The first time I heard about the Maintenance Planning Document I was a bit confused and mislead it with the Maintenance Program.
It was during a meeting few years ago, where I decided to keep a quite low profile, until I would have found the chance to clarify myself about the difference between these two apparently similar documents.

The Maintenance Program (MP) and the Maintenance Planning Document are actually linked each other, in the sense that each MP of each single aircraft, comes from the MPD for that aircraft type.

In fact, the MPD (Maintenance Planning Document) is a task-driven document providing the information needed to define the aircraft maintenance program.
It is “task-driven” because it refers to the each known maintenance task, identified by its Manual and the ATA Chapters.
Still in the MPD, such tasks are associated to the relevant deadline in terms of flight cycles or flight hours or calendar days.

So once a maintenance task is identified with its AMM reference (for example), then the related required equipment and tools can also be identified, this is why this document may help a lot to figure out what an organisation needs to purchase or somehow make available, once it is clear the intended “maintenance level”.

The MPD also identifies some “planning information”, like man hours and the required skills so you should know clearly see, for all what above mentioned, that an analysis of the MPD may help a lot in order to identify the intended maintenance limit of a maintenance organisation willing to introduce a new aircraft in its scope of work.

Ok, this was the MPD but what about the MP (Maintenance Program)?

First of all, to make it crystal clear: there is one MPD and one MPD only for each Aircraft Type (e.g. A380-800) but there are as much MPs (Maintenance Programs) as the number of the flying aircraft of that type.

That is why, if you have come across some Aircraft Maintenance Programme (MP), you have perhaps noticed that, beside the aircraft type (e.g. B747-8), the document is identified with the specific aircraft MSN (Manufacturer Serial Number) and its current registration marks (e.g. D-ABCD). Within the MP all the scheduled maintenance is defined in terms of cycles, flight hours or calendar days, exactly like in the MPD but for some reason, agreed with the competent authority for that document, the limits might be here different (e.g. because an operator may use their accumulated reliability data in order to justify to their Authority a proposed escalation of the MP’s limits ..and in this way, under certain circumstance, give a contribute for an MPD’s amendment as well!).

Anyway, ensuring the compliance with the Maintenance Programme (MP) means ensuring the so called “airworthiness” of that specific aircraft identified by its type (i.e. Airbus A-380) and its registration mark (i.e. HB-CDE).

There is still another relevant difference between the MPD and the MP: while the MP is a document made by the Operator by means of the MPD, this latter is instead made by the manfacturer (i.e. Airbus).

Therefore, while the MP is approved by the relevant Aviation Authority of the Operator (i.e. FOCA in Switzerland), the MPD is not approved by any Authority, although it is also made up by documentation coming directly from the Authority (e.g. the MRBR and the ADs).

The MPD is made by the MRBR (Maintenance Review Board Requirements), the ALS (Airworthiness Limitation Section), the Inspection Service Bulletins (ISB) and the Airworthiness Directives (ADs). From the MPD, each operator defines its MP.

Furthermore, while both the documents (MP and MPD) defines maintenance deadlines in terms of Flight Hours, Cycles and/or Calendar days, the MP might instead use a different nomenclature, proper of the Operator who issued such MP. That is why some “Check C” identified in some operator Maintenance Program (MP) may not have any sense in the MPD where only numbers (Flight Cycles, Flight Hours, Days) are displayed.

In the MPD you will always find quite clear information that are supposed to be “public” (in the sense that are understandable by any user and are applicable to all the aircraft belonging to that specific aircraft type), in the MP no: it is a “private” document made up for a specific aircraft of a specific company, who may have agreed different limits with its competent Authority.

That is why an MRO / Maintenance Organisation may be required by his surveyor (EASA) to point out in the MOE 1.9 (Scope of Work), the intended maintenance limits by referring to the MPD and not to the MP: a Maintenance Organisation should in fact refer to all the aircraft of a certain type and cannot be dedicated to one or few aircraft only by using their MPs.

In fact, try to think about this: one or more operators could define each one their own “Check C” in their own MPs. These “Check C” maybe different from each other, so it will not make sense for a Maintenance Organisation (supposed to serve all of them) declaring that a “Check C” can be done within its facilities, but it will certainly make sense declaring maintenance limits according to the MPD, which only show numbers and tasks.

I have finally got what an MPD is, and what the differences with an MP are. I guess that I can even say something at the next meeting 😉

But wait, what are those things underneath the MPD? Ok, here is a very short but intense answer:

  • The MRBR (Maintenance Review Board Requirements) is a kind of maintenance program developed through the joint effort of Aviation Regulators, Manufacturers and Operators. They are gathered togheter within a group called the “Industry Steering Committee” or “ISC”, which follows the guidance outlined in the Advisory Circular AC 121-22A (based on the American Transport Association ATA MSG 3 methodology) in order to develop the scheduled maintenance program for a given aircraft systems structure and engines.
  • The Airworthiness Limitations Section (ALS) is part of the certificated product (aircraft, engine, propeller) type design (Part 21.A.31.a), that contains the mandatory scheduled maintenance items and the limitations for part replacement, necessary to maintain compliance with that type design. For each individual aircraft, an approved aircraft maintenance programme (MP) must be created, initially containing the ALS at the revision level applicable at the time of the aircraft’s first certificate of airworthiness. (EASA source).
  • The Inspection Service Bulletins are Service Bulletins identifying (recurrent) inspections and issued by the Manufacturer / Type Certificate Holder.
  • The Airworthiness Directives  (ADs) are legally enforceable rules issued by the competent authority (e.g. EASA or FAA) to correct an unsafe condition in an aircraft, aircraft engine, propeller, or appliance. In this case the (MPD) endorsed ADs are those having no terminating action and that are therefore recurrent.