AIRCRAFT MAINTENANCE
2
KAMILA KUSTROŃ, Ph.D
TODAY LECTURE
INTRODUCTION – FEBRUARY 25
DESIGN PHILOSOPHIES v. MAINTENANCE PHILOSOPHIES,
RELIABILITY & MAINTENANCE CHARACTERIZATION, AVIATION
ORGANIZATIONS, AUTHORITY REGULATIONS – MARCH 4
OPTIMIZATION OF MAINTENANCE, RELIABILITY OF SYSTEMS,
FMEA/FMECA, RCM, MSG3 – MARCH 11
DEGRADATION PROCESSES, DAMAGES – MARCH 18
INTRODUCTION TO DIAGNOSTICS, DIAGNOSTICS, NDT, NDE, SHM,
EHM, HUMS – MARCH 25
HUMAN FACTOR, FLIGHT SAFETY – APRIL 8
STUDENTS’ ARTICLES – DEADLINE – APRIL 8
FINAL TEST, APRIL 15
SUMMARY OF THE TEST, SUMMARY, APRIL 22
MAINTENANCE THINKING
Concept of Aircraft
Maintenance
Types of Aircraft Maintenance
Maintenance
Scheduled
Unscheduled
 Routine maintenance Plannable
check
 Replacement of life
limited items
 Performance of
 Cleaning
modification originated
work
 Rectification of deferred
defects
Mar-15
Unplannable
Activities originated from:
 Cabin log book
 Technical log book
 Ground findings
6
General
MAINTENANCE DEFINITION
Those actions required for
restoring or maintaining an item
in serviceable condition
TYPES
• Unscheduled
LEVELS
• Scheduled
( Line ( Ramp )
• Servicing
( Hangar or Main base
( Workshop
Mar-15
Mainly
unscheduled
maintenance
limited to the
replacement of
faulty components
that will have
immediate or short
term influence on
aircraft operations
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(MMEL).
General
TYPES OF MAINTENANCE
Unscheduled (or corrective):
Maintenance performed to restore
an item to a satisfactory condition
by providing correction of a known
or suspected malfunction and/or
defect.
Unscheduled maintenance action is
performed if there is a pilot report
or a complaint from the scheduled
maintenance.
Mar-15
Scheduled:
Maintenance performed at defined
intervals to retain an item in a
serviceable condition (availability,
safety and reliability to their inherent
levels)
Scheduled maintenance action is
performed according to the
Maintenance Program requirements
Servicing:
Any act of replenishment for the
purpose of maintaining the inherent
design operating capabilities of an
item.
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General
Unscheduled
(8.5%)
DIRECT OPERATING COST BREAKDOWN
Scheduled
(3.5%)
Maintenance (12%)
Depreciation
/ Finance
(41%)
Fuel
(25%)
Insurance
(2%)
Landing /
Navigation
taxes (9%)
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Material
50
Labour
50
40
10
Powerplant Systems Structure
Crew (11%)
DMC = 700 $/FH
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Aircraft maintenance checks are periodic inspections that
have to be done on all commercial/civil aircraft after a
certain amount of time or usage; military aircraft normally
follow specific maintenance programmes which may be or
not similar to the commercial/civil operators.
Airlines and other commercial operators of large or
turbine-powered aircraft follow a continuous inspection
program approved by National Aviation
Each operator prepares a continuous airworthiness
maintenance program (CAMP)
under its Operations Specifications or ‚OpSpecs’
The CAMP includes both routine and detailed inspections
Airlines and airworthiness authorities casually refer to the
detailed inspections as "checks"
Types of Scheduled Maintenance
Light or Line Maintenance:
 Preflight Check
 Daily Check
 Weekly Checks
 A (Multiple A) and B Checks
► Base or Heavy Maintenance:
 C (Multiple C) and D Checks
► Shop or Component Maintenance:
 Maintenance on components when
removed from aircraft
►
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11
Introduction
Operational Aspects
Operational interruption or disturbances have
repercussions on the following areas:
Passengers Comfort
Corporate Image Of The Operator
Operating Cost
WHAT KIND OF SCHEDULED MAINTENANCE ARE WE
PREPARED TO TOLERATE IN ORDER TO OPTIMISE THE
ABOVE CRITERIA ?
COST OF SCHEDULED MAINTENANCE
<
COST OF FAILURE CONSEQUENCES
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Typical inspection interval
Check type
Interval
Content
Pre-Flight
Pre-Flight
General visual from ground for signs of obvious
discrepancies or damage such as fluid leaks,
FOD, lightning strike.
Check logbook .
Check engine oil levels and replenish if
necessary
Terminal Check Each terminal
(Ramp)
stop
Mar-15
Pre-flight plus tires, tire pressure, wheels and
brakes.
Cabin check.
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Typical inspection interval
Check type
Interval
Content
Service Check
8 Cal. days
1A-Check
500 FH
Hydraulic qty, escape slide gas pressure, oxygen
pressure, brake wear, IDG oil, APU oil, oleo
pressures. Visual check of engine inlet and
exhaust. Optional check of CMS for degraded
fault tolerance (to avoid potential No Go
situation)
Mar-15
Exterior general visual from ground. Interior
general visual cockpit, cabin, cargo
compartment, avionics, electrical, hydraulic and
ECS equipment bays, landing gear, landing gear
bays ad doors. IDG oil.
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Typical inspection interval
Check type
Interval
2A-Check
1000 FH
Simple operational checks (failure finding tasks)
from cockpit which cannot be accomplished at
4A and above.
Inspection of engine fan blades. Check engine
chip detectors. Engine starter oil change.
Landing gear lubrication.
4A – Check
2000 FH
Lubrication of some flight control items in
accordance with past service experience.
Simple operational checks (failure finding tasks)
which cannot be accomplished at C and above.
8A – Check
4000 FH
Mar-15
Content
Check fuselage drainage system
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Typical inspection interval
Check type
Interval
1C-Check
15 months
Content
External general visual inspection of areas with
moderate sensitivity to damage or deterioration
such as lower and mid fuselage, windows,
doors, wing lower surfaces, flight control
surfaces, horizontal and vertical stabiliser
leading edges and pylons. General visual
inspection of power plant and engine with cowls
open, landing gear and landing gear bays, wing
fixed leading edge, rear fuselage and tail cone.
Cleaning or replacement of air conditioning
filters.
Systems operational checks (failure
finding tasks).
Flight control general lubrication
and gearbox oil
replenishment. Hydraulic
system internal leakage. Cabin
check.
Check drainage systems.
Mar-15
16
Typical inspection interval
Check type
Interval
2C-Check
30 months
Intermediate
Layover (4C)
60 months
Mar-15
Content
External general visual inspection of areas with
low sensitivity to damage or deterioration such
as upper fuselage, horizontal and vertical
stabilisers and wing top surface. Internal general
visual inspection installations in equipment bays
and pylons.
Internal general visual inspection of structure
and installations in areas of moderate to high
sensitivity to damage or deterioration such as
cargo compartments, area below cargo and
cockpit floors and below toilets and galleys.
Internal general visual inspection of wing in
sump areas. Systems operational and functional
checks. Detailed cabin check including floors in
high traffic areas, galleys and toilets.
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Typical inspection interval
Check type
Major Layover
(8C)
Interval
Content
120 Months
General and detailed external and internal
structural (sampling or 100%) inspection for
corrosion and fatigue damage. Systems
operational and functional checks.
Remarks:
Aircraft on jacks
Note:
some operators may wish to integrate items into
C- Check packages.
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Boeing Typical Inspection Interval
Letter
check
Aircraft
757
737-100
737-200
737-300
737-400
737-500
727
Recommended initial interval (FH)
A
B
750
200
80
(Structural
Inspection)
3,000
3,200
400
20,000
20,000
(Structural
Inspection)
170 700
2,840
21,000
220
3,300
21,500
500 or
70 days
650
Cathay Pacific
450
C
5,000 18,500
747-400
Mar-15
B
16,000
777
(Cathay Pacific)
MD-80
A
D
6,000 FH
(Sys.)
3,000 FC
(Struc.)
500 FH (Sys.)
300 FC (Stru.)
125
C
D
World weighted fleet interval (FH)
3,500
150 365 Days
days or 3000 hrs
6,750
?
30,000
15,000
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Airbus Typical Inspection Interval
Letter
check
Aircraft
Recommended interval
A
C
D
=
4C
A310
400 FH
15 Months
A300-600 Initial: 250 FH Initial: 12 months
Structural inspection
FD threshold: 18,000 FC
ED threshold: 10/7.5/5/2.5 years
5 Years
A319
A320
A321
500 FH
15 Months
A330
A340
700 FH

500 FH
18 months

15 months
A380
Objective:
750 FH
Objective:
24 months
Mar-15
Cathay
Pacific
5 Years
Cathay
Pacific
FD threshold: 24,000 FC
ED threshold: 9/5/2.5 years
FD threshold: 20,000/8,000 FC
ED threshold: 10/5/2.5 years
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Economics aspects
of scheduled maintenance
C
MH
A
2
A
A
3
A
A
4
A
2
A
A
1
2
3
4
MH
Mar-15
4
A
2
A
A
1 year
2
3
4
4
A
2
A
A
2 year
Semi
equalise
d plan
A + x% of 2A + y% of 4A
1
Block
check
plan
C
1year
2year
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Aviation Authorities
Today the most important responsibilities of the EASA are:
Expert advice to the EU for new legislations
Implementing and monitoring the aircraft safety rules
Authorization of third – countries (Non – EU) operators
Safety research and analysis
Aircraft and component type – certification
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AVIATION AUTHORITIES, ICAO INTERNATIONAL CIVIL AVIATION ORGANIZATION, SARPs
SARP – Standards and Recommended Practices
SARP – Standards and Recommended Practices are developed by ICAO and cover all technical
and operational aspects of international civil aviation, such as safety, personnel licensing,
operation of aircraft, aerodromes, air traffic services, accident investigation and the environment.
Annex
Annex
Annex
Annex
Annex
Annex
Annex
Annex
Annex
Annex
Annex
Annex
Annex
Annex
Annex
Annex
Annex
Annex
Annex
Annex
Annex
Annex
Annex
Annex
1 Personnel Licensing
2 Rules of the Air
3 Meteorological Service for International Air Navigation
4 Aeronautical Charts
5 Units of Measurement to be Used in Air and Ground Operations
6 Operation of Aircraft
Part I International Commercial Air Transport – Aeroplanes
Part II International General Aviation – Aeroplanes
Part III International Operations – Helicopters
7 Aircraft Nationality and Registration Marks
8 Airworthiness of Aircraft
9 Facilitation
10 Volume I
Radio Navigation Aids
10 Volume II
Communications Procedures
10 Volume III Communications Systems
10 Volume IV Surveillance Radar and Collision Avoidance Systems
10 Volume V Aeronautical Radio Frequency Spectrum Utilization
11 Air Traffic Services
12 Search and Rescue
13 Aircraft Accident and Incident Investigation
14 Volume I
Aerodrome Design and Construction
14 Volume II
Heliports
15 Aeronautical Information Services
16 Volume I
Environmental Protection – Aircraft Noise
16 Volume II
Environmental Protection – Aircraft Engine Emissions
18 The Safe Transport of Dangerous Goods by Air
19 Safety Management
https://www.caa.govt.nz/ICAO/ICAO_Compliance.htm
System of Civil Aviation
Aviation Authorities (ICAO, EASA)
SARP, CS25
Air Operator (Airline)
Part M
AOC
CAME
Maintenance Program (MP)
MSG-3
MRBR
TC
Designer/Manufacturer (Airbus)
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Certification Process of a Maintenance Program
ANK496 Aircraft Maintenance Management
MRB Process
The organization, which develops the MRBR consists of the following working bodies:
 Industry Steering Committee (ISC)
 Maintenance Working Groups (MWGs)
 Maintenance Review Board (MRB)
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Policy and Procedures Handbook (PPH)
The PPH consists of:
Organizational outline and duties and responsibilities of all
working bodies and personnel
Details to technical and maintenance development training
Timetables and meeting schedules
Proposed check interval parameters
Analysis procedures
Documentation standards
General administration procedures
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MSG – 3 (Maintenance Steering Group) Methodology
The MSG – 3 results the work in 3 sections:
1. Systems/Powerplant – including components and APUs
2. Aircraft structure
3. Zonal inspections and L/HIRF (Lightning/High Intensity Radiated
Fields)
or 4 Major sections:
1. Systems / Powerplant, including components and APUs
2. Aircraft structure
3. Zonal inspections
4. Lightning / High Intensity Radiated Field (L / HIRF)
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Systems/Powerplant section
•
•
•
•
Loss of redundancy
Loss of functions
Wear
Leak
Aircraft structure section
•
•
•
•
•
Accidental damage
Environmental deterioration
Fatigue damage
Ageing
Wear
Zonal & L/HIRF section
• General condition of the area:
• Accidental damage, Corrosion, Wiring chafing, defective fasteners, defective clamps,
accumulation of combustible materials
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MSI
(Maintenance Significant Item) Analyses
An MSI analysis must be performed if at least one of the following 4 questions are
answered “Yes”:
Could a failure affect the safety (flight or ground)?
Could a failure be undetectable during operations?
Could a failure have a significant operational impact?
Could a failure have a significant economical impact?
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The process of the MSI analysis is divided into 5 phases:
Administrative Information
Descriptive Part
Data Sheet A
Failure Analysis
Data Sheet B
MSI Logical Analyses
Level 1 & Level 2
Task Summaries
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4 steps of developing Data Sheet B
Function
The normal characteristic actions of the item
Functional Failure
How does the item fail to perform its function?
Failure Effect
What is the result of the functional failure?
Failure Cause
Why does the functional failure occur?
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The process of the MSI analysis is divided into 5 phases:
Administrative Information
Descriptive Part
Data Sheet A
Failure Analysis
Data Sheet B
MSI Logical Analyses
Level 1 & Level 2
Task Summaries
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MSI Logical Analyses:
Level 1:
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MSI Logical Analyses:
Level 2:
Due to the MSG – 3, the following 5 maintenance tasks can be
selected:
 Lubrication (LUB)/Servicing (SVC)
 Operational (OPC)/Visual Check (VCK)
 Inspection/Functional Check (FNC)
 Restoration (RST)
 Discard (DIS)
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Task Summaries
The Task Summaries are divided into 3 sheets:
Task Summary Sheet (TSS): The goal of this sheet is to summarize all tasks
selected during the Level 2 analysis, including the intervals, Failure Effect
Categories and Failure Causes. It is not the purpose of the TSS to combine
tasks from the Level 2 analysis.
Maintenance Review Board Report Interface Sheet (MRBR IS): The
Maintenance Review Board Report Interface Sheet is the source document for
the Maintenance Review Board Report (MRBR). All TSS tasks can be directly
transferred to the MRBR IS, where it is allowed to combine TSS tasks in order
to combine tasks, which should be performed together due to technical
reasons. Each task combination must be approved by the Industry Steering
Committee (ISC), before it can be integrated into the MRBR proposal. There
are certain criteria, which have to be maintained in order to combine TSS
tasks:
The task types have to be similar (OPC, FNC, GVI, etc.)
Compatibility of intervals
Failure Effect Categories (In order to combine two tasks with different FECs,
the intervals have to be the same)
Task Data Sheet (TDS): The function of the Task Data Sheet is to provide
procedural information for the accomplishment of a task and additional task
planning data. For each MRBR IS, one TDS must be established
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SSI (Structure Significant Item) Analyses
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SSI (Structure Significant Item) Analyses
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Accidental Damage (AD) metallic & non – metallic structures)
Environmental Deterioration (ED)(metallic structures)
Fatigue Damage (FD)
(metallic structures)
Ageing Deterioration (ED-compo) (non – metallic structures)
Wear Damage (WD) (metallic & non – metallic structures)
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Zonal and L/HIRF Analyses
Major zones of the A350 – 900 (authorized by Airbus S.A.S.)
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an example of the zoning principles
power plant of the A318
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There are three types of zonal analyses
1. Standard Zonal Analysis
2. Enhanced Zonal Analysis
3. L/HIRF Zonal Analysis
(Lightning/High Intensity Radiated
Field)
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1st Phase
- Preparation Phase
MRB
Report
Establishment of the organization (ISC, WG, MRB)
Development of procedures and interval frame (PPH)
Meetings of the ISC and MRB - Planning
2nd Phase - Working Phase
ISC/MWG/MRB members training
Manufacturer MSIs and SSIs selection
ISC agreement with the selection of the MSIs and SSIs
Manufacturer preparation of the MSG - 3 analysis for MSIs, SSIs
and Zonal
Review of the MSG - 3 analysis during MWG meetings
Harmonization of MSI & SSI tasks with Zonal
MWG results are presented to the ISC
Preparation of the MRBR Proposal by the ISC
Submission of the MRBR Proposal to the MRB
3rd Phase - Approval Phase
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• Final review on the MRBR Proposal by the MRB
• Approval of the MRBR
• Publication of the MRBR
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