Investigations
WELD SEPARATION
NHTSA Preliminary Evaluation PE09018 - closed, opened 2009-04-01.
NHTSA investigation PE09018 is a Preliminary Evaluation opened on 2009-04-01 and currently closed. The subject is tracked inside the Office of Defects Investigation queue. Latest activity on this investigation was logged on 2009-05-08 - NHTSA updates that field whenever an Information Request goes out, a supplement is filed, or a status change is recorded in the public docket.
A Preliminary Evaluation like PE09018 is the entry point of the federal defect-investigation process. NHTSA engineers scan complaint databases, field reports, and manufacturer data to decide whether an Engineering Analysis is warranted, whether a voluntary recall is already sufficient, or whether the pattern does not rise to a defect finding.
Investigators summarized the matter as follows: "THIS INVESTIGATION WAS OPENED AS THE RESULT OF A REPORT ALLEGING THAT AN ARTICULATING BUS OWNED BY THE CHICAGO TRANSIT AUTHORITY (CTA) HAD EXPERIENCED A WELD FAILURE AT THE ARTICULATION JOINT OF THE BUS. IN EARLY APRIL,..." Investigations are the early-warning layer of the federal auto-safety system, sitting upstream of formal recalls and defect orders. Whether this one closes without action or escalates into an Engineering Analysis, the full history stays in the ODI archive so researchers, litigators, and buyers can pull the paper trail at any time.
Investigation Summary
THIS INVESTIGATION WAS OPENED AS THE RESULT OF A REPORT ALLEGING THAT AN ARTICULATING BUS OWNED BY THE CHICAGO TRANSIT AUTHORITY (CTA) HAD EXPERIENCED A WELD FAILURE AT THE ARTICULATION JOINT OF THE BUS. IN EARLY APRIL, ODI AND VRTC ENGINEERS VISITED WITH THE CTA AND CONFIRMED THE FAILURE ALLEGATION. THE SEPARATION OF THE NABI ARTICULATING BUS WAS THE RESULT OF A WELD FAILURE THAT OCCURRED IN THE PARENT METAL OF THE ROLLED PLATE BRACKET. THE FRACTURE OCCURRED JUST BEYOND THE WELD LINE WHERE THE BRACKET IS WELDED TO THE ARTICULATING JOINT CASTING. THE FATIGUE FRACTURE APPEARED TO BE CAUSED BY TORSIONAL FORCE LOADING THROUGH THE JOINT CONFIGURATION. BENDING MOMENT FATIGUE INITIATED THE FRACTURE CAUSED BY FORE AND AFT ROTATIONAL LOADING THAT COULD BE GENERATED BY, AMONG OTHER FORCES, BOTH POSITIVE AND NEGATIVE WHEEL TORQUE (ACCELERATION AND BRAKING). A VISUAL EVALUATION OF THE SURROUNDING STRUCTURE SUGGESTS THAT SEVERAL WELDED MEMBERS FORM A BOX BEAM AND ARE INTENDED TO REACT TO THE TORQUE AND PREVENT THE MAIN STRUCTURAL WELD FROM BENDING, BUT THE UN-REINFORCED MATERIALS APPEAR TO BE INADEQUATE FOR THE FORCES GENERATED IN THIS APPLICATION. ON APRIL 16, 2009, NABI IDENTIFIED A DEFECTIVE WELDED CROSSMEMBER ASSEMBLY IN THE UNDERSTRUCTURE OF THESE BUSES. AFTER FURTHER EVALUATION, NABI DECIDED TO FILE A DEFECT REPORT WITH THE AGENCY. NABI WILL ARRANGE TO INSPECT AND REPAIR ALL AFFECTED BUSES, INCLUDING INSTALLATION OF ADDITIONAL REINFORCEMENT TO THE AFFECTED AREAS. THIS RECALL ACTION RESOLVES THE ISSUES RAISED BY THIS INVESTIGATION. ACCORDINGLY, THIS INVESTIGATION IS CLOSED.
About This Investigation Type
A Preliminary Evaluation (PE) is the first phase of NHTSA's investigation process. It is opened when the agency identifies a potential safety defect pattern, usually triggered by consumer complaints, manufacturer reports, or field monitoring. During a PE, NHTSA gathers information to determine whether a formal engineering analysis is warranted.
Data from NHTSA Office of Defects Investigation. Cross-references: NHTSA recall campaign API and NHTSA FARS where fatality records overlap. PlainCars does not rate or recommend vehicles. about how PlainCars sources NHTSA data.
Read our methodology - how this data is sourced, computed, and verified.