2017 af corrosion conference corrosion in the aircraft
TRANSCRIPT
Corrosion in the
Aircraft Structural
Integrity Program
(ASIP)
7 June 2017
Chuck Babish
AFLCMC/EZ
DSN: 785-5312
2017 AF Corrosion Conference
DISTRIBUTION A. Cleared for Public Release, Distribution Unlimited
Aircraft Structural Integrity Program
Outline
• ASIP Introduction
• Corrosion Requirements in ASIP
• Corrosion Metrics in ASIP Reviews
• Corrosion R&D Needs
• Other CP&C Needs
2
Aircraft Structural Integrity Program
Why Does USAF Have ASIP?
3
Aircraft Date Failure
Location
Number of
Flight Hours
Cause of
Failure
B-47B 13-Mar-58Center Wing,
BL 452,077 Fatigue
TB‑ 47B 13-Mar-58Center Wing,
BL 352,419 Fatigue
B-47E 21-Mar-58 Disintegration 1,129 Fatigue
B-47E 10-Apr-58Wing to Fuse
Fitting, FS 5151,265 Fatigue
B-47E 15-Apr-58 Disintegration 1,419 Overload
• Established on 12 June 1958 to control structural fatigue
in response to four B-47 aircraft losses in one month
Aircraft Structural Integrity Program
4
Why Damage Tolerance
Philosophy in ASIP?
Defect
• 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)
Aircraft Structural Integrity Program
5
Aircraft Safety Record Since ASIP Damage Tolerance Implemented
1.E-08
1.E-07
1.E-06
1.E-05
1.E-04
1.E-031945
1950
1955
1960
1965
1970
1975
1980
1985
1990
1995
2000
2005
2010
2015
2020
US
AF
De
str
oye
d A
irc
raft
Ra
te
USAF Destroyed Aircraft Rate (Annual Rate for All Causes, Cumulative Rate for Structural Failures)
All Causes Except Combat
Structures
Aircraft Structural Integrity Program
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 63-101, Acquisition and Life Cycle Management
– “5.4.1.3 For each Aircraft Mission Design Series (MDS)
the Air Force acquires, uses, or leases, the PM shall
establish an Aircraft Structural Integrity Program (ASIP)
IAW AFI 63-140, Aircraft Structural Integrity Program.”
• “5.4.1.3.1. Corrosion prevention and control (CPC)…is an
important element of product and system integrity. The PM shall
integrate CPC with program integrity efforts.”
• “5.4.1.3.2. Each ASIP shall be developed, documented, approved,
and executed according to MIL-STD-1530, Aircraft Structural
Integrity Program (ASIP).”
6
Aircraft Structural Integrity Program
ASIP Policy (2 of 2)
• AFI 63-140, Aircraft Structural Integrity Program– “3.1. The PM shall establish an ASIP for each Mission Design Series
(MDS) the Air Force acquires, uses, or leases.”
– “3.2. For each aircraft MDS developed or modified by the Air Force,
the ASIP shall comply with MIL-STD-1530, DoD Standard Practice for
Aircraft Structural Integrity Program (ASIP).”
• “3.2.2. Obtain PEO approval for the ASIP Master Plan before the
System Requirements Review (SRR).”
• “3.2.5. 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, Aircraft Structural Integrity Program
– With Change 1 published 13 October 2016
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Aircraft Structural Integrity Program
8
Task III, Full-
Scale
Testing
ASIP Framework
Established in MIL-STD-1530
Task I, Design
Information
Task IV,
Certification &
Force Management
Development
Task V, Force Management Execution
Task II, Design
Analyses &
Development Tests
Aircraft Structural Integrity Program
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-61-141, 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-1568”
Aircraft Structural Integrity Program
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.”
Aircraft Structural Integrity Program
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.”
– “5.1.5.2 Evaluation of corrosion susceptibility”
– “5.2.8 Corrosion assessment”
– “5.2.14.2 Corrosion tests”
– “5.5.6.2 Corrosion assessment updates”
Aircraft Structural Integrity Program
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Corrosion Requirements in ASIP:
A Continual Evolution (4 of 4)
• MIL-STD-1530D Change 1, 13 October 2016Task I Task II Task III Task IV Task V
Design InformationDesign Analyses &
Development TestingFull-Scale Testing
Certification & Force
Management DevelopmentForce Management Execution
1. ASIP Master Plan 1. Materials and Structural
Allowables1. Static Tests 1. Structural Certification 1.L/ESS Execution
2. Design Service Life & Design
Usage 2. Loads Analysis
2. First Flight Verification Ground
Tests
2. Strength Summary & Operating
Restrictions (SSOR)2. IAT Execution
3. Structural Design Criteria 3. Design Loads/Environment
Spectra 3. Flight Tests
3. Force Structural Maintenance
Plan (FSMP)3. DADTA Updates
4. Durability & Damage Tolerance
Control4. Stress and Strength Analysis 4. Durability Tests
4. Loads/ Environment Spectra
Survey (L/ESS) System
Development
4. L/ESS and IAT System Updates
5. Corrosion Prevention & Control 5. Durability Analysis 5. Damage Tolerance Tests 5. Individual Aircraft Tracking (IAT)
System Development 5. NDI Updates
6. Nondestructive Inspection 6. Damage Tolerance Analysis 6. Climatic Tests 6. Force Management Database
Development
6. Structural Risk Analysis
Updates
7. Selection of Materials,
Processes, Joining Methods &
Structural Concepts
7. Corrosion Assessment 7. Interpretation & Evaluation of
Test Findings7. 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 Analysis10. 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 Analysis14. Economic Service Life
Analysis Updates
15. Economic Service Life
Analysis15. Others as Required
Aircraft Structural Integrity Program
Corrosion Metrics in ASIP Reviews
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Corrosion Prevention
& ControlCriteria for Compliance Metric Green Yellow Red
Corrosion Manager1. 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 &
Control Plan
1. CP&C Plan is approved by AF CPCO, it's current (within 5 years) and it's executed as written.
2. It drives all aspects of aircraft program planning, funding & scheduling related to CP&CBoth 1 of 2 0 of 2
Corrosion Prevention
Advisory Board
1. CP Advisory Boards are conducted annually and AF CPCO participates.
2. Results are evaluated and used to revise maintenance requirements as required.Both 1 of 2 0 of 2
Standards &
Specifications
1. MIL-STD-1568 & MIL-HDBK-1587 are used or equivalent incorporated into approved specs.
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 Specs1. -23 or equivalent is sufficient or planned if program not at this phase.
2. -6, -3 and PDM work specs (if applicable) are sufficient.Both 1 of 2 0 of 2
Corrosion
Assessments
1. Performed every 5 years or more often.
2. Results are evaluated and used to revise maintenance requirements as required.Both 1 of 2 0 of 2
Analytical Condition
Inspection
1. Sufficient corrosion tasks are included in annual ACI requirements.
2. Results are evaluated and used to revise maintenance requirements as required.Both 1 of 2 0 of 2
Operational
Environment
1. Basing locations tracked: time at mild, moderate, & severe environment determined for each a/c
using T.O. 1-1-691 and input from AF CPCO for base locations not included in T.O.
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
Impacts
1. All aircraft structure corrosion related maintenance is included in the FSMP or CPCP or other.
2. Includes cost & schedule impacts associated with aircraft structure corrosion maintenance.Both 1 of 2 0 of 2
Life Cycle Cost Benefit
Analysis
1. Life cycle cost-benefit analyses are conducted to evaluate inspection and repair versus
modification/replacement approaches for corrosion damage.
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
Aircraft Structural Integrity Program
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
Aircraft Structural Integrity Program
Corrosion Metrics in ASIP Reviews
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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
#1#2 #3#4 #5
0
5
10
15
20
25
30
CM CPCP CPAB Spec TOs CA ACI Env MX CBA
# o
f M
DS
's
Corrosion Management, Aircraft in Sustainment
Aircraft Structural Integrity Program
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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
Aircraft Structural Integrity Program
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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?
Aircraft Structural Integrity Program
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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!
Aircraft Structural Integrity Program
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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
Aircraft Structural Integrity Program
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
Aircraft Structural Integrity Program
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