NHTSA Office of Defects Investigation
Preliminary Evaluation PE11-029: Thomas Built CNG Tank Abrasion
- Closed
NHTSA's Office of Defects Investigation opened Preliminary Evaluation PE11-029 on September 2, 2011 and closed it on February 17, 2012. NHTSA's investigations file lists the 2003–2011 Thomas Built Buses SAF-T-Liner HDX for it.
Updated daily from NHTSA's investigations file
Key facts
- NHTSA number
- PE11-029 (also written PE11029)
- Investigation type
- Preliminary Evaluation The first stage of most defect investigations: NHTSA's Office of Defects Investigation gathers basic information about a possible safety defect, including from the manufacturer.
- Status
- Closed February 17, 2012
- Opened
- Closed
- Vehicle or equipment manufacturers
- FREIGHTLINER LLC; Daimler Trucks North America, LLC
- Components
- Fuel System, Other — Storage; Fuel System, Other — Storage — Tank Assembly
- Vehicles and equipment
- 2003–2011 Thomas Built Buses SAF-T-Liner HDX
A recall appears here only when NHTSA's investigations file links one to the investigation; NHTSA's summary or record can name others.
NHTSA's summary
As NHTSA's Office of Defects Investigation wrote it for Preliminary Evaluation PE11-029.
On August 29, 2011 ODI received a Vehicle Owner's Questionnaire (VOQ) from a Los Angeles school district indicating a 2003 Thomas Built Saf-T-Liner HDX compressed natural gas (CNG) school bus in their fleet had insufficient clearance between the CNG tank and mounting bracket resulting in damage to the outer tank wrapping.
The Mathematical Analysis Division of NHTSA calculated that a sample size of thirty (30) buses would give a high confidence (90%) estimation of whether similar buses were experiencing tank abrasion.
In the course of this investigation nearly 70 buses (over 300 tanks) were inspected; no tank other than the subject of the VOQ was found to have insufficient clearance.
Busses manufactured before and after the subject vehicle were inspected.
As a result of this investigation, Daimler Trucks North America (DTNA) developed an improved inspection procedure that addresses the concerns identified in the Los Angeles complaint.
In early February 2012 DTNA will mail an owner letter along with the new inspection procedure.
See the investigative file for copies of DTNA's bulletin and owner letter.
This preliminary evaluation is closed.
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 circumstances.
The ODI report cited above can be reviewed at www-odi.nhtsa.dot.gov/owners/SearchNHTSAID under the following identification (ODI) number:10423400
Vehicles and equipment listed for this investigation
NHTSA's investigations file lists these vehicles and equipment for Preliminary Evaluation PE11-029. A listed model year means only that an investigation names it; it says nothing about any particular vehicle. Model years with a try.vin recall page link to that page's NHTSA investigations section.
What an NHTSA investigation is
NHTSA's Office of Defects Investigation (ODI) looks into possible safety defects in vehicles and equipment, often after owner complaints. An investigation usually starts as a Preliminary Evaluation, or as a Recall Query when it concerns whether an existing recall covers the right vehicles or fixes the problem, and ODI can upgrade it to a more detailed Engineering Analysis. A Defect Petition asks NHTSA to open an investigation, and Audit and Equipment Queries are administrative investigations into whether companies complied with federal vehicle safety requirements, such as reporting, recall and certification rules.
An open investigation is not a finding that a safety defect exists, and NHTSA can close one without a recall.
To see whether a specific vehicle has an open recall, enter its VIN at nhtsa.gov/recalls.
Free VIN check: decode a VIN to see its year, make and model.
Sources
NHTSA's investigation record for PE11-029
Investigation details come from NHTSA's investigations file, which try.vin imports once a day. The investigation types are described from the U.S. Department of Transportation Inspector General's May 2023 report on NHTSA's Office of Defects Investigation, NHTSA's petition rules (49 CFR Parts 552 and 557) and NHTSA's Office of Defects Investigation procedures. How try.vin reads NHTSA investigations.