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A300 VERTICAL TAIL STRUCTURAL EVALUATION DESIGN FLAW IN LOWER REAR SPAR By Xavier J. Maumus.

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Presentation on theme: "A300 VERTICAL TAIL STRUCTURAL EVALUATION DESIGN FLAW IN LOWER REAR SPAR By Xavier J. Maumus."— Presentation transcript:

1 A300 VERTICAL TAIL STRUCTURAL EVALUATION DESIGN FLAW IN LOWER REAR SPAR By Xavier J. Maumus

2 A300 VERTICAL TAIL STRUCTURAL EVALUATION DESIGN FLAW IN LOWER REAR SPAR PART 1—DESIGN FLAW DETAILS PART 2--FAILSAFE CRITERIA PART 3--ULTIMATE CRITERIA PART 4—FAILURE SCENARIO

3 A300 VERTICAL TAIL STRUCTURAL EVALUATION PART 1—DESIGN FLAW DETAILS

4 Spar Design Susceptible to Lateral Deflection Spar and Yoke Reaction System Designed Primarily to React Lateral Load. Relieves Lateral Shear and Bending in the Main Lugs. Geometry makes Yoke Design Very Efficient in Resisting Lateral Deflection. Poor in Resisting Vertical Deflection.. CRITICAL DESIGN FEATURE Rear Reaction System

5 NTSB Docket No , Factual Report , pg 9 of 63, Section Suspected Description of a Bearing Failure in LHS Rear Transverse Spar Lug Located at the Upper/Outboard Edge of the Lug Bore. This Failure Produced Substantial Compression in the LH Yoke which is Inconsistent with the FEM Boundary Loads. Working Model Demonstrates that the Lower Rear Spar moves to the Right which is necessary to Produce Compression Load in the LH Yoke. DISCOVERY OF FLAW

6 MECHANICAL LEVER Lever Bar Main Lug Reaction Py 0 Yoke Reaction Rotation of Lever Bar Develops Resistance Ps Vertical Tail

7 Geometry of Lower Rear Spar Design Produces a Mechanical Lever (ML) in the Spar Reaction System. As Aft Portion of the VT Deflects, its Lower Spar Rotates and Produces Lateral Deflection at Spar Attachment to the Yokes. Spar Reaction System is Very Efficient in Developing Lateral Resistance. Yokes Resist and Develop Large Internal Loads in VT Reaction System. Loads are Reacted at the Main Lugs (Shear and Out-of Plane Bending) and Additive to the VT Loads. DESIGN FLAW

8 REAR REACTION SYSTEM FAILSAFE CONFIGURATION.480 in. Deflection of Lug ROTATION OF NO 1 RIB AND REAR SPAR Py Rotation of Spar Produces Large Deflections at Yokes Fulcrum S P

9 LOAD DEVELOPMENT IN LEVER MECHANISM Spar Rotates and Produces Lateral Deflections at its Lug Attachment to the Yokes Spar Rotates and Produces Lateral Deflections at its Lug Attachment to the Yokes Yokes Resist Lateral Deflection and Develop Large Internal Loads in Reaction System Yokes Resist Lateral Deflection and Develop Large Internal Loads in Reaction System Large Shear and Bending Loads are Reacted at the Rear Main Lugs Large Shear and Bending Loads are Reacted at the Rear Main Lugs

10 MECHANICAL LEVERAGE Failed RHS Main Lug Vertical Movement of Fulcrum—Located near Rib No. 1 in Skin Transition Area above LHS Lug Transverse Spar Rotates Counterclockwise about Fulcrum Resistance to Spar Deflection Develop Large Loads in Yokes.480 in 0 Additional Side Load Reacted at LHS Main Lug FAILSAFE CONFIGURATION

11 EVIDENCE OF DESIGN FLAW For Failsafe Criteria with the RHS Rear Main Lug Disconnected, the FEM shows the RHS Lug moves to the Right and Up. Deflections Consistent with the Mechanical Leverage Model, Shows Rotation of Spar. Most Significant is the Deflection to the Right which Verifies the Spar’s tendency to move Laterally. This Lateral Movement is what Produces the Interference Resistance Between the Spar and Yoke. Working Model Demonstrates the Flaw. Loads and Deflection Analysis Results are Consistent when Mechanical Leveraging is Consisted.

12 FREEBODY OF LUG Additional Load on Lug Bore M XX P S 3.70 Lateral Resistance in Yokes Produce Additional Shear and Bending in Lug

13 SIGNIFICANCE OF ML Mechanical Leveraging makes the Design Susceptible to small Deflections in the Lower Spar Structure. Large Internal Loads are Produced in all members of the VT Reaction Systems, Main Lugs are especially Susceptible. Airbus FEM does not Account for Mechanical Leverage in the Loads Analysis. FEM Deflections are Correct. Mechanical Leverage supports a Pre-mature Failure in the RHS Rear Main Lug below Ultimate Renders Failsafe Capability Ineffective

14 TEST TO PROVE DESIGN FLAW Full Scale Test Failsafe Criteria RHS Rear Main Lug Released Apply Load 25% Limit BI 17 Vertical Tail and Rudder mounted on Aircraft TEST CASE VS. AIRBUS FEM Note the large load in the RHS Yoke for Test Case

15 TEST TO PROVE DESIGN FLAW Full Scale Test Ultimate Criteria Apply Load 25% Limit BI 17 Vertical Tail and Rudder mounted on Aircraft TEST CASE VS. AIRBUS FEM Note the difference in sign between the two load cases

16 TEST TO PROVE DESIGN FLAW Perform Full Scale Calibration Test of Vertical Tail on A300 Aircraft Perform Full Scale Calibration Test of Vertical Tail on A300 Aircraft Disconnect Fairings, Control Rods and Systems to Avoid Damage to A/C Disconnect Fairings, Control Rods and Systems to Avoid Damage to A/C Mount Cameras to Record Movement of Rear Spar Mount Cameras to Record Movement of Rear Spar Strain Gauge and Calibrate Aft Yokes Strain Gauge and Calibrate Aft Yokes Apply Side Load (12,000 lb about 25% Limit Load) to VT about 157 Inches Above Attachment Apply Side Load (12,000 lb about 25% Limit Load) to VT about 157 Inches Above Attachment Read Gauges and Measure Rotational Deflection of Rear Spar Read Gauges and Measure Rotational Deflection of Rear Spar Disconnect RHS Rear Main Lug and Repeat Test Disconnect RHS Rear Main Lug and Repeat Test

17 Questions The Effectiveness of the Mechanical Lever is Dependent on the Location of the Fulcrum, how was this Point Located? In the Failsafe Analysis, the Fulcrum is located near the Intersection of the LH Skin and N0. 1 Rib. The Fulcrum location is a Function of the Stiffness of Two Primary Structural Members. One is the VT Box that is very Stiff and whose Lower Side is Bound by the No. 1 Rib. The other being the LH Main Lug Area whose Stiffness is a Function of its Moment of Inertia and Fixity at the Lug Attachment. These Stiffness Parameters Produce a Natural Inflection Point 2.83 inches above the Main Lug Bore. In the Ultimate Criteria Analysis, no Fulcrum Location is Determined. A.0125 inch Lateral Displacement is Assumed since no FEM Defection Data is Available for Ultimate.

18 PHYSICAL EVIDENCE Supports Mechanical Leverage Bearing Failure in LHS Aft Transverse Spar Lug Located at the Upper/Outboard Edge of the Lug Bore. NTSB Docket No , Factual Report , pg 9 of 63, Section Bearing Failure in LHS Aft Transverse Spar Lug Located at the Upper/Outboard Edge of the Lug Bore. NTSB Docket No , Factual Report , pg 9 of 63, Section The Bearing Failure indicates that the Lower Spar moved to the right to Produce this Failure. Deformation of Left Transverse Yoke Sleeve. NTSB Docket No , page 5 of 63. Deformation of Left Transverse Yoke Sleeve. NTSB Docket No , page 5 of 63.

19 A300 VERTICAL TAIL STRUCTURAL EVALUATION PART 2--FAILSAFE CRITERIA DESIGN FLAW IN TRANSVERSE SPAR

20 FAILSAFE CRITERIA Requires That Vertical Tail Structure Sustain Limit Load With One Major Structural Member Failed Requires That Vertical Tail Structure Sustain Limit Load With One Major Structural Member Failed

21 AIRBUS FAILSAFE PHILOSOHY When one of the Main Lugs Fail, the Loads of that Lug are Redistributed, Primarily to an Adjacent Main Lug When one of the Main Lugs Fail, the Loads of that Lug are Redistributed, Primarily to an Adjacent Main Lug In the Case of a Failure in the RHS Rear Main Lug, 90% of the Load goes Forward and only 10% is Resisted by the Yokes In the Case of a Failure in the RHS Rear Main Lug, 90% of the Load goes Forward and only 10% is Resisted by the Yokes In Order for this Redistribution to Occur the Design must Allow the Failed Lug to Deflect In Order for this Redistribution to Occur the Design must Allow the Failed Lug to Deflect

22 AIRBUS FAILSAFE ANALYSIS Assumes RHS Rear Main Lug Fails Results Based on Non-Linear FEM Analysis—Set for Strain Solution Results Based on Non-Linear FEM Analysis—Set for Strain Solution Design Certification Lateral Gust Condition at Limit Load Design Certification Lateral Gust Condition at Limit Load LHS Spar Lug Critical LHS Spar Lug Critical Max Deflection of the Right Rear Main Lug in A/C Coordinates is: Max Deflection of the Right Rear Main Lug in A/C Coordinates is: x =.004 in., y =.037 in and z =.480 in. x =.004 in., y =.037 in and z =.480 in.

23 AIRBUS FEM RESULTS Non-Linear Analysis FAILURE ANALYSIS—RHS REAR MAIN LUG FAILSAFE—BI17 LIMIT LOAD (LB)

24 AIRBUS DETAIL ANALYSIS LHS SPAR LUG CRITICAL Load Capacity of Lug = 40,271 lb. Ulti. Margin of Safety = +.23 Limit Margin of Safety = +.23 Limit Critical for Shear Tear Out DIA Dia P LUG = 32,742 lb. LHS

25 MECHANICAL LEVERAGE FAILSAFE ANALYSIS Assumes Right Rear Main Lug Fails Results Based on Deflection Analysis (Virtual Work) Results Based on Deflection Analysis (Virtual Work) Considers Mechanical Leverage in Lower Spar Considers Mechanical Leverage in Lower Spar Design Certification Lateral Gust Condition at Limit Load Design Certification Lateral Gust Condition at Limit Load Deflection of the Right Rear Main Lug in A/C Coordinates is: Deflection of the Right Rear Main Lug in A/C Coordinates is: y =.037 z =.480 in. y =.037 z =.480 in.

26 REAR REACTION SYSTEM FAILSAFE CONFIGURATION.480 in. Deflection of Lug ROTATION OF NO 1 RIB AND REAR SPAR Py Rotation of Spar Produces Large Deflections at Yokes Fulcrum S P

27 LOADS ANALYSIS Analysis Considers Mechanical Leverage FAILURE ANALYSIS—RHS REAR MAIN LUG FAILSAFE—BI17 LIMIT LOAD

28 DETAIL STRESS ANALYSIS RHS SPAR LUG CRITICAL Load Capacity of Lug = 40,271 lb. Ulti. Margin of Safety = -.24 Limit Margin of Safety = -.24 Limit Critical for Shear Tear Out DIA Dia P LUG = 52,811 lb. RHS

29 TRANSITION AREA INTER-LAMINA SHEAR CRITICAL Inter-lamina Shear Capacity = 50,215 lb. Ulti. Margin of Safety = -.37 Limit Margin of Safety = -.37 Limit A SECTION A-A A P INTER-LAMINA SHEAR = lb. LHS REAR MAIN LUG UP FWDLOOKING INB’D

30 CONCLUSIONS Based on Analysis Considering Mechanical Leverage RHS Rear Spar Lug will Fail at 76% of Limit Load RHS Rear Spar Lug will Fail at 76% of Limit Load LHS Rear Main Lug will Fail at 63% of Limit Load LHS Rear Main Lug will Fail at 63% of Limit Load Vertical Tail does not Meet Failsafe Criteria when Considering Mechanical Leverage Vertical Tail does not Meet Failsafe Criteria when Considering Mechanical Leverage

31 Question The Component Tests were Used to Support Failsafe Certification. Why didn’t this Flaw Show Up During those Tests? To my Knowledge none of the Spar Component Tests Included Yokes attached to the Spar, so the Additional Internal Loads from Mechanical Leverage wasn’t Allowed to Develop. Additionally, Component Testing never Examined a Failsafe Condition in which a Main Lug was disconnected. The Boundary Loads used in all Component Tests were Controlled by the FEM Loads Analysis that did not Account for Mechanical Leverage.

32 A300 VERTICAL TAIL STRUCTURAL EVALUATION PART 3--ULTIMATE CRITERIA ANALYSIS IS INCOMPLETE NEED DEFLECTION DATA OF REAR SPAR

33 ULTIMATE CRITERIA Requires That Vertical Tail Structure Sustain 1.5 Times Limit Load Without Failure of any Major Structural Member Requires That Vertical Tail Structure Sustain 1.5 Times Limit Load Without Failure of any Major Structural Member

34 AIRBUS ANALYSIS--ULTIMATE Results Based on Non-Linear FEM Analysis—Set for Strain Solution Results Based on Non-Linear FEM Analysis—Set for Strain Solution Design Certification Lateral Gust Condition at Ultimate Load Design Certification Lateral Gust Condition at Ultimate Load RHS Rear Main Lug Critical RHS Rear Main Lug Critical

35 AIRBUS FEM RESULTS Non-linear Analysis BI17 LOAD CASE—ULT. S = 3,100 LB P = 160,319 LB M XX = 41,109 IN-LB Margin of Safety = +.18 Critical for Shear Tear Out M XX P RHS Lug View looking Aft S

36 REAR REACTION SYSTEM NORMAL CONFIGURATION Rotation of Spar Produces Deflections at Yokes Py Fulcrum Py 0 S S PcPt

37 Additional Side Load Reacted at RHS Main Lug MECHANICAL LEVERAGE Fulcrum—Located near Rib No. 1 Rear Spar Rotates Counterclockwise Produces Deflection at Lugs Resistance to Spar Lateral Deflection at Lugs are Developed in Yokes Mechanical Leverage Influences the Distribution of Internal Load in Rear Reaction System Additional Side Load Reacted at LHS Main Lug 0

38 DETAIL ANALYSIS RESULTS Considers Mechanical Leverage BI17 LOAD CASE—ULT. NO DEFLECTION DATA AVAILABLE, ASSUMES LATERAL INTERFERENCE IN YOKES =.0125 IN. (.030 Vertical Deflection of Rear Spar) S = 26,075 LB P = 160,319 LB M XX = 74,376 IN-LB Margin of Safety = -.13 Critical for Shear Tear Out M XX P S RHS Lug View Looking Aft

39 CONCLUSIONS Based on Analysis Considering ML Assume Lateral Deflection of.0125 in. in Rear Spar Assume Lateral Deflection of.0125 in. in Rear Spar --Need Deflection Data-- Rear Main Lugs will Fail at 87% of Ultimate Load Rear Main Lugs will Fail at 87% of Ultimate Load Must be Substantiated by FEM Analysis and Full Scale Static Test on Aircraft Must be Substantiated by FEM Analysis and Full Scale Static Test on Aircraft Vertical Tail may not Meet Ultimate Criteria Vertical Tail may not Meet Ultimate Criteria

40 Questions The Full Scale Static Test was Used to Support Ultimate Certification. The Test Article Failed at 126 % of Ultimate. Why didn’t this Flaw Show Up During this Test? The Full Scale Static Test didn’t Include Yokes, so the Additional Internal Bending Load in the Rear Main Lugs from Mechanical Leverage wasn’t Allowed to Develop. The Boundary Loads of the Static Test were a Duplication of the FEM Loads Analysis that did not Account for Mechanical Leverage..

41 RECOMMENDATION FEM ANALYSIS Current Airbus FEM Internal Loads Analysis needs Modification to Account for Mechanical Leverage of Rear Spar Current Airbus FEM Internal Loads Analysis needs Modification to Account for Mechanical Leverage of Rear Spar FEM should be run on Non-linear set for Geometry Solution FEM should be run on Non-linear set for Geometry Solution

42 RECOMMENDATION NTSB Perform Proof Test Perform Proof Test Full Scale Tests to Failure should be Preformed for both Failsafe and Ultimate Criteria Full Scale Tests to Failure should be Preformed for both Failsafe and Ultimate Criteria

43 A300 VERTICAL TAIL STRUCTURAL EVALUATION PART 4—FAILURE SCENARIO QUESTIONS

44 FAILURE SCENARIO The RHS Rear Main Lug Failed First at below Limit and Initiated a Series of Failures in the Rear Attachment System. RHS Rear Main Lug Weakened by Overload Event 7 Years Earlier--Second Wake Encounter RHS Rear Main Lug Weakened by Overload Event 7 Years Earlier--Second Wake Encounter LHS Rear Main Lug--Thump LHS Rear Main Lug--Thump Rear Transverse Spar Lugs, RHS then LHS --Two Thumps Rear Transverse Spar Lugs, RHS then LHS --Two Thumps Rib No. 1 between Middle and Rear Spar– Snap and Loud Thump Rib No. 1 between Middle and Rear Spar– Snap and Loud Thump Fwd and Middle Main Lugs and Yokes Instantaneously– Loud Bang Fwd and Middle Main Lugs and Yokes Instantaneously– Loud Bang

45 Questions What Caused the RHS Rear Main Lug to Fail? There is no way of knowing the exact Strength of the failed RHS Main Lug, but in Part 3 of this Presentation, Ultimate Analysis shows that the Lug might not meet Design Strength Requirements when Mechanical Leverage is Considered. The Lug had been Weakened by an Overload Event that Occurred Seven Years Earlier. During this Event the Lug came very Close to Failure and Caused Delamination around the Lug Bore. Increase Stress from the Mechanical Leverage Phenomena caused further Delamination and Weakening of the Damaged Lug Continued Until Failure.

46 QUESTIONS How does Mechanical Leverage support Pre-mature Failure of the RHS Rear Main Lug? Bending Loads in the Lug are reacted at the Lug Bore and Produce Strain in the Critical Outer Fibers of the Lug. Mechanical Leverage Increases these Bending Strains making the Lug even more Susceptible to Delamination. If the Lug has been Damaged from a Previous Overload Event, it is even more Susceptible to further Delamination. As the Lug Continues to Weaken from Delamination, the Bending Strains in its Outer Fibers are Driven to Larger Levers Promoting Delamination Growth.

47 Questions Why do you believe the RHS Rear Lug Failed below Limit? My Analysis supports a Failure Scenario in which the RHS Rear Main Lug may have been severely damaged from the Overload Event that the Aircraft Experienced Seven Years earlier. The Mechanical Leverage Effect Develops larger than expected Bending Loads in the Lug that caused further Delamination Growth. Over the Years, the Lug continuously Weakens until it Pre- maturely Fails (below Limit Load) when Exposed to the Loads of the Second Jet Wake Encounter about 17 Seconds before Separation.

48 Questions What Proof Exist to Support a Failure of the RHS Rear Main Lug below Limit? No Direct Evidence Exist to show that the Lug Failed below Limit. Failure Scenario Assumes that the Lug Ruptured at Second Wake Encounter. Wake Encounter Load seems Less than Limit. Need Analysis supported by Testing. (Yes, you can say that Failsafe did not work but remember that Airbus will say that it was a load beyond Limit that caused the VT to go at once. You need some evidence that there was no overload or that the intact system is not capable of carrying the load.)

49 Questions What Evidence Exist to Support a Zipper Type Failure of the VT? This Presentation provides Physical Evidence and Failsafe Analysis that Supports a Series of Failures (below Limit) in the Rear Attachment System that may have Lasted a number of seconds. The Physical Evidence suggests a Series of Component Failures that is Consistent with a Zipper Type Failure and takes some Time to Develop because the Loading is not Overwhelming. The Mechanical Leverage Design Flaw and Delamination Damage of the other AA Aircraft proves a problem exist with the Design. Cockpit Voice Recording suggest that something was happening to the Aircraft 17 seconds before the VT Departure.

50 Questions What does the Voice Recording Suggest to you? Its an indication that the Vertical Tail may have been coming apart at least 17 seconds before separation from the aircraft. During the time between 0915:51.8 and 0915:58.5, there are recorded the sounds of three thumps, one snap, one loud thump and one loud bang. These sounds were probably the sounds of the VT's aft reaction system failing and No. 1 Rib breaking apart with the last 'loud bang' at 0915:58.5 being the sound of the simultaneous failure of the fwd and middle structure. During the time between 0915:51.8 and 0915:58.5, there are recorded the sounds of three thumps, one snap, one loud thump and one loud bang. These sounds were probably the sounds of the VT's aft reaction system failing and No. 1 Rib breaking apart with the last 'loud bang' at 0915:58.5 being the sound of the simultaneous failure of the fwd and middle structure.

51 Questions Why do you believe the LHS Rear Main Lug Failed before the Rear Spar Lugs? Failsafe Analysis in this Presentation shows the LHS Main Lug to be more Critical than the Spar Lugs. The Physical Evidence: Two Large Areas of Delamination in the Lower Aft Transverse Spar above both Lug Bores, NTSB Public Docket No , Factual Report App. A, page 9 of 52, Figure 06. These Failures Result from Bending Produced by Out-Of-Plane Loading on the Rear Spar. These Delaminations Indicate that the Lower Spar moved Substantially before Failure. In Order for the Lower Spar to Move that much Meant that the LHS Rear Main Lug had to be Disconnected.

52 PHYSICAL EVIDENCE Supports Failure Scenario Witness Marks on Forward LHS Aft Transverse Spar Upper/Outboard Area between the Lug Bore and Rib No. 1. Roll No M.jpg. Witness Marks on Forward LHS Aft Transverse Spar Upper/Outboard Area between the Lug Bore and Rib No. 1. Roll No M.jpg. Marks Result from Contact with the Outboard Edge of the LH Yoke. Indicates that the Lower Spar moved Substantially Downward and to the Right. The Photo also shows the Bearing Failure at the Edge of the Lug Bore of the Previous Slide. Failure located at the 1 o'clock position. The Photo also shows the Bearing Failure at the Edge of the Lug Bore of the Previous Slide. Failure located at the 1 o'clock position.

53 PHYSICAL EVIDENCE Supports Failure Scenario Two Large Areas of Delamination in the Lower Aft Transverse Spar above both Lug Bores, NTSB Public Docket No , Factual Report App. A, page 9 of 52, Figure 06. These Failures Result from Bending Produced by Out-Of-Plane Loading on the Rear Spar. Two Large Areas of Delamination in the Lower Aft Transverse Spar above both Lug Bores, NTSB Public Docket No , Factual Report App. A, page 9 of 52, Figure 06. These Failures Result from Bending Produced by Out-Of-Plane Loading on the Rear Spar. Because the RHS and LHS Rear Main Lugs were Failed, the Aft Structure of the VT was free to Twist. As this occurred, Resistance Developed in the Yokes. The Canted Transverse Spar rotated in a Vertical Plane about the A/C Longitudinal Axis. This Twisting of the aft structure could only occur while the Fwd Structure remained Attached. This Twisting of the aft structure could only occur while the Fwd Structure remained Attached.

54 PHYSICAL EVIDENCE Supports Failure Scenario Witness Mark on the RHS Rear Main Lug. Impact Damage to the Fracture Surface of the Fwd Outboard Leg of the Lug may have come from the VT moving to the right after failure of the two Rear Main Lugs. The damage was caused by contact with a piece of No. 1 Rib. Roll No M.jpg Witness Mark on the RHS Rear Main Lug. Impact Damage to the Fracture Surface of the Fwd Outboard Leg of the Lug may have come from the VT moving to the right after failure of the two Rear Main Lugs. The damage was caused by contact with a piece of No. 1 Rib. Roll No M.jpg

55 Questions What was the Configuration of the VT at the Instant of Departure? Analysis supports a Failure Scenario in which the VT was Supported only by the Fwd and Middle Attachment Systems at Departure. Ultimate Analysis shows that the RHS Rear Lug may be Under Strength and Failsafe Analysis shows that the remaining Rear Attachment System, LHS Main Lug and Yokes and the No. 1 Rib is not Capable of Sustaining Limit Load.

56 PHYSICAL EVIDENCE Supports Failure Scenario In order for the No. 1 Rib between the Aft and Middle Spars to become Overloaded means that the Rib became a Primary Load Member. The Rib acted as a Cantilevered Beam and Attempted to Restrain Movement of the Aft VT, and in doing so, Provides effective Evidence that the Forward Structure of the VT remained Intact and Attached for some time after the Failure of the Aft Reaction System. In order for the No. 1 Rib between the Aft and Middle Spars to become Overloaded means that the Rib became a Primary Load Member. The Rib acted as a Cantilevered Beam and Attempted to Restrain Movement of the Aft VT, and in doing so, Provides effective Evidence that the Forward Structure of the VT remained Intact and Attached for some time after the Failure of the Aft Reaction System.

57 Questions What Load was on the VT at Time of VT Departure? Consistent with Failure Scenario, at the Time of Complete Failure and Departure of the VT only the Fwd and Middle Reaction Systems were Attached. Failure Load was Equal to the Strength of the LHS or RHS Middle Main Lug and probably Less than Airbus’s Predicted Load (192 % of Limit).

58 PHYSICAL EVIDENCE Supports Failure Scenario Lack of Witness Marks NTSB Public Docket No , Factual Report App. A, page 9 of 52, Figure 05. Middle Transverse Spar shows no Out-of-plane Delamination Damage or Bearing Failure in the LHS Lug Bore. The two Forward and Middle Main Lugs Failed Instantaneous and resulted in no Out-of-plane Delamination in the Middle Spar. As the VT departed, the VT Structure was free to move aft and vertically in the plane of the Canted Spar, and hence, no Out-of-plane Resistance produced by the Yokes. NTSB Public Docket No , page 5 of 63. Both Forward and Middle Yokes were free to rotate on their Lower Attach bolts. NTSB Public Docket No , page 5 of 63. Both Forward and Middle Yokes were free to rotate on their Lower Attach bolts.

59 Questions How do you Explain Airbus’s Prediction of a Failing Load of 192% of Limit? Airbus’s Load Prediction is Based on a Fully Effective Rudder and Fin Completely Supported by the Fwd, Middle and Rear Attachment Systems. In Failure Scenario at the Time of Departure, the VT was only Supported by the Fwd and Middle Attachment Systems and Missing the Aft Section of No. 1 Rib. This Configuration Reduced the Effectiveness of both the Rudder and Fin which in turn, Restricted Load Development on the VT System.


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