8/25/2015 Aircraft Maintenance Module1 Aircraft Maintenance Management Module Aircraft Maintenance Introduction.

04/21/23 Aircraft Maintenance Module 1

Aircraft Maintenance Management Module

Aircraft Maintenance Introduction

General definition

Maintenance cost is broadly defined as the sum of incurred labour, material costs and various overheads otherwise known as indirect maintenance costs. The labour is normally a process time controlled and productivity related where certain tools such as lean processes or “Six sigma” can be employed to enhance productivity and consequently improve consumed labour.

The material element is dependant on negotiated supplier’s contracts and products reliability programs.


1. Aircraft Maintenance Cost Philosophies & Economics The maintenance costs represent 10-20% of the

worldwide airlines direct operating costs. These costs

are growing in view of introduction of new more

expensive material, highly sophisticated repair

schemes especially those associated with structural

parts and core Engine parts, and increasing labour

costs.


Boeing suggests that there are many other influencing

factors to the maintenance costs such as Aircraft

utilisation, Environment and Age. Furthermore,

Airlines influence costs of its operations and

maintenance support practices; similarly component

Manufactures influence product support and

reliability.


The Airlines overall maintenance costs are categorised

as Controllable and Non Controllable Costs. The

controllable cost element is further split into

contractual and non contractual costs. The contractual

cost elements are either outsourced or accomplished

In-house depending on potential benefits or savings in

the short or long runs.


Thus it is of extreme importance to understand all

elements of airlines maintenance costs and contain

such costs where practicable through introduction of

processes and manpower improvements, enhanced

training and optimisation of maintenance interval

requirement for both ON/OFF aircraft maintenance in

liaison with the OEMs.


The Airline industry currently under tremendous

pressure in light of the current downturn reducing

demand especially on premium cabin, hence the

competition which resulted in fares reduction and

subsequently low yields than breakeven costs.


2. Maintenance Costs (Direct /Indirect) Breakdown The Maintenance costs are the sums of total costs pertain

to Direct and Indirect Maintenance. Per IATA, Direct

Maintenance comprises the following, by Cost segment:

- Airframe, Engines and component maintenance. And

by cost element: Labour, Material and Outside repair

Where, Indirect Maintenance includes the Overheads

costs.


Boeing elaborates on these definitions further as follows:

- Direct Maintenance Cost is, the direct airframe and Engine maintenance which consist of the labour and material required to perform service, repair, modification, restoration, inspection, test, and troubleshooting tasks during on-airplane and shop maintenance activities.


Maintenance Overhead consists of maintenance supervision, maintenance training, maintenance planning, unallocated labour costs, rentals and Utilities.


We have to understand the elements that comprise the

Direct Maintenance Cost (DMC) and Indirect

Maintenance Cost (IMC). The breakdown of these

costs is:

2.1 Direct maintenance costs

2.2 Indirect maintenance costs


2.1.1 ON aircraft maintenance

This type of maintenance is normally carried out

during the scheduled aircraft checks as defined by the

Manufacturer’s MPD documents where an extensive

part of Labour Man-hours is expended as compared to

materials consumed such as filters, oil, greases,

fittings and minor structural parts.


Additionally, allotted portion of check time is dedicated to tests, inspection, minor airframe corrections and components removals which are due for routine maintenance. IATA as shown in Figure (1) below refer to this maintenance category as 1st Level Maintenance costs segments that include Airframe and Engines Labour, materials and subcontracted work.



Maintenance Cost Task Force 20097

1- Direct Maintenance Cost OverviewAirframe /

On Aircraft- Labor- Material- Subcontracted

Engine

- Labor- Material- Subcontracted

Component /Off Aircraft- Labor- Material- Subcontracted

1st Level : Total Cost during period

Labor (MH)- routine- non routine- modifications- cabin ...

Material- P/N- Quantity- Cost ...

Detailed listing- P/N- Quantity- MTBUR- Repair Cost ...

Per Remove- MSN- ETT- Repair Cost ...

2nd Level : Cost per Maintenance Event

1. Maintenance Cost Breakdown


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Aircraft Maintenance Costs - Guest Lecture - Cranfield University - March 2009 - CSMAM - Ref. D09005085 -Issue 1

Aircraft Maintenance Costs in Perspective

Direct operating cost Indirect operating cost

Life cycle cost

Total operating cost Disposal cost

Cash operating cost

Financial

Fuel and oil

Landing & Navigation fees

Direct maintenance cost

Crew

Insurance

Passenger services

Marketing and sales

Indirect maintenance cost

Other

2.1.2 OFF Aircraft Maintenance This is normally carried out away from aircraft on Engines

and components in either In house or outsourced overhaul

shops as these costs comprise expended labour, material,

testing and modifications.

The above two categories are generally split as per below

percentages.



The ON aircraft Maintenance checks are further summarised as

follows:

1. Aircraft Transit checks- this is a normal minor check that

occurs every flight where walk around is conducted by the

Engineers to detect any obvious damage and/or discrepancy

which my obstruct aircraft despatch or serviceability for further

flights. Also aircraft Log books will be reviewed to clear or

defer all recorded snags.


1. Aircraft Service or Weekly checks- This check is a little

more extensive hours are expended in general visual

inspections and overall Aircraft condition. Minor

modification (Engineering Orders) can be conducted and

additional defects clearances which require extended times

can be accomplished during this check.


1. Aircraft “A” checks- This is a routine MPD check that

occurred almost every three months or 500 flight hours

with various tasks scheduled for accomplishment. Few

access panels, Engine cowlings and other doors will be

opened to perform certain visual inspections and

rectifications.


1. Aircraft “C” checks- within this check the aircraft is grounded

for an extended time where many routine MPD tasks will be

carried out. As majority of access panels are opened, a detailed

visual inspection will be carried out on airframes linkages,

structural fittings and main systems (such as oil, hydraulic and

fuel) functional or leak checks and major components defect

rectification. The interior cabin such as seats will be removed

fro refurbishment. Galleys and toils will receive servicing and

repairs.04/21/23 Aircraft Maintenance Module 21

1. Heavy Aircraft checks or “D” checks as some airlines

call it. The aircraft will undergo a detailed visual

inspection almost in every area including main structure

where a NDT and application of special die pent rants will

be carried out to detect possible skin cracks. Within the

cabin the primary structural parts removed for corrosion

treatment especially galleys, floor panels and seat main

frames.


OFF Aircraft Maintenance

The OFF aircraft Maintenance are further summarised

as follows:

a) Engine Repair and Overhaul Maintenance – during aircraft operations, The Engines are the most stressed items where every time the aircraft takes off, Engines parts rotate at a very high speed with thrust causing certain wear to such parts at an accelerated pace. Engine internal parts especially turbine and combustion chambers are manufactured from special materials in order to withstand the high temperatures and pressure put on the engine during operations.


Hence, the maintenance is often significant and expensive and that is the reason where majority of airlines outsource engine maintenance to OEMs/MROs to alleviate the burden off airlines from investment in development of such highly sophisticated overhaul shops with special required repairs.

Normally the Engine initial shop visits expenses from Aircraft induction to maturity is relatively less expensive than aging Engine maintenance as main LLP parts requires replacement then and such parts impose a high cost to the Engine Maintenance.


In general terms, the difference between engine and airframe

maintenance is that Engine material costs will exceed 80% of

the total maintenance while airframe maintenance will

equally share labour and material by 50/50%.

The Engine performance maintenance costs optimisation is

measured by the time it stays on wing as achieved by the

continuous OEM development causing less removals and

subsequently lower maintenance costs.04/21/23 Aircraft Maintenance Module 25

1. Component Repairs, Modifications, and

Replacements This maintenance includes normal scheduled and unscheduled

components repairs to restore its serviceable condition. The parts are often categorised into rotables, repairable and expendables whereby a multiple number of repairs/resets is possible to rotables parts and considered as assets for the airline.

The maintenance costs associated with this part depend significantly on whether these can be repaired In house or outsourced. This decision highly depends on two factors, the Turn around time and the Warranty aspect.


In other words, if the OEM TAT is reasonable, then it is quite

sensible to despatch such components for repairs outside under

warranty without spending much hassle to develop such

capability and waste Engineers energy on warranted

components especially during the initial five years from

Aircraft induction. There are occasions where rotables or

repairable parts are scrapped due to economic conditions

BER ,i.e. Where the Repair cost exceeds the 65% threshold of

the unit cost04/21/23 Aircraft Maintenance Module 27

In-Direct Maintenance Costs

2.2 Indirect Maintenance Costs

The Indirect maintenance cost or otherwise known as Overhead

cost is defined as the sum of all labour and material costs for

support services which add to the total maintenance of the

aircraft. The elements of IMC include the overhead costs of but

not limited to, Facilities, Stores, Equipment, administration,

Engineering technical services, Materials management and Engg

training.


The IMC costs vary significantly amongst airlines subject

together with organisational structure and the level of

In/outsourcing plus work efficiencies.

Therefore The IMC costs fall within the category of

controllable airline maintenance costs but this factor

cannot be controlled nor quantified by Aircraft

manufacturers.


The use of automation and sophisticated control system

especially in the tech records, planning and materials

management, drastically reduce the labour requirement

and size of these support services departments and

subsequently slash the IMC costs.

Therefore, the IMC costs overheads need to be reviewed

frequently to envisage possibility of introducing processes

improvements. 04/21/23 Aircraft Maintenance Module 30

The ideal tool for this exercise would be Six Sigma which

looks at the work environment to analyse the adopted

processes, then propose solutions for the purpose of

working smarter and cut inefficiencies (Turner 2005).




Operating Cost Breakdown

10% - 25%Ownership CostOwnership Cost

Cash Airplane RelatedOperating Cost

(CAROC)

Cash Airplane RelatedOperating Cost

(CAROC)

• Fuel• Cockpit crew• Cabin crew• Maintenance• Landing• Navigation • Ground handling

• Depreciation• Financing (airplane and

introductory investment)• Operating lease cost• Hull insurance

Passenger Related

Cost

Passenger Related

Cost

Cargo Related

Cost

Cargo Related

Cost

• Food• In flight services• Handling• Baggage

handling • Commissions • Reservations

and sales• Advertising

• Handling• Commissions • Reservations

and sales• Advertising

System Related

Cost

System Related

Cost

• Airplane general and administrative

• Passenger general and administrative

• Cargo general and administrative

Total Operating Cost(TOC)

Total Operating Cost(TOC)

Airplane RelatedOperating Cost

(AROC)

Airplane RelatedOperating Cost

(AROC)

System RelatedOperating Cost

System RelatedOperating Cost

Payload RelatedOperating Cost

Payload RelatedOperating Cost

8/25/2015 Aircraft Maintenance Module1 Aircraft Maintenance Management Module Aircraft Maintenance Introduction.

Documents

indirect maintenance

component maintenance

engine maintenance

aircraft maintenance

onoff aircraft maintenance

aircraft maintenance

maintenance support

labour costs