AGEING AIRCRAFT MANAGEMENT PLAN STAGE 2 INDUSTRY FEEDBACK & AWARENESS

Transcription

1 AGEING AIRCRAFT MANAGEMENT PLAN STAGE 2 INDUSTRY FEEDBACK & AWARENESS

2 Mike Higgins Manager Continuing Airworthiness Take a closer look..

3 CASA Definition of Ageing Aircraft All aircraft are ageing from the day of manufacture (even earlier for sub-components) However, the rate at which an individual aircraft ages depends on a range of factors specific to that particular aircraft

4 We do have an Ageing Aircraft Problem Outside looks OK

5 Take a closer look inside

6 and

7 Log Book stated corrosion removed and treated

8 ...but Take a closer look

9 Breakdown of AAMP Stage 1 Articulate the scope of the Ageing Aircraft issue in Australia and recommend strategies to allow ageing aircraft to continue to operate safely Stage 2 Phased implementation of key strategies Stage 3 Ongoing annual review of Stage 2 strategies

10 AAMP Stage 1 Broad Findings 1. Australia has an ageing aircraft problem 2. Ageing aircraft here to stay 3. Main concerns under 5,700kg (GA) 4. No One size fits all solution 5. Minimal availability of ageing aircraft data 6. Minimal industry awareness of the science of ageing

11 1. Australia has an Ageing Aircraft Problem Average age of registered piston engine fleet approx 40 years and rising State of the fleet (approx 14,000 aircraft) Potentially 8,700 aircraft of concern State of AOC fleet (approx 1,800 aircraft) Potentially 700 aircraft of concern

12 2. Ageing Aircraft here to Stay Replacement rate of GA aircraft relatively low Many ownership/ business models revolve around use of older aircraft Older aircraft require additional types of maintenance - which is not necessarily occurring

13 3. Main Concerns under 5,700kg Average age of higher capacity RPT aircraft significantly less than that of GA fleets Higher capacity RPT aircraft tend to have: Manufacturer s support programs that address ageing issues Comprehensive Systems of Maintenance Higher manpower resources Many GA aircraft types have none of the above

14 4. No One Size Fits All Solution Every aircraft ages from the day it leaves the factory Blanket legislation to address chronological age factor alone is not justified e.g. taxis However, the rate at which it ages depends on many independent factors: Flying hours, cycles Type of operations Chronological age Standard of maintenance Certification basis Hangarage, cleaning, sea salt etc.

15 5. Minimal Availability of Aircraft Ageing Data The ability to access individual aircraft data which is necessary to determine the likelihood of ageing issues is limited Prototype Matrix Tool to be developed for aircraft operators Remember what your responsibilities are as the owner of an (ageing) aircraft

16 5. Matrix Tool cont.

17 6. Minimal Industry Awareness of the Science of Ageing AAMP Stage 1 consultation with industry personnel revealed minimal awareness of ageing concepts i.e. fatigue, corrosion, wiring degradation etc. Owner awareness of the science of ageing is key to the success of any Stage 2 strategy implementation.

18 Ageing Composites

19 Ageing composites What should I be looking for as an operator? Damage using techniques specified in the Manufacturer s Maintenance Manual

20 Ageing composites Are ageing issues included in my maintenance package? It depends - ask your respective manufacturer i.e. Which places to look? What time intervals to inspect? What inspection techniques to use? Who can inspect my aircraft for ageing issues? Any maintenance organisation approved by the manufacturer

21 Composites continued What if I find damage not covered by the Manufacturer s Maintenance Manual? VH Registered submit SDR Advise manufacturer Who can I go to for further info? Manufacturer in the first instance CASA if VH registered

22 Introducing Dr Bob Holdsworth Ageing Aircraft 101

23 CASA Ageing Aircraft Management Plan Ageing 101 Awareness Seminar

24 An Owner s Perspective The real questions for you are: What do I have to do? When do I have to do it by? How much it will cost? Who can I go to for help or further information and assistance? 24

25 The Menu At completion of the Ageing 101 awareness seminar, each participant will have some knowledge of: the definition of an ageing aircraft the common manifested effects of ageing i.e. fatigue, corrosion, wiring degradation, increased wear/deterioration rates, reduced aerodynamic and system performance, etc the potential consequences of such ageing effects i.e. catastrophic failures, in-flight emergencies, repair costs, foregone revenue, etc the common causes of or contributors to such ageing effects the likely locations of occurrence of such ageing effects the warning signs of existence of such ageing effects methods of detecting such ageing effects i.e. systems, processes, procedures, tools, techniques, education and training, shared information, etc methods of preventing and/or mitigating the impact of such ageing effects i.e. systems, processes, procedures, tools, techniques, education and training, shared information, etc where to find more information on the ageing aircraft phenomenon 25

26 AAMP Stage 1 Summary What We Know, Have Addressed, but Don't Do Well 8 recommendations What We Don't Know We Don't Know 1 recommendation What We Know, Have Addressed And Do Well 3 recommendations What We Know We Don't Know, But Have Not Yet Addressed 16 recommendations

27 Life Discussion Notional Life How long did the design engineer expect it to last? What were the design assumptions? Fatigue Life What was the load spectrum? Has it changed? Corrosion Life Where is it hangared? Exposure Life How long do non-lifed items last in air? On-Condition - is it inspectable? 27

28 Life Discussion Document Life Is it still appropriate today? Was the document meant to be read with a certain level of inherent knowledge? Do the current maintainers have that knowledge? Airworthiness System Life Has the airworthiness system changed? Has the maintenance, engineering, technology, etc changed? Economic Life What does this mean? 28

29 Extending the Bathtub Curve F Burn-in Constant Failure Rate Phase Wear-out a Phase Phase i l u r e R a t e Time in Service Figure: The Bathtub Curve

30 Why? Again, why do I have to do anything differently, when my aircraft seems to be perfectly good now according to the Manufacturer s manual? 30

31 Why? Regulations Registered Operator must prove airworthiness, not by omission Remember CASA s perspective Finite Life Recall discussion on finite life of data/understanding We ve seen aircraft that are not safe, even though they are operated/maintained in accordance with Manufacturers manuals Business Imperatives Profit, given business decision to keep old aircraft Reduce costs Increase revenue/utility Increased on-line availability Need an airworthy aircraft to operate and produce revenue safely Reputation/business risk 31

32 Colin s Equation of Life SALES COSTS = PROFIT Less Unscheduled Maintenance + Less Repair COSTS = More Flying Availability Unlike classic maintenance, AAMP delivers on both fronts!! 32

33 Aircraft Accident Causal Factors ACCIDENT FAILURES AIRFRAME ENGINES FUNCTIONAL Landing Gear X Engine X Fuselage X Wings X Hydraulic Power X Structures X Equipment X Pylons X Fuel System X Doors X Stabiliser X Engine Exhaust X Navigation X Electrical Power X Auto Flight X Air Conditioning X Canopy X 28% 18% 54% 33

34 Is it Safe? Where are the missing parts now?

35 Corrosion Corrosion rate Time Generally Corrosion rate naturally slows with time

36 Cost of Corrosion This is actual data The better prepared, the longer they last and the cheaper to operate in the longer term

37 Corrosion Types Corrosion is commonly classified based on the appearance of the corroded material The classifications used vary slightly from reference to reference but there is generally considered to be several different forms of corrosion.

38 Corrosion Types Uniform or general corrosion that is distributed more or less uniformly over a surface. Localized corrosion that is confined to small area. Localized corrosion often occurs due to a concentrated cell. A concentrated cell is an electrolytic cell in which the electromotive force is caused by a concentration of some components in the electrolyte. This difference leads to the formation of distinct anode and cathode regions. Pitting corrosion that is confined to small areas and take the form of cavities on a surface. Crevice corrosion occurring at locations where easy access to the bulk environment is prevented, such as the mating surfaces of two components. Filiform Corrosion that occurs under some coatings in the form of randomly distributed threadlike filaments. 38

39 Corrosion Types Intergranular preferential corrosion at or along the grain boundaries of a metal. Exfoliation a specific form of corrosion that travels along grain boundaries parallel to the surface of the part causing lifting and flaking at the surface. The corrosion products expand between the uncorroded layers of metal to produce a look that resembles pages of a book. Exfoliation corrosion is associated with sheet, plate and extruded products and usually initiates at unpainted or unsealed edges or holes of susceptible metals. Galvanic corrosion associated primarily with the electrical coupling of materials with significantly different electrochemical potentials. Erosion corrosion a corrosion reaction accelerated by the relative movement of a corrosive fluid and a metal surface. Fretting corrosion damage at the interface of two contacting surfaces under load but capable of some relative motion. The damage is accelerated by movement at the interface that mechanically abraded the surface and exposes fresh material to corrosive attack.

40 Corrosion Types Environmental Cracking brittle fracture of a normally ductile material that occurs partially due to the corrosive effect of an environment. Corrosion fatigue fatigue cracking that is characterized by uncharacteristically short initiation time and/or growth rate due to the damage of corrosion or buildup of corrosion products. High temperature hydrogen attack the loss of strength and ductility of steel due to a high temperature reaction of absorbed hydrogen with carbides. The result of the reaction is decarburization and internal fissuring. Hydrogen Embrittlement the loss of ductility of a metal resulting from absorption of hydrogen. Liquid metal cracking cracking caused by contact with a liquid metal. Stress corrosion cracking of a metal due to the combined action of corrosion and a residual or applied tensile stress. Dealloying the selective corrosion of one or more components of a solid solution alloy. Dezincification corrosion resulting in the selective removal of zinc from copper-zinc alloys.

41 Corrosion Pitting Corrosion Pits Spar cap

42 Exfoliation Corrosion Floor beam

43 Filiform Corrosion

44 Crevice Corrosion Fuselage skin beneath antenna

45 Galvanic Corrosion Non-passivated stainless steel screw and aluminium sheet

46 Uniform Corrosion Corrosion of cadmium on fastener

47 Mum goes in this Not covered by Manufacturer s Maintenance Schedule Found by accident

48 Looky Here Corrosion inside rudder, indicator = 1 missing rivet

49 Fatigue - Cracks Growth rate Time Cracks take a while to initiate but move quickly Tests are done on a factory part

50 Cracking Aircraft fuselage structure is a good example of structure that is based largely on a slow crack growth rate design. Many years ago, the USAF reviewed a great number of malfunction reports from a variety of aircraft. The reports showed that the preponderance of structural failures occurred from 1) built-in preload stresses, 2) material flaws and 3) flaw caused by inservice usage. These facts led to a design approach that required the damage tolerance analysis to assume a material flaw exists in the worst orientation and at the most undesirable location. The analysis helps to ensure that structures are designed that will support slow stable crack growth until the crack reaches a length where it can reliably be detected using NDT methods.

51 Fatigue Cracks Crack started by corrosion on other side

52 Stress Corrosion Cracking

53 Cracking Cracks from fastener holes Note before and after

54 Finding Cracks May be difficult May not be guaranteed May be expensive

55 Wiring Who does this? USE OLD WIRE MIX WIRE TYPES NOT USE CLAMPS How many times can you depend on the operation of a relay or switch?

56 Wiring Considerations Categorization Grounding Shielding Replace wire Replace connectors What is the failure mode? Reduce cost Increase safety Design out problems Trade-off weight

57 Finding Problems PROGRAM ELEMENTS - System Monitoring Boeing Australia Look using a different spectrum Not as expensive as you might think 57

58 Hidden Treasures But it s a Manufacturer s sealed cable with no specified inspection!

59 The Passage of time, Certain Death Not able to be inspected Not lifed On-condition

60 Ageing Wiring TWA 800 was another one, 17 July 1996 This was a Boeing 747, 25 years old All 230 people were lost Ageing wiring caused a fuel tank explosion.

61 More Ageing Wiring Some GA examples

62 Finding the Unknowns Those issues lurking just beneath the surface waiting to happen, or those things that could potentially happen, given the right set of circumstances Identify and investigate unseen components or areas of structure Review on condition components is this still the most appropriate maintenance policy? What does on-condition actually mean? Design deficiencies can strike at any time in an aircraft s life day one, ten years, or maybe never... 62

63 Infrared Other applications May show up issues not addressed by the Manufacturer s Maintenance Schedule Where are the leaks?

64 On condition item Boeing Australia Difficult to access How do you know they are still serviceable? - Boroscope? - x-rays, MRI?

65 Ageing Effects May be cumulative over time Beyond scope of designer s original expected life Why Supplemental Inspection Documents (SIDs) exist (for some aircraft) Potential need for enhanced maintenance schedules (accumulation of unknowns) 65

66 Consequences Linked back to Profit via reduced costs or increased revenue or both Failures, possibly catastrophic Decreased availability may mean loss of revenue Increased maintenance costs Increased operating costs Need for upgrades Spares harder to source increased costs Increased fuel consumption increased costs Swiss Cheese model 66

67 Definition of Ageing Aircraft Logical conclusion is that an aircraft is ageing from day dot Every aircraft is an ageing aircraft Every part of the aircraft is ageing Every aircraft ages at a different rate Every aircraft requires different management strategies to maintain airworthiness and cost-effectiveness 67

68 What do I do? Take a closer look! Tools/techniques Think beyond existing documentation What We Know, Have Addressed, but Don't Do Well What We Know, Have Addressed And Do Well What We Don't Know We Don't Know What We Know We Don't Know, But Have Not Yet Addressed Systematic review to validate Airworthiness Review documentation Get into the red zone of the Venn diagram look for the unknowns

69 What? Preventive maintenance Replace Upgrade Alter environment Corrosion Prevention Control Programs Storage Dehumidify Etc.

70 Who do I talk to? LAMEs Engineers (CAR35 and/or 42) Type Clubs Manufacturers Type Certificate Holders Non Destructive Testing (NDT) Specialists

71 What Next? Familiarise yourself with your System of Maintenance System of Maintenance? Manufacturer s Maintenance Program? CASA Maintenance Schedule 5? Continue with your own education Read journals and magazines eg Flight Safety Australia Visit websites eg CASA, FAA Discuss ageing issues with experts Contribute to CASA s Ageing Aircraft Management Plan Discussion Paper Notice of Proposed Rule Making

72 Revisiting Your Business/Ownership Plan Consider If your aircraft: Is really old, or has flown significant hours Is operated and/or hangared in a corrosive environment Has accumulated many take-offs and landings Is not supported by an adequate manufacturers continuing airworthiness program, or is on Schedule 5 72

73 Revisiting Your Business/Ownership Plan Then you will need to do something Consult with the manufacturer or industry to develop a continuing airworthiness program for your aircraft or Change aircraft operating category or Retire the aircraft.because remember, the onus is on YOU to prove that your ageing aircraft is airworthy. 73

74 The end

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76 CASA s Role Civil Aviation Act 1988, Part II, Section 9, 1(c), (d), (f) & (g) Raise the awareness of aircraft owners and industry of ageing aircraft issues Legislate in the public interest so that ageing aircraft can continue to operate safely

77 Owner s Role The Registered Operator is responsible for airworthiness & maintenance of their aircraft: Regulation 39 (1) Class A Aircraft Regulation 41 (1) Class B Aircraft Advisory Circular 47-01(3) Registration of Aircraft and Related Matters Paragraph 9.3.2

78 Bottom Line Many existing Systems of Maintenance (SoM) may not necessarily ensure the continuing airworthiness of older GA aircraft including: CASA Maintenance Schedule 5 Some operator s SoMs Some manufacturer s SoMs SIPs, SIDs, SIRM etc.

79 What Happens Next? CASA intends to develop and publish a Discussion Paper (DP) seeking industry input on proposed directions on ageing aircraft issues. Opportunity for everyone in industry to comment and contribute CASA must consider all views expressed and points raised

80 Then After the DP..? CASA may then develop and publish a Notice of Proposed Rule Making (NPRM): Further opportunity for industry to comment and contribute on proposed options Potential to implement specific strategies that have been refined as a result of the DP

81 And Then? Following any DP and possible NPRM consultation process, legislation may be made to give effect to the roll out of enhanced maintenance strategies, specifically targeted at ageing aircraft issues

82 In Conclusion CASA supports continued operation of ageing aircraft provided it can be done safely Aircraft owners cannot continue to operate the existing fleet of ageing aircraft, in the current manner, and expect the inherent risks to remain at an acceptable level indefinitely

83 Important question Ask your LAME what parts of your aircraft they may not be inspecting?

84 Take a closer look

85 Further Contact Pieter van Dijk Wendy McIntosh

86 More Examples Cessna Structural Inspection Documents (SIDs) Aircraft had undergone SIDs Aircraft had a valid Maintenance Release when entered workshop And this is what they found

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99 With Special Thanks to.. Michael Kelly - Proprietor Flinders Aviation Redcliffe QLD

100 The End