Sofema Aviation Services (SAS)Â www.sassofia.com considers the requirements related to Corrosion Prevention & Control Program (CPCP) in compliance with AMC4 CAMO.A.305(g) Personnel requirements (ED Decision 2020/002/R) –Â Related to AMC 20-20 âContinuing Structural Integrity Programmeâ.
Note – Sofema Aviation Services offers the following training in support of the understanding regarding the regulatory obligations: AMC 20-20 Continuing Structural Integrity Programme â 1 Day
Corrosion Prevention & Control Program (CPCP Introduction)
A corrosion prevention and control program (CPCP) is a systematic approach to prevent and control corrosion in the Aircraftâs Primary Structure.
- The objective of a CPCP is to limit the deterioration due to corrosion to a level necessary to maintain airworthiness and where necessary to restore the corrosion protection schemes for the structure.
- A CPCP consists of a basic corrosion inspection task, task areas, defined corrosion levels, and compliance times (implementation thresholds and repeat intervals).
- The CPCP also includes procedures to notify the competent authority and TCH of the findings and data associated with Level 2 and Level 3 corrosion and the actions taken to reduce future findings to Level 1 or better.
Note on Corrosion Levels
- Level 1 Corrosion is the damage occurring between successive inspections that is local and can be reworked/blended-out within allowable limits as defined by the manufacturer in a structural repair manual (SRM), service bulletin, etc.
- Level 2 Corrosion is damage occurring between successive inspections that require rework or blend-out that then exceeds the manufacturerâs allowable limits, requiring a repair or complete/partial replacement of a principal structural element.
- Level 3 Corrosion is damage found during the first or subsequent inspection(s) which is determined by the operator to be a potential airworthiness concern requiring expeditious action.
General Comments
A CPCP requires a method to notify the Relevant Competent Authority as well as the aircraftâs manufacturer regarding findings as well as any data associated with such damage. The definitions for different corrosion levels have changed over time, causing issues for air carriers with mixed fleets so to check carefully the applicable documentation relevant to your aircraft type.
Across Industries there are some differences in reporting requirements for the three corrosion levels. A potential issue exists related to âsuccessive blendingâ (i.e., blending performed in a series versus multiple blends at different times) of corroded areas.
For example, if a Level 1 area is blended a second time, it becomes Level 2. However, successive blends after the second blend (up to five in a row) may remain defined as Level 1.
How does your organisation track successive level 1?
Are you tracking blending very well or not at all? This information may have to be built into maintenance program revisions. Operators CAMOâs may be required to show they are recording these blending repairs especially if they wish to take advantage of successive blending allowances.
Concerning Damage Tolerance (DT)
With Level 1 repairs, the amount of material loss during the blending process does not affect the strength requirement; therefore, this would not require DT considerations. However, a Level 2 corrosion repair that would necessitate a major repair to restore the structural integrity and function of the structure may require a DT inspection or task. â How is this managed?
Instructions for Continued Airworthiness
As part of the ICA, the TCH should provide an inspection programme that includes:
- The frequency and extent of inspections necessary to provide the continued airworthiness of the aircraft.
- The ICA should include the information needed to apply protective treatments to the structure after inspection.
- In order for the inspections to be effectively accomplished, the TCH should provide corrosion removal and cleaning procedures and reference allowable limits.
- The TCH should include all of these corrosion-related activities in a manual referred to as the Baseline Programme. This Baseline Programme manual is intended to form a basis for operators to derive a systematic and comprehensive CPCP for inclusion in the operatorâs maintenance programme.
- The TCH is responsible for monitoring the effectiveness of the Baseline Programme and, if necessary, recommending changes based on operators reports of findings.
Note – In line with Part-M requirements, when the TCH publishes revisions to their Baseline Programme, these should be reviewed and the operatorâs programme adjusted as necessary in order to maintain corrosion to Level 1 or better.
Operators CPCP Program
An operator may adopt the Baseline Programme provided by the TCH or it may choose to develop its own CPCP or may be required to if none is available from the TCH.
Note â for Aircraft Certified In accordance with MSG-3 processes the baseline program is included in the Maintenance Review Board Report (MRBR) and provided to the airlines in the Maintenance Planning Document (MPD)
- In developing its own CPCP an operator may join with other operators and develop a Baseline Programme similar to a TCH developed Baseline Programme for use by all operators in the group.
- Before an operator may include a CPCP in its maintenance or inspection programme, the competent authority should review and approve that CPCP.
- The operator should show that the CPCP is comprehensive in that it addresses all corrosion likely to affect Primary Structure, and is systematic in that it provides:
- Step-by-step procedures that are applied on a regular basis to each identified task area or zone, and…
- These procedures are adjusted when they result in evidence that corrosion is not being controlled to an established acceptable level (Level 1 or better).
Note: For an aeroplane with an ALS, in addition to providing a suitable baseline programme in the ICA and to ensure compliance with CS 25.571 it is appropriate for the TCH to place an entry in the ALS stating that all corrosion should be maintained to Level 1 or better. (This practice is also described in ATA MSG-3)
Please see the following related to Part CAMO Transition Support: https://sassofia.com/download-area/#part-camo-transition-support
For additional questions or to register please email team@sassofia.com
Tags:
Continued Airworthiness, Aircraft Inspection, SAS training, Aircraft Corrosion Prevention, Corrosion Levels, Damage Tolerance, CPCP Program, Continuing Structural Integrity Program
