CHAPTER 4. OPERATOR TASKS FOR REPAIRS AND ALTERATIONS
400. General Information About This Chapter. This chapter provides guidance to operators for developing a means for addressing the adverse effects repairs and alterations may have on fatigue critical structure (FCS). The final product of this guidance is the development of an Operator Implementation Plan (OIP) which, upon approval by the operator’s Principal Maintenance Inspector (PMI) and incorporation into its maintenance program, constitutes compliance with §§ 121.1109(c)(2) and 129.109(b)(2). The OIP will contain the processes and timelines the operator will use for obtaining and incorporating into its continuous airworthiness maintenance program (CAMP) DTIs that address the adverse effects of repairs and alterations.
401. Developing an Operator Implementation Plan. Using the guidance in this chapter, operators can develop an OIP by incorporating processes, data, and schedules developed by TC and STC Holders, and by themselves. The OIP should contain information describing how the operator will identify repairs and alterations affecting FCS, how the operator will obtain and incorporate DTIs for those repairs and alterations, and the timelines of these actions. Operators will first need to determine how they will obtain the information necessary to develop the OIP by considering the following conditions:
a. The TC or STC Holder exists and will make the DTIs available to the operator;
b. The DTIs already exist and are available;
c. The DTIs are not available from TC or STC Holders;
d. DTIs are not available for alterations developed by persons other than TC or STC Holders.
NOTE: For paragraphs 401c and 401d, above, the operator is responsible for developing or obtaining the DT Data. If the operator is unable to obtain the data it will need to coordinate the development of necessary DT Data through a third party.
402. Contents of an OIP. The OIP should include processes and procedures to ensure that all new and existing repairs and alterations affecting FCBS are evaluated for damage tolerance and have implemented DTIs. Operators should use information contained in TC and STC Holder Compliance Documents (see Chapters 2 and 3 of this AC), which provide processes, timelines, lists of FCS, and airplane design service goals or other necessary data. For alterations developed by the operator or third parties, and those developed by TC or STC Holders that are no longer in business, the operator will need to use the guidance in this AC to develop the processes and timelines for obtaining and incorporating into its CAMP the DTIs for those alterations. The contents of the OIP should include:
a. A process that implements the elements of the Repair Evaluation Guidelines (REGs) obtained from the TC Holder’s Compliance Document that will assist the operator in obtaining, developing, and implementing DTIs on its airplanes. The REGs include:
(1) A process for conducting surveys to identify and determine if existing repairs and alterations affect FCBS,
(2) A process for obtaining DTIs, and
(3) An implementation schedule for repairs establishing timelines for accomplishing the survey and for incorporating DTIs into the CAMP.
b. A process to determine if DTIs exist for those repairs and alterations identified in the airplane survey.
NOTE: This includes alterations not developed by TC or STC Holders and those that have not been identified through operator records review.
c. A process to obtain DTIs for repairs. See Appendices 5 and 6 of this AC for an acceptable approach.
d. A process for producing a list of alterations that affect FCBS on an operator’s airplane(s).
e. A process to review documents (such as instructions for continued airworthiness) relating to alterations developed by persons other than a TC or STC Holder to ensure DTIs are provided or developed for those alterations.
f. A process for obtaining DTIs for new alterations.
g. A process for obtaining DTIs for alterations not supported by a TC or STC Holder.
h. A process describing how DTIs for repairs and alterations will be incorporated into the part 121 or part 129 operator’s maintenance program, and for showing where the DTIs exist within the operator’s maintenance program.
i. A means of ensuring that the airplane will not be operated past the time limit established for obtaining DTIs.
403. Repairs. Repairs affecting FCBS need to be evaluated to determine if DT-based inspections are needed to ensure continued airworthiness. If a repair survey is utilized, use the survey parameters from Chapter 2 of this AC to identify repairs that may need DT Data developed. The survey plan may be divided into three groups of airplanes, as described in paragraph 404 of this AC. The DTIs will be implemented in accordance with paragraph 406 of this AC. Unless already required by the airplane certification level or other FAA-approved program, beginning December 21, 2010, and thereafter, all new repairs affecting FCBS must have a DTE performed. Implement any DTIs established from the DTE according to the process described in Appendix 5 of this AC. This includes blendouts, trim-outs, etc. that are beyond published TC Holder limits. For repairs installed on structure that has been altered, the operator is responsible for coordinating development of the required DT Data with the party responsible for the design of the alteration.
404. Schedule for Implementing DTI for Existing Repairs.
a. To implement DTIs for existing repairs, an operator should use the assessment process in Appendix 6 of this AC. For existing repairs that require DTIs, an implementation schedule should be established providing timelines for airplane repair surveys, identifying and dispositioning repairs requiring immediate action, and developing DTIs (see Appendix 6 of this AC for additional information). The survey should enable operators to identify existing repairs that affect FCBS and would apply to all affected airplanes in an operator’s fleet, as defined in the OIP. The different elements included in the airplane survey are contained in paragraph 216 of this AC. Existing repairs that already have DTI in the CAMP require no further action.
b. The timelines established for any given airplane depends on the age of the airplane on December 18, 2009. To support development of the implementation schedule, the TC Holder will identify the design service goal (DSG) for each of its affected airplane models.
The DSG will be used to establish the following timelines for conducting airplane surveys:
(1) Airplanes less than 75 percent of the DSG on December 18, 2009.
Operators should complete a survey of an individual airplane at the first heavy maintenance check (time limit equivalent to a “D-check”) after the airplane reaches 75 percent of its DSG, not to exceed its DSG. Within 6 months after FAA approval, the required DTIs must be incorporated into the operators CAMP.
(2) Airplanes between 75 percent of the DSG and the DSG on December 18, 2009. Operators should complete a survey of these airplanes at or before each individual airplane’s next heavy maintenance check (equivalent to a D- check) after December 20, 2010, not to exceed the DSG or 6 years, whichever occurs later. Within 6 months after FAA approval, the required DTIs must be incorporated into the operator’s CAMP.
(3) Airplanes beyond the DSG on December 18, 2009. Operators should complete a survey of these airplanes at or before each individual airplane’s next heavy maintenance check (equivalent to a D-check) after December 20, 2010, not to exceed 6 years. The highest time airplanes should be inspected first. Within 6 months after FAA approval, the required DTIs must be incorporated into the operator’s CAMP.
405. Implementing DTI For Repairs.
a. To implement DTIs for repairs, the operator should review inspection methods and intervals from an FAA-approved DTE. The operator may choose to implement DTIs as part of the regularly scheduled maintenance program, on an individual basis (by conducting inspections at established thresholds and repetitive intervals), or a combination of both.
b. Once the DTIs are known, accomplish the first inspection of the repair according to the following schedule:
(1) Inspect the repair before the inspection threshold or within a time limit equivalent to a “C-check” from accomplishment of the survey, whichever occurs later.
(2) If the age of the repair is unknown, use the airplane’s age in flight cycles or flight hours.
(3) Implement repetitive inspection intervals per the instructions provided.
c. DTIs must be developed for any repair installed after December 20, 2010, that affects FCBS. As determined necessary by the DTE, the DTIs would apply to the repair and the FCBS that are affected by the repair for compliance with the Aging Airplane Safety Final Rule (§§ 121.1109 and 129.109). DTI thresholds and repetitive intervals for individual repairs cannot be exceeded without approval of the FAA Oversight Office or an FAA Designee.
406. Alterations.
a. The operator should identify the alterations that exist in its fleet of airplanes. The operator should consider the list of alterations contained in Appendix 9 of this AC in determining which alterations may affect FCBS. If an operator’s records are complete, this may be done by review of airplane configuration records. Otherwise, the airplane survey may be used to identify all alterations. The operator should then establish which alterations have been installed on or likely affect FCBS and prepare a list of alterations by airplane.
The FAA-approved Compliance Documents from the TC Holder may be used to identify the FCBS. An operator can develop the list of alterations by using the following steps:
(1) Compile a list of all alterations that are currently installed on its fleet.
(2) Include in the list those alterations that affect FCS, but have since been removed (components removed) but the altered structure remains.
(3) Delete from the list those alterations that are not installed on its current fleet.
(4) Delete from the list those alterations that do not affect FCS. The remaining alterations that affect FCS on this list will require DT Data.
(5) Review each alteration to determine whether:
(a) The DT Data already exist; or
(b) The DT Data need to be developed.
(6) Submit a letter to the FAA Oversight Office, through the operator’s PMI, providing a list of alterations developed by an STC Holder on the operator’s active fleet.
b. Some individual alterations may not be identified through a review of airplane maintenance records. In these situations, the means of compliance is a plan to survey the airplane for alterations similar to the repair survey in Chapter 2 of this AC. The DTIs developed for those alterations identified in the survey should be implemented into an operator’s maintenance program according to the schedule identified in paragraph 408 of
this AC. It is anticipated that most airplanes will need to be surveyed in order to ensure all alterations are identified. This survey can be conducted at the same time the survey for repairs is performed. The operator should begin developing the list of alterations as soon as the TC Holders make their list of FCBS available.
407. Schedule for Developing and Incorporating DTIs for Alterations.
a. Operators should develop a schedule for obtaining and incorporating DTI for alterations installed on their airplanes. For existing and new alterations developed by a TC or STC Holder, the timelines for incorporating the DTI into an operator’s CAMP are provided in paragraph 313 of this AC and should be contained in the TC and STC Holder’s Compliance Document.
b. For alterations where DTIs are not made available by TC or STC Holders, or for alterations developed by persons other than a TC or STC Holder, the operator is responsible for obtaining or developing the DT Data and for establishing a schedule using the timelines provided in this paragraph. The schedule would include timelines for submitting the DT Data to the FAA Oversight Office for approval, and for incorporating the DTIs into the operator’s maintenance program. The operator may develop the DT Data using the guidance in paragraph 312 of this AC or the operator may contract the work out to a third party who may also use the same guidance. The operator must submit operator-developed DT Data and timelines to the FAA Oversight Office for approval. DT Data developed by a third party may be submitted to the FAA Oversight Office for approval by the operator or by the third party. The following are acceptable timelines for submitting DT Data to the FAA Oversight Office and for incorporating the approved DTIs into the operator’s maintenance program:
(1) For alterations identified through the records review (see paragraph 407 of this AC), the operator or third party-developed DT Data should be submitted to the FAA Oversight Office no later than December 20, 2012, or prior to the airplane reaching 75 percent of the design service goal, whichever occurs later. The operator should incorporate the DTI into its CAMP no later than 6 months from the date the FAA approves the data.
(2) For alterations that are found during the airplane survey for repairs, the operator or third party-developed DT Data should be submitted to the FAA Oversight Office no later than 12 months from the time of discovery. The operator should incorporate the DTIs into its maintenance program no later than 6 months from the date the FAA approves the data.
(3) Once the DT Data is developed for an alteration on one airplane, the data may be used for other airplanes in the operator’s fleet with the same alteration.
408. Implementing DTIs for Alterations. Operators should accomplish the first inspection of an alteration according to the DTI schedule. If the age of the alteration is unknown, use the airplane age in total flight cycles or total flight hours, as applicable.
a. For airplanes which have not reached the inspection threshold for a DTI, accomplish the first inspection of the alteration before the inspection threshold or within a time limit equivalent to a C-check interval from incorporation of the DTI into the operator’s approved maintenance program, whichever occurs later.
b. For airplanes which are beyond the inspection threshold for a DTI, accomplish the first inspection within a time limit equivalent to a C-check interval from accomplishment of the DTE for the alteration.
c. Implement repetitive inspection intervals per the DTI.
d. Any alteration installed after December 20, 2010, that affects FCBS must have DT Data that address the affected FCBS or FCS of the alteration for compliance with the Aging Airplane Safety Final Rule (§§ 121.1109 and 129.109).
409. Existing Responsibilities.
a. Reporting Requirements. Existing reporting requirements under § 121.703 still apply, however, the FAA encourages operators to report significant findings to the TC Holders to ensure that prompt fleet action is taken.
b. Recordkeeping Requirements. Existing record-keeping requirements still apply.
Section 121.380 requires operators to retain records of the current inspection status of the airplane, including the times since the last inspections required by the inspection program.
In addition, § 121.707 requires operators to prepare a report of major repairs and alterations which include repairs or alterations to FCBS.
c. Transfer of Airplanes after December 20, 2010. After December 20, 2010, before adding an airplane to its operations specifications or fleet, the operator should perform the following actions:
(1) For an airplane previously operated under a part 121 or part 129 maintenance program, the new operator may use either the previously PMI-approved OIP for that airplane or its own PMI-approved implementation plan for repairs and alterations, if that plan applies to the airplane being acquired. Operators may also develop a new OIP for the new airplane.
(2) For airplanes not previously operated under a part 121 or part 129 maintenance program, the operator develops and implements an OIP.
d. Operation of Leased Foreign-Owned Airplanes. Acquisition of a leased foreignregistered airplane for use in operations under part 121 requires the operator to develop and implement an OIP. The OIP should be developed in a manner that ensures that all repairs and alterations that affect FCBS are assessed, and any required DTIs for those repairs or alterations are incorporated into the maintenance program using the guidance in this AC.
410. FAA Principal Maintenance Inspector Approval of OIP. The operator’s PMI is responsible for approving the means for incorporating the DTI for repairs and alterations into a
part 121 or part 129 operator’s maintenance program. The PMI will compare the operator’s OIP with any Compliance Documents approved for a TC or STC Holder that are applicable to an operator’s airplane. The PMI will then approve incorporation of the OIP into the operator’s maintenance program by a revision to the operations specification. The operation specification will include the OIP by name, document number, and date.
411. Maintenance Program Changes. When revising a maintenance program containing DTIs for repairs and alterations affecting FCBS, the operator should evaluate any impact of the change on the DTIs. This evaluation should be made in accordance with the operator’s Continuing Analysis and Surveillance Program and FAA-approved REGs. If the evaluation shows that a DTI needs to be revised, any revision to a DTI must be submitted through the PMI to the FAA Oversight Office for approval. Revisions made to the maintenance program to incorporate new or revised DTIs for FCS, or repairs or alterations to FCBS, or adding new FCS, must be approved by the operator’s PMI and the operations specifications revised to show the revision.
412. thru 499. [RESERVED].
CHAPTER 5. ADMINISTRATIVE REQUIREMENTS
500. AC Availability – How Do I Get a Copy of the Publications Referred to in this AC?
a. The CFR and those ACs for which a fee is charged may be obtained from the Superintendent of Documents at the following address. A listing of the CFR and current prices is located in AC 00–44, “Status of Federal Aviation Regulations,” and a listing of all ACs is found in AC 00–2, “Advisory Circular Checklist.”
Superintendent of Documents P.O. Box 371954 Pittsburgh, PA 15250–7954
b. To be placed on our mailing list for free ACs contact:
U.S. Department of Transportation Subsequent Distribution Office M-30 Ardmore East Business Center 3341Q 75th Avenue Landover, MD 20785
c. You may view and print the CFR and Aircraft Certification Service and Flight Standards Service ACs on the FAA Web page at http://rgl.faa.gov.
501. Who Do I Submit Comments to About this AC?
Submit direct comments regarding this AC to:
U.S. Department of Transportation Federal Aviation Administration Aircraft Maintenance Division, AFS-300 800 Independence Avenue SW.
Washington, DC 20591
502. thru 599. [RESERVED].
Appendix 1 APPENDIX 1.
REGULATORY AND GUIDANCE MATERIAL RELATED TO THIS AC
The following related documents are provided for information purposes and are not necessarily directly referenced in this AC. An electronic copy of the current revision levels of the following rules, ACs, and FAA Policy Statements that are noted by an (*) can be downloaded from the Internet at http://rgl.faa.gov.
1. Title 14 of the Code of Federal Regulations (14 CFR):
a. Part 21, §21.101, Designation of applicable regulations.*
b. Part 25, § 25.571, Damage-tolerance and fatigue evaluation. *
c. Part 25, § 25.1529, Instructions for continued airworthiness.*
d. Part 26, Holders of type certificates —Repairs*
e. FAA Final Rule – “Fuel Tank Safety Compliance Extension and Aging Airplane Program” (69 FR 45936, July 30, 2004).*
f. Part 43, § 43.13, Performance rules (general). *
g. Part 43, §43.16, Airworthiness Limitations.*
h. Part 91, § 91.403, General. *
i. Part 121, § 121.1105, Aging airplane inspections and records reviews.*
j. Part 121, § 121.1107, Special maintenance program requirements.*
k. Part 121, § 121.1109, Supplemental inspections. *
l. Part 129, § 129.109, Supplemental inspections for U.S.-registered aircraft.
m. Part 129, § 129.107, Special maintenance program requirements.
n. Part 129, § 129.105, Aging airplane inspections and records reviews for U.S.-registered multiengine aircraft.*
2. Advisory Circulars (AC):
a. AC 21.101-1, Change Product Rule*
b. AC 25.571-1C, Damage Tolerance and Fatigue Evaluation of Structure*
c. AC 25.1529-1, Instructions for Continued Airworthiness of Structural Repairs on Transport Airplanes*
d. AC 26-1, Part 26, Continued Airworthiness and Safety Improvements*
e. AC 91-56A, Continuing Structural Integrity Program for Large Transport Category Airplanes *
f. AC 120-73, Damage Tolerance Assessment of Repairs to Pressurized Fuselages*
3. FAA Policy Statement: PS-ANM110-7-12-2005, Policy Statement, Safety – A Shared responsibility – New Direction for Addressing Airworthiness Issues for Transport Airplanes,” issued July 6, 2005, effective July 12, 2005.*
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Appendix 1
4. FAA Orders:
a. Order 8900.1, Change 0, Flight Standards Information Management System, Volume 4 Aircraft Equipment and Operational Authorizations, Chapter 9, Selected Field Approvals, dated September 13, 2007.
b. Order 8110.104, Responsibilities and Requirements for Implementing Part 26 Safety Initiatives
5. Other Documents referred to in this AC:
a. A Final Report of the AAWG – Continued Airworthiness of Structural Repairs**
b. A Report of the AAWG – Recommendations for Regulatory Action to Prevent Widespread Fatigue Damage in the Commercial Airplane Fleet**
c. A Report of the AAWG - Recommendations For Regulatory Action To Enhance Continued Airworthiness Of Supplemental Type Certificates
d. Air Transport Association (ATA) Report 51-93-01***
e. ATA Response to FAA Docket 1999-5401, dated May 5, 2003***
f. FAA-Approved, Model Specific, Repair Assessment Guidelines ****
g. FAA-Approved, Model Specific, Supplemental Inspection Documents****
** An electronic copy of the AAWG reports can be downloaded from the Internet at http://www.faa.gov.
*** Please contact the ATA. Air Transport Association of America, Inc.,1301Pennsylvania Avenue., NW, Suite 1100, Washington, DC 20004-1707;
telephone (202) 626-4000.
**** Various manufacturers publish these documents. Please contact the applicable manufacturer regarding the general availability of the documents. The addresses are provided below.
• Airbus, 1 Rond-Point Maurice Bellonte, 31700 Blagnac Cedex, France
• The Boeing Company, P.O. Box 3707, Seattle, Washington 98124-2207
• Bombardier Aerospace, Bombardier Inc., 400 Cote Vertu West, Dorval, Quebec, H4S 1Y9
• British Aerospace, British Aerospace Regional Aircraft American Support, 13850 Mclearen Road, Herndon, Virginia 20171
• Fokker Services B.V., P.O. Box 231, 2150 AE Nieuw-Vennep, the Netherlands A1-2
Appendix 1
• Lockheed Martin Corporation/Lockheed Martin Aeronautics Company, Airworthiness Office, Dept. 6A0M, Zone 0252, Column P-58, 86 S. Cobb Drive, Marietta, Georgia 30063 A1-3
Appendix 2 APPENDIX 2. DEFINITIONS
a. Airplane Structural Configuration is the approved type certificate design, including the original; any model variations or derivatives; and alterations or replacements mandated by AD.
b. Airworthiness Limitations Section (ALS) is a collection of mandatory maintenance actions required for airplane structure and fuel tank system. For structural maintenance actions, the ALS includes structural replacement times, structural inspection intervals, and related structural inspection procedures.
c. Alteration or Modification is a design change that is made to an airplane. Within the context of this AC, the two terms are synonymous.
d. Amended Type Certificate (ATC) is an approval of a change to the type design proposed by the Type Certificate Holder.
e. Baseline Structure means structure that is designed under the original type certificate or amended type certificate for that airplane model.
f. Damage Tolerance Data are damage tolerance evaluation (DTE) documentation and the damage tolerance inspections (DTIs).
g. Damage Tolerance Evaluation (DTE) is a process that leads to a determination of maintenance actions necessary to detect or preclude fatigue cracking that could contribute to a catastrophic failure. As applied to repairs and alterations, a DTE includes the evaluation of the repair or alteration and the fatigue critical structure affected by the repair or alteration.
The process utilizes the damage tolerance procedures as described in AC 25.571-1, 1A, 1B, or 1C.
h. DTE Documentation are data that identify the evaluated FCS, the basic assumptions applied in a DTE, and the results of a DTE.
i. Damage Tolerance Inspections (DTIs) are the inspections developed as a result of a DTE. A DTI includes the areas to be inspected, the inspection method, the inspection procedures, including acceptance and rejection criteria, the threshold, and any repetitive intervals associated with those inspections. The DTIs may specify a time limit when a repair or alteration needs to be replaced or modified. If the DTE concludes that DT-based supplemental structural inspections are not necessary, the DTI documentation should include a statement that the normal zonal inspection program is sufficient.
j. Design Service Goal (DSG) is the period of time (in flight cycles, flight hours, or both) established by the TC Holder at design and/or certification during which the fatigue critical structure will be reasonably free from significant cracking.
k. Fatigue Critical Baseline Structure (FCBS) is the baseline structure of the airplane that is classified as fatigue critical structure.
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