrosion Prevention 1. CP Advisory Boards are conducted annually and AF CPCO participates. Advisory Board 2. Results are evaluated and used to revise maintenance requirements as required. Both 1 of 2 0 of 2 Standards & 1. MIL-STD-1568 & MIL-HDBK-1587 are used or equivalent incorporated into approved specs. Specifications 2. Process/finish specs exist, are coordinated with AF CPCO & AF CTIO, and are used. Both 1 of 2 0 of 2 T.O.s / Work Specs or equivalent is sufficient or planned if program not at this phase , -3 and PDM work specs (if applicable) are sufficient. Both 1 of 2 0 of 2 Corrosion 1. Performed every 5 years or more often. Assessments 2. Results are evaluated and used to revise maintenance requirements as required. Both 1 of 2 0 of 2 Analytical Condition 1. Sufficient corrosion tasks are included in annual ACI requirements. Inspection 2. Results are evaluated and used to revise maintenance requirements as required. Both 1 of 2 0 of 2 1. Basing locations tracked: time at mild, moderate, & severe environment determined for each a/c Operational using T.O and input from AF CPCO for base locations not included in T.O. Environment 2. Corrosion sensors are being or have been used to characterize environment (sampling is OK). Both 1 of 2 0 of 2 CP&C Maintenance 1. All aircraft structure corrosion related maintenance is included in the FSMP or CPCP or other. Impacts 2. Includes cost & schedule impacts associated with aircraft structure corrosion maintenance. Both 1 of 2 0 of 2 1. Life cycle cost-benefit analyses are conducted to evaluate inspection and repair versus Life Cycle Cost Benefit modification/replacement approaches for corrosion damage. Analysis 2. Results are effectively communicated to decision makers. Both 1 of 2 0 of 2 Overall CP&C Metric Weight factor method used to combine these 10 metrics into an overall CP&C metric 13

14 Corrosion Metrics in ASIP Reviews Issue #1: CP&C cost & schedule impacts on MX not well understood or readily available for most a/c Data should be included in the FSMP, CP&C Plan or other document Issue #2: CP&C Plan needs improvement for many a/c Use AF CPCO CP&C Plan Template for next update Issue #3: ACI program use needs improvement Corrosion inspections should be part of annual ACI Issue #4: Corrosion Manager improvements needed More CMs and/or more training and/or more time Issue #5: CPAB improvements needed Use AF CPCO personnel, invite MX personnel, ensure adequate time to discuss issues 14

15 Corrosion Metrics in ASIP Reviews 30 Corrosion Management, Aircraft in Sustainment # of MDS's Legend: CM: Corrosion Manager CPCP: Corrosion Prevention & Control Plan CPAB: Corrosion Prevention Advisory Board Spec: Specifications & Standards TOs: Technical Orders CA: Corrosion Assessments ACI: Analytical Condition Inspection Env: Operational Environment MX: Maintenance Impacts CBA: Life Cycle Cost Benefit Analysis 0 CM CPCP CPAB Spec TOs CA ACI Env MX CBA #4 #2 #5 #3 #1 15

16 Corrosion R&D Needs to Improve ASIP Execution (1 of 3) 1. Ability to decompose top-level design service life requirements (e.g., years) and sustainment requirements (e.g., maintenance man-hour per flight hour, aircraft availability) into verifiable requirements that: Leads to proper selection of materials, processes, coatings, etc., during the design phase Eliminates the debate on what is adequate corrosion prevention to achieve the design requirements Establishes periodic maintenance requirements such as wash intervals, exterior topcoat replacement intervals, etc., that are acceptable Survives pressures to reduce cost, weight, etc. 2. Accelerated test methods (designs, quantities, environment, duration, etc.) and pass/fail criteria that enables above 16

17 Corrosion R&D Needs to Improve ASIP Execution (2 of 3) 3. Ability to define the appropriate corrosion-related maintenance requirements throughout a/c life cycle What are the appropriate adjustments to periodic maintenance requirements such as wash intervals, exterior topcoat replacement intervals, etc.? How does corrosion damage degrade damage tolerance, static strength, rigidity, etc.? When are damage tolerance based inspections combined with corrosion surveillance inspections no longer sufficient to protect safety? How should corrosion damage and rates be considered in damage-tolerance based inspection intervals? How should corrosion damage be repaired? What is the ROI for use of CPCs? 17

18 Corrosion R&D Needs to Improve ASIP Execution (3 of 3) 4. Validated methods to improve detection of corrosion damage and characterize corrosion severity 5. Ability to adequately consider corrosion damage when establishing service life limits (SLL) and during evaluation of a service life extension program (SLEP) Can quantitative methods be used to determine structural risk due to corrosion damage vs time? When does corrosion damage become uneconomical? When do non-replaceable coatings simply no longer provide adequate corrosion protection? IOW, need an ability to design, analyze, test, and manage corrosion in the same manner as fatigue! 18

19 Other CP&C Needs (1 of 2) Knowledge and data to enable credible and convincible business case and Life Cycle Cost (LCC) analysis for any trade studies involving corrosion prevention & control such as: Service life extension programs Changes to depot induction frequency Changes from field-level to depot-level corrosion inspection & repairs Requests for a/c wash extensions Pre-coated vs. wet-installed fasteners Pre-coated vs. faying surface seal & edge seal structural assemblies Top-coat or not in corrosion-prone internal locations Proposed use of T6 temper 19

20 Other CP&C Needs (2 of 2) DoD-wide evaluation, recommendation and/or approval for cross-cutting initiatives that impact corrosion prevention & control such as: Environmental law changes (e.g., hexavalent chrome, cadmium) Material or product form substitutions during sustainment Process changes (e.g., paint removal) Coating systems (surface treatment + primer + topcoat) that meet coating specifications, environmental regulations, and aircraft cost, schedule and performance requirements 20

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