Post on 16-Mar-2020
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Textron Aviation Safety Initiative January 21, 2017
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Textron Aviation is the company formed from
Cessna and Beechcraft in March 2014 – together
250,000+ airplanes have been delivered
Cessna 172 Skyhawk Beech Bonanza Cessna 208 Caravan
Cessna O-2 Skymaster
Beechcraft T-6A Texan II Cessna Latitude Hawker 4000
Beechcraft 1900D Cessna O-2 Skymaster
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Textron Aviation Piston Engine Airplanes
• 205,000+ produced since 1946
• Of which 190,000 produced before 1987
• Average age is 43 years old
• Certified CAR 3
• Made of Aluminum
• Single Engine Airplanes flown 100-150 hours annually
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2015 Piston Engine Usage - Active US Aircraft Total of 141,141 Airplanes Representing All Manufacturers
Over sixty-five percent of active piston engine airplanes are Cessna or Beechcraft
Textron Aviation Piston Engine Airplanes
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• Between 2000-2011 Cessna Aircraft developed new structural inspection programs to assure the continued safe operation of piston engine airplanes
• For single engine airplanes, visual inspection techniques are utilized to detect – Corrosion – Cracks caused by metal fatigue
• New structural inspection programs for Beechcraft airplanes are in work
Textron Aviation Safety Initiative
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• Why Inspect?
– Corrosion (rust) and metal fatigue are inevitable
– Corrosion and metal fatigue reduce the load carrying capability of the airframe – Like people, airplanes age, and more frequent and intrusive inspections are
required to maintain health (safety)
Textron Aviation Safety Initiative
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• Cessna SID Implementation in New Zealand – Mandatory compliance
– 90 to 95% of inspected airplanes required maintenance action – 20% of those which required action needed major repair – 80% of the findings were corrosion and 20% cracking
– Most common cracking area is around front and rear door posts – Another common area of cracking is at lower strut fuselage attachments
Textron Aviation Safety Initiative
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• The key to corrosion prevention is to keep the airframe free of moisture
• A major contributing factor to corrosion is the environment – Aircraft that operate in coastal environments are more susceptible to metal
corrosion – While water vapor already has a corrosive effect, the water vapor and salt
combination found in coastal environments creates a powerful corrosive agent
– Aircraft that operate in areas that contain high amounts of industrial particles and fumes in the atmosphere also are more susceptible to corrosion
– Aircraft that operate in areas where “environmentally friendly” runway deicers are used (i.e., potassium formate, potassium acetate, etc.) are more susceptible to corrosion
Corrosion Prevention
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Corrosion Severity Map
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• There are several common options available to shield the aluminum from electrolytes including:
– Cladding – 2024 sheet can be coated ("clad") with very thin layers (.001”) of pure
aluminum to protect from corrosion, known as 2024-T3 AlClad – The sheet material is vulnerable when the cladding is compromised at
edges, drilled rivet holes, or if it is scratched – Most airframe corrosion occurs at seams and joints, which is why cladding
alone is not sufficient – Additional steps are necessary to protect seams, holes, and un-clad parts
from exposure to electrolytes
Corrosion Prevention
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• There are several common options available to shield the aluminum from electrolytes including:
– Chemical Treatments – Alodine or other chemical treatments are used to enhance the corrosion
resistance of the pure aluminum cladding
Corrosion Prevention
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• There are several common options available to shield the aluminum from electrolytes including:
– Sealants – Paint is the most commonly used sealant for corrosion protection and is the
best defense against airframe corrosion – Modern polyurethane aircraft paints create a thick, impenetrable barrier
that effectively keeps moisture away from the metal, and lasts a long time - - 10 years or more
– Paint only protects the exterior of the airframe – Cessna airframe interiors of most pre-1986 airframes were not
painted (primed) – Many Beech airframe interiors were only partially painted (primed)
Corrosion Prevention
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• There are several common options available to shield the aluminum from electrolytes including:
– Corrosion Preventative Compounds (CPCs) – Effective means for protecting those parts of an airframe that were not
originally protected from corrosion – Guidelines for application and use of CPCs are provided in the revised
Service Manual – CPCs must be reapplied periodically
– The following CPCs are recommended for use on Textron Aviation airplanes
Dry film compounds: ARDROX AV-8* and AV-15 Cor-Ban 23* and Cor-Ban 35
Non-dry grease: Cor-Ban 27L
Non-dry oil: Corrosion X
* Preferred where high penetration of corrosion inhibiting compound is required.
Corrosion Prevention
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• As airplanes continue to age, these numbers are likely to increase
• Corrosion is responsible for approximately: – 7% of the airworthiness directives 1
– 20% of service difficulty reports (SDRs)
• Corrosion can be deadly – Corrosion contributed to 91 accidents/incidents in the United States between
1983 and 1994 2
– These and other accidents have resulted in hundreds of fatalities 3
1 Swift, S., “Rusty Diamond”, 24th ICAF Symposium, May 2007.
2 Hoeppner D,, Chandrasekaran V., Taylor A., “Review of Pitting Corrosion Fatigue Models”, 20th ICAF Symposium, 1999.
3 Aviation Safety Network Database, http://aviation-safety.net/index.php
Corrosion Results
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• Corrosion and metal fatigue both reduce the load carrying capability of the airframe
• Corrosion and fatigue are not entirely independent processes - corrosion affects the expected fatigue life of airframe parts
– Corrosion pitting creates a stress concentration which leads to crack initiation and potentially faster crack
– Corrosion reduces the thickness of a part and therefore increases the stress in the part
View of Spar Cap Fracture Surface View of Spar Cap Lower Surface
Corrosion and Metal Fatigue
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• Beech 18 Wing Front Spar
• Beech Bonanza/Baron Control Surfaces
• Beech Bonanza/Baron Front Spar Leading Edge Lower Hinge-Pin Attachment
• Cessna 177 Wing Spar
• Cessna 200 Series Wing Spar
• Cessna 182 Lower Strut Fitting
• Cessna Single Engine Wing Spar
• Cessna Single Engine Rudder Pedal
• Cessna Single Engine Main Landing Gear
Corrosion Examples
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Beech Bonanza/Baron Control Surfaces
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Special Airworthiness Information Bulletin (SAIB) CE-15-22
Beech Bonanza/Baron Front Spar Leading Edge Lower Hinge-Pin Attachment
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177RG
177B Found as a result of SEB-57-03
Special Airworthiness Information Bulletin (SAIB) CE-16-16
Cessna 177 Wing Spar
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Found as a result of SID Inspection 57-11-01
Cessna 200 Series Wing Spar
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Found as a result of SID Inspection SID 57-40-01
Cessna 182 Lower Strut Fitting
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Wing Spar Corrosion
Found as a result of CPCP Inspection
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Cessna Single Engine Rudder Pedal
Fractured Pedal Arm Tube
SID 27-20-01
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Cessna Single Engine Main Landing Gear
• Made from 6150M High- Strength Steel
• A pit as small as .005” can initiate a fatigue crack which will result in fracture of the gear
• Keep surface painted with polyurethane paint and blend out pits per Service Manual
Rust
Model 182 Flat Spring Gear SID 32-13-01
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.017” Pit
Cessna Single Engine Main Landing Gear
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– Over 700 people have died in fatigue related accidents since 1980
Metal Fatigue
• Aviation has had to address metal fatigue in the design and inspection of airframes since 1954
• Fatigue can be deadly – Metal fatigue contributed to 2240 deaths in 1885 airplane accidents between
1927 and 1980 1
– The five most common fatigue crack initiation sources in these accidents were: (1) bolt, stud or screw; (2) fastener or other hole, (3) fillet, radius or sharp notch; (4) welds and (5) corrosion
1 Campbell and Lahey 1984, ‘A Survey of Serious Aircraft Accidents Involving Fatigue Fracture’, International Journal of Fatigue, January 1984
2 ‘Investigation into Ansett Australia Maintenance Safety Deficiencies and the Control of Continuing Airworthiness of Class A Aircraft’, Appendix 8 from the Australian Transport Safety Bureau’s web site, www.atsb.gov.au.
2
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Fatigue Under Microscope Typical Fatigue Failure
What is Metal Fatigue?
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Aloha Airlines 1988
Dan Air 1977
F111 1969
Beech T-34 1999-2004
Cessna 172 Certified 1955
Cessna 206 Certified 1963
Hig
h-P
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ents
Te
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iatio
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AR
/FA
A P
art 2
3 R
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Fuselage Fatigue Evaluation 1965
Wing Fatigue Evaluation 1969
Instructions for Continued
Airworthiness 1980
Empennage Fatigue
Evaluation 1989
AC91-82 Fatigue Management Program 2008
Comet 1954
1940 1950 1960 1970 1980 1990 2000 CAR FAA
Beech 23 Certified 1962
FAA Regulations Through the Years
Beech 35 Certified 1947
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Key Lessons Learned From High Profile Accidents
• Comet – Fatigue must be considered in design, not just static strength
2,703 & 3,680 total hours
• F111 - Manufacturing or accidental damage must be considered
105 total hours
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• Boeing 707-321C - Fail-safe alone doesn’t work, need inspections
Key Lessons Learned From High Profile Accidents
47,621 total hours
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• Boeing 737 - Inspection programs do not keep airplanes safe indefinitely. Eventually there needs to be a terminating action of modification or retirement.
Key Lessons Learned From High Profile Accidents
35,496 total hours
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• Beech T-34 – Detailed inspection programs are needed for the entire airframe, not just for known areas of cracking
Key Lessons Learned From High Profile Accidents
3200, 8257 & 9316 total hours
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• Model 402C designed in 1979 • Twin-Engine unpressurized airplane • Seats up to 9 passengers • Often used for cargo hauling or scheduled airline passenger service
Case Study – Cessna 402C
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• Wing spar cracking discovered in 1999 led to addition of wing spar strap (SID 57-10-16)
• Engine beam cracking discovered in 2015 led to life limit of engine beams (SID 54-10-01)
• Nacelle fitting (engine beam to wing attachment) cracking discovered in 2016 led to life limit of nacelle fittings
• Carry-thru forward spar cracked in 2017 (SID 57-10-14)
Case Study – Cessna 402C
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• Model 210 with cantilevered wing designed in 1967 • Single-Engine unpressurized high performance airplane • Seats up to 6 passengers • Used for a variety of missions including cargo hauling, geophysical
survey, sight seeing as well as private usage
Case Study – Cessna 210
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• Eight reports of wing spar cracking reported in 2012 (SID 57-11-03)
• Horizontal stabilizer aft attachment fitting cracking discovered in 2011
• Horizontal stabilizer forward spar cracking discovered in 2011 (SID 55-10-01)
Case Study – Cessna 210
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• Beech Bonanza/Baron Rudder Brake Pedal Pivot Hole
• Beech Bonanza/Baron Flight Control Cables
• Cessna 180/185 Tailcone Stringer
• Cessna 172 (Restart) FS 108 Bulkhead
• Cessna 172/182/206/210 Forward Doorpost at Strut Attachment
• Cessna 150/152 Vertical Stabilizer Attach
• Cessna 177 Lower Wing Spar
Metal Fatigue Examples
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Fractured Rudder Brake Pedal Pivot Hole
Beech Bonanza/Baron Rudder Brake Pedal Pivot Hole
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Beech V35A Aileron Control Cable
CASA AD/GENERAL/87 - primary flight control cable assemblies using terminals constructed of SAE-AISI 303 Se or SAE-AISI 304 stainless steel must be replaced after 15 years
Beech Bonanza/Baron Flight Control Cables
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Special Airworthiness Information Bulletin (SAIB) CE-16-16 SID 53-10-01 AD under consideration
Cessna 180/185 Tailcone Stringer
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Found as a result of SID Inspection SID 53-12-03
Cessna 172 (Restart) FS 108 Bulkhead
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Crack AD or SAIB under FAA consideration SID 53-12-01
Cessna 172/182/206/207/210 Forward Doorpost at Strut Attachment
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Crack Special Airworthiness Information Bulletin (SAIB) CE-16-03 SID 55-11-02
Cessna 150/152 Vertical Stabilizer Attach
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Special Airworthiness Information Bulletin (SAIB) CE-16-16 SID 57-11-03
Cessna 177 Lower Wing Spar
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• Inspections – Based on field history – Reviewed by customer focus group
• Inspection Details – Corrosion prevention and control program – Directed visual inspection for corrosion – ~15-20 visual inspections to look for cracks – Boroscope and magnifying glass required to complete inspections
• SID inspections are designed to be accomplished at an annual when airplane is opened up
• Anticipated cost is dependent on flight hours and overall airplane condition – Approximately 10 hours for low time airplane maintained per service manual – Approximately 25 hours for high time airplane maintained per service manual – Any required repairs are additional cost
SID Inspections
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• Safety is a partnership between owners (maintainers), manufacturers and the FAA
• Comply with airworthiness directives
• Report anomalies
• Send Pictures!!
Summary