Investigation Lab

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Investigation Lab Introduction

The major tasks of investigation lab include, but not limited to, site survey, flight recorders read-out and analysis (FDR & QAR), performance analysis, flight animation, and research and development on the relevant investigation techniques. The purpose is to assist the investigation team to find the root cause of an occurrence, by recovering the sequence of events through reconstruction of the event site using computing technologies.

I. Flight Recorder read-out

The definition of Flight Recorders: any type of recorder installed in the aircraft for the purpose of complementing accident/incident investigation, it include the Flight Data Recorder (FDR) and Cockpit Voice Recorder (CVR), both CVR and FDR are crash-survival units, it could suffered the severe conditions and no damage on the recording media. With the popularity of Global Positioning System (GPS), an increasing trend of the usage of portable GPS on government aircraft and general aviation rotorcraft, ultra-light vehicles can be seen. However, portable GPS does not possess sustainability to crash damage, hence increasing the difficulty in data readout. The investigation lab has established full flight recorder readout capability, and is on track to setup the readout capability on GPS machines.

Flight recorders-1 Flight recorders-2

II. Site-Survey and Data Mapping

ASC Investigation Lab using GPS and Laser Ranger as site-survey measurement instruments to meet the variety and emergency of the accident site survey. The GPS equipments including hand-held(Low accuracy) and shouldered type(high accuracy). After differential, the accuracy of GPS could be approximated to 20cm.and the accuracy of Laser Ranger is 0.5cm. Besides these, we also using 3-D scanner to build up the 3-D model (terrain, tree, building…etc)of the occurrence scene. Then, the on-scene information will be integrated with satellite image, aerophoto, and DTM(Digital Terrain Model)to show the relation between wreckage, flight track, terrain and some important landmarks.

Hand-held, shouldered type, and higher accuracy site survey equipments Flight occurrence site survey and GIS information multi-layer superposition

III. Audio Spectrum analysis

Cockpit voice recorders, it recording the crew's communication voice and operation sounds in the cockpit, are important evidences in the investigation process. Because some of the voices are hard to be distinguished or heard by human, the spectrum and energy analysis could be adopted by ASC Investigation Lab to identify the source, starting and lasting time, or some specific voice of warning activation in the cockpit. In this way, this technology is very helpful to identify the voice, power failure analysis, whether the aircraft explosive in the air or not.

Demonstration of CVR data sound spectrum analysis

IV. Multi-data sets integration and performance analysis

In order to reconstruct the flight path rapidly and accurately, ASC Investigation Lab develops the program, it called Flight Path Reconstruction System (FPRS), to superposing the GIS-related layers. Now, the FPRS contains the function of flight path calculation and data process, including primary radar, secondary radar, and FDR parameters. Furthermore, ASC has been developing the Occurrence Investigation Management and Information System (OIMIS) in 2008, which can effectively enhance the efficiency of survey operations, has been set up after several operational tests. Any aviation occurrence involving spatial- temporal relationship can be analyzed and demonstrated by this system. OIMIS consists of four modules: Flight Recorders Under-Water Locating System (FRULS), flight path analysis tools, multi-radar data extraction tools, and flight path spatial- temporal visual tool.

ASC Investigation Lab also maintains aircraft performance analysis capabilities to provide the investigation team members more occurrence relevant flight parameters, to overcome the limited parameters recorded in the flight recorders. Over the years, ASC Investigation Lab has developed the wind field estimation, runway performance analysis, weather hazard analysis (i.e. icing performance, wind shear, and turbulence), runway excursion/veeroff performance analysis and TCAS event analysis.

An multi-layer GIS map of an runway excursion occurrence OIMIS interface Braking performance analysis (typical landing condition)

V. Flight Animation

The sources for flight animation come from aircraft operational and mechanical configurations recorded by flight recorders, such as positions, attitude, control surfaces, control column location, engine status, and cockpit environment as heard from CVR. Besides, those environmental factors that could affect flight operations such as visibility, snow, and rain, need to be integrated with the animations. Data from CVR, FDR, radar, site survey and GPS need to be synchronized to illustrate the relationship between the aircraft (or flight crew) and environment, thus play back the sequence of events of the aviation occurrence.

Flight animation of a hard-landing event

VI. Flight Recorder Underwater Locating System

To take advantage of the work of searching and salvage flight recorders, the Aviation Safety Council established Flight Recorder Underwater Locating System (FRULS) in which the investigation lab integrated underwater locator, differential GPS with short baseline, and self-developing program to estimate the position of the recorders. The second generation of FRULS (FRULS) has been evoluted with portability where it can be operated in different environment such as sea, lakes, or even at a reservoir.

Overview of the flight recorder underwater locating equipments

VII. Engineering Failure Analysis

ASC's engineering failure analysis system emphasizes on construction of three dimensional models of targeted objects, followed by Finite Element Analysis (FEA). The core consists of a reverse engineering module, a finite element analysis module, a material analysis module and a 3-D visual demo module. The reverse engineering module transforms the point data obtained from 3-D scanner to surface model, and then compiles as the information that can be read by CAD software. Macro observation and photographic documentation, chemical analysis, metallographic examination, hardness testing, Scanning Electron Microscope (SEM) examination on fracture surface, will follow to determine the root cause of failure. Furthermore finite element analysis is conducted for stress analysis purpose. Finally, the root cause of engineering failure would be illustrated by a 3-D visual demo module.

Engineering failure analysis system