New Tools in Aircraft Accident Reconstruction to Assist the Insurer Steven L. Steve Morris Senior Managing Consultant and Manager of Colorado Operations Engineering Systems Inc (ESI) Overview ESI has reconstructed aircraft accidents since the company was founded in 1987 Since then, we have participated in numerous aviation accident investigations both in and outside the U.S. Tape measures and cameras were essential accident reconstruction tools in 1987 and they are still very important tools today However, new powerful tools are now available and more are arriving every day Overview X ray Computed Tomography (CT) of Parts Laser Scanning LiDAR New Aircraft Simulation Capabilities 1
Overview X ray Computed Tomography (CT) of Parts Laser Scanning LiDAR New Aircraft Simulation Capabilities X rays Energetic, penetrating electromagnetic radiation Sensitive to electron density variations Higher Z, greater density materials increased X ray attenuation Real time imaging possible X rays Film or Detector X ray source Sample 2
Ejector Flow Valve X ray X ray Limitations Image is a projection of everything intervening between the source and recording system (film or electronic detector) High density can obscure low density constituents X ray Example Consider 4 balls arranged in a box How are they positioned in the box? 3
X ray Example X ray image X ray source? X ray Example Possibility 1 X ray image X ray source X ray Example Possibility 2 X ray image X ray source 4
X ray Example Possibility 3 X ray image X ray source X ray Example All 3 result in the same X ray image X ray image 1 X ray image indeterminate for internal structure X ray Example X ray source? 5
X ray Example X ray image? X ray source X ray image 1 X ray Example X ray image 2 Mental Sudoku Need even more images to completely determine ball locations Correct Answer! X ray CT X ray Computed Tomography 6
X ray CT Technique X ray source Intensity vs pixel position Turntable with sample Detector X ray CT Technique X ray source Turntable with sample Intensity vs pixel position Detector X ray CT Technique X ray source Intensity vs pixel position Turntable with sample Detector 7
Tomographic Reconstruction From thousands of 2D X ray images, the computer reconstructs the sample in 3D revealing internal structure Tomographic Reconstruction Original Object CT Voxel Model ( x, y, z, ρ e ) Industrial CT Scanning CT Scanning 3D voxel computer model Orient and view in any direction Slice stacks of top, side, and front views Cut away and view internally (x, y, z, thresholding) View different material constituents (ρ e thresholding) Dimensioning/metrology/CAD Advanced imaging and video capabilities 8
Industrial CT Scanning Industrial CT Scanning X ray source Sample stage Detector Detectors 2 D Linear 9
Ejector Flow Valve CT Image CT X Ray Ejector Flow Valve CT Image Valve Closed Valve Open Altimeter 10
Carburetor Carburetor Video Click on photo to play video Carburetor Video Click on photo to play video 11
Project Example Pitch Servo Pitch Servo Pitch Servo Pitch Servo 12
Pitch Servo Capstan Pinion Gear Capstan Gear Pitch Servo CT Scan of Pitch Servo 2D detector X-ray source 13
CT Scan Slices of Pitch Servo Pitch Servo Disassembly Capstan Pinion Gear Pitch Servo Capstan Gear Contact marks on gear teeth 14
Pitch Servo Capstan Gear Contact marks on gear teeth Contact marks Pitch Servo Capstan Gear Pitch Servo Pinion Gear 5 mm Contact marks evidence of gear train particle ingestion and binding 15
CT Scan of Pitch Servo Capstan Gear Pinion Gear Pitch Servo CT Slices Y_347 Y_682 Pinion Gear Capstan Gear 122 μm = 0.0048 inch slices Pitch Servo CT Slices Y_347 Y_682 Pinion Gear Capstan Gear 122 μm = 0.0048 inch slices 16
Pitch Servo CT Slices Pinion Gear Capstan Gear Pitch Servo CT Slices Pinion Gear Capstan Gear Pitch Servo CT Slices Pinion Gear Y_682 Capstan Gear Subject Exemplar 17
Pitch Servo CT Slices Pinion Gear Capstan Gear Contact Points Pitch Servo Gear Interaction Summary Contact marks nothing more than marks imparted post accident with gears misaligned and partially rotated likely during wreckage retrieval. 18
Pitch Servo Capstan Mount Plate Y_347 Pinion Gear engaged here Pitch Servo Capstan Gear Y_347 Position at disassembly Pinion Gear engaged here Shadow from hole position during postcrash fire Overview X ray Computed Tomography (CT) of Parts Laser Scanning LiDAR New Aircraft Simulation Capabilities 19
Laser Scanning An extension of surveying equipment Provides a cloud of millions of points in color By moving the scanner to several locations but keeping the same reference points, a true 3 D object is created You can view the cloud from any vantage point and get very accurate measurements Laser Scanning Laser Scanning 20
Laser Scanning Laser Scanning Laser Scanning Has yet to be used on scene for an aircraft accident (to my knowledge) A laser scanning unit could be deployed and provide valuable information to every aircraft accident scene Excellent method for preserving evidence Can capture data/information that investigator does not immediately know is important 21
Laser Scanning Laser Scanning Laser & Camera Articulating Arm Hard Contact Probe Laser Scanning Camera Laser 22
Laser Scanning Laser Scanning Laser Scanning Triangulation Laser Camera Camera Image Laser line projected over an object gives the profile of the object which is imaged by the camera Software renders a visual surface model 23
Laser Scanning Point Cloud Data Surface Deviation Map Exemplar Subject Section Deviation Map 24
Overview X ray Computed Tomography (CT) of Parts Laser Scanning LiDAR New Aircraft Simulation Capabilities LiDAR Light Detection And Ranging Optical remote sensing technology that can measure the distance to targets by illuminating the target with laser light and analyzing the backscattered light Highly accurate vertical measurements Can get a 3 D digital image of an accident scene, regardless of the site s remoteness LiDAR 25
LiDAR LiDAR LiDAR 26
LiDAR LiDAR Was recently used to document an aircraft accident scene Can provide VERY accurate 3 D accident scene documentation Particularly useful for remote accident sites Can be very useful to subsequent accident reconstruction Overview X ray Computed Tomography (CT) of Parts Laser Scanning LiDAR New Aircraft Simulation Capabilities 27
Simulations If animated, simulations help provide Visualization that posters cannot match 4 dimensional (x, y, z, time) aspect to the understanding Understanding of the dynamic sequence of events in an accident More detailed reconstructions Simulations Simulations 28
Simulations Radar Data Simulations Reconstructed Data Altitude and Airspeed Histories 250 11000 200 Altitude 10000 Calibrated Airspeed, kt 150 100 Airspeed 9000 8000 Altitude, ft MSL 50 7000 Approximate Airspeed for Stall Warning Horn and Autopilot Disconnect 0 6000 20:40 20:41 20:42 20:43 20:44 20:45 20:46 20:47 20:48 20:49 UTC Simulations Plaintiffs alleged that all three occupants were overcome by carbon monoxide poisoning and the plane entered a hands off spiral Could it be shown that the plaintiff s spiral could not be flown without human input? J2 Aircraft Dynamics software provides a tool that can accurately relate the control deflections required to fly the flight path defined from the radar data 29
J2 Dynamics Software Provides aircraft modeling and analysis Used to construct a reliable simulator model Simulator validated with Aircraft Flight Manual and/or Flight Test data Yields the control deflections required to fly a given flight path with tolerances provides insight on what the pilot was doing J2 Dynamics Software J2 Dynamics Software Virtual function allows user to produce instant 3D animations of the reconstructed flight path with a graphic of the subject airplane and terrain map Data can be used to produce a high fidelity, courtroom quality animation 30
Summary This has been a quick look at some of the tools that can be used in aircraft accident reconstruction Most of these tools came from other disciplines, so a broad view beyond the accident reconstruction community discipline is necessary Technology is changing rapidly new tools continue to become available 31