Inspection

 Rules(CAR, FAR, JAR) places primary

responsibility on the owner or operator
for maintaining an A/C or engines in an
airworthy condition.

 Certain
inspections shall be performed
on A/C or Engines, and you must
maintain the airworthiness of the aircraft
between required inspections by having
any defects corrected.
 Inspection
 All inspections shall follow the
Manufacturer Maintenance Manual,
including the Instructions for
Continued Airworthiness concerning
inspection intervals, parts
replacement, and life-limited items
as applicable to your aircraft.
 The Inspector
The inspector is expected to;
 Recommend changes to civil aviation
legislation and regulations as may be
appropriate.
 Manage the development of technical guidance
materials to enable effective implementation of
SUCAR instructions.
 Approve staff and regulations after making sure
all requirements are met.
 Inspect and audit for continuous surveillance of
compliance with regulations and safety.
 The Inspector
The inspector is expected to;
 Have a high degree of integrity
 Be impartial in carrying out the tasks
 Be tactful and able to relate with people.
 Show good management,
communication and interpersonal skills
 Preparation
 In order to conduct a thoroughly inspection, a
great deal of paperwork and/or reference
information must be accessed and studied
before actually proceeding to the
aircraft/engine to conduct the inspection:

- Logbooks
- Check List
- Publications (by Manufacturer)
 Aircraft & Engines Logbooks
 All supplemental records concerned with the
aircraft, Engines and Components.
 They may come in a variety of formats.
 In the form of a three-ring binder.
 Information gathered in this log is used to
determine the aircraft condition, date of
inspections, time on airframe, engines and
propellers.
 When the inspections are completed, appropriate
entries must be made in the aircraft logbook
certifying that the aircraft is in an airworthy
condition and may be returned to service.
 Checklists
 Always use a checklist when performing an
inspection.
 The checklist may be of your own design, one
provided by the manufacturer of the equipment
being inspected, or one obtained from some
other source.
 The checklist should include the following:
1. Engine & nacelle group:
a) Engine section—for visual evidence of excessive oil, fuel, or
hydraulic leaks, and sources of such leaks.
b) Engine controls—for defects, proper travel, and proper safe
tying.
c) All systems—for proper installation, general condition defects,
and secure attachment
 Publications
 Aeronautical publications are the sources of
information for guiding aviation mechanics in the
operation and maintenance of aircraft and
related equipment. These include:
- Manufacturers’ Service Bulletins (SB).
- Maintenance Manual (AMM)
- Overhaul Manual (OM).
- Structural Repair Manual (SRM).
- Illustrated Parts Catalogue (IPC).
- Airworthiness Directives (AD).
- Type Certificate Data Sheets.
 Maintenance Inspection
A very skilled and labor intensive part of
aircraft maintenance.
What is gained by having inspection:

 Potential dangerous incidences can be prevented.

 Costly maintenance and replacements can be avoided.
 Manufacturer, owners and operators can be alerted to
design, or aging problems.
 The numbers of ramp/pre-departure snags can be reduced.
 Safety and PAX comfort/confidence can be increased.
 Maintenance programs can be adjusted to take into account
areas of weakness highlighted by inspections.
Inspection Techniques
 It is all about the task of “Looking” & “Finding”
for defects of all kinds.

 The first kind of work in the overall maintenance

process.

 The job card tasks are usually specific, and tell

the maintenance engineer what to check for.

 Defects should be assessed as “within limits”

and remain in service.
 Inspection Techniques
Inspection divided into 2 types:

1. Inspection by variables - product or

part dimensions of interest are MEASURED by
the appropriate measuring instruments.

2. Inspection by attributes – product or

part dimensions are GAUGED to determine
whether or not they are within tolerance limits.
The Role of Aircraft Technician
 Inspecting & Maintaining Parts

 Routine Inspection
 Non Routine Inspection
 Routine Inspection
 Mandated by Approved Schedule or
CAA.

 Performed Periodically at intervals.

 Pre-flight Inspection (Visual Inspection)
 Progressive/continuous Inspection (100 hrs, 25
hrs, 90 days, A check, No. 1 Service)
 Using Approved Maintenance
Manuals by CAA
Cold Section Inspection
 Compressor, Inlet, Diffuser.
 FOD (sand & ice) cause the blades to be
eroded
 Accumulation of dirt & oxides form on
blades & vanes deteriorate engine
performance.
 Cold section inspection usually done by
using Boroscope method through access
ports.
Hot Section Inspection
 Combustion, Turbine, Exhaust.
 Shrinks & Expansion of metals cause
cracks
 Where parts subjected to very great
heat and stress.
 Using Borescope extensively.
 Stress Rupture Cracks on turbine
blades very critical.
Non Routine Inspection
Must be done as a result of a component
failure or incident that could potentially
damage an engine.
 Ingestion of birds
 Ice
 FODs
 RPM over-limit incidents
Special Inspections
 Hard or Overweight Landing Inspection
 Severe Turbulence Inspection
 Lightning Strike
 Fire Damage
 Flood Damage
 Seaplanes (accelerates corrosion)
 Aerial Application Aircraft
- Corrosive Nature
- Typical Flight Profile
Heavy Landing Inspection
 Check engine controls for full and free
movement.
 Examine engine mountings and pylons.
 Check freedom of rotating assemblies.
 Examine cowlings for wrinkling, distortion,
and fasteners for security.
 Check for fuel, oil, and hydraulic fluid leaks.
 Carry out engine run IAW MM.
 Check run down time.
Lightning Strike Inspection
It results in High Voltage and current
passing through the structure.

Indications:
 Circular holes in the A/C skin.
 Burning.
 Dis-coloration.
 Lightning Strike Inspection
 Inspect engine cowling for signs of burning, if
this is evident, tracking of the bearings could
have occurred.
 Remove engine filters and check for
contamination.
 Examine engine structure, pipelines, electric
cables and bonding for buffing.
 Operate all engine controls for free
movement.
 Engine ground run for Satisfactory Operation.
 ATA Spec 100 Systems
 Air Transport Association of America
 (ATA) Issues specifications for Manufacturers
Technical DATA
 Has been Mandated, Revised & Updated over
years
 Has the A/C divided into systems, subsystems,
 Standardized the Numbering of Manuals:
Sys. Sub. Title
21 Air-conditioning
21 00 General
21 10 Compression
21 20 Distribution
ATA Spec 100 Systems
ATA Spec 100 Systems
Standardized Wording of Manuals:
ATA Description
DIS Discard
DVI Detailed Visual Inspection
FNC Functional Check
GV General Visual Inspection
LUB Lubrication
OPC Operational Check
SDI Special Detailed Inspection
SPC Special Check
SVC Servicing
ZON Zonal Check
VCK Visual Check
Engine Removal & Overhaul

Quick Engine Change Assembly

(QECA)
Modular
Sections
Accessories
Quick Engine Change Assy.
 The engine structure is formed
by a number of separate
modules.
 Allow ease of maintenance.
 Ease of removal, replacement
 Minimum man-hour expenditure.
 Maintenance and change can be
done Insitu
Quick Engine Change Assy.
Quick Engine Change Assy.
Reasons for Engine Removal
 Engine Life Span
 FOD’s
 Hot Start:
ignition occurs when there is excessively rich
fuel/air mixture.
Compressor Wash
 Gas turbine compressors consume approx.
60% of the overall cycle energy during
operation.
 The compression cycle consumes large
quantities of air and despite intake filtration,
small quantities of dust, aerosols and water
pass through and deposit onto the blades.
 These deposits impede airflow through the
compressor and over time degrade overall
performance of the gas turbine.
Compressor Wash
 Compressor washing is the single most cost-
effective maintenance procedure for any jet
engine.
 Since the compressor typically consumes 60-
70 percent of power generated, compressor
health is critical to engine health
management.
 Contamination in the compressor section
leads to deteriorating thermal efficiency which
causes reduced engine performance.
Compressor Wash
Compressor washes can dramatically improve
engine performance, increase engine life
cycles and lower operating costs by:

 Improving compressor efficiency

 Lowering fuel consumption
 Reducing exhaust gas temperatures (EGT)
 Increasing hot section parts lives
 Reducing corrosion
 Extending time between overhauls (TBOs)
Compressor Wash
Compressor Wash
Basic Steps in Overhaul Process
Basic Steps in Overhaul Process
 Receiving Inspection
 This is the inspection of the engine as it is
removed from the aircraft and received at
the overhaul site.
 The purpose of the receiving inspection is
to begin to detect engine defects or
required maintenance and to schedule the
overhaul process.
 Look at the history of the engine as recorded in the
logbook - hours, repairs, routine service, etc…..
 Perform a conformity inspection to reveal unapproved
accessories
 Review the applicable AD records to determine which
AD’s are required during overhaul
Receiving Inspection Form
 Receiving Inspection
 Review Service Bulletins
 Review the Overhaul Manual and Parts
Manual
 Perform a Visual Inspection to detect
obvious external defects .
 Perform this inspection prior to cleaning the
engine. Look at paint condition, signs of
heat damage, fretting, and oil leaks.
 Make an Inventory of all extra parts received
with the engine such as baffles, fittings, or
ignition parts, so that nothing is lost
Regulations Governing Overhaul
Time Before Overhaul (TBO)
 The manufacturer determines the
recommended number of hours that an
engine may be operated before it is
overhauled
 Each engine model has a different TBO
and they range from around 600 to 2400
hours
 All engines wear, build-up sludge, form
deposits, crack, and parts fail that cause
them to require overhaul.
Regulations Governing Overhaul
 Rebuilt is the term used to describe an engine that has
been disassembled, inspected, repaired, reassembled, and
tested utilizing new tolerances

 Overhauled is the term to describe an engine that has been

disassembled, inspected, repaired, reassembled, and
tested utilizing serviceable tolerances
 An engine equipped with an integral supercharger that has
its case halves separated is a major repair and must be
approved by an IA

 An engine equipped with other than spur type propeller

reduction gearing, that has its case halves separated, is
also a major repair
How to do an Inspection ????
To carryout an effective and reliable inspection,
certain points must be considered:
1. Requirements must be known
2. Check-card must be available (Insp. Sheet)
3. Technician must have appropriate education
4. System knowledge, tolerances, etc. must be
known.
5. Provision of auxiliary devices as stairs, mirrors
and sufficient light.
6. Cleanliness of area of inspection.
Personal Attitude to the Inspection
 Inspection must be carried out without pre-
judgment.
 Never assume that there are no discrepancies in an
area where never any damage have been found
before.
 Do not let you disturb during an inspection.
 Work always concentrated.
 Whenever tired, take a short break.
 Do an inspection carful and conscientious.
 Only a reliable inspection is a good inspection, and
provide an adequate safety standard.
 Doing the Inspection
 First of all get a general overview about the
zone or component to be inspected.
 Check for damages, leaks, loose & missing
parts.
 Secondly, do a more detailed inspection.
 Check all installations for damages, chafing
marks and conditions.
 Perform the inspection track by track.
 If damage is found, the damage must be
examined.
Disassembly & Reassembly
Techniques
 Tagging Parts:
Serv., Unserv., Scrap, Non- Conformity CARDS.
 Discarding “O” Rings & Gaskets:
It is not allowed to be used again.
 Securing the Work Area:
Must be properly secured.
 Rule of Thumb for Bolts Installation:
Head should be upward, in a forward direction,
outboard.
Disassembly & Reassembly
Techniques
 Components:
When removed, always plug any open tube or
connection on both the component and the system,
this is to prevent FOD.
 Mating Surfaces:
- Sensitive to corrosion.
- Must be sealed with a sealant applied to each
part before installation.
- Fasteners are installed wet with a sealant to
prevent Galvanic Corrosion.
 Once an engine arrives at shop activity, it is
cleaned and evaluated for repair.
 If inducted for repair, a major inspection and all
repairs required to place the engine back in
ready for issue the status are accomplished.
 The first steps for inspecting engines include
the cleaning and the marking of parts.
 After cleaning, engines are inspected IAW
applicable Maintenance Manual’s (MMs) or
disassembled for further repair.
 Permit thorough inspection of components for
flaws, damage, and dimension wear.
 Prepare surfaces for repair (plating, welding,
or painting).
 Remove organic or inorganic coatings for
inspection of underlying surfaces or remove
coatings adversely affecting engine
performance.
Cleaning
 Degreasing (Solvent Cleaning)
 Steam Cleaning
 Vapor Degreasing
 Decarbonizing
 Abrasive Blasting
Markings
Temporary Markings:
 Certain materials must be used for temporary
marking during assembly and disassembly.
 Use only approved pure dye markers to mark
engine hardware. You may use layout dye
(lightly applied) to mark parts that are directly
exposed to the engine gas path.
 Some exposed items are the turbine blades
and disc, turbine vanes, and combustion
chamber liners.
Markings
Permanent Markings:
 Should be positioned in the area of lowest
stress.
 Choose an area where markings will not be
worn off or obliterated by contact with another
part. If possible.
 Methods of permanent markings include
using a metal stamp, vibro-pen, blasting, and
acid-etching.
Compressor
Compressor cases are machined in matched
sets. Damage beyond repair to one case is
cause for rejection of the opposite case. A new
compressor rotor is not required when replacing
the entire case assembly.

 Compressor Contamination.
 Compressor Leaks.
 Compressor Failures.
Compressor Blade Damage
Compressor Blade Repair
Combustion
 The combustion section can be removed,
repaired, or replaced in part or entirely
depending on the extent of damage
encountered.
 The combustion section consists of liners,
support duct, outer and inner case, and the
first stage turbine nozzle assembly.
 Most repairs to this section are accomplished
by welding or replacement of components.
Combustion
Combustion
Turbine Blade Sulfidation
 Sulfidation is high-temperature corrosion.
 This is permissible if evidenced only by a
rough or crusty appearance at the leading
edge, on the concave side of the airfoil
section, or on the platform at the root of the
airfoil.
Turbine Blade Damage
 Deformation,due to  Stress rupture cracks.
over temperature,
appears as waviness
along the leading
edge.
Exhaust
 Very susceptible to heat cracking.
 Hot spots on the tail cone are a good
indication that a fuel nozzle or combustion
chamber is not functioning properly.
 Accomplish the repair and replacement of
parts of the exhaust section using the latest
technical instructions for that particular
engine.
ENGINE TEST CELLS
 Engine testing is accomplished primarily in a
test cell or test house that is fully equipped to
measure the entire desired engine operating
parameters.
 The engine Test Log Sheets, records the data
obtained during the engine test run.
 Test schedules will vary with each different
model of engine and manufacturer. Always
refer to the appropriate engine manual when
performing engine test runs.
ENGINE TEST CELLS Layout
ENGINE TEST CELLS Layout
 Starboard side of the
Engine as received
from site

 Port side of the

Engine
 Ram Assembly and
pipe work

 Main oil inlet to wheel

case customers
adapter fitted
 Over flow pipes and
static oil pipes

 Hydraulic Distribution
Block
 Damaged pipe for the
P2 filter housing

 Exhaust Unit
 Low pressure Turbine
Disc

 Fir Tree with sand

build around the disc
area
 Combustion Flame
tubes # 1 and # 2

 Cracked Cooper
Beam
 High pressure nozzle
guide vanes

 Nozzles have an
orange color, with a
small nick
 8 off snouts fitted to the
Compressor Outlet
Casing

 Main oil feed and return

to the rear and centre
Bearing
 Nozzle box assembly

 Oil feed and return

tubes for the rear
bearing
 Low pressure Turbine
Disc

 High Pressure
Turbine Disc
 Discharge nozzle
with sand build up on
inner wall

 All 8 Discharge
Nozzles
 Low Pressure
Turbine Blades

 High Pressure
Turbine Blades
 Intermediate Turbine
Blades

 Intermediate Nozzle
Guide Vanes
 8 off Burners Pintle
type

 All 8 Intake Snouts

 High Pressure
Nozzle guide vanes

 Variable Inlet Guide

Vanes with worn lugs
 Internal wheel case
bearing rollers spalled

 Bearing race for the

same bearing also
spalled
 Low pressure turbine
disc sand build up

 Bleed valve
assembly
 Trident channels tip
worn

 Channel segments
 Alignment segment
distorted

 Alignment segments
 Rear Bearing
housing minor oil
leak

 Combustion Can with

minor thermo
cracking
 Combustor Inter
Connector
 Combustion Air
Scoop

 Normal Cooper
Beam
 Trident lug and bolt
 High Pressure
Turbine Blades Inner
Shroud

 Normal High
Pressure Turbine
Blade
 Engines turbine Shaft
to Rear Seal
 No Internal Oil
Leakage

 Minor Oil staining

along with burnt
Hylomar
 Normal Flame Patterns
on Inside of Combustion
Walls

 Cooling Air Holes From

the Inside of the
Combustion Walls
 Compressor Outlet
Guide Vanes

 Stage 15
Compressor Blades
It’s not always easy to determine when, or if, an
engine should be completely overhauled, as a number
of factors must be considered.

High mileage is not necessarily an indication that an

overhaul is needed, while low mileage doesn’t
preclude the need for an overhaul. Frequency of
servicing is probably the most important
consideration.

Maintenance & inspections, will most likely give many

thousands of miles of reliable service. Conversely, a
neglected engine may require an overhaul very early
in its life.
Excessive oil consumption is an indication
that piston rings, valve seals and/or valve
guides are in need of attention.

Make sure that oil leaks aren’t responsible

before deciding that the rings and/or
guides are worn.

Perform a cylinder compression check to

determine the extent of the work required
Loss of power, rough running, knocking or metallic
engine noises, excessive valve train noise and high
fuel consumption may also point to the need for an
overhaul, especially if they’re all present at the same
time. If a complete tune-up doesn’t remedy the
situation, major mechanical work is the only solution.

To ensure maximum life and minimum trouble

from a rebuilt engine, everything must be
assembled with care, in a spotlessly-clean
environment.
Engine Storage
 Installedturbine engine which are to be
out of use for a period of up to 7 days,
require no protection apart from fitting
covers or blanks to the intake, exhaust
and any other apertures to prevent
ingress of dust, rain, snow, etc.
 For storage periods in excess of 7 days,
additional precautions may be necessary
to prevent corrosion.
Short Term Storage
When stored for a month:

 Inhibit fuel system IAW MM.

 Protect lubrication system, clean filters
and fill with storage oil.
 Clean externally.
 Place desiccant or vapor phase inhibitor in
the intake and exhaust and fit approved
covers or blanks to all apertures.
Long Term Storage
When stored for up to 6 months:
 Grease all control rods and fittings.
 Wrap grease proof paper around rubber parts
and spray a thin coat of approved preservative
over whole engine forward of the exhaust.
 At the end of each 6 months period, the engine
should be re-preserved for a further period of
storage.
 Alternatively, remove engine from A/C and
preserve in a moisture vapour proof (MVP) bag.
Uninstalled Engines
 Engines which have been removed from A/C for
storage, or uninstalled engines being returned
for repair or overhaul, should be protected
internally and sealed in (MVP) bags:
 Carry out short term storage procedures
 Install quantities of desiccant and humidity
indicator.
 Inspect humidity after 24hrs:
BLUE = Safe
Pink = Unsafe
Fuel System Inhibiting Methods
Motoring Method:
Used on engines that capable of being turned by
normal starting system.
Pressure Rig Method:
Used for engines which can not be turned with
external pump unit to supply the inhibiting fluid to the
engine fuel system components.
The equipment is bulky and expensive and rarely
used by commercial airlines.
Gravity Method:
Used on engines capable of being motored over, but
where a pressurized inhibiting rig is not available.
Maintenance
Maintenance is any one or combination of
activities such as:
 Inspection
 Modification
 Repair
 Replacement
 Overhaul (to restore an engine or engine
component or to keep it in working
condition).
Authorities Involved in Maintenance
Program Development

Authorities

Regulatory Operators
Manufacturers
Bodies

1. CAA (Civil Aviation Authority)

2. EASA (European Aviation Safety Agency)
3. ICAO (International Civil Aviation Organization)
 Maintenance Processes Types
 Preventive maintenance
Predictive maintenance, is performed in
order to prevent failure of an item or to
discover a hidden failure.
 Corrective maintenance
Corrective maintenance is performed
after the failure occurrence to correct the
fault.
Maintenance Processes
in Aviation
1. Hard time
2. On condition
3. Condition Monitoring
 Hard-Time Maintenance
 It is the oldest, primary preventive maintenance
process.
 It requires that an appliance or part be
periodically overhauled at certain intervals in
accordance with the carrier’s maintenance
program, or it should be removed from the
service.
 As soon as the part age reaches
predetermined time (flight hour, cycle, or
calendar time), it is overhauled or replaced with
a new component.
On-condition Maintenance
 This is a primary preventive maintenance process.

 It requires that an appliance or part be periodically

inspected or checked against some appropriate
physical standards to determine weather it can
continue in service.

 The purpose is to use the part as long as possible

before it fails during normal operation (in service
operation).
 Scheduled Service.
 Unscheduled Service.
Condition Monitoring
 This is a maintenance process for items
that have neither “hard time” nor “on-
condition” maintenance as their primary
maintenance process.

 Condition monitoring is the maintenance

process for locating and resolving problem
areas through analytical study of
malfunctions or failures, not affecting safety
of aircraft.
 Condition Monitoring
Has 3 main methods:
 Flight Deck Indicators:
These are used to monitor thrust, RPM, EGT, Oil
Pressure etc.
 In-flight Recorders:
Parameters are recorded manually or automatically
and later analyzed. A/C Integrated Data System
(A.I.D.S.) record pressure, temperatures and flows.
 Ground Indictors:
Boroscope, Magnetic Chip Detectors, Oil Filters,
Spectrometric Oil Analysis Program.
 ENGINE CONDITION TREND
MONITORING (ECTM)
ECTM is a maintenance tool that allows the user to
monitor the engine performance and:
 Permit early detection of engine deterioration
 Help determine source of problems
 Increase dispatch reliability
 Perform repairs at the most economical time
 Do HSI’s on condition
Maintenance Program Development
Maintenance
Review Board
(MRB)

MRB
Report

Manufacturer Maintenance
(Maintenance Planning
Operators
Document
Program Proposal)
(MPD)

Maintenance
Program
Aircraft Operator Maintenance
Program
An airliner's maintenance program
should contain at least the following
information:

1) Item to be maintained
2) Time limit
3) Task
1) Items to be maintained (What ?)
 The item (part, component, or
system) to be maintained should
be indicated clearly and
accurately. This is done usually by
ATA (Air Transport Association)
Chapter numbers, part serial
numbers, etc.
2) Time Limit (When ?)
 The time limit is the maintenance interval when
you perform the maintenance task.

 There are three (3) units of measure used to

establish these limits. An item may have no
limits, one limit, or any combination of these
limits.
 CALENDER TIME
 FLIGHT HOURS
 CYCLES (Number of landings)
3) Maintenance Tasks (How ?)
These include the maintenance services to
be done. The maintenance program
consists of three types of tasks:

 Scheduled maintenance tasks

 Unscheduled maintenance tasks
 Specific maintenance requirements for
major components of aircraft (engine,
propeller, etc.)
Types of Scheduled Maintenance
Tasks (SERVICES)
 Pre-flight/ Post-flight
 Transit Service
 Overnight Heavy Service
 Heavy Maintenance Service
 Overhaul Service
Maintenance tasks and letter
checks
 In maintenance program, the maintenance
tasks which are carried out at the same time
are grouped into maintenance packages.

 These maintenance packages are indicated

by "A", "B", "C" and "D" checks. For this
reason they are called "letter checks".
Transfer of task types in
maintenance program
Operating life and failures
of a component
Operating life of a component may include
three periods from the failures point of view:

 Earlylife period
 Useful life period
 Wear-out life period
Early Life Period
 Early failures occur early in the operating life
of a component and are characterized by a
decreasing failure rate with increasing age.
 Main causes of early failures are:

Poor manufacturing techniques

Poor quality control
Improper storage of the component
Improper installation
Contamination
Useful Life Period
 Useful life period is characterized by
constant (or random) failure rate. During
useful life components fail by change
unexpectedly.
 Main causes of change failures are:

Misapplication
Abuse
Storms, lightning, etc.
Foreign object damage (FOD)
Wear-out Period
 Wear-out failures occur late in operating
life and characterized by an increasing
failure rate with increasing age.
 Main causes of wear-out failures are:

 Aging
 Wear
 Fatigue
 Corrosion and erosion
 Poor service, maintenance, and repair.
Introduction
 With the traffic growth and increased
demands upon aircraft utilization, the
pressure of maintenance operations on-
time performance tends to increase.

 The safety and effectiveness of airline

operations are becoming more directly
related to the performance of the people
who maintain, inspect and service the
aircraft fleets and its engines.
KAAT/Maint/EI/13
Introduction
 Human failures are often recognized as
being a contributor to incidents and
accidents.

KAAT/Maint/EI/13
Introduction
 The interaction between 3 factors
affects human performance at
work:
 The Environment.
 The Individual.
 The Organization.

(The Ideal World)

KAAT/Maint/EI/13
Most Common Maintenance Errors

KAAT/Maint/EI/13
Most Frequent Types of Errors

KAAT/Maint/EI/13
Errors During Maintenance

KAAT/Maint/EI/13
Errors During Installation

KAAT/Maint/EI/13
 Example:
 “Improperclosing and securing of access
panels” were cited as being amongst the most
frequent maintenance errors conducted by the
A/C Personnel.

 One of the most “visible”, and probably most

expensive consequence of not correctly
securing panels, are the number of fan cowl
door losses reported after take-off.
KAAT/Maint/EI/13
 Findings:
 The events of fan cowl door losses were
reported randomly over the past years, and in
every case the post-incident investigations
revealed the same findings:
 The cowls were opened for maintenance prior
to the flight
 The cowls were found un-latched and not
properly hooked and secured
 Air scooping after T/O resulted consequently in
the cowls separation
KAAT/Maint/EI/13
KAAT/Maint/EI/13
 Findings:
 In each case the aircraft performed an in-flight
turn-back followed by a safe landing.

 Consequential structural damage further to

impact with pylons, slats, flaps, fuselage skin
and engines, was ranging from minor to
severe.

KAAT/Maint/EI/13
 Modifications:
 Fluorescent paint on the forward cowl door
latch handles.
 Caution decal on the outboard fan cowl doors
 Latch Assy. modification to ensure that latch
handles will hang down if unlatched (weighted
latch and improved anti-swivel plate).
 Design Change by installation of improved
latch handle hook spring.

KAAT/Maint/EI/13
KAAT/Maint/EI/13
 Conclusion
 The A/C manufacturer has the privilege of receiving
operational information worldwide from a diverse
customer base.
 As one can see, maintenance errors during
installation procedures, and securing of components,
are one of the most frequent error types.
 Despite technical modifications and improvements of
tech manuals, the human being, i.e. the maintenance
technician in our case, is an essential and non-
replaceable element in the chain to ensure a safe and
cost efficient aircraft operation.
KAAT/Maint/EI/13
KAAT/Maint/EI/13
 Suspected Unapproved Parts
(SUPs)
 There are four types of aircraft parts:
1. Good parts with good paperwork.
2. Good parts with bad paperwork.
3. Bad parts with “good” (bogus) paperwork.
4. Bad parts with bad paperwork.
 The first of those listed represents properly authorized parts and when
properly installed are approved parts, and the aircraft can be returned to
service.
 The last of those listed represent obviously unauthorized and unapproved
parts. The technician should be alert for these, and must never install them
on an aircraft.
KAAT/Maint/EI/13
Suspected Unapproved Parts
(SUPs)
 The center two categories of parts represent
suspected unapproved parts. If either the physical
part or the paperwork associated with the part is
questionable, it is best to contact the shop foreman,
shift supervisor, or the assigned quality individual to
discuss your concerns.
 Suspected unapproved parts (SUPs) should be
segregated and quarantined until proper disposition
can be determined. Contacting the manufacturer of
the product is a good way to start gathering the
facts concerning the product in question.
KAAT/Maint/EI/13
 WHAT IS AN
“UNAPPROVED PART?”
IF A PART IS NOT AN
“APPROVED PART”

THEN IT IS AN
“UNAPPROVED
PART”
…AND IF YOU DON’T KNOW,

THEN IT IS A

SUSPECTED
“UNAPPROVED PART”
 SUP

IF A DETERMINATION
CANNOT BE MADE,
QUARANTINED THE PART,
BECAUSE IT MIGHT REQUIRE
REPORTING AS A SUP
IN CONCLUSION WE M U S T !!!
PREVENT
“UNAPPROVED PARTS”
FROM ENTERING THE
AVIATION SYSTEM.
PREVENT
“UNAPPROVED PARTS” FROM
BEING INSTALLED.
PURGE
THE AVIATION SYSTEM OF
“UNAPPROVED PARTS”
KAAT/Maint/EI/13
 Introduction
 The failure rate of aircraft engines has reached
an all-time low.
 This means that many flight crews will never
face an engine failure during their career, other
than those in the flight simulator.
 The rate of In-Flight Shut Downs (IFSD) has
decreased as follows:
IFSD (per 100,000 engine FH)
1960s 40
Today Less than 1
KAAT/Maint/EI/13
 In other words:
 In the 1960s, in average each engine failed
once a year.
 Today, in average, each engine fails every 30
years.
 This improvement in the rate of IFSD has allowed
the introduction of ETOPS (Extended Twin
Operations) in 1985. Among other criteria, to be
approved for ETOPS 180, the rate of IFSD must be
less than 2 per 100 000 engine flight hours.
 However, despite the significant improvement in
engine reliability, the number of accidents (per
aircraft departure) due to an incorrect crew
response following an engine malfunction has
remained constant for many years.
KAAT/Maint/EI/13
 This prompted a study with all major industry
involved (aircraft and engine manufacturers,
authorities, accident investigation agencies, pilot
organizations).
 Among the results were:
o The vast majority of engine malfunctions are
identified and handled correctly. However, some
malfunctions are harder to identify.
o Most crews have little or no experience of real (i.e.
not simulated) engine malfunctions.
o Simulators are not fully representative of all
malfunctions.
o Training does not sufficiently address the
characteristics of engine malfunctions.

KAAT/Maint/EI/13
Identifying Engine Malfunctions
 Most engine malfunctions can be easily
identified, thanks to dedicated
warnings/cautions or indications.

 However, some malfunctions are harder

to identify, and require some flight crew
knowledge, in order to properly
understand and handle them.

KAAT/Maint/EI/13
Engine Fire
 An engine fire is easy to identify, and is also
sometimes referred to as an “external fire”,
or “nacelle fire” because it occurs inside the
engine nacelle but out of the engine core
and gas path.
 An engine fire can occur at any time, both
on ground and in flight.
 It is usually due to inflammable fluid coming
into contact with very hot engine parts, such
as the compressor, turbine or the
combustion chamber casings.
KAAT/Maint/EI/13
Engine Fire
 Engine fire detection is based on
temperature sensors (loops) located in
sensitive areas around the engine and in the
pylon. This location differs for each engine
type, based on the engine’s characteristics.

KAAT/Maint/EI/13
Engine Tailpipe Fire
 Engine tailpipe fire is harder to identify, and is
sometimes confused with an engine fire. It is
also referred to as an “Internal Fires” (i.e.
located in the gas path).
 A tailpipe fire will only occur on ground,
during engine start or engine shutdown.

KAAT/Maint/EI/13
Engine Tailpipe Fire
 It is due to an excess of fuel in the
combustion chamber, the turbine or the
exhaust nozzle, that ignites.
 It can result in a highly visible flame or smoke
coming from the exhaust.

KAAT/Maint/EI/13
Engine Vibrations
 Engine vibrations may be caused by:
 Engine unbalance.
 Birdstrike or FOD cause blade deform.
 Compressor blade loss.
 Icing conditions (ice may build up on the fan
spinner and blades).
 Engine Vibrations alone should not lead to an
in-flight shutdown
 Compressor Surge:
A compressor surge (sometimes called a compressor
stall) is the result of instability of the air flow through
compressor. It is recognized by a loud bang similar to
an explosion.

 Flame out:
A flameout is a condition where the combustion
process within the burner has stopped.

 Hot Start:
During engine start, due to fuel scheduling, strong tail
wind, etc. turbine temperature rises to relatively high
temperatures. This is known as a hot start.
KAAT/Maint/EI/13
 Foreign Object Damage:
Foreign Object Damage (FOD) is ingestion of
objects such as tire fragments, runway debris
or animals into the engine.

 Engine Seizure:
Engine seizure describes a situation where the
engine rotors stop turning in flight, perhaps
very suddenly. The static and rotating parts
lock up against each other, bringing the rotor to
a halt.
KAAT/Maint/EI/13
 OilLow Pressure / Oil Low Level:
In service experience shows that some rejected
takeoffs and in-flight shutdowns have been
commanded because of a low oil level.
However a low oil level alone is not a symptom
of an engine malfunction.

 Reverser Unlock:
The full deployment of thrust reverser in flight is
a potentially catastrophic situation, which can
lead to the loss of control of the A/C.
KAAT/Maint/EI/13
 Engine Failure Causes
Major failure
causes of aircraft
engine during the
last four years:
-Vibration
-Low pressure
compressor (N1)
problem
-Compressor vane

KAAT/Maint/EI/13
 Engine Failure Causes
􀂄 Cold Section
- Compressor
- Foreign Object Damage

􀂄 Hot Section
- Combustion chamber, turbine, exhaust
- Cracks due to thermal shocks
- Dictates TBO (time before overhaul)

KAAT/Maint/EI/13
 Aircraft Engine
Management (AEM)
 What it can do for you?
 The cost of ignoring it
 Some low hanging fruits
 How to go about it?

KAAT/Maint/EI/13
What is a Cost effective Engine
Management?
 Itis all about management of Engines, APU
and their Accessories in a manner that
Minimizes the overall Cost of Ownership
while maintaining and improving their
Reliability.
 It start before the induction of the engine
in the fleet and continues till its disposal or
return to the Lessor

KAAT/Maint/EI/13
What it can do for you?
A well managed Powerplant means ensuring the
following:
 Optimizing Performance on Wing
- Reduces fuel Cost
- Reduces Surprises
 Scientific Planning and Work-Scoping
- Optimizes Life on Wing
- Reduces cost of Shop Visits
 Making Lease returns easy and cost effective
 Improving Re-sale Value of the Aircraft
KAAT/Maint/EI/13
The Cost of Ignoring Powerplant
Management
Operational: Line Maintenance:
 Rejected Takeoffs  Unexpected
 Flight Diversions Removals
 Higher Fuel Consumption  High number of pilot

 Reduced range/Payloads
Reported Defects
 Unplanned
 Removals at Remote
Stations Repairs/Rectifications
 Operating under
 Long Delays
multiple MEL’s
KAAT/Maint/EI/13
The Cost of Ignoring Powerplant
Management (2)
Off Wing Maintenance: Planning/Financial:
 Unplanned Shop Visits  Unplanned expenditures
 High Cost Failures due to:
 Unplanned Leases - Leasing on AOG
 Unscheduled Work - Logistics to/and from
 Delays in offloading to Remote stations
shop  Higher than expected
 Working on AOG Shop Invoices
 Extra TAT  High lease Return cost
 Lower Assets Value
KAAT/Maint/EI/13
The Fruits of Powerplant Management
Unmanaged: Well Managed:
 Most engines removed in  Less or no surprises-most
an unplanned manner engines removed as planned
 Poor engine condition on  Better engine condition at
wing & at removal removal – lower cost
 Little idea about engine’s  All concerned have a fair idea
health for Pilots & of engines condition and
management performance on wing through
 Engines fails to deliver
analysis of Trend
power at last minute  Timely advices for improving
 High (and unpredicted)
reliability and prolonging their
shop visit cost longevity on wing
 Optimized and predictable
shop visits costs
KAAT/Maint/EI/13
How? – Transition to Effective
Powerplant Engineering Management
On wing maintenance:
 Establish a powerplant Engineering Cell:
- Recruit & Train your own people OR;
- Outsource the activities to one or more service providers
 Select and implement best Engineering ERP
Solutions
 Involve PEM from the very beginning in:
- Evaluate and selecting the engines
- Agreement Negotiations with lessors and service providers
- Predicting an Optimized Bill of Work
KAAT/Maint/EI/13
How? – Transition to Effective
Powerplant Engineering Management
On wing maintenance:
 Establish, implement and monitor programs for:
- On wing Trend Monitoring and analysis.
- Reliability Programs
 Use Trend and reliability data to determine proper
time periods for:
- NDT Inspection of critical areas
- Compressor wash
- Hard and Soft time limits for components
KAAT/Maint/EI/13
How? – Transition to Effective
Powerplant Engineering Management
On wing maintenance:
 Properly evaluate and select services providers/MRO
shop for a long term.
 Prepare and optimize Bill of Work
 Predict and then periodically update the expected
shop visit/PFH cost.
 Physically inspect and monitor the engine/APU in the
shop (MRO) as much as viable.
 Properly Scrutinize the Invoices
 Outsource any activity for which you do not have
expertise at the moment.
KAAT/Maint/EI/13
Organization Structure
Three Basic Concepts

- Two Traditional management thinking

- Span of control
- The grouping of similar
function
- Some what unique to aviation
(inspection, control and monitoring)
Under the FAA philosophy (self-
monitoring function)

KAAT/Maint/EI/13
Typical MEO

VP Maintenance
& Engineering

Maintenance
Technical Aircraft Shop
Materials Program
Services Maintenance Maintenance
Evaluation

Engineering Hangar Engine Purchasing Quality Assurance

Planning Line Avionics Stores Quality Control

Training MCC Mechanical Inventory Reliability

Publication Structure Receiving Safety

Computer

KAAT/Maint/EI/13
Technical Services Directorate
 Engineering
(a) the development of the initial maintenance program
(tasks, intervals, schedules)
(b) the evaluation of service bulletins (SBs) and service letter
(SLs) for possible inclusion into airline ‘s equipment.
(c) Overseeing the incorporation of airworthiness directives
(ADs)

(d) the evaluation of maintenance problems

(e) establishing the policies and procedures for M&E
organization

KAAT/Maint/EI/13
Technical Services Directorate
 Production planning and control
(a) all planning activities related to maintenance
and engineering (short, medium and long term)
(b) the establishment of standards for man hours,
materials, facilities, tools, and equipment.
(c) work scheduling
(d) control of hangars
(e) on-airplane maintenance
(f) monitoring of work progress in the support shops
KAAT/Maint/EI/13
Aircraft Maintenance Directorate
 Hangar Maintenance : work done on the aircraft in
the hangar, such as modifications, engine changes, C
checks (and higher), corrosion control, painting
including welding, seat and interior fabric, composite
as ground support equipment.
 Line Maintenance : work done on the aircraft on
flight line while the aircraft is in service.(Turnaround
maintenance and servicing, daily checks, short
interval check( less than A check interval)
 Maintenance Control Center : keeps track of all
aircraft in flight and at outstations.

KAAT/Maint/EI/13
Reliability
Engine maintenance cost
management has a significant impact
on the profitability and even survival
of airlines, a business that over time
has presented poor economic
performance together with an
intrinsic glamour that exercises a
strong attraction for new investors.
Reliability
 The purpose of a reliability program is to
ensure that the A/C maintenance program
tasks are effective and their recurrence at
regular intervals is adequate.
 The reliability program may give rise to the
optimization of a maintenance task interval, as
well as the addition or deletion of a
maintenance task.
 The reliability program provides an appropriate
means of monitoring the effectiveness of the
maintenance program.
The program should contain the following
elements:
 an organizational structure;
 a data collection system;
 a method of data analysis and display;
 procedures for establishing performance
standards or levels;
 procedures for program revision;
 procedures for time control; and
 a paragraph containing definitions of terms
used in the program.
To be consistently successful in the
airline business requires:
 Competent costs and revenue
management,
 Flexible organization with a high
degree of “escapability of costs”.
 Excellent skills and tools for boosting
sales and profit in times of
macroeconomic decline.
 Low air transport demand.
Reliability
 Ideally engine maintenance should be
managed in order to achieve the minimum
maintenance unit cost, in full compliance with
safety requirements.
 The cost of engine maintenance in a small
airline, would be about 40% of the total
maintenance cost, which may represent
between 10 and 20% of the total operating
cost of the flight of a scheduled or full charter
airline.
Engine maintenance cost depends on a
certain number of factors, including:

 Average stage length of each flight;

 Percentage of engine de-rating (reduction of the
maximum engine power) at take-off and climbing;
 Good maintenance practices;
 Definition of the shop visit (SV) workscope,
including service bulletins’ incorporation policy;
 Selection of Maintenance, Repair and Overhaul
(MRO) organization and contract negotiation skills;
 Adequate decisions about the time to remove an
engine from the aircraft and send it for an SV.
FINAL CONCLUSIONS
 A maintenance program is a combination of
management procedures as well as scheduled
maintenance tasks.
 In order to be applicable and effective, a
maintenance program requires an integrated
organizational structure and qualified
personnel to manage the scheduled
maintenance.
 The management process is of primary
importance –what is scheduled is meaningless
without the management process