1

393SYS 393SYS Airport Engineering Airport Engineering

PracticePractice

Lecture 5Lecture 5Engineering & Engineering &

ProductionProduction

2

6.0

Engineering

3

6.0 EngineeringIntroduction

There is an on-going, open discussion in the aviation industry about whether or not an airline needs an engineering

“department”.

At one time, airlines decided what they wanted in terms of aircraft –

- size- range- operating systems

In more recent years, however, the trend has been to leave the design and development of new aircraft to the aircraft manufactures.

The airlines ask only that these manufacturers … “build something we can use effectively and something we can afford.”

4

6.0 Engineering

This situation has led many airlines to actually reduce their engineering staff.

However, there are still good reasons for hiring people with engineering skills and background.

Engineers are usually identified by some speciality – civil, mechanical, electrical, aeronautical, transportation, nuclear, etc.

However, none of these specialisms apply directly to aviation except aeronautical engineering.

What is really needed in a typical airline maintenance organization are people trained as “maintenance engineers”.

This type of engineer would need to know basic engineering as well as the technical details of the equipment used in aviation, and in the maintenance and operation of that equipment.

5

6.0 Engineering

If employed by aircraft manufacturers, these engineers would develop maintenance programs from MSG-3 activity and also produce the various documents identified in last week’s lecture.

However, most colleges and universities do not have courses in maintenance engineering.

Note that the engineering department of an airline can vary widely.

The size of the airline often determines the function provided by the engineering department.

Ideally, an airline engineering department would have both –

engineers with a degree in engineering, and

senior licensed mechanics

6

6.0 Engineering

Mechanics and Engineers

• Mechanics know the details of systems and components on aircraft and are experienced in the rules and regulations of maintenance.

• However, they tend not have had the same analytical training as graduates of engineering.

• Engineering graduates, on the other hand, often lack a detailed understanding of aircraft, aircraft engines, and the multitude of systems and components need in aircraft.

Mechanics

• Mechanics, and technicians study the practical aspects of aviation systems.

7

6.0 Engineering

They specialize in avionics systems –

electrical, electronic, communications, computers

or hydraulic systems –

hydraulics, pneumatics, flight controls and structures.

A mechanic is trained to understand how each system or unit is supposed to work, and how it is supposed to be operated.

When there is a discrepancy, the mechanic follows standard procedures for trouble shooting, fault isolation, and repair.

Procedures for removal, and installation, as well as for testing the installed unit, are all standardized.

An experienced mechanic also knows what kinds of things can go wrong – in operation, installation and in testing.

8

6.0 Engineering

However, no matter how well trained a mechanic may be, and no matter how much experience he or she might have, there are often problems that cannot be resolved with these

standard approaches.

It might then be necessary to “dig deeper” than the standard approaches or else call upon the engineering staff for help.

Engineers

The term engineer is usually reserved for those who have academic degrees in some engineering field.

These people are trained differently than mechanics.

Engineers are trained in the basics of science and engineering.

9

6.0 Engineering

They are also trained in –

- the techniques of inductive and deductive reasoning- statistical analysis- problem solving, and- systems engineering.

They will generally specialize in one particular kind of engineering – electrical, mechanical, aeronautical, structural.

If all the usually effective procedures applied by the mechanic fail, then the engineer must begin by looking at the problem from a new angle.

The engineer must be capable of developing new and innovative procedures for studying and analyzing problems, and must understand the “big picture”.

10

6.0 Engineering

Homework Exercise :

Read through –

Appendix C (trouble shooting techniques), and

Appendix D (problem solving example)One important thing – for all the engineer knows about

engineering, problem solving, and about systems and their interactions, he or she must know about the airplanes, the engines, and their associated systems to effectively apply this knowledge to the solution of real airplane problems.

It therefore takes both disciplines – engineering and maintenance – as well as both types of experts – engineers and mechanics – for a maintenance and engineering organization to run smoothly.

11

6.0 Engineering

Engineering Department Functions

Each model of aircraft has an initial maintenance program developed by an Industry Working Group.

The initial maintenance program is a generalized program and must be tailored to the individual airline operator’s

requirements from the very beginning.

The manufacturer produces the FAA approved MRB report and a maintenance planning document.

It is the responsibility of the engineering department of the airline to package these tasks into workable units based on factors such as –

time, space, personnel, fleet schedules, and overall airline capabilities.

12

6.0 Engineering

Aircraft Maintenance Checks (from http://en.wikipedia.org/wiki/C_Check)

Aircraft maintenance checks are periodic checks that have to be done on all aircraft after a certain amount of time or

usage.

Airlines casually refer to these checks as one of the following: A check, B check, C check, or D check.

A and B checks are lighter checks, while C and D are considered heavier checks.

A Check — This is performed approximately every month.

This check is usually done overnight at an airport gate.

13

6.0 Engineering

The actual occurrence of this check varies by aircraft type, the cycle count (takeoff and landing is considered an aircraft

"cycle"), or the number of hours flown since the last check.

The occurrence can be delayed by the airline if certain predetermined conditions are met.

B Check — This is performed approximately every 3 months.

This check is also usually done overnight at an airport gate. A similar occurrence schedule applies to the B check as to the A check.

C Check — This is performed approximately every 12-18 months.

This maintenance check puts the aircraft out of service and requires plenty of space - usually at a hangar at a maintenance base.

14

6.0 Engineering

The schedule of occurrence has many factors and components as has been described, and thus varies by aircraft category and type.

D Check — This is the heaviest check for the airplane.

This check occurs approximately every 4-5 years.

This is the check that, more or less, takes the entire airplane apart for inspection.

This requires even more space and time than all other checks, and must be performed at a maintenance base.

15

6.0 Engineering

The A and B checks are no problem for airlines because they do not take the aircraft out of service.

Large airlines have a large fleet of aircraft - enough for the airline to schedule people and facilities for regular “C” checks – e.g. one airplane per week or month.

In small airlines, there are not enough airplanes or manpower for the regular scheduling of “C” checks.

To solve this problem, the “C” check is divided into parts, called “phases”, and each phase is conducted separately.

For example, a C check could be divided into four phases – C1, C2, C3 and C4 – each one carried out every 3 months

until the entire C check is performed.

16

6.0 Engineering

Alternatively, a C check could be divided into 12 packages with one package completed every month together with the A check.

In both cases, the manpower utilization is more constant throughout the year.

The airline “engineering department” is responsible for selecting the tasks to be done, for packaging the tasks into workable packages, and for ensuring that all task time limits are met.

The “Production, Planning and Control department” is then responsible for scheduling the checks.

The tasks to be performed by the maintenance unit of the airline at any of these checks can be quite detailed.

To endure that they are carried out correctly, tasks cards are issued to the mechanics.

17

6.0 Engineering

Evaluation of New Aircraft for the Airline Fleet

One of the primary functions of an airline engineering department is to evaluate new equipment for the airline.

A typical question here is – “What airplane/engine combination should we buy ?”

The answer to this question will be influenced by –

the routes to be flown and the destination cities

the expected market share

the cost of the equipment

Another important question, however, is “What is the best equipment to buy from the standpoint of maintenance and engineering ?”

18

6.0 Engineering

There exists a trade-off here between technical priorities and business priorities. The following example focuses only on

technical priorities from a maintenance point of view :

Example :

Boeing 767 or Airbus A330 ?

There are a number of questions to be answered in regard to maintenance :

1. Engines

What engines are available for these models ?

Are they the same or similar to engines in the airline’s current fleet ?

Note that is question is important because there may be a need for additional maintenance and test facilities for these new engines.

19

6.0 Engineering

2. Aircraft Range

What is the range of these airplanes ?

Will the airline need to position their own personnel at outstations or arrange for contract personnel at the site to support maintenance.

Can existing outstation personnel handle these new airplanes ?

Can they do so with or without additional training ?

3. New Technologies

What new technology is included in these new models ?

Are the skills of the current maintenance and engineering staff sufficient to maintain these new airplanes or will they require additional training ?

20

6.0 Engineering

4. Maintenance Check Schedules

Will the maintenance check schedules for the new aircraft be compatible with the current schedules for the existing fleet ?

5. Ground Support

Will additional ground support equipment (GSE) be needed for these new aircraft ?

If so, what equipment ?

6. Hangers

Will the existing hangers be suitable for these airplanes ?

Will they need to be modified or will a new hanger be required ?

21

6.0 Engineering

7. Aircraft Parts

What new aircraft parts, and storage for parts, will be required at both the home base and the outstations to support the new airplanes ?

Could this involve a considerable amount of financial investment for parts not common to the existing fleet ?

8. Industry Experience

What is the industry experience on these new aircraft relative to maintenance ? i.e. – parts availability ? parts delivery ? failure rates ? removal rates ? amount of maintenance required ?

22

Engineering

Question

What new aircraft would probably require the most changes in M&E support ?

23

6.0 Engineering

Evaluation of Used Aircraft for the Airline Fleet

If the airline is considering leasing used aircraft, then other items must be considered.

These items would include information on –

the engine type

the maintenance program and check schedule the status of any modifications to the aircraft e.g. AD & SB

Questions to be asked would include –

Are the above the same as, similar to, or different from your airline’s equipment ?

How will this affect training, maintenance support, etc. ?

24

6.0 Engineering

What modification and configuration standards must be met by the operator or by the lessor ?

What configuration should the airplane be in at the termination of the lease ?

Example

An aircraft in ETOPS* configuration is leased to an airline. The airline did not need the ETOPS capability and did not keep up with the newer ETOPS modifications. When the aircraft was returned at the end of the lease, the airline discovered that they were responsible for returning the airplane to ETOPS configuration at their own expense. Note that the condition of the aircraft at termination of the lease should be clearly stated and understood.

*ETOPS – Extended Range Operations with Two-Engine Airplane (e.g. Boeing 777 ER)

25

6.0 Engineering

Other functions of an airline engineering department include –

Evaluation of the need for new equipment in support of aircraft added to the fleet.

The requirements for new facilities such as hangars, engine test facilities, component shops, and storage facilities.

The issuing of engineering orders (EOs) :

Any work performed by maintenance in the form of standard checks – A, B, C checks – is perfumed on “standing orders” from the airline Vice President of M&E, as identified in the maintenance section of the Ops Spec.

Any work not included in these standard checks must be assigned by an “engineering order”.

26

7.0 Production Planning and Control

Introduction

The “Production Planning and Control” (PP&C) activity within an airline is one of the key organizations within M&E.

It is actually the “heart” of the maintenance organization.

The title implies two functions – planning and control.

Actually, PP&C has three primary functions – forecasting, planning, and control.

Forecasting includes the estimated maintenance workload for the long term and short term based on the existing fleet and business plans, and on any known changes in these for the

forecast period.

27

7.0 Production Planning and Control

Planning involves the scheduling of upcoming maintenance and includes the planning and scheduling of all manpower,

parts, facilities, and time frame requirements.

Control allows adjustment of the plan and keeps (or attempts to keep) the check on schedule.

There are several methods of adjusting the plan, including –

deferral of maintenance to a later check,

addition of personnel to complete the work,

outsourcing the work to a contractor

Feedback from a check allows PP&C to adjust the planning effort for future checks.

28

7.0 Production Planning and Control

Without planning, action would be impulsive and produce unpredictable results.

The diagram below illustrates how work in expended on a typical project with and without proper planning :

WO

RK

LO

AD

TIME

Planning Performance

Start Planning

Start Check

End Check

Planned Check

Unplanned Check

29

7.0 Production Planning and Control

The preliminary planning consists of the development of a maintenance program and its schedule.

With proper planning, once the check has begun, the work progresses smoothly (dashed yellow line).

Without preliminary planning, the effort swells as the work progresses, mostly due to unexpected events and delays (solid red line).

30

7.0 Production Planning and Control

Example for “C” Check

Normally, a C check requires about 4 or 5 days.

A new airline operator started to consult the maintenance manual for the C check one week before the check was due.

Without adequate preplanning, the C check took 4 weeks to perform !

The goals of PP&C are -

to maximize the M&E contribution to the airline

to plan and organize work prior to execution

to adjust plans and schedules to meet changing requirements

31

7.0 Production Planning and Control

Production Planning

The goal of M&E is to deliver airworthy vehicles to the flight department in time to meet the flight schedule, with all

maintenance activities completed or properly deferred.

The airline engineering department will have developed the maintenance plan from the MRB (Maintenance Review Board report) or Ops Specs document and divided the work into

appropriate work packages indentifying –

the tasks to be done

the intervals at which they will be done, and

the manpower requirements for each task.

The check package schedule for a typical mid-sized airline is shown in the following table …

32

7.0 Production Planning and Control

From “Aviation Maintenance Management”, H.A.Kinniston, McGraw-Hill 2004.

FH = Flight Hours, HMV = Heavy Maintenance Visit

33

7.0 Production Planning and Control

PP&C must now take this engineering package and then plan, schedule and adjust the work for each check and for each aircraft.

The estimated man hours for the various checks and aircraft for the same mid-sized airline are as follows :

From “Aviation Maintenance Management”, H.A.Kinniston, McGraw-Hill 2004.

34

7.0 Production Planning and Control

Daily, 48-hour and transit checks are usually standardized and require little or no effort on the part of PP&C other than

scheduling.

All “A” checks and higher are planned, scheduled, and coordinated by PP&C and their content varies from check to check.

These activities are more involved than the daily, 48-hour and transit checks, so the panning is started well in advance of the actual check.

For “A” checks, planning begins 1 to 2 weeks prior to the scheduled check.

For “C” checks, planning begins about 4 weeks in advance.

35

7.0 Production Planning and ControlMaintenance Tasks for “Less-than-A-Check” Intervals

Certain items in the MRB report must be checked daily, bi-weekly, and weekly.

The scheduling is the responsibility of PP&C.

These checks can be scheduled overnight, or at certain turn-around times, or may be included in the “A” checks.

This is up to the airline and is usually determined by local conditions and man-power availability.

Airlines can experience problems if they defer these tasks day after day due to heavy work loads.

The deadline for completion gets nearer and nearer and, finally, the airline has to take the aircraft out of service for several hours to get the work done without exceeding FAA time limits. These delays can be costly.

36

7.0 Production Planning and ControlMultiple Checks

Some MRB items are done at intervals like every other; every third check. This is true for A & C checks. That means that different “A” check have different task set and require different amount of time depending on where that “A” check is in the maintenance cycle.

The following table shows a typical aircraft “A” check and “C” check schedule :

From “Aviation Maintenance Management”, H.A.Kinniston, McGraw-Hill 2004.

37

7.0 Production Planning and ControlEvery “C” check includes all the “A” check items.

The “C” check items can also be scheduled for longer intervals.

A chart similar to the one on the previous slide can be drawn for multiple “C” checks.

Phased Checks

These are different from multiple checks.

An “A” check may be split into two phases, each one performed on successive nights to minimize maintenance crew needs and down time.

The right side of an aircraft might be done on the first phase (called an “A1” check and the left side on the second phase (the “A2” check).

38

7.0 Production, Planning and ControlA “C” check may be broken down into four parts (C1, C2, C3,

and C4) and performed every 3 months or so depending on the full “C” check cycle.

The “C” check can also be divided into 12 parts, with one part being completed each month (C1, C2, … C12).

The table on the following slide shows a typical airline estimate for the man-hours planned for a “C: check on the Airbus A300B4.

The check will consist of three categories of task – routine, variable routine, and non-routine.

Routine tasks are identified in the MRB report document.

Variable routine tasks vary from one check to another and from one aircraft to another.

Nonroutine tasks are generated by the accomplishment of other, routine tasks.

39

7.0 Production Planning and Control

From “Aviation Maintenance Management”, H.A.Kinniston, McGraw-Hill 2004.

40

Summary

Engineering

Introduction

Mechanics and Engineers

Engineering Department Functions

Aircraft Maintenance Checks

Evaluation of New and Used Aircraft for the Airline Fleet

Production Planning and Control

Introduction

Production Planning

Maintenance Tasks for “Less-than-A-Check” Intervals

Multiple Checks

Phased Checks

Summary

41

What you need to know for the exam ! Why do all airlines require a maintenance department, regardless of whether or

not they actually do the maintenance themselves ?

Explain the difference between mechanics and engineers in terms of their role in aircraft maintenance.

What is the MRB report, who is responsible for producing it and what are airlines required to do with it ?

Explain, briefly, what is meant be aircraft A, B, C and D checks.

What approach is adopted by small airlines in conducting “C” checks ?

What issues need to be addressed in evaluating new (used) aircraft for an airline fleet ?

Explain, briefly, the function of Production Planning and Control department within an airline ?

What is the relationship between Engineering and PP&C in an airline ?

Explain the purpose of Production Planning.

Explain “Multiple Checks” and “Phased Checks” and also the difference between the two.