Aging and Sustainment Issues With the General Aviation Fleet

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Aging and Sustainment Issues With the General
Aviation Fleet
Beth Gamble Cessna Aircraft Company
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Today over 192,000 Cessna airplanes are flying in
nearly every country of the world
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High Usage Airplanes
High Time Caravan 30,000 Hours
50,000 Landings
High Time 404 Titan 37,000 Hours 61,000
Landings High Time 402 - 34,000 Hours M402C
Fleet - Many over 20,000 hours
High Time Citation 28,000 Hours
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Aging and Sustainment Issues

• Airframe Modifications
• Type Design Requirements
• Regulatory Requirements
• Education
• Summary

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Model 336/337
Model 336 1962
Certified to CAR 3 Requirements
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Model 336/337
Strut Attachment
Outboard
Crack Locations
Wing Forward Spar Cap
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Model 336/337
Model 337 1964
Certified to CAR 3 Requirements
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Model 336/337
Fuel Tank Access Panel
Skin Panel Cracks
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Type Design Requirements

• Most general aviation airplanes are certified per
  CAR 3 requirements
• CAR 3 Criteria
• CAR 3.20(a) Airplane Categories
• Normal Suffix N - Airplanes in this category are
  intended for nonacrobatic, nonscheduled passenger
  and nonscheduled cargo operation
• CAR 3.307 Fatigue Strength
• The structure shall be designed, insofar as
  practical, to avoid points of stress
  concentration where variable stresses above the
  fatigue limit are likely to occur in normal
  service.
• Airframe designed and certified based on static
  strength
• Actual airplane usage may differ from original
  design intent
• Airplanes may be used in severe flight regimes
• Island hopping (15-20 minute flights)
• Pipeline patrol or ground survey (low altitude)

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Type Design Requirements

• FAR 23 requirements for fatigue evaluation added
  over time
• 23.571 Fuselage (1965)
• 23.572 Wing (1969)
• 23.572 Empennage (1987)
• Many airplanes certified in late 1960s and 1970s
  were grandfathered to CAR 3 requirements

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Type Design Requirements

• Today
• Average age of general aviation fleet is 40
  years
• Majority of airframes are aluminum
• PSE components made from 7075-T6, 2014-T6 and
  other materials which are no longer used in new
  design
• Many older airplanes were not primed at the
  factory
• Airplanes used in corrosive environments (regions
  of South America, Africa, Australia, etc.)

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Regulatory Requirements

• Cessnas continued airworthiness program
  (Supplemental Inspection Document or SID) is
  contained in airplane maintenance manual
• SID compliance varies by country
• Australia
• In January 2003 CASA required compliance with
  Cessna SID documents
• Europe
• EASA has required a continued airworthiness
  program since September 1, 2008
• Cessna SID meets EASA requirement
• Several South American and African countries
  require compliance with the SID

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Regulatory Requirements

• SID compliance varies by country
• United States
• Compliance with SID depends..
• Engine (turbine or piston)
• Operation (Part 91 or Part 135)
• Defined maintenance program at time SID was
  introduced
• Continued airworthiness requirements for
  airplanes without a defined program

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Regulatory Requirements - Example

• Continued airworthiness requirements differ by
  country
• Model 208 Chapter 4
• Limit of Validity added to Chapter 4 for EASA
• For EASA certified airplanes, the Airworthiness
  Limitations section is applicable to airplanes
  with less than 50,000 flight hours
• SID requirements added to Chapter 4 for Ukraine
  registered airplanes
• For airplanes registered in the Ukraine, the
  supplemental inspections defined by the Listing
  of Supplemental Inspections (5-14-00) are
  mandatory.

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Education

• Educate owners, operators and mechanics on
  physics fundamentals
• Metal fatigue
• NDI methods and limitations
• Corrosion
• Educational Opportunities
• Inspection Authorization (IA) Renewal Seminars
• Government sponsored discussions/seminars
• Newsletters
• Type clubs
• Report findings
• Example

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Summary

• Cessnas philosophy is to do what is right for
  customer safety, including going beyond the
  regulatory requirements
• Updates to continued airworthiness programs are
  on-going
• Continued cooperation between OEMs, regulators
  and operators/maintainers is required to assure
  operational safety of the fleet

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Questions