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2. Introduction. Cessna 441 is a twin turboprop, pressurised aircraft.In 2007, as a result of a Cessna Supplemental Inspection Document (SID), all 441s in Australia with over 22,500 hours flight time were grounded by CASA.This life is now also included in the Cessna system of maintenance.Several aircraft were grounded immediately, and others are close to 22,500 hrs.
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1. 1 Cessna 441 Life Extension
Graham Swannell / Kim White August 2010
2. Very popular aircraft in 80s and 90s for mining company charter and crew changes in WA
It is fast and economical. 260 kts 500 pph (although smaller cabin volume than Kingair it is much more economical than the Kingair)
Total 362 built and 30 in Australia (first delivery 1977 out of production 1986)Very popular aircraft in 80s and 90s for mining company charter and crew changes in WA
It is fast and economical. 260 kts 500 pph (although smaller cabin volume than Kingair it is much more economical than the Kingair)
Total 362 built and 30 in Australia (first delivery 1977 out of production 1986)
5. Feasibility / CASA agreement on cert plan / AEA & Tenix (TAE)
STC HOLDER RESPONSIBILITIES
Will act like the aircraft TC holder.
Responsible for continuing airworthiness support of the entire aircraft for the remainder of the aircraft life.
Feasibility / CASA agreement on cert plan / AEA & Tenix (TAE)
STC HOLDER RESPONSIBILITIES
Will act like the aircraft TC holder.
Responsible for continuing airworthiness support of the entire aircraft for the remainder of the aircraft life.
6. 6
7. AEA database showed 175 structural repairs
Reviewed Service Difficulty Reports (SDRs)
We spoke with operators and did an operators survey
Broke responses down into ATA chapters so we captured not only the structural aspects but also systems problems. AEA database showed 175 structural repairs
Reviewed Service Difficulty Reports (SDRs)
We spoke with operators and did an operators survey
Broke responses down into ATA chapters so we captured not only the structural aspects but also systems problems.
8. Cessna SIDs inspections based in F&DT , should be appropriate inspection intervals
Cessna SIDs inspections based in F&DT , should be appropriate inspection intervals
9. We verified from our analysis that the Cessna wing inspection intervals could be carried out to the new life
Based on F&DT principlesWe verified from our analysis that the Cessna wing inspection intervals could be carried out to the new life
Based on F&DT principles
11. Because there are so many components to the fuselage we needed to classify them
And use standard methods of analysis for each classificationBecause there are so many components to the fuselage we needed to classify them
And use standard methods of analysis for each classification
13. Tension cap are the areas of interest
Inner cap at corners
Outer cap fuselage sidesTension cap are the areas of interest
Inner cap at corners
Outer cap fuselage sides
14. Inner frame caps at the corners needed reinforcing to reduce stress levels
Outer cap on fuselage side will talk about more shortlyInner frame caps at the corners needed reinforcing to reduce stress levels
Outer cap on fuselage side will talk about more shortly
16. A failure of the outer skin and resulting frame outer cap failure would be significant
Initially a pin joint would develop at this location as the internal structure stayed in tact but the bending moment re-distribution would cause a major structural failure. Cannot accept that type of failure hence the external straps.
This was a major area of discussion with the engineering team and we decided on the external strap solution although there were other solutions.A failure of the outer skin and resulting frame outer cap failure would be significant
Initially a pin joint would develop at this location as the internal structure stayed in tact but the bending moment re-distribution would cause a major structural failure. Cannot accept that type of failure hence the external straps.
This was a major area of discussion with the engineering team and we decided on the external strap solution although there were other solutions.
17. 17 AEA uses elastic course mesh models for light gauge sheet metal structures
Then do refined models as required and non-linear analysis if appropriateAEA uses elastic course mesh models for light gauge sheet metal structures
Then do refined models as required and non-linear analysis if appropriate
18. 18
24. Location of strain gauges
Note external straps
Jack the aircraft to simulate wing deflection and any interaction with fuselage attachmentLocation of strain gauges
Note external straps
Jack the aircraft to simulate wing deflection and any interaction with fuselage attachment
25. Talk a bit about the damage tolerance analysis methodsTalk a bit about the damage tolerance analysis methods
27. Talk a bit about the damage tolerance analysis methodsTalk a bit about the damage tolerance analysis methods
30. 2 frames modelled and the skins
Crack analysis with crack starting at the middle of the external strap.
This crack will not be seen until it emerges from underneath the external strap.
Need to see how well we can detect the crack and maintain residual strength
Note that all fasteners were modelled as well with spring elements2 frames modelled and the skins
Crack analysis with crack starting at the middle of the external strap.
This crack will not be seen until it emerges from underneath the external strap.
Need to see how well we can detect the crack and maintain residual strength
Note that all fasteners were modelled as well with spring elements
31. Crack is visible once it appears from underneath the strap
It becomes dangerous at 4.25 and we are easily able to find it from our inspections well before it becomes dangerousCrack is visible once it appears from underneath the strap
It becomes dangerous at 4.25 and we are easily able to find it from our inspections well before it becomes dangerous
33. Flange cracking is the issue
Very difficult to inspect, and in some areas impossible to inspect.
This is one area of the Cessna SIDs program that does not work wellFlange cracking is the issue
Very difficult to inspect, and in some areas impossible to inspect.
This is one area of the Cessna SIDs program that does not work well