Section 6
AIRCRAFT MAINTENANCE
Initial Provisioning
(Spare parts Management)
1
Apr-15
Production Planning and Control
“Plan your work and then work your plan.”
2
Apr-15
Production Planning and Control
 Production planning and control (PP&C) is one of the key
organizations within M&E. It is the heart of the maintenance
organization.
 The PP&C organization is primarily responsible for planning
and scheduling all aircraft maintenance activity within the
airline.
 Actually PP&C has three primarily functions:
forecasting, planning and control.
3
Apr-15
Forecasting
 Forecasting activities include the estimated maintenance workload for
the long term and the short term based on the existing fleet and
business plans and on any known changes in these for the forecast
period.
 Forecasting is concerned with the future workload of the M&E
organization. It must take into account the routine maintenance
requirements as well as all planned changes in the future operations
relative to maintenance.
 Any changes in fleet size and make up, changes in route structure, and
changes in facilities, manpower, and skill requirements must be tracked.
 Future plans must also accommodate aging and replacement of
equipment, adding new equipment, and the planned incorporation of
ADs and SBs.
4
Apr-15
Forecasting
 Forecasts are usually made for the long and short term but
often an intermediate term forecast is also made.
- Short-term forecasts are more detailed and usually
cover 1-2 years. These forecasts contain more definitive
plans with attention to actual manpower and budget
numbers.
- Long-term. Larger airlines may also develop intermediate
forecasts for periods of 2 to 5 years.
5
Apr-15
Production Planning & Controls
 Planning involves the scheduling of upcoming maintenance
and includes the planning and scheduling of all manpower,
parts, facilities, and time frame requirements for such
maintenance: less than “A” check items, daily checks, 48-hour
checks, transit checks, and letter checks (A, B, C, etc.).
 These plans would include incorporation of SBs, SLs, and
ADs as well as other modifications deemed necessary by the
airline.
 Coordination with flight operations and with ground
handling and support activities is also included in the
planning effort.
6
Apr-15
Feedback for planning
- What the planners need to know to adjust future plans are the
following:
1. The amount of time required to perform each task
2. The amount of time lost in waiting for delivery of parts
and supplies
3. The down time for unusual circumstances
4. The additional time required for non-routine findings
5. The variation in manpower availability
6. Lost time due to parts robbing from other jobs (or from
the aircraft in check)
7
Apr-15
The need of Spares
An airline sells speed safety and regularity
An aircraft is a highly complex device
It is expected to operate at 99% + Technical regularity
It is expected to fly up to 15 hours per day and sometimes even
more
 It is expected to fly 4000 hours per year
 Without a readily available stock of spares these targets will not be
met
 A two hours delay costs around 4000$. A cancellation around
16,000$




Plus The damage to a company’s image
8
08/04/58
Reliability / Consumption Data
MTBF : Mean Time Between Failure
MTBUR : Mean Time Between Unscheduled removals
TAT
: Turn Around Time
[Time in days from equipment failure to it being available, serviceable
again to the airline]
In a
given
Fleet
MTBF
=
Number of equipment hours flown
MTBUR =
9
Number of Hard failures
Number of removals of equipment considered faulty
Number of equipment hours flown
08/04/58
Sources of Spares
 From the aircraft manufacturer





One stop shopping
Good pressure on suppliers
Reduced administration load
Equipment matches the aircraft
Make up charged
 From the equipment supplier
 Negotiate special deals
 No mark up
 Heavy administration
10
08/04/58
Sources of Spares
 From second hand dealers
 Low prices
 Immediate availability
 Doubts on history
 May need early overhaul
 Pooling Schemes
 Reduced capital investment
 Pay from cash flow
 Possible availability problems
11
08/04/58
Different types of Spares
12
 No-Go
Essential to be operational for the aircraft to
be dispatched
 Go-If
Can be failed and the aircraft allowed to be
dispatched if some reservations are met
 Go
Can be failed and the aircraft can be dispatched.
To be changed or repaired at the first
(sometimes defined) opportunity
08/04/58
Typical Figures for Spares Potential
 A320 Example :
 Number of removable part numbers 25000
 Number of structure part numbers 15000
 Number of standard part numbers
9000
 Number of equipment part numbers 1100
13
08/04/58
How can Initial ProvisioningCost be
reduced?
CASH FLOW
 Lease spares
 Join pool scheme as a user only
 Purchase only as need arises
 Spares included in a larger support scheme from a third part or airline service
provider
14
08/04/58
Pooling
 Basic principle is to take advantage of scale effects. The larger





15
the fleet the smaller the expenditure per aircraft on spares
becomes. Members contribute spares or capital
However at about 20 aircraft the effect begin to become less
noticeable
Demand is random and so the pool may empty a particular
time
Not all prospective candidates are welcome in a pool
Costs may be high. 1/365 of book value per day is common
and this may be higher for longer leases by occasional users
Repair costs are to be added
08/04/58
Lease and Exchange Schemes
Lease Schemes
 Spares are leased against a fixed percentage of their cost in much the
same way as are aircraft. However, because of the higher risk and
administration load, required rates are higher. -1.6% - 1.7% - per
month is normal
 At the end of the lease the equipment does not belong to the airline
Exchange Schemes
 Instead of repairing and item a serviceable unit is given in exchange
 The exchange unit may be newer or older than that for which it is
exchanged. There may be cash/cost adjustments
 Maybe difficult in some areas of the world due to extra customs charges
16
08/04/58
Package Schemes
 The major players – big airlines, airframe manufactures and engine
companies are looking at spares repair and leasing packages. A
“spares by the hour” approach
 User would pay a fixed or pre-determinable fee ensuring
replacement of failed items by serviceable ones
 Main Advantage are





17
Reduced capital expenditure
Easier budgeting
Reduced administration
Reduced risk from random need for spares
Sometimes attached to an overall support scheme, particularly by
airlines – “Big Brother”
08/04/58
Non availability of Spares
 Loss of service
 Extension of overhaul downtimes
 Cost of spares loaned or purchased hurriedly
 Lease of aircraft
 Damage to company image
18
08/04/58
A.O.G. System
A.O.G. Aircraft On Ground
 Literally it means the aircraft cannot operate because of





19
damage or an equipment failure
Often used when the aircraft is close to such a condition
The manufacturer is expected to react within a minimum
period of time to advise of and take action
It costs much more than normal shipping
It occasionally carries a surcharge
Its abuse costs the industry a lot of money – The innocent pay
for the guilty
08/04/58
Parts and Materials Information
 Approved parts is one that meets approved design data
20
applicable to the part and having been manufactured and
subsequently maintained in accordance with the
requirements of the State of Design, Manufacture or
Registry, as applicable.
 Standard parts are approved parts conforming to national
or industry accepted standard.
 Parts and material acceptance: The process of evaluating
parts and material for acceptance involves establishing that
the part/material is authentic, conforms to the relevant type
design, customers order, physical state and accompanying
release documents.
Apr-15
Parts and Materials Information
 Unapproved Parts: These are parts that do not meet the
criteria, they also include parts improperly returned to
service.
 Original Equipment Manufacturer (OEM) parts
 OEMs are the primary source of approved parts
21
Apr-15
Parts Manufacturer Approval (PMA)
 Parts Manufacturer Approval (PMA) is a combined design
and production approval for modification and replacement
articles. It allows a manufacturer to produce and sell these
articles for installation on type certificated products.
 FAA Orders 8110.42 and 8120.2 prescribe the approval
procedures for FAA personnel and guides applicants in the
approval process.
22
Apr-15
OEM vs PMA
 Compatibility, Price and Availability
 Customer Bases
 The Airlines
 The Cargo Carriers
 The Military
 The Commercial and Business Operators
 The GA Community
23
Apr-15
OEM vs PMA
The Battle Wages On
 The war between the PMAs and the OEMs is a heated one.
And even though there seems to be revenue enough to go
around today, more contenders and products enter the
market every year, causing everyone to worry about their
own market share. Ironically, there are even some cases of
combatants defecting.
24
Apr-15
Approved technical stores
Approved technical stores comprise of Quarantine and
Bonded stores.
 Quarantine stores
Quarantine Store - Incoming: Provide storage for incoming
material and parts.
Quarantine store – Unserviceable: Provide storage for parts
and material awaiting investigation and dispatch for repair.
 Bonded stores
Bonded store: Provide storage of parts and material that have
been proved authentic.
25
Apr-15
Approved Technical Stores
The approved technical stores will be contained in the user
manual which could be a stand alone document or part of the
GMM/TPPM/MPM / MCM and will address the following:
a ) Quarantine and Bonded stores;
b) Incoming and outgoing inspections;
c) Shelf/storage life;
d) Records control;
e) Parts identification ( markings);
f) Storage of instruments, tools, rubber items etc;
g) Segregation of parts and materials in the bonded store;
h) Storage facility;
i) Special storage.
26
Apr-15
Parts and Material Authenticity Evaluation
 Involves establishing that the parts and material conforms to
approved design specifications, and have retained the essential
properties assumed in the design as qualified by the
supporting documents.
 Information on the supporting documents shall include the
following:
a) The authority under which they are issued;
b) Reference identification for the purposes of traceability;
c) Name, address and approval reference of the issuing
organization;
27
Apr-15
Parts and Material Authenticity Evaluation
d) Work order, contract or invoice number;
e) Quantity, description, part numbers and, if applicable,
serial numbers of the parts;
f) Relevant information concerning any shelf life limitations,
special storage condition requirements, compliance or noncompliance with any airworthiness directives, etc;
g) The signature and approval reference of the person issuing
the document; and
h) Whether the part is new or used.
28
Apr-15
Materials
and
Parts
Management
29
Apr-15
Tags
30
Apr-15
More Details
More information please going through “Aviation
Maintenance Management, chapter 16 Materiel Support” by
Harry A. Kinnison, Ph.D.
or
Any questions please contact samrit.aero@gmail.com
31
Apr-15
32
Apr-15