Par 10-1 Page 43 (and 44) CHAPTER 10. MAINTENANCE REVIEW BOARD REPORT (MRBR)/MAINTENANCE
TYPE BOARD REPORT (MTBR) LOW-UTILIZATION MAINTENANCE
REQUIREMENTS
10-1. GENERAL. A logic process is necessary to ensure that minimum scheduled tasking/interval requirements are met for low-utilization aircraft. This will ensure early detection of deterioration in areas that are sensitive to time rather than cycles or flight-hours.
10-2. APPLICABILITY. These requirements apply to aircraft that have an MRBR or an MTBR or have been analyzed under the Maintenance Steering Group (MSG) to define the minimum scheduled tasking/interval requirements.
10-3. REQUIREMENTS. The OEM/TCH should specify utilization parameters in its Policy and Procedures Handbook (PPH)/MRBR/MTBR. The intervals for tasks identified in the MRBR/MTBR are based on normal utilization. Operators operating outside the parameters listed in the PPH/MRBR/MTBR should consider the application and employment of a utilization program based on alternate criteria. Tasking requirements will be addressed on a task-by-task basis to ensure the proper utilization parameters.
a. MSG Logic. When the aircraft has been analyzed using MSG logic, it is not necessary to revisit the analysis before applying the proper low-utilization parameter for a task.
b. Operations Outside the PPH. The OEM/TCH is responsible for developing a set of recommendations for operations outside the PPH utilization parameters. This should be a stand-alone program, and not a supplement to the MRBR/MTBR.
Par 11-1 Page 45 (and 46) CHAPTER 11. FLIGHTCREWS ACCOMPLISHING MAINTENANCE
11-1. GENERAL. This section addresses flightcrews performing maintenance tasks. Title 14 of the Code of Federal Regulations (14 CFR) defines people authorized to accomplish maintenance.
Flightcrews may not perform any task that is used to fulfill Maintenance Review Board Report (MRBR)/Maintenance Type Board Report (MTBR) tasking requirements.
11-2. APPLICABILITY. Inspections are considered maintenance. This is based on 14 CFR part 43, § 43.7(f), which states: “A person holding at least a private pilot certificate may approve an aircraft for return to service after performing preventive maintenance under the provisions of § 43.3(g).” Flightcrews are not permitted to accomplish any maintenance accomplished outside the scope of preventive maintenance as defined in part 43, appendix A(c).
Air carriers/commercial operators are not allowed to accomplish maintenance/preventive maintenance tasks without an exemption to perform those tasks. The only exception to this is rotorcraft under 14 CFR § 43.3(h).
Par 12-1 Page 47 CHAPTER 12. IMPLEMENTATION AND OPTIMIZATION OF TASKING
INTERVALS
12-1. INTRODUCTION. The guidance in this document is intended for use by Original Equipment Manufacturers (OEM), type-certificate holders (TCH), and Maintenance Review Board (MRB)/Industry Steering Committee (ISC) members who are involved with the evolution/optimization of tasks in an initial/current Maintenance Review Board Report (MRBR).
Apply this guidance for evolution/optimization or deletion/addition activities where no official correspondence has been forwarded to the airworthiness authorities. The following is guidance for developing and assessing proposals for changes to the MRBR.
a. The initial MRBR for any new aircraft is developed in the absence of actual in-service experience. As a result, the tendency is to be conservative in the decisionmaking process. As service experience is accumulated, task intervals (thresholds/repeats) should be adjusted to reflect the results of actual in-service data.
NOTE: Additional Federal Aviation Administration (FAA) guidance for development of evolution/optimization may be found in FAA Order 8900.1, Volume 8, Chapter 2, Section 7, Maintenance Review Boards.
b. The OEM/TCH evolution/optimization process does not assume any operational control over an operator’s maintenance program.
c. Definitions for use with this program can be found in Appendix 2, Evolution/Optimization Definitions.
NOTE: When intervals are stated in this document, they include both threshold and repeat values.
NOTE: If this chapter is not followed, the OEM/TCH will be limited to no more than 10 percent escalation with approved data. Further escalation is not allowed until a task is repeated and sufficient data are available.
12-2. PURPOSE. While this guidance is not exhaustive, use it as the basis for a Policy and Procedures Handbook (PPH) procedure when the OEM/TCH, MRB, and ISC wish to proceed with evolution/optimization regarding the MRBR. Evolution/optimization or deletion/addition of a task through the management of data is a means to assure the continued applicability and effectiveness of the task, while simultaneously improving the integrity of the MRB process. This policy allows the OEM/TCH to develop and use a process that serves as a continuous analysis and evolution/optimization or deletion/addition for the MRBR. It is based on performance data and experience for model-specific fleets flown by multiple operators under a variety of operating conditions and environments.
12-3. POLICY DESCRIPTION. The OEM/TCH must meet the policy requirements defined by the regulatory authorities of the country of origin and will define further details and procedure clarifications in the PPH. As the PPH is a dynamic document, a response by the MRB chairperson must be given within 60 days after ISC acceptance/OEM submission. The following should occur:
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a. The ISC approves, and the MRB chairperson accepts, PPH revisions.
b. Evaluation of in-service data, both scheduled and unscheduled maintenance findings related to the intent of the Maintenance Steering Group (MSG) task.
c. Weighing of the relevance and significance of findings.
d. Standardization of the data format and content (Air Transport Association of America (ATA) Specification (SPEC) 2000 Chapter 11 or equivalent).
e. Ensuring of data quality, integrity, completeness, and clarity.
f. Consideration of each task individually.
g. A review of original design and engineering specifications, as required.
h. A review of all information related to continuing airworthiness (e.g., Airworthiness Directives, Service Bulletins (SB), in-service reports/letters, and modifications/repairs).
i. Basing MRBR task evolution/optimization or deletion/addition on worldwide representative samples that span the operating environment and age groupings of the aircraft.
j. Basing interval evolution/optimization or deletion/addition on risk management (RM).
RM is the systematic application of management policies, procedures, and practices to the tasks of identifying, analyzing, evaluating, treating, and monitoring risk.
k. The use of safety management principles at the OEM level. Safety management is the application of engineering and management principles, criteria and techniques to optimize safety.
It is an integrated and comprehensive engineering effort.
l. Application of statistical models to support the evolution/optimization or deletion/addition exercise. In a data-driven statistical decisionmaking process, data size is determined based on the level of confidence. Confidence level refers to the likelihood that the overall fleet performance lies within the range specified by the sample fleet performance. The confidence level is usually expressed as a percentage. For example, a 95 percent confidence level implies that the probability that the fleet parameter lies within the confidence interval is 0.95. For a given confidence level, data size may vary depending on the fleet size and variability of in-service data.
m. The OEM/TCH collects data sufficient to support the expected confidence level.
However, engineering judgment will remain a part of the evaluation. Statistical analysis should be supported and validated by engineering judgment.
n. Measurement of task effectiveness should be measured and demonstrated, including the ability to:
(1) Detect and prevent defects before loss of function/structural integrity.
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(2) Mitigate risk of exposure to hidden defects.
o. Recording of and response to operators’ and regulators’ feedback.
p. Ensuring the effectiveness and integrity of the process by:
(1) Collecting in-service data in an ATA SPEC 2000 Chapter 11 format or equivalent;
(2) Analyzing it; and
(3) Comparing the results with existing MRBR task requirements.
NOTE: This policy allows for evolution/optimization or deletion/addition of MRBR, scheduled maintenance tasks, intervals, and enhances the use of reliability-driven maintenance analysis processes.
q. Adjustment of the MRBR based on performance data and analysis processes. However, operator reliability programs should continue to ensure continuous evolution/optimization of their maintenance programs.
NOTE: The OEM/TCH evolution/optimization process does not assume any operational control over an operator’s maintenance program.
12-4. RESPONSIBILITIES. The OEM/TCH applicant must notify the approving authorities in writing of their intent to begin an evolution/optimization or deletion/addition process. This will be in the form of an official correspondence, as defined by the approving authorities.
NOTE: Approving authorities are those authorities that approve the MRBR.
The approving authorities will respond, in writing, to inform the OEM/TCH of their intent to participate in the evolution/optimization or deletion/addition exercise for a given fleet or model.
a. OEM/TCH (PPH Amendment and ISC/MRB Acceptance/Approval). The OEM/TCH will include within the PPH the policy requirements and criteria contained within this document. The OEM/TCH will further define the details and procedural actions necessary to conduct the evolution/optimization or deletion/addition exercise. The MRB/ISC will coordinate and approve this plan. When documents that support the evolution/optimization or deletion/addition are incorporated by reference within the PPH, the current document number and revision number must be stated.
b. OEM/TCH Data Collection. The OEM/TCH system must include a data quality, data integrity, data quantity, audit system, and historical data tool, as defined in the next steps.
c. Data Format. The OEM/TCH will use in-service data in a standardized format (ATA SPEC 2000 Chapter 11 format or equivalent), as deemed acceptable by the regulatory authority, to ensure data quality and integrity. ATA SPEC 2000 Chapter 11 is an industry-sanctioned maintenance reliability data communication format. In order to use this
Page 50 Par 12-4 format, operators would have to transition to this type of format, or the OEM/TCH would have to convert the operator data into this standardized format.
d. Regulatory Authorities. It is incumbent upon the OEM/TCH to demonstrate to the regulatory authorities compliance with these guidelines.
12-5. DATA QUALITY. The OEM/TCH should have a system in place that allows for the collection of data found during the operator’s accomplishment of tasks to be delivered to the OEM/TCH and then entered in a standardized format into their data collection system. The data collected and used by the OEM/TCH regarding evolution/optimization will include the following information:
a. Aircraft Age. Aircraft age (since delivery) is measured in calendar-days, flight-hours, or flight cycles, as applicable. MRB task evolution will be based on in-service data collected from a representative sample of older and newer aircraft incorporating more current production standards and modifications. Fleet age representation will be summarized in the analysis report.
b. Geographical or Operational Environment Representation. MRB task interval adjustments will be based on in-service data collected from a representative sample that spans all operating environments. The data will be in proportion to the specific model fleet size of each geographical area; however, it is not necessary to sample all geographical regions, nor is it required to collect data from all extreme operating conditions (e.g., extremely hot and sandy (desert), extremely cold (arctic)). A brief summary of the operating environments of the sampled aircraft will be provided in the report.
c. Number of Tasks Accomplished. The number of times the task has been accomplished, including “nil/no findings,” will be captured and used in the evaluation.
Participating operators should provide task findings and non-routine writeups for the related tasks of the sample fleet for the evolution/optimization or deletion/addition exercise reporting period.
d. Interval of Tasks Findings Applied. The actual task interval of each participating operator will be captured and evaluated.
NOTE: The actual intervals may vary between operators and may be different from MRBR requirements. The impact of these variations will be assessed and accounted.
e. Component Data (Shop Findings, No-Fault-Found Removals and Failures).
Information regarding component removal and replacement activity and vendor repair documents should be evaluated, as applicable and when available. This information provides the data necessary to perform component failure-mode and life-cycle analysis, which is necessary to support the evolution/optimization or deletion/addition of the tasks associated with the component.
f. Correct Mapping to the MRBR Task. Non-routine writeups and in-service findings should be linked to appropriate MRBR tasks, as applicable. Only findings related to the Maintenance Steering Group - 3rd Task Force (MSG-3) task intent are relevant.
Par 12-5 Page 51
g. Failure Effect Category (FEC) Considerations. MRBR task interval optimization is based on principles that reflect the criticality of airplane systems components identified during MSG analysis. Account for FECs during the analysis.
h. Operational Representation—Flight-Hour vs. Cycles, Calendar Time. Aircraft utilization (flight-hours or cycles, as applicable) should be captured and evaluated. Include a summary of fleet-wide service experience, high-time aircraft (hours, cycles, years), time in service, daily utilization (high, low, average), etc. in the analysis report.
i. Consecutive Tasking Requirements. To the extent possible, capture consecutive task check data to assess reliability of aircraft systems, components, or structural elements related to the MRBR task.
NOTE: This requirement may be applied to lower interval tasks.
Consecutive check data can be impractical for higher interval tasks.
j. Unscheduled Maintenance Findings. Mechanical irregularities and the resulting corrective actions captured from pilot reports (PIREP) and maintenance reports should be reviewed, as applicable. Unscheduled maintenance is a prime indicator of the effectiveness of the scheduled maintenance program.
k. Scheduled Maintenance Findings.
(1) Routine Maintenance Tasks That Generate No Findings. Tasks that generate no findings are as important as are tasks that generate findings in determining failure-mode and life-cycle analysis.
(2) Routine Maintenance Tasks That Generate Non-Routine Cards. These findings, which require corrective action, involve structures, aircraft zones, and aircraft systems categorized by ATA chapter.
l. Unrelated Significant Findings (If Applicable). Operators should capture significant non-routine writeups generated in the course of an unrelated maintenance task, if applicable.
These findings, which require corrective action, may not correlate to a routine maintenance task.
m. Four-Digit ATA Code (If Available). To the extent possible, operators should provide four-digit ATA codes for scheduled/unscheduled maintenance writeups to facilitate transfer of findings to appropriate MRBR tasks.
n. Serial Numbers of Aircraft. The operator should provide an aircraft manufacturer serial number that uniquely identifies each aircraft in the sample fleet.
12-6. DATA INTEGRITY. Data integrity is the quality of correctness, completeness, and compliance with the intention of the creators of the data. It is the condition in which data are identically maintained during any operation, such as transfer, storage, and retrieval. Data integrity is achieved by preventing accidental or deliberate but unauthorized insertion, modification, or destruction of data in a database.
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a. Data Validation. An OEM/TCH must have a data validation process that does the following:
(1) Verifies that operator data are converted to ATA SPEC 2000 Chapter 11 or an equivalent standard format.
(2) Ensures that all required data elements and attributes are satisfied for submitted data.
b. Audit System. The audit system must ensure that all data be traceable to the original task.
12-7. DATA REVIEW.
a. Analysis Schedule—Evolution/Optimization or Deletion/Addition Timeline. MRB task interval adjustments should be considered after sufficient service experience is accumulated since entry into service. Subsequent task interval adjustments should be considered after additional service experience has been accumulated and since the last interval adjustment. In both cases, data sufficiency is measured by the level of confidence, as stipulated in these guidelines.
b. Statistical Analysis. The OEM/TCH will develop and implement a statistical analysis system to provide justification that a 95 percent confidence level has been achieved for the evolution/optimization or deletion/addition exercise on a task-by-task basis. Exceptions can be presented to, and may be approved by, the MRB chairperson.
c. Engineering Analysis. Engineering analysis will verify that findings are relevant to the scheduled task under evaluation. Non-routine writeups will be evaluated to determine the significance or severity of findings. PIREPs and component reliability reports will also be examined to account for line maintenance activities that may be relevant to the task under evaluation. The severity of the findings must be considered and evaluated.
NOTE: Scheduled servicing (e.g., lubrication/oil replenishment) task data do not result in reported related findings; therefore, an engineering assessment must be conducted to support an evolution/optimization or deletion/addition.
Negative long-term effects (e.g., corrosion) resulting from inappropriate servicing intervals must be considered.
d. Modification Status, Airworthiness Directives, SBs, Service Letters (SL), etc.
Review all information related to the task (SBs, Airworthiness Directives, SLs, and other in-service reports/resolutions, as applicable). Also assess fleet configuration.
e. Internal Review. The OEM/TCH will develop and implement internal quality procedures to review and validate the MRBR revision process, as defined in the PPH. The OEM/TCH will develop and implement internal processes to validate MRBR revised tasks and/or intervals resulting from evolution or will demonstrate that an equivalent, written internal process already exists to reach the same intent.
Par 12-8 Page 53 (and 54)
12-8. DATA CORRELATION. Correlate mean time between unscheduled removals, failures, PIREPs, non-routines, technical followups on open technical issues, and all other pertinent data, as applicable.
a. Working Group (WG) Activity—Interval Recommendation to the ISC. Examples include increasing, decreasing, remaining the same, introduction of a new task, and deletion of a task.
(1) MRB task intervals can be escalated based on the results of in-service experience. In addition, tasks should be de-escalated when in-service data support interval reductions. A task may also be deleted when it is determined that it is ineffective or when the failure mode for which the task was selected never developed due to effective design provisions.
(2) Task deletion, addition, or modification of intent requires new/revised/amended MSG-3 analysis. However, complete reanalysis of the MSG package is not required. Any decision, together with justification, will be recorded and traceable in the associated MSG-3 analysis. Applicable and effective criteria, as specified in MSG-3, will be observed.
(3) The intervals of potential failure-finding tasks (i.e., those looking for degradation) should be less than the shortest likely interval between the point at which a potential failure becomes detectable and the point at which it degrades into a functional failure. If the specific failure data are available, this interval may be referred to as the “P to F” interval. Assess consecutive task accomplishments to show that failures are not occurring before the new initial interval.
(4) Interval determination should be validated with a maintenance engineering analysis based on consideration of all the items listed in the quality and quantity of data. The process will be referred to or mentioned in the PPH for ISC and regulatory acceptance.