Appendix E Note 1.
- Consider aircraft structure, systems, and installations within the zone to ensure unintended degradation or loss of function will not occur.
- Traceability o f revisions to approved electrical wiring interconnection system (EWIS) instructions for continued airworthiness (ICA) to include task, intervals, procedures, protections, and cautions must be maintained.
- As a pplicable, operators must apply any additional procedures or restrictions based on their compliance document requirements.
- Deletions of EWIS tasks must be approved by the FAA oversight office via the operator’s principal maintenance inspector (PMI).
Note 2.
Example:
Some zonal tasks may partially satisfy damage tolerance requirements which must be performed at originally-established l imits after a certain fatigue threshold. Intervals may be escalated prior to that threshold, but must be adjusted to the original levels at the threshold.
Note
3.
- Relative to the targeted failure mode and original intent.
- Refer t o Maintenance Steering Group – 3rd Task Force (MSG -3), volume 1, section 2-3-7 .1 (Table 2-3-7.1, Criteria for Task Selection) for applicability and safety effectiveness guidance.
Note 4. This evaluation doesn’t necessarily include the concept of actually measuring contamination or accumulation r ates. However, each task adjustment should be sufficiently substantiated, which includes whether the desired results will continue to be achieved at the revised interval. Refer to AC 25-27, AC 120-94, and AC 120-102 for additional information on contaminants.
Note
5. Lightning/High Intensity Radiated Fields (L/HIRF) protection may include:
- Wires, shields, connectors, bonding straps, raceways between connectors.
- L/HIRF p rotection within conduit or heat shrink or other covering.
- Non-metallic structure with conductive mesh and/or antistatic coatings.
Note
6. Consider:
- The environment and effects of corrosive produces, condensation, temperature, and vibration on the protection.
- Increased susceptibility to damage during maintenance or operations (e.g., where connectors could be stepped on, or effects of deicing fluid on a connectors during winter operations).
Note 7. Awareness of these relationships support a quality analysis. Zonal working groups may have modified zonal intervals to accommodate these interfaces.
Note 8.
- For example, findings associated with bonding straps, lightning wicks, tank plate wiring/connector bonding, etc.
- Ensure unintended consequences such as Environmental Deterioration (ED) or Accidental Damage are not introduced due to frequency of access/egress.
E-2
Appendix F APPENDIX F. STRUCTURE Note 1. General Information:
- The actuating portions of items such as landing gear, flight controls, doors, etc. are treated under systems analysis. Structures Tasks
- Dynamic components such as hinge bearings are treated as system component.
- Attachment fittings of the actuators to the airframe are treated as a structure analysis. Ensure data selection criteria conforms with guidance in
- Structure-to-structure attach points, not this AC (or as accepted by carrier's CMO).
otherwise associated with an aircraft system
(e.g., pylon attach fittings and diagonal braces) that feature bearings are be treated as Ensure TCH ICA structure. document
- Special consideration should be given to Does the TCH ICA guidance is analysis associated with attach points to structure since the structural analysis may not provide full consideration for wear and document contain specific instructions for structures program adjustment? Yes → section 9), (e.g., MPD followed deterioration. These analyses should be and...
compared with the appropriate system analysis, as applicable.
- Wear is typically found in/at bushings, bearings, stops, latches, locks, tracks, guides, Ensure data selection criteria conforms with guidance in cams, rollers, cables, pulleys, or floors. Wear can this AC (or as accepted by carrier's CMO).
influence loads and strength, lead to inaccurate positioning and adverse free play or change resistance to environmental deterioration.
Wear can be systematic for parts intended to be Is task still Consider alternative task in contact, or random for parts that should applicable and normally not come in contact or should not be effective? 2 task deletion, aircraft procedures, subjected to relative motion. modification, or consult TCH.
- Non-metallic structure is susceptible to damage and/or deterioration such as disbonding and delamination. These structures are not normally susceptible to Perform analysis of appropriate data.
degradation due to the environment
(e.g., corrosion). Special consideration should be given for non-metallic structure and any uniqueness associated with applicable damage sources.
Does the Appendix H. Follow End. analysis Is the task AD requirements for No change to task substantiate a a corrosion Yes Is the CPCP -Yes→ interval type, scope, or revised task interval detection AD-mandated? adjustments.
interval. and remain task?
effective? 3 Note 2.
Ensure
- Relative to the targeted failure mode and substantiating data original intent. - Refer to MSG-3 section 2-3-7.1 credit for DT for repairs or Is the task used to take accounts for (Table 2-3-7.1, Criteria for Task Selection) for alterations? previous findings and corrective applicability and safety effectiveness guidance. actions. 4
- Coordinate with the TCH when data from the MSG-3 task analysis is necessary to perform Note 4. The program is expected to control the evaluation. corrosion to Level 1 or better. Initial programs assume an aircraft is operated in Review previous repair or alterations a typical environment. If the analysis Note 3. Consider all damage sources: records to identify repairs or alterations reflects a trend in corrosion defects that Environmental Damage (ED) (corrosion, which may require individual tracking exceed Level 1, the corrosion control stress corrosion, delamination, disbonding, based on new interval. program for the affected area should be etc.); Fatigue Damage (FD); Accidental reviewed by the operator with the Damage; and Wear Damage (WD). objective to ensure Level 1 or better.
Revise task scope/type and/or End accomplishment interval.
F-1
Appendix G APPENDIX G. LIGHTNING/HIGH INTENSITY RADIATED FIELDS (L/HIRF) TASKS Note 1. Coordination with OEM is L/HIRF Task ' recommended. L/HIRF protection may include:
- Wires, shields, connectors, bonding straps, raceways between connectors.
- L/HIRF protection within conduit or Review TCH ICA heat shrink or other covering. rules.
- Non-metallic structure with conductive mesh and/or antistatic coatings.
Ensure TCH ICA rules are followed, if applicable.
Ensure data selection criteria conforms with guidance in this AC (or as accepted by carrier's CMO).
Perform analysis of appropriate data. 2 Note 2: Analysis should consider:
- The environment and effects of corrosive products, condensation, temperature, and vibration on the protection. Does the
- Susceptibility of damage during maintenance or analysis operations (e.g., where connectors could be stepped substantiate a task interval and/or scope revision that -No on, or effects of deicing fluid on a connector during maintains acceptable levels winter operations. of L/HIRF
- Scheduled maintenance findings associated with protection?
bonding straps, lightning wicks, tank plates wiring/ connector bonding, etc.
Yes Revise task scope, type, and/or interval.
End G-1
Appendix H APPENDIX H. OPERATOR PROGRAMS AND APPEARANCE Note 1. This decision tree applies to Operator Program tasks developed and implemented by the operator, such as: and Appearance Tasks 1
- Tasks that support other tasks;
- Administrative support tasks;
- Branding/image objectives; and standards established by the operator. - Cabin appearance and cleanliness task a response, Is this Appendix A; or other defined or is it otherwise related to a deficiency in the Yes→ analysis process operator's CAMP?
No Based on risk, determine the data set and analysis needed to evaluate the proposed change Does the Is the analysis anticipated impact +No- substantiate a acceptable? revised or deleted task?
No Yes Yes Delete or revise task scope, type, and/or accomplishment interval.
End H-1
Appendix I APPENDIX I. REGULATORY SOURCED REQUIREMENTS Regulatory Sourced Task ' Note 1. Examples include:
AD, CMRS, ALI, AL, and FTS tasks.
Does the Ensure regulatory regulatory authority/ authority source source requirement contain specific YesT requirements are instructions for task followed.
adjustment?
No Ensure data selection criteria conforms with guidance in this AC (or as accepted by carrier's CMO).
Note 2. Relative to the targeted failure mode and original intent.
Does Refer to MSG-3 section 2-3-7.1 analysis substantiate (Table 2-3-7.1, Criteria for Task adjustment of the task Selection) for applicability and safety interval and remain effectiveness guidance. No effective? 2 Coordinate with the TCH when data from the MSG-3 task analysis is necessary to perform the evaluation.
Submit proposal to the regulatory authority/source requirement holder.
Was approval obtained from the regulatory authority/ source requirement No holder?
Yes Revise task as approved.
End I-1
Advisory Circular Feedback Form If you find an error in this AC, have recommendations for improving it, or have suggestions for new items/subjects to be added, you may let us know by contacting the Flight Standards Directives Management Officer at 9-AWA-AFS-140-Directives@faa.gov.
Subject: AC 120-17B, Reliability Program Methods—Standards for Determining Time Limitations Date: _____________________ Please check all appropriate line items:
An error (procedural or typographical) has been noted in paragraph ____________ on page _______.
Recommend paragraph _____________ on page __________ be changed as follows:
______________________________________________________________________ ______________________________________________________________________ In a future change to this AC, please cover the following subject:
(Briefly describe what you want added.)
______________________________________________________________________ ______________________________________________________________________ Other comments:
______________________________________________________________________ ______________________________________________________________________ I would like to discuss the above. Please contact me.
Submitted by: Date: ______________________