City University London
Course: Air Transport Operations and Management
Course: Aircraft Maintenance Planning
Year: 3
Exam Prep/ Lecture Notes
Topic 1: Maintenance Categories
Basics definitions:
Why do we do maintenance?
The performance of tasks required to ensure the continuing airworthiness of an
aircraft, including of overhaul, inspection, replacement,
defect rectification, and the embodiment of modification or repair, in order to ensure a safe operation.
On the other hand, it is an error provoking practice as there is areas within the maintenance effort
(overhaul – inspection – defect rectification, component installation, etc) where malfunctions may be the
result of bad maintenance practices. Thus, there needs to be a balance to ensure maintenance does not
introduce extra risk of error.
• However, maintenance is also about ensuring aircraft/fleet can cope with the technical and
operational requirements of an airline’s flight schedule, which generates revenue, being the core of
airlines as a business, therefore being efficiency and commercially driven as well.
• Airframe:
• Engine:
• Component
What categories of maintenance planning are there?
• Technical planning: Airline’s function to comply with EASA Part M. It defines what the goals are in
terms of availability,
• Production Planning & Control: MRO’s Function to comply with Part 145: the PP&C organisation is
primarily responsible for the planning and scheduling of all aircraft maintenance activity within the
airline. Its 3 main functions are in fact: forecasting, planning and control.
o Forecasting activities include: estimated maintenance workload for the short and long term
based on existing fleet and business plans and any known changes in these for the forecast
period.
o Planning involves: the scheduling of up coming maintenance, manpower, parts, facilities,
time frame requirements for such maintenance: (A,B, C checks, etc). These plans would
include incorporation of SBs, SLs and ADs.
o The control function allows adjustment of the plan and keeps (or attempts to keep) the
check on schedule. There are several methods of adjusting a plan: deferral to later checks,
addition of personnel to complete work, outsourcing the work to a contractor, etc.
o PLAN YOUR WORK and WORK YOUR PLAN.
Production Planning
• The organisation shall have a system appropriate to the amount and complexity of work to plan the
availability of all necessary personnel, tools, equipment, material, maintenance data and facilities
in order to ensure the safe completion of the maintenance work.
• The planning of maintenance tasks, and the organising of shifts, shall take into account human
performance limitations.
• When it is required to hand over the continuation or completion of maintenance tasks for reasons of
a shift or personnel changeover, relevant information shall be adequately communicated
between outgoing and incoming personnel.
• FAIL TO PLAN = PLAN TO FAIL
, o Example: One of the methods that can be used for planning maintenance checks in order
to ensure minimum turn around times is: Critical Path Analysis which predicts that may be
encountered in the process of carrying out maintenance and how to go about it.
Thus, the goals of PP&C is (a) to maximize its contribution to the airline, (b) to plan and organize work prior to
execution, (c) to adjust plans and schedules to meet changing requirements. Thus the activities of line, hangar
and shop maintenance constitute the production planning aspect of M&E. Production planning is then the
planning of that work with the stated goals in mind.
Topic 2: RAMS & Availability
o Life: the period for which it has been calculated that an item can safely remain in situ performing its
designed function without the need of overhaul or schedule replacement.
o Reliability: the probability of a product performing its purpose/function satisfactorily for a specified
period of time, given specified operating conditions. And/or,
o Availability: The proportion of time that an item is capable of operating to specification within a large
time interval.
o Maintainability: The probability that a failed item will be restored to operational effectiveness within a
given period of time when the repair action is performed in accordance with prescribed procedures.
o Safety-Integrity: The probability of a system performing specific safety functions in a sated period of
time.
RAMS Relationships:
o Availability is dependent / determined by both reliability and maintainability and/or part availability (of
an item). For instance: Technical availability is defined as the ratio of the total time that the fleet is
available fro revenue service, during an operating day, to the period of the operating the period of
the operating day when the fleet was not available or where dispatch was prevented and where the
root of the cause is attributable to a failure of a component or an aircraft system.
o Reliability & Risk Prediction: Failure of a system or component may occur not only due to mechanical
breakdown but also a number of other factors, such as: software, human factors, operating
documentation, environmental factors, common mode failure whereby redundancy is defeated by
factors common to the replicated units, etc.
o Reliability, Safety Integrity and maintainability results from efforts in 3 main areas:
• Design: reduction in complexity, duplication to provide fault tolerance (redundancy), De-rating
of stress factors, Qualification-Testing & Design Review, feedback of failure information to
provide reliability growth.
• Manufacture: (Control of materials, methods & changes), (Control of work, methods and
standards)
• Field Use: Adequate operating maintenance instructions, Feedback of field failure info,
replacement and spares strategies (e.g. early replacement of items with a known wearout
characteristic)
• THUS it’s much more difficult, expensive to add reliability/safety after the design stage.
o Safety is another factor driven by reliability and maintainability
o See coursework and elaborate on their relationship.
What type a measure of performance used when you outsource your maintenance?
There are several parameters available for describing the reliability for describing the reliability and
maintainability characteristics of an item. Some parameters are more appropriate than others, depending
on the item.
o Availability / Unavailability: Very useful where the cost of lost revenue, owing to outage, is of
interest. Combines reliability and maintainability.
o Dispatch reliability and Operational availability.
Course: Air Transport Operations and Management
Course: Aircraft Maintenance Planning
Year: 3
Exam Prep/ Lecture Notes
Topic 1: Maintenance Categories
Basics definitions:
Why do we do maintenance?
The performance of tasks required to ensure the continuing airworthiness of an
aircraft, including of overhaul, inspection, replacement,
defect rectification, and the embodiment of modification or repair, in order to ensure a safe operation.
On the other hand, it is an error provoking practice as there is areas within the maintenance effort
(overhaul – inspection – defect rectification, component installation, etc) where malfunctions may be the
result of bad maintenance practices. Thus, there needs to be a balance to ensure maintenance does not
introduce extra risk of error.
• However, maintenance is also about ensuring aircraft/fleet can cope with the technical and
operational requirements of an airline’s flight schedule, which generates revenue, being the core of
airlines as a business, therefore being efficiency and commercially driven as well.
• Airframe:
• Engine:
• Component
What categories of maintenance planning are there?
• Technical planning: Airline’s function to comply with EASA Part M. It defines what the goals are in
terms of availability,
• Production Planning & Control: MRO’s Function to comply with Part 145: the PP&C organisation is
primarily responsible for the planning and scheduling of all aircraft maintenance activity within the
airline. Its 3 main functions are in fact: forecasting, planning and control.
o Forecasting activities include: estimated maintenance workload for the short and long term
based on existing fleet and business plans and any known changes in these for the forecast
period.
o Planning involves: the scheduling of up coming maintenance, manpower, parts, facilities,
time frame requirements for such maintenance: (A,B, C checks, etc). These plans would
include incorporation of SBs, SLs and ADs.
o The control function allows adjustment of the plan and keeps (or attempts to keep) the
check on schedule. There are several methods of adjusting a plan: deferral to later checks,
addition of personnel to complete work, outsourcing the work to a contractor, etc.
o PLAN YOUR WORK and WORK YOUR PLAN.
Production Planning
• The organisation shall have a system appropriate to the amount and complexity of work to plan the
availability of all necessary personnel, tools, equipment, material, maintenance data and facilities
in order to ensure the safe completion of the maintenance work.
• The planning of maintenance tasks, and the organising of shifts, shall take into account human
performance limitations.
• When it is required to hand over the continuation or completion of maintenance tasks for reasons of
a shift or personnel changeover, relevant information shall be adequately communicated
between outgoing and incoming personnel.
• FAIL TO PLAN = PLAN TO FAIL
, o Example: One of the methods that can be used for planning maintenance checks in order
to ensure minimum turn around times is: Critical Path Analysis which predicts that may be
encountered in the process of carrying out maintenance and how to go about it.
Thus, the goals of PP&C is (a) to maximize its contribution to the airline, (b) to plan and organize work prior to
execution, (c) to adjust plans and schedules to meet changing requirements. Thus the activities of line, hangar
and shop maintenance constitute the production planning aspect of M&E. Production planning is then the
planning of that work with the stated goals in mind.
Topic 2: RAMS & Availability
o Life: the period for which it has been calculated that an item can safely remain in situ performing its
designed function without the need of overhaul or schedule replacement.
o Reliability: the probability of a product performing its purpose/function satisfactorily for a specified
period of time, given specified operating conditions. And/or,
o Availability: The proportion of time that an item is capable of operating to specification within a large
time interval.
o Maintainability: The probability that a failed item will be restored to operational effectiveness within a
given period of time when the repair action is performed in accordance with prescribed procedures.
o Safety-Integrity: The probability of a system performing specific safety functions in a sated period of
time.
RAMS Relationships:
o Availability is dependent / determined by both reliability and maintainability and/or part availability (of
an item). For instance: Technical availability is defined as the ratio of the total time that the fleet is
available fro revenue service, during an operating day, to the period of the operating the period of
the operating day when the fleet was not available or where dispatch was prevented and where the
root of the cause is attributable to a failure of a component or an aircraft system.
o Reliability & Risk Prediction: Failure of a system or component may occur not only due to mechanical
breakdown but also a number of other factors, such as: software, human factors, operating
documentation, environmental factors, common mode failure whereby redundancy is defeated by
factors common to the replicated units, etc.
o Reliability, Safety Integrity and maintainability results from efforts in 3 main areas:
• Design: reduction in complexity, duplication to provide fault tolerance (redundancy), De-rating
of stress factors, Qualification-Testing & Design Review, feedback of failure information to
provide reliability growth.
• Manufacture: (Control of materials, methods & changes), (Control of work, methods and
standards)
• Field Use: Adequate operating maintenance instructions, Feedback of field failure info,
replacement and spares strategies (e.g. early replacement of items with a known wearout
characteristic)
• THUS it’s much more difficult, expensive to add reliability/safety after the design stage.
o Safety is another factor driven by reliability and maintainability
o See coursework and elaborate on their relationship.
What type a measure of performance used when you outsource your maintenance?
There are several parameters available for describing the reliability for describing the reliability and
maintainability characteristics of an item. Some parameters are more appropriate than others, depending
on the item.
o Availability / Unavailability: Very useful where the cost of lost revenue, owing to outage, is of
interest. Combines reliability and maintainability.
o Dispatch reliability and Operational availability.
