Cannot talk about airworthiness without mention The Approved Maintenance Program AMP, The AMP is develop by the Engineering of an operator and considered the main reference for airworthiness management it has to be available for every aircraft and it needs to be consulted with regards to every maintenance action to be performed.
The aircraft maintenance program include the minimum scheduled tasking/interval requirements for derivative or newly type -certificated (TC) aircraft and powerplants and certification maintenance requirements.
When a new aircraft is being designed and produced, the aviation authority, the manufacturer, and selected industry participants form groups called maintenance steering groups (MSG) and industry steering committees (ISC). These groups, through numerous meetings determine the frequency and scope of aircraft inspections to be performed. This information is provided to another group called the Maintenance Review Board (MRB). The MRB will issue their final recommendations to the manufacturer on how an aircraft should be maintained (Maintenance Review Board Report MRBR). The manufacturer then publishes this information in Maintenance Planning Documents (MPD) to be provided to the customer. For small private aircraft the aircraft owner usually follows the inspections and maintenance practices published by the manufacturer. For airline or commercial operators, the recommendations of the MRB and subsequent MPD are used to develop Airworthiness Maintenance Program (AMP), which is then approved by the operator local authority.
What Are Expected To Be Inside The Approved Maintenance Program?
As the maintenance program is the main reference for maintenance scheduling, planning and all maintenance tasks required to put the aircraft in airworthy condition, so AMO expected to include:
- Maintenance Program Approval letter (from local authority).
- Distribution list (to all concerned person).
- Summary of changes.
- Airworthiness limitation.
- Aircraft and APU utilization ratio - flight hour to flight cycle ratio and flight hour per year -which the AMP developed depending on it ().
- All applicable modifications.
- A list (in the form of a long table) of all maintenance tasks which need to be performed on an aircraft from time to time.And repairs need periodic inspection .In other words, based on the AMP an airworthiness engineer knows exactly what tasks need to be performed after an aircraft reaches a certain point in life, be it calculated based on calendar age, flight hours of flight cycles.How to group the maintenance tasks ? - i will make complete article about this important topic -
- Airworthiness Directives ADs status.
- Service Bulletin SBs status.
- Reliability Control Board RCB recommendations.
- Certification Maintenance Requirements (CMR).
- System Equipment Maintenance Requirements (SEMR).
- ETOPS Configuration, Maintenance and Procedures (CMP).
- Fuel Airworthiness Limitations.
- Maintenance escalations rules.
- Life Limited Parts /Time Change Items.
- Local authority maintenance requirements for airworthiness.
- Structure program.
- Corrosion Prevention program.
- Engine Monitoring program.
- Aircraft Utilization Limitation / Limit Of Validity (LOV)
- Cat II/Cat III landing capabilities, Reduced Vertical Separation Minima (RVSM) capabilities and Extended Twin Engine Operations (ETOPS) are inherent functions of the basic design standard of the aircraft. Scheduled tasks necessary for these operations have been considered in the development of the AMP. Operators should comply with National Requirements as applicable.
What are the Reference Documents for an Approved Maintenance Program?
To create / develop Approved Maintenance Program AMP, you have to use the reference documents:
- Maintenance Planning Document (MPD)
On first sight, the MPD looks exactly like an AMP. Just like the AMP, it contains a long table with entries for different maintenance tasks. Therefore, there may be some confusion as to what it is, and I even met people who believed that a copy of the MPD can be approved as an AMP. However there is many huge differences like:
- MPD is generic. It is being issued by the aircraft manufacturer and applies to many aircraft in the world wide fleet. Therefore, it is not customized and several (hundreds of) tasks are dependent for example on the aircraft modification status and its serial number. It cannot be considered as a final list of tasks for a given tail number.
- MPD of course not contain the Reliability Control Board RCB recommendations and engineering orders.
- MPD of course not contain the local authority requirements.
- MPD of course not contain custom modifications.
- Aircraft modification status:
The applicability of several tasks is dependent on the aircraft modification status. In several cases, the MPD may list a task as “pre mod” or “post mod”. The author of the AMP must know whether the aircraft is “pre” or “post” in order to know which task applies and should be carried out. Also, the aircraft may have custom modifications embodied, which often come with their own maintenance tasks.
- Aircraft Airworthiness Directives ADs status:
The final AMP should include all applicable tasks which need to be performed on the aircraft. This includes applicable and repetitive inspections called for by airworthiness directives.
- Aircraft Service Bulletins SB status:
All service bulletin approved by aircraft operator /owner to carry out should be included in AMP.
- Operator Reliability Program Reliability recommendations:
Based on an analysis of the operator’s reliability program, the author of the AMP can decide to shorten some maintenance intervals for given tasks, or – on the contrary – extend them. In both cases, will need to convince the appropriate aviation authority that such a decision is well supported by maintenance but this can (and, in fact, should) be done to fully account for the type of operations in a given airline.
- Local authority requirements
- Company procedures, customer experience values, and similar requirements :
These are things which also may affect the AMP. Perhaps the company wishes to have carpets replaced every 6 months or would like to inspect and repair some commercial decals once every week? Those are also maintenance tasks, which need to be supported by proper documentation and should be included in the AMP.
- Manufacturer Maintenance Manual MMM.
How Does an Approved Maintenance Program Change Over Time?
AMP is a living creature. It changes over time and it has to be. In fact, a regular (at least twice a year) review of the AMP and implication of relevant changes is a legal requirement under EASA. So why and how can an AMP change?
Because all reference documents regularly changes, so this force the operator to amend / release new issue of AMP
- AMP will need to change because the source documents change. Top aircraft manufacturers, like Airbus or Boeing release new revisions of the MPD at least twice a year.
- Aircraft are modified and have new airworthiness directives ADs and service bulletins embodied. In many cases, this will impose changes on the AMP.
- The operator’s reliability program continues to work and bring in new reliability data. This data should be regularly analyzed and proper conclusions should be drawn with respect to aircraft maintenance and airworthiness. This is why there is a requirement to analyze the effectiveness of an AMP at least twice a year.
The CAMO director and personnel must be convinced that the AMP indeed “foresees” aircraft damage and provides appropriate maintenance tasks at appropriate intervals, and have to regularly revised /amend / re issue.
How Approve The Maintenance Program?
Each AMP and also every AMP revision needs to be approved by the competent aviation authority. This can be a lengthy process, as the authority will need to time to (at least briefly) ensure that the AMP is corresponding to the source documents.
Also, every deviation from the source documents (like interval changes for certain tasks) need to be applied for from the authority and only with their approval can they be changed to suit the operator’s needs.
As you can see, creating and monitoring of an AMP can be a tedious process, but the Approved Maintenance Program is the most vital document in airworthiness, after all.
- Airbus (A330 MRB report).
- Airbus (A320 MPD).
- The Aircraft Maintenance Program and its importance on Continuing Airworthiness Management (Vitor Monteiro Correia - Instituto Superior Técnico)