BLUE BIRD CORPORATION Download PDF Report
Blue Bird Corporation submitted a model Ultra LF, diesel-powered 31 seat 9including the driver) 35-foot bus, for a 12 yr/500,000 mile STURAA test. The odometer reading at the time of delivery was 9,555 miles. Testing started on March 11, 2003 and was completed on March 10, 2004. The Check-In section of the report provides a description of the bus and specifies its major components.
The primary part of the test program is the Structural Durability Test, which also provides the information for the Maintainability and Reliability results. The Structural Durability Test was started on March 24, 2003 and was completed on February 23, 2004.
The interior of the bus is configured with seating for 31 passengers including the driver. Free floor space will accommodate 35 standing passengers resulting in a potential load of 66 persons. At 150 lbs per person, this load results in a measured gross vehicle weight of 30,020 lbs. In order to avoid exceeding the GAWR (10,000 lbs) of the front axle and (18,695 lbs) of the rear axle, ballast for twelve standing passengers was eliminated. This reduction from full capacity resulted in an adjusted measured gross vehicle weight of 28,620 lbs and was used for all dynamic testing. The middle segment was performed at a seated load weight of 24,900 lbs and the final segment was performed at a curb weight of 20,390 lbs. Durability driving resulted in unscheduled maintenance and failures that involved a variety of subsystems. A description of failures, and a complete and detailed listing of scheduled and unscheduled maintenance is provided in the Maintainability section of this report.
Accessibility, in general, was adequate, components covered in Section 1.3 (Repair and/or Replacement of Selected Subsystems) along with all other components encountered during testing, were found to be readily accessible and no restrictions were noted.
The Reliability section compiles failures that occurred during Structural Durability Testing. Breakdowns are classified according to subsystems. The data in this section are arranged so that those subsystems with more frequent problems are apparent. Also the problems also are listed by class as defined in Section 2. The test bus encountered no Class 1 or Class 2 failures. Of the seventy-two reported failures, fourty-one were Class 3 and thirty-one were Class 4. Note; since the completion of testing, it has been determined by Blue Bird and BTC personnel, that twenty-four of the twenty-seven Class 3 failures (broken shock studs & bolts) were due to improper installation of the front shock mounts. This reduced the amount of shock travel by approximately 2 inches.
The Safety Test, (a double-lane change, obstacle avoidance test) was safely performed in both right-hand and left-hand directions up to a maximum test speed of 45 mph. The performance of the bus is illustrated by a speed vs. time plot. Acceleration and gradeability test data are provided in Section 4, Performance. The average time to obtain 50 mph was 31.34 seconds.
The Shakedown Test produced a maximum final loaded deflection of 0.253 inches with a permanent set ranging between 0.000 to 0.004 inches under a distributed static load of 24,750 lbs. The Distortion Test was completed with all subsystems, doors and escape mechanisms operating properly. Water leakage was observed during the test at the 2nd, 3rd and rear windows on the left side and the 3rd window on the right side.
The Static Towing Test was performed using a target load (towing force) of 24,468 lbs. All four front pulls were completed to the full test load with no damage or deformation observed. The test bus was not equipped with rear tow eyes or tow hooks, therefore, a rear tow was not performed. The Dynamic Towing Test was performed by means of a front-lift tow. The towing interface was accomplished using a hydraulic under-lift wrecker. Clearance between the towing equipment and the steering linkage was limited, yet could be accomplished with no damage. The bus was towed without incident and no damage resulted from the test. The manufacturer does not recommend towing the bus from the rear, therefore, a rear test was not performed. The Jacking and Hoisting Tests were also performed without incident. The bus was found to be stable on the jack stands, and the minimum jacking clearance observed with a tire deflated was 3.7 inches.
A Fuel Economy Test was run on simulated central business district, arterial, and commuter courses. The results were 4.65 mpg, 5.08 mpg, and 9.15 mpg respectively; with an overall average of 5.56 mpg.
A series of Interior and Exterior Noise Tests was performed. These data are listed in Section 7.1 and 7.2 respectively.