| Components - Details | |
|---|---|
| NHTSA Action Number: EA11011 | Vehicale/Equipment Name: STERLING |
| Vehicale/Equipment Model: L-LINE | Vehicale/Equipment Year: 2007 |
| Component Name: PARKING BRAKE:CONVENTIONAL:AIR | Manufacturer's Name: FREIGHTLINER LLC |
| Date Opened: Sep, 09 2011 | Date Closed: Sep, 25 2013 |
| Subject: Haldex Spring Brake Failures | Summary: Odi opened a preliminary evaluation (pe11-007) based on one fleet report alleging it had experienced multiple wheel-end fires involving the subject vehicles.the fleet believed the fires were due to a power spring fracturing and puncturing a brake chamber diaphragm resulting in a loss of compressed air to the brakes.the loss of air was believed to cause the brakes to drag and overheat.odi upgraded pe11-007 to this engineering analysis to further evaluate the cause of the wheel fires and assess the scope, frequency, and safety consequences of the alleged defect.after a comprehensive review of the data related to brake chamber failures or replacements on the subject vehicles, odi did not identify the existence of a safety related defect trend.of the two vehicle fires initially reported, only one was subjected to a fire investigation.the fire investigator in that case could not identify the component responsible for the vehicle fire.driver statements reviewed from one fleet which experienced two brake overheating events indicated that the vehicles had not been operating at normal air system pressure levels prior to the events.in addition, the failed or replaced chambers had been in service on average nearly 50 months.odi reviewed 477 warranty claims and fleet reports of brake chamber failure or replacement.from the data review, three (3) brake overheating incidents involving a subject size 24/30 failed brake chamber were identified.in reviewing the time in service for the overheating incidents, it was found that vehicles had an average of 50 months in service.this time in service represents a typical service life wear out.the injuries reported in the opening resume for this investigation are no longer being considered as having resulted from the alleged defect in the subject brake chambers.in the case of the smoke inhalation originally reported, the fire was not determined to have been caused by a failed brake chamber.in the case of the injuries that resulted while replacing a subject brake chamber, it was found that these chambers have a limited service life and are subject to wear out.as a result, brake chambers are replaced frequently and standard safety precautions should be followed during this maintenance procedure that would prevent any chamber being replaced from experiencing an uncontrolled release of the compressed spring.dtna has informed nhtsa that it will take the following action to further reduce the likelihood of subject component failures.dtna will offer owners of subject vehicles, equipped with the original size 211/212 chambers, a free replacement of the chambers.the chambers will be replaced with the more robust 003/004 sealed chambers.in light of the low rate of wheel end fires resulting from a premature failure of the power spring in the subject vehicles, and dtna's actions to reduce the likelihood of a failed brake chamber, further use of agency resources does not appear to be warranted.the closing of this investigation does not constitute a finding by nhtsa that no safety-related defect exists.the agency reserves the right to take further action if warranted by the circumstances.for additional information, see the attached closing report. |
