1. Aviation Maintenance Management
Starting Out

2. Introduction The Flight Line is a business
Approx 1 billion will travel by end of decade
Commerce, mail, defense and logistics by air
20% of every revenue dollar is maintenance
Early days one person knew all systems
Today systems very complex and interdependent
Competing priorities and dwindling resources require expert management

3. Management
Given Task to perform; Resources to make it happen; Time to accomplish Task
Strike harmony in the variables so that the end result is achieved
Align the personnel characteristics with the organization – which is the most regulated industry in the world and you have an extreme challenge

4. Key Elements Flying is the safest mode of transportation
28 million refuse to fly and another 25 % of those that do fly experience apprehensive behavior
After a major air disaster, regulatory changes often take effect
Impacts maintenance practices and flight revenues

5. Managerial Challenges
Schedule pressures, parts shortages, equipment deficiencies, regulatory and agency compliance inspections, union pressures etc..
Technology advancements and diverse equip require perpetual training
Parts issues – no parts, cannibalization, aircraft on ground, weather conditions
Personnel issues – financial, family, substance abuse, late, no-show, vacations, trng, meetings – impact (touch labor)
Unscheduled Maintenance

6. Managerial Challenges
Aircraft out of service impacts –
crew training and readiness
Lost of revenue (no passengers – and maint/labor costs)
Loss of customer loyalty (customer is price based)
Intent of course not to make you an expert maintenance manager but to expose you to the various influences and the functions and techniques of the job
Knowledge is power

7. Aviation Maintenance Management
Early Days of Aviation
Inspections
Early Evolution of Aircraft Maintenance
Post World War II Aircraft Maintenance
Modern Day Aircraft Maintenance
Summary

8. Introduction Safest Mode of travel Aviation in the Beginning
Today’s aircraft cargo holds are longer & sit higher than the Wright Brother’s first flight
Flight – 120 ft in 12 sec with an altitude of 10ft
747 freighter – 150 ft inside & sits16 ft off the deck
Safest Mode of travel
Walking is far more dangerous than flying or driving, per mile traveled:
0.16 deaths per 100,000,000 miles aboard an airplane.
1.4 deaths per 100,000,000 miles in a car.
Almost 50 deaths per 100,000,000 miles walked.

9. Which type of flying is safer?
Type of Flight
Fatalities per million flight hours
Airliner (Scheduled and nonscheduled Part 121)
4.03
Commuter Airline (Scheduled Part 135)
10.74
Commuter Plane (Nonscheduled Part Air taxi on demand)
12.24
General Aviation (Private Part 91)
22.43
Sources: NTSB Accidents and Accident Rates by NTSB Classification

10. Odds of being involved in a fatal accident
Odds of being on an airline flight which results in at least one fatality
Odds of being killed on a single airline flight
Top 25 airlines with the best accident rates  1 in 5.4 million 
Top 25 airlines with the best accident rates  1 in 9.2 million 
Bottom 25 with the worst accident rates  1 in 159,119
Bottom 25 with the worst accident rates  1 in 843,744
Source: OAG Aviation & PlaneCrashInfo.com accident database,

11. Accidents and Fatalities by Phase of Flight

12. Early days of Aviation
“If God had meant for man to fly He would have given us wings.”
Many early pioneers:
Octave Chanute, Otto Lilienthal, Samuel P. Langley, Glenn Curtiss & Orville & Wilbur Wright
Most intriguing problem was finding a power plant that provided the sufficient power-to-weight ratio for flight
Wright Brothers (recognized as first) both engineers & mechanics
Made 4 flights (Dec. 17, 1903,, Kitty Hawk, NC) 4th was 59 sec. for over 852 feet.
Designed own engine, propeller, & aerodynamic tables
First maintainers – when they melted cement to repair nut holding the propeller shaft sprockets in place

13. Inspections No such thing as scheduled maintenance
Spark plug cleaning and occasional oil change
WWI French pilot cut engines to allow him to sweep down and drop bombs
Couldn’t restart because he failed to “burn” the oil off the spark plugs by blipping his ignition switch – forced to land he was captured
The “standard” practice was to land, remove, and clean plugs
Wright Brothers favored simple skid landings over wheeled gear (gain in power-to-weight ratio)
Resulted in structural damage (On Condition)
Never performed preflight or post flight tasks
Simple look to see any hanging or items missing
No inspections of the structural elements (dry rot, cracking, corrosion)
Repair or replace as required
Instrumentation was simple – no inspections

14. Promotion of Flight
First airline in US carried passengers from St. Petersburg to Tampa (Jan – Mar 1914)
Carried only 1 passenger at a time
After WWI, airmail service began – if room, a passenger may sit upon the mail
US Gov’t encouraged operators to use bigger planes & carry more passengers so they wouldn’t have to rely on mail contracts to stay in business
Early days – no navigational aids (only roads, railways), could not fly at night unless bonfires lit along the route
By 1929, 10,000 miles of lighted airways, 275 lighted airports, 1352 navigational beacons

15. Promotion of Flight WWII brought massive surge in production
Monetary prizes for aviation accomplishments
WWI used aircraft as observation platforms
Migrated to pistols, shotguns and rifles with limited success
First machine guns mounted on upper wing of bi-plane
Pilot had to stand to fire and still try to pilot aircraft
Fuselage mounted to fire through propeller – led to prop damage until invention of the interrupter gear
WWII brought massive surge in production
Increased complexity brought potential failure
Inspired preventive maintenance
Material breakthroughs and powerplant advances influenced maintenance programs

16. Promotion of Flight Scheduled Maintenance Programs
Periodic inspections of structure and components and component change-outs
Periodic inspection was preventive
Component change out or Time Change Item (TCI) was to remove item before failure
Unscheduled Maintenance was massive
Operating environment, battle damage and tactics stressed airframe beyond design limits, and accumulated flight hours
Mass production impacted reliability and maintainability
Took 117 days from contract to first flight
No thought for maintainer accessability or inspection
Components went where they could fit

17. Promotion of Flight 1927 – 18,679 flew; 1931 – 385,000 flew
After WWII, US has fostered the jet age
Maintenance Inspection became a discipline
1954, F-86D delivered to Korean theater of war
Required 50-hr Periodic, 25-hr HPO (Hourly Post Flight), and a preflight
By definition - unsafe to fly after 50 flt hrs

18. Promotion of Flight 50-hr periodic inspection:
Items that never failed were checked and rechecked resulting in maintainer induced failures (fasteners on panels); TCI components changed out – with no failures
Resulting in waste of man-hours and dollars
Inspection changed to 100-hr and items for inspection reduced
No balance of aircraft usage to inspection requirements
Assumptions more inspections safer aircraft

19. Promotion of Flight Safety includes redundant systems Also includes:
Failure and damage tolerant designs
Safety for flight loads
Normal and emergency systems
Interconnected electrical systems
Reliability is:
“A measure of the probability that an item will survive to a specified operating age or time, under specified operating conditions, without a failure”

20. Promotion of Flight From periodic inspection to phased inspection
Simply put same amount of items inspected just in increments ¼ now, ¼ next time etc. etc.
Isochronal Inspection based on number of days not flight hours (28 days, 180 day 365 day, etc)
Military provided insight into maintenance preventive maintenance, & inspection concepts
Civilian – “A” check; “B” check; “C” check and “D” check
General Aviation – 100-hr; Time Before Overhaul (TBO), calendar inspections, time-in-service inspection
Key is aircraft require preventive or corrective maintenance at frequent intervals
Kind of operation; environmental conditions; storage facilities avail; age and construct of aircraft

21. Modern Day Aircraft Maintenance
Since deregulation it has become “survival of the fittest”
Cost of ownership – fuel, wash, oil, tires etc…
Scheduled maintenance
Goal is to correct any deficiency before it occurs
Checks cost money – labor and parts, fluids costs and loss of passenger revenue when not flying
Design Manufacturer can help reduce costs
Through before design specification of PBL (Performance Based Logistics)
Total up all Maintenance associated costs subtract from revenue from aircraft and you get profit or loss

22. Design & Role of Manufacturers
Maintenance Man-hours per Flying hour (MMH/FH)
Cost to maintain a particular type of aircraft
We can design perfect systems on paper but we can not build perfect systems in the “real” world
Nothing is perfect

23. Design & Role of Manufacturers
Cost of Ownership and scheduled maintenance are 2/3 of equation
Unscheduled Maintenance – random failures
Reliability studies have led to MTBF (Mean Time Between Failure) – components / system guesstimated reliability factor
Induced failures – FOD, damage from servicing vehicles, maintenance malpractices
Inherent failures – delamination of composites, substandard bearings, inefficient seals etc.
No defect – A-799 or fault within tech data limits (require expenditure of maintenance resources)

24. Design & Role of Manufacturers
Present all data with respect to MMH/FH to manufacturer
Scheduled Maint –
Unscheduled Maint –
Cost of Ownership –
Good, Fast, Cheap
Allocate Unscheduled MMH/FH by system
A design engineer may be limited from making the perfect system by technology or the state of the art within any facet of the design effort
Limited by ability, technique or economics
Economics may force a redesign with reduced tolerances, cheaper materials & gap between:
perfect & “ perfect” realism

25. Role of the Mechanic
For the mechanic the gap between “perfect” & “perfect” realism always changes & predominantly for the worse
Components or systems tend to wear out from use or lack there of (time or environmentally related)
Misuse may cause premature deterioration or degradation of the system or even outright damage
The engineer’s responsibility is to design the system with as high degree of perfection within reasonable limits/constraints
The mechanic’s responsibility is to combat the gap between ideal & realism during the operational lifetime of the equipment

26. Summary
The purpose of aircraft maintenance is to ensure the aircraft will remain airworthy throughout its operational life
Inspections & modifications to aircraft help ensure the programs are getting closer to “perfection” within the inherent limits possible