lecture  42   Aircraft Maintenance Guidelines
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lecture 42 Aircraft Maintenance Guidelines

August 23, 2019


hello i am barfer matodh chief engineer flight
lab iit kanpur i am here to present a small presentation about the aircrafts how the aircrafts
are operated maintained in a small organization in our country before understanding the operations
the maintains it is very important to understand what are the things involved for any aircraft
to operate right from designing developing an aircraft the regulatory authorities involved
the various inspections involved the various guidelines by the manufactures it is very
important to understand the intricacies involved in addition to the inspections we will also
be showing you the various inspections which we carry out during a daily inspection how
the aircraft is released for flight what are the inspections that are carried out on an
airplane before releasing an airplane followed by an engine grounded up s
so you can see aviation anything related to aircraft is aviation that is the practical
aspect or art of aeronautics that is either designing an aircraft development of an aircraft
development of the design production of the designed aircraft operation and the use of
aircraft specially heavier than air aircraft there first of all you have to design a machine
based on the design that machine has to be developed produced and once the production
is done finally it has to be operated and put into use so aviation is all about design
development production operation and use of aircraft now since this aircraft operation
involves machine life and property so stakes are very high and everything revolves
around safety we have to be very careful about safety everybody working at aircraft operation
whether it is a pilot an engineer or the regulatory authority all of us together are working for
safety safety it is prevention of failures through regulations education and training
the failures can be prevented by making rules regulations by educating the personal involved
in the operation involved in maintenance involved in handling the machine and there training
proper training it means the state in which the risk of harm to persons or property or
damage is reduced to and bill maintained at or below an acceptable level of safety by
making regulations by educating and training personnel involved the risk of harm to persons
and property is minimized and it is a continuous process of hazard identification and risk
management so you can see safety is prevention of failures
through regulation education and training it means the state in which the risk of harm
to persons or property of damage is reduced to and maintained at or below an acceptable
level of safety through a continuing process of hazard identification and risk management
so all of us are working for safety by minimizing the hazards involved by minimizing the risks
involved we manage the risk what is an aircraft now aircraft is any machine which can derive
support in the atmosphere from reactions of the air other than reactions of the air against
the earths surface and it includes balloons whether fixed or free airships kites gliders
and flying machines so you can see any machine which can derive support in that atmosphere
from reactions of the air other than the reactions of the air against the surface earth surface
is an aircraft it may be a free it may be a balloon with the fixed or free it may be
an airship a kite glider or any flying machine it is an aircraft now what is an aeroplane
aeroplane is a power driven heavier-than-air aircraft which derives its
lift in flight chiefly from aerodynamic reactions on surfaces which remain fixed under given
conditions of flight so you can see the difference between an aircraft and an aeroplane aeroplane
it is also an aircraft but a power driven heavier-than-air aircraft which derives its
lift and flight chiefly from the aerodynamic reactions on surfaces now this aircraft operation
all over the world is governed by an international body a un specialized agency called the international
civil aviation organization ikaw it is a un specialized agency which was established by
states in nineteen forty four so that the aircraft operation the aviation
all over the world can be administered and governed and the international rules and regulations
and the the norms are in sync all over the place a cow has its headquarters in montreal
canada in india the civil aviation regulatory authority is the directorate general of civil
aviation dgca in u.s. the civil aviation regulatory authority is federal aviation administration
faa and in europe it is the european civil aviation regulatory authority called the europeans
aviation safety agency easa so now the indian rules the indian aircraft
rules the indian civil aviation operates under the aircraft act nineteen thirty four which
was passed in parliament as part of that act the aircraft rules nineteen thirty seven were
formulated which are you can see the rules there are various parts the indian aircraft
rules nineteen thirty seven is divided into various parts you can see part one preliminary
part two general conditions of flying part three general safety conditions part four
is registration and markings of aircraft part five is personal of aircraft part six is airwilderness
part seven radio telegraph apparatus part eight aeronautical beacons ground lights and
false lights part nine log books part eleven aerodromes part twelve personnel of air traffic
services part twelve a aeronautical telecommunication twelve b regulatory provisions twelve c engineering
inspection and manual requirements for organizations other than operators about thirteen air transport
services an aerial work or thirteen a engineering inspection and manual requirements owners
or operators and part fourteen is general so you can see the aircraft rules they are
divided into various parts and in front of them in the brackets you can see they are
the rules rule numbers for example in preliminary one dash three b from rule one to three b
there are some curtain rules you can see part six airworthiness we the we the aircraft main
maintenance people we are mainly concerned with the air worthiness of aircraft and the
rules are from rule number forty nine to rule number sixty two section four of the aircraft
at nineteen thirty four enables the central government to make rules to implement the
conventions relating to a cow so there are certain requirements which the
regulatory authority which the country the civil aviation in the country has to comply
with the requirements of a cow with the convention relating to a cow so in order to comply with
those requirements the section four of the aircraft act enables the central government
to make rules this enables dgca to lay down standards and procedures civil aviation requirements
ca which we call them a c ar are issued to specify the detailed requirements and compliance
procedures it standardizes and harmonizes the requirements taking into account the rules
and regulations of other regulatory authorities it addresses any other issues related to safety
of aircraft operations as may be considered necessary by the director general director
general here implies as director general civil aviation it implements the recommendations
of the courts of enquiry or any other committee constituted by the central government or director
general now you can see the civilization requirements
that is the car which is issued it also has got various sections you can see section one
is general section two is air worthiness section three air transport section four aerodrome
standards and licensing section five air safety section six design standards and type certification
section seven flight crew standards training and licensing section eight aircraft operations
section nine airspace and air navigation services standards section ten aviation environment
protection section eleven safe transport of dangerous goods by air again aircraft maintenance
is mainly concerned with section 2 airworthiness so you can see the various sections in civil
aviation requirements now this was all about the regulations the aircraft rules the civil
aviation requirements now coming to the designing of an aircraft
once the aircraft is designed and developed in order for the designed aircraft to be certified
a dgca issues are type certificate a type certificate it is a document which is issued
validated or accepted by the director general to signify that the design of a type of aircraft
or engine or propeller complies with the applicable type design standard specified by the director
general the type certificate signifies that the aircraft is manufactured according to
an approved design and that this design ensures compliance with the airworthiness requirements
the regulating authority compares design documents and processes to determine if the design meets
the requirements established for the type of equipment once the aircraft is type certified
a certificate of airworthiness is issued certificate of airworthiness means an aircraft specific
document it is it is specific to the aircraft issued by the director general to signify
that it confirms to its applicable type design and is a condition for safe operation
in accordance with the norms as is specified by the director general the cfa the certificate
of airworthiness is the essential requirement to fly an aircraft it is this document is
a specific to the aircraft and confirms that the aircraft has been designed as per the
applicable type design as per the applicable type certificate and it complies with all
the requirements as specified by the director general the regulatory authority and the aircraft
is in a safe condition for operation the cr stipulates the conditions necessary for a
certificate of airworthiness to remain in force that is to keep the aircraft in a state
of continued air worthiness this is ensured by issuing certificates of airworthiness to
an aircraft and subjecting to the aircraft to annual airworthiness review certificates
we call them arc once the c of a is issued in order to ensure the continued airworthiness
of an aircraft the aircraft is subjected to annual review and is followed by issuance
of an annual ah arc or the airworthiness review certificate
so the ca the c of a and the arc is the essential requirement for any aircraft to fly the c
of a is deemed to be valid if the arcs are valid it also specifies technical requirements
to be complied by organizations and personnel involved in the maintenance of aircraft aircraft
which may be registered in india or registered in a foreign country but used by an indian
operator for which india ensures oversight of operations and aeronautical products parts
and appliances in order to demonstrate the capability and means of discharging the obligations
and associated privileges there off now we will see what are the owner responsibility
what are the responsibilities for the aircraft owner before operating an any aircraft in
india the owner is responsible for the continuing airworthiness of an aircraft and shall ensure
that no flight takes place unless the aircraft is maintained
in an airworthy condition any operational emergency equipment fitted is correctly installed
and serviceable or clearly identified as unserviceable the airworthiness certificate remains valid
and the maintenance of aircraft is perform in accordance with the approved maintenance
program so you can see the various responsibilities first the aircraft has to be maintained airworthiness
condition all the equipments whether operational emergency everything has to be serviceable
in case if something is unserviceable the it has to be clearly identified clearly mentioned
clearly the pilot operating the machine needs to be aware of what is unserviceable and whether
it is within the regulations to operate the aircraft with that unserviceable equipment
the airworthiness certificate that is the airworthiness review certificates is valid
the maintenance of aircraft is performed in accordance with the approved maintenance program
and as per the requirements mentioned by the manufacturer of that aircraft
now there is a classification of aircraft aircrafts are classified as complex motor
powered aircraft category one light aircraft and category two light aircrafts complex motor
powered aircraft means an aeroplane which is above five thousand seven hundred kg maximum
takeoff mass or certificated for more than nineteen seated passengers or certificated
for operation with at least two pilots or equipped with turbojet engine or engines or
more than one turboprop engine so any aeroplane which is above five thousand seven hundred
kg weight or anything which is it can carry for more than nineteen passengers or it has
to be operated by at least two pilots or it is equipped with at least one turbojet engine
or more than one turboprop engine any of this these is a complex motor powered aircraft
in case of a helicopter it has to be above three one seven five kg mtom or certificated
for more than nine seated passengers or certificated for operation with at least two pilots or
if it is a tiltrotor aircraft so it in case of aeroplanes and in case of helicopters you
can see in if any machine is falls in this category falls in this weight category or
it is certified to carry these the number of passengers or it has to be operated by
these number of pilots it has a complex motor powered aircraft category one light aircraft
means the following aircrafts an aeroplane sailplane or powered sailplane maximum takeoff
mass less than one thousand kg that is not classified as complex motor powered aircraft
a balloon with a maximum design lifting gas or hot air well volume of not more than thirty
four hundred meter cube for hot air balloons one zero five zero meter cube for gas balloons
and three hundred meter cube for tethered gas balloons an airship designed for not more
than two occupants and a maximum design lifting gas or hot air volume of not more than twenty
five hundred meter cube for hot air ships and one thousand meter cube for gas airships
so youve seen the various requirements for any machine to fall under category one light
aircraft again for category two light aircraft means the following aircraft an aeroplane
with a maximum takeoff mass of two thousand kg or less that is not classified as complex
motor powered aircraft a sail plane or powered sail plane of two thousand kg mtom or less
a balloon a hot airship a gas airship complying with all of the following characteristics
three percent maximum static heaviness non vectored thrust except reverse thrust conventional
and simple design of structure control system and ballonet system and non power assisted
controls or a very light rotor aircraft rotor craft so these are the requirements for any
aircraft to fall under the category two light aircraft
now coming to air worthiness what is a worthiness every means the status of an aircraft engine
propeller or part when it confirms to its approved design and is in a condition of safe
operation in accordance with the norms specified by the director general so any machine any
aircraft engine or propeller which is manufactured as per the approved type design is maintained
as per the requirements mentioned by the manufacturer by the regulatory authority is maintained
as per the approved aircraft maintenance program and is in a condition of safe operation as
per the regulations as per the norms specified by the director general is considered to be
airworthy what is continuing air worthiness continuing air worthiness means all of the
processes ensuring that at any time in its operating life the aircraft complies with
the a worthiness standard and is in a condition for safe operation the aircraft has to be
maintained in continuing air worthiness condition it at any point point of time in its operating
life it has to comply with all the requirements all the regulations regulatory requirements
all the requirements specified by the manufacturer by the regulatory authority it has to be maintained
as per the air worthiness standard it has to be maintained
as per the approved type design and has to be in a condition for safe operation at all
times if the aircraft or any engine or propeller or any machine complies with all these requirements
it is considered to be in a state of continuing air worthiness what is maintenance maintenance
it is a combination of overhaul a repair inspection replacement modification or defective rectification
of an aircraft or component with the exception of pre flight inspection so any one or a combination
of these overhaul repair inspection replacement modification or defective rectification of
any aircraft or component is considered to be maintenance there are various types of
maintenance hot time maintenance on condition maintenance condition monitoring preventive
maintenance hard time maintenance hard time maintenance is the primary maintenance process
requiring assembly inspect of aircraft and aircraft components at fixed periods
in this maintenance the components the items of inspection they are to be performed at
fixed periods there that is why they are called hard time for example any component which
has been specified whose life has been specified say for example four years then that particular
component has to be removed after four years irrespective of whether the component is serviceable
at that point of time or unserviceable the that particular component has to be removed
so there is a specific life for that particular component that is called hard time maintenance
where the component has to be removed at a fixed period on condition maintenance on contingent
maintenance is the accomplishment of repetitive visual inspections physical measurements institute
bench tests excreta to determine the continued serviceability of aircraft and aircraft components
without having to dismantle them completely and before such components reach a critical
stage in their operation so you can see in on condition maintenance
you have to perform repetitive inspections they are visual inspections they may be physical
measurements they may be bench tests or institute tests so that the continued serviceability
of the aircraft and aircraft components can be ensured without having to dismantle them
completely and by doing this we ensure that the component can be removed before it reaches
a critical stage in their operation for example any instrument which has been specified to
be maintained as per on condition maintenance we carry out been checked for that instrument
for say after two years so every two years we remove the instrument carry out been check
or there may be some certain instrument or certain equipment where we are not supposed
to remove it from the aircraft or the check has to be performed in situ so but it that
particular cheque that particular inspection has to be done at two years if it has been
specify a specified to be carried out at two years
similarly visual inspections if they are called for or physical measurements the that particular
component is maintained as per the on condition maintenance but at a specified period that
inspection or measurement or check has to be performed we do not remove the component
if it is serviceable but we ensure that the component doesnt reach a critical stage in
its operating life in condition monitoring it is the maintenance process for locating
and resolving problem areas through analytical study of malfunctions or failures not affecting
safety of aircraft so in this kind of maintenance we are constantly
monitoring the condition of the component of the equipment by locating and resolving
problem areas by studying the malfunctions or failures so that the safety of the aircraft
is not affected preventive maintenance it constitutes work performed at predetermined
intervals to maintain an aircraft aircraft components or aircraft systems in an air worthy
condition so you can see the maintenance that we are doing all preventive maintenance by
constituting work which are performed at predetermined intervals
so that the aircraft and aircraft components are kept in a state of continued air worthiness
they are maintained in an air worthy condition at all time you can see the various manuals
logbooks certificates required for aircraft operation coming to manuals there is a pilot
operating handbook which specifies the normal procedures the emergency procedures and various
guidelines required to be followed by the pilot to operate an aircraft then there is
another aircraft maintenance manual which specifies various procedures which mentions
various steps to be followed in order to maintain an aircraft the then is there is an illustrated
parts catalog which mentions the various parts various components in an aircraft it mentions
there part numbers it mentions the quantity it illustrate gives illustrations then there
is a wiring diagram manual which mentions about the wiring diagrams the electrical diagrams
the wiring diagrams for different systems in the aircraft there is another manual called
the service and repair manual which mentions about the repair for an aircraft then there
is an operators manual for various components for example propeller engine
we have the operators manual and the installation manual apart from these manuals to operate
an aircraft to we need to maintain various logbooks journey logbook journey logbook mentions
the duration of the flights the name of the pilot the place from where the aircraft has
flown to the lesser nation place it mentions the type of flight it mentions the fuel and
oil carried by the aircraft it mentions the various snags or incident involved in aircraft
operation so journey logbook is all about the journey of the aircraft then there is
an aircraft logbook aircraft logbook again mentions the number of hours the aircraft
has flown it mentions various inspections that have been carried out on that particular
aircraft the number of replacements the modifications that have been carried out on the aircraft
the engine log book mentions the number of hours the engine has
completed the inspections the modifications the replacements that have been carried out
on that particular engine same is with the propeller and say radio
so we have journey logbook aircraft logbook engine logbook propeller logbook and radio
logbook then there are various certificates required certificate of release to service
this certificate of release to service is required after the aircraft has been inspected
this certificate has to be issued by the engineer who is releasing the aircraft stating that
the aircraft is fit for flying that that the aircraft is in an air worthy condition so
once the certificate of release to services issued the pilot accepts the aircraft by signing
the pilot acceptance apart from this certificate of release to service there are various other
certificates for an aircraft that is the certificate of registration you can see which is we call
as c of r certification of airworthiness which we are mentioned earlier it is the c of a
called c of a air worthiness review certificate called a rc the c of a and a rc is very much
required to operate an aircraft then there is a noise certificate issued by the dca stating
the acceptable level of noise the aircraft is permitted to make then there is an aircraft
station license called the air mobile license and there is aircraft insurance certificate
for any aircraft to operate so that the aircraft is insured so in order
to operate an aircraft the organization needs to be approved by d d c a there are various
requirements there are various guidelines specified by the d g c a for any organization
to be approved some of the requirements some of the facilities which are required for any
dgc approved organization to have are that it should have a continuing a air worthiness
management cell it should have a hangar facility it should have an aircraft store aircraft
stores are again there were different types of stores bonded store quarantine store fuel
store then it needs to have a battery shop a radio shop again and you need to have a
tarmac where you can park the aircrafts after having all these facilities and various audits
by ddca by internal audits different spot checks and after complying with all the requirements
of ddca organization is approved by d g c a
so the various certificates required you can see this is a certificate of registration
of one of the aircraft issued by d g c a this is certificate of airworthiness issued by
the director general of civil aviation you can see it mentions the nationality and registration
mark of the aircraft at manufacture it mentions the manufacturer of the aircraft and the aircraft
serial number the category in which the aircraft is approved and you can see in this case it
is normal private the minimum crew required to operate the aircraft and the maximum all
operate authorized for this aircraft you can see again the certificate mentions that this
certificate of airworthiness is issued pursuant to the convention on international civil aviation
dated the seventh december nineteen forty four and aircraft rules nineteen thirty seven
as amended from time to time in respect of the above mentioned aircraft which is considered
to be a worthy when maintained and operated in accordance with the foregoing and pertinent
operation limitations this certificate shall remain valid subject to the above compulsory
conditions being fulfilled until the date shown unless withdrawn or suspended earlier
so once the aircraft is issued with c of a it is subjected to annual review and subsequently
issued with an airworthiness review certificate you can see air worthiness the certificate
review certificate here this certificate is valid for one year and in order for c of a
to remain valid the aircraft needs to have a valid air worthiness review certificate
in case the air worthiness review certificate is not valid the c of a is deemed to be suspended
then you can see this is the noise certificate for the for one aircraft which mentions the
nationality and registration marks the manufacturer of the aircraft the aircraft serial number
the type of engine installed the type of propeller installed the maximum takeoff mass the maximum
landing mass the noise certification standards which are to be followed and the takeoff noise
level you can see the noise certificate this is certificate is required for every aircraft
then every aircraft has to have a weight schedule so you can see the weight schedule which is
required for every aircraft the aircraft has to be weight the aircraft empty weight has
to be computed then this weight schedule you can see the it mentions the weight of crew
members plus baggage the usable fuel the maximum payload with fuel tanks full and the aircrafts
cg range so this weight schedule has to be prepared
and approved by d g c a for every aircraft so now coming to a craft maintenance the aircraft
manufacturer has designed a care program called a progressive care program so that the aircraft
maintenance aircraft inspections are performed in a planned manner and at the same time the
aircraft downtime is minimized you can see since the scope and detail of complete aircraft
inspection is very extensive and it can keep an any aircraft out of service for a considerable
length of time so alternative inspection programs are designed to minimize the downtime a progressive
inspection program allows an aircraft to be inspected progressively inspecting the aircraft
progressively means that we can inspect the aircraft stage wise for example we can inspect
the aircraft one portion of the aircraft at one stage
in the second stage we can inspect the aircraft we can inspect a different area of the aircraft
and we can divide the complete aircraft the different areas of the aircraft in different
stages and in each stage we can inspect the aircraft the scope and detail of complete
aircraft inspection is essentially divided into segments or phases typically four to
six and completion of all the phases completes our cycle which satisfies the requirements
of complete aircraft inspection the advantage of such a program is that any required segments
may be completed overnight and thus enabled the aircraft to fly daily without messing
missing any revenue earning potential this progressive care program is divided into four
primary operations operations one through four which covers all fifty hours hundred
hours and two hundred hours inspection requirements the remaining operations include all the inspection
requirements due at other intervals so you can see the main operations are operations
one through four and which have to be done at every fifty hours hundred hours and two
hundred hours inspections there are various other inspection requirements which are to
be complied at various other intervals the inspection program is divided into operations
to enable the progressive inspections to be accomplished
the component time limits should be checked at each inspection interval to ensure proper
overhaul and replacement requirements are accomplished at the specified times the inspection
operations have been developed based on normal usage under average environmental conditions
airplanes operated in extremely humid areas tropics or in exceptionally cold damp climates
excreta may need more frequent inspections for wear corrosion and lubrication under these
adverse conditions do the periodic inspections in compliance with the inspection operations
at more frequent intervals until the operator can set his own inspection periods based on
field experience the operators inspection intervals must not deviate from the inspection
time limits so based on the local conditions based on
the geographical conditions in which the aircraft is being operated the frequency of inspections
the type of inspections can be modified but the minimum requirements as is specified by
the manufacturer have to be followed in any case so you can see operation one it consists
of all the fifty are in interval inspection items and those hundred or two hundred are
interval inspection items contained in the fuselage area so operation one is related
to fuselage area which consists of fifty hour interval inspections hundred our interval
inspections and two hundred hour interval inspections all related to fuselage area operation
two is related to the engine compartment area consisting of all the fifty hour interval
inspections hundred hour two hundred our interval inspections
similarly operation three con is related to the wing area which consists of all the fifty
hour interval inspections hundred hour interval inspections and two hundred hour interval
inspections operation four is related to landing gear consisting of all fifty hours hundred
hours and two hundred hour interval inspection items so you can see operation one covers
fuselage area operation two covers engine compartment area operation three covers wing
operation four covers landing gear so with these four operations more or less the main
areas are covered fuselage engine wing landing gear
now from operation five onwards we have various specific inspections which have different
time limits which are to be complied at different frequencies some of the examples are given
here like operation five for example four hours one year operation six hundred hour
and each five hundred hour thereafter that means this operation six has got a repeat
inspection every five hundred hour us operation seven six hundred hour or one year whichever
occurs first similarly you can see various operations up to operation twenty five they
have got different frequencies different time limits and there are specific inspections
in different areas of the aircraft operation twenty six onwards we have a corrosion program
corrosion prevention and control of program inspections again see we call them cp cp inspections
corrosion prevention and control program inspections they are to be complied with they are to be
examined at different frequencies twelve months twenty four months thirty six months forty
eight months sixty months so cp cp program the corrosion prevention
and control program inspections are also required to be carried out at different frequencies
different time intervals twelve months twenty four months thirty six months forty eight
months sixty eight sixty months now there are various principal structural elements
in the in an aircraft an airplane component is classified as a principal structural element
if the component contributes significantly to carrying flight and ground loads and if
this component fails it can result in a catastrophic failure of the airframe the monitoring of
these principal structural elements is the main focus of supplemental structural inspection
program we call it as ssip any aircraft has to be
maintained as per the requirements mentioned in the approved director of maintenance program
as per the guidelines manufacture specified by the manufacturer of the aircraft those
are regular inspections carried out at various intervals as we had seen operation one two
operation four and from operation five to operation twenty six and different operations
requiring specific inspections at specific specific frequencies apart from the regular
inspections we have seen the aircraft has to be inspected for corrosion which we call
as cp cp corrosion prevention and control program again it was to be carried out at
different frequencies operation at say twelve months twenty four months thirty six months
sixty months now there is another program called the ssip which is required to be complied
to take care of the principal structural elements we call it ssip program supplemental structural
inspection program you can see these are the various supplemental
sorry these are the various structural members the principal structural elements in the aircraft
in the wings and amperage in the fuselage so in order to take care of the principal
structural elements our supplemental inspection document has been prepared by the manufacturer
this supplemental structural inspection program called as ssip is based on the affected aircraft
current usage testing and inspection methods a principle state of the art inspection program
is established for each principle structural element a principle structural element is
that structure whose failure if it remained undetected could lead to loss of the airplane
selection of a principle structural element is influenced by the susceptibility of a structural
area part or element to fatigue corrosion stress corrosion or accidental damage [FL]
start the principle structural elements cut so in order to take care of the principal
structural elements a supplemental inspection document called supplemental structural inspection
program is prepared by the manufacturer which is based on the current usage of the airplane
testing and inspection methods a practical state of the art inspection program is established
for each principal structural element a principal structural element is that structure whose
failure if remains undetected could lead to loss of an aircraft selection of a principal
structural element is influenced by its susceptibility to fatigue corrosion stress corrosion or accidental
damage the supplemental structural inspection program is developed through the combined
efforts of manufacturer operators and the concerned regulatory authorities the inspection
program consists of current structural maintenance inspection plus supplemental inspections as
required for continued awareness of the airplane as years of service are accumulated
so you can see this ssip program is based on the inputs from the operators from the
regulatory authorities from the research by the manufacturers so based on all the inputs
ah ssip program is prepared to take care of all the principal structural elements because
as the aircraft gets older the principal structural elements need to be taken care of need to
be closely monitored for corrosion for structural damage so the manufacturer has come out with
this supplemental inspection document to take care of all the principal structural elements
in that particular aircraft the current inspection program is considered to be adequate in detecting
corrosion and accident damage the emphasis of the supplemental structural inspection
program is to detect fatigue damage whose probability increases with time since fatigue
damage increases at an increasing rate with increasing crack length earlier detection
and repair minimizes the damage and the magnitude of the repair the supplemental structural
program is valid for model tooth two two zero six airplanes with less than forty thousand
flight hours beyond this continued awareness of the airplane can no longer be assured retirement
of airframe is recommended when forty thousand flight hours has been accumulated
so this is one example where the manufacturer has limited the aircraft life to forty thousand
flight hours it states that after forty thousand five dollars this aircraft is will not be
considered as air worthy this is for cessna two zero six airplane the function of the
supplemental structural inspection program is to find damage from fatigue overload or
corrosion through the use of non destructive inspections and visual inspections this supplemental
inspection document is only for primary and secondary airframe components engine electrical
items and primary and secondary systems are not included in this document if the sid is
for a specific part or component you must examine and evaluate the surrounding area
of the parts and equipment if problems are found outside
these areas report them to manufacturer this is very important any inspection which is
to be performed the surrounding areas the adjacent areas also needs to be inspected
and in case if some malfunction some problem is found in these adjacent areas it should
be reported to the manufacturer a corrosion prevention and control program cp cp should
be established for each airplane in addition to the regular maintenance and the principal
structural element inspections the corrosion inspections manufacturer of the aircraft or
an engine or propeller also issues regular service bulletins service instructions and
service letters for the guidance of the operators you can see here there is one example of a
service bulletin it is a mandatory service bulletin that is why it is marked in red color
it mentions the subject the models affected the time of compliance and the reason why
this service bulletin has been issued it mentions the maintenance which has to be performed
on that particular aircraft you can see here there is a service instruction thus the service
instruction mentions the maintenance steps which are in detail related to that particular
service bulletins then there are service letters also issued by the manufacturers there are
various types of inspections which are carried out on an aircraft they may be a mechanical
inspection visual inspection capacity check overhaul leakage test calibration check coming
to mechanical check it is an operation which includes both routine inspection and detailed
inspection it involves ensuring that a part or its condition it complies with the requirements
by taking measurements or using an inspection instrument visual inspection consists of careful
visual inspection of the component in situ to check its condition capacity checks they
are testing of the battery in the approved battery shop
as per the battery manufacturers laid down procedures to check the condition of the battery
in order to ascertain that the battery can provide minimum eighty percent of its rated
capacity when discharged at the rate of eighty percent of the thirty minutes emergency capacity
of the battery overhaul means stripping a unit and restoring it to its original design
performance level and replacing or reworking parts to a given standard leakage test to
apply a controlled pressure to the pitot static system to check for leaks and proper operation
of the pitot static instruments such as altimeter a speed indicator and vertical speed indicator
calibration checks it is a procedure to ascertain correct indication against known standards
to determine the accuracy of the unit in addition to the inspections mentioned above there are
various special inspections which are to be carried out
in case there is an incident in case if there is a hard landing or overweight landing some
inspections are required the structural stress induced by a lending depends not only upon
the gross weight at the time but also upon the severity of impact however because of
the difficulty in estimating vertical velocity at the time of contact it is hard to judge
whether or not a landing has been sufficiently severe to cause structural damage for this
reason a special inspection should be performed after the landing is made at a weight known
to exceed the design landing weight or after a rough landing even though the latter may
have occurred when the aircraft did not exceed the design landing weight
so wrinkled wing skin is the most easily detected sign of an excessive load having been imposed
during a landing another indication which can be detected easily is fuel leakage along
the repeated seams so these are the signs in case if you see a wrinkled wing skin or
a few leakage along the riveted seen seams these are some of the indications which indicate
that your aircraft has carried out a hard landing or a rough landing and you need to
carry out inspection for hard landing other possible locations of damage are spar webs
bulkheads nacelle skin and attachments firewall skin and wing and fuselage strangers if none
of these show areas show adverse effects it is reasonable to assume that no serious damage
has occurred if the damage is detected a more extensive inspection and alignment check may
be necessary in case if the aircraft has flown through severe turbulence then a special turbulence
inspection has to be carried out it should be performed after a flight through severe
turbulence emphasis should be placed upon inspecting the upper and lower wing surfaces
for excessive buckles or wrinkles with permanent set where wrinkles have occurred remove a
few rivets and examine the river shanks to determine if there ever have sheared or were
light highly loaded in shear in case the aircraft has encountered a lightning
strike although it is very rare the aircraft must be carefully inspected to determine the
extent of any damage that might be occurred when lightning strikes an aircraft the electrical
current must be conducted through the structure and be allowed to discharge or dissipate at
controlled locations these controlled locations are primarily the aircrafts static discharge
wicks on or more sophisticated aircraft null null field discharges when surges of high
voltage electricity passed through good electrical conductors such as aluminum or steel damage
is likely to be minimal or nonexistent when surges of high voltage electricity passed
through nonmetallic structures such as a fiberglass or a dome engine cowl or fairing glass or
plastic window or a composite structure that does not have built in electrical bonding
burning and more serious damage to the structure could occur visual inspection of the structure
is required look for evidence of degradation burning or erosion of the composite resin
at all affected structures electrical bonding straps static discharge wicks and null null
field discharges

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