Freightliner Custom Chassis Corp. submitted a model MB 55, CNG-powered 25 seat including the driver), 31-foot bus, for a partial STURAA test in the 10 yr/350,000 mile category. The Federal Transit Administration determined that 1.3 Removal and/or Replacement of Selected Subsystems need not be performed.  The odometer reading at the time of delivery was 92.0 miles.  Testing started on August 31, 2005 and was completed on March 10, 2006.  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 August 31, 2005 and was completed on March 1, 2006.

The interior of the bus is configured with seating for 25 passengers including the driver. Free floor space will accommodate 15 standing passengers resulting in a potential capacity of 40 persons.  Note: the bus submitted for testing was not equipped with a handicap device.  At 150 lbs per person, this load results in a measured gross vehicle weight of 22,330 lbs. The first segment of the Structural Durability Test was performed with the bus loaded to a gross vehicle weight of 22,330 lbs.  The middle segment was performed at a seated load weight of 20,160 lbs and the final segment was performed at a curb weight of 16,740 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 are 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), were found to be readily accessible and no restrictions were noted.  Difficulty was encountered accessing the oil filler tube and the coolant filler hole.             

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. The problems are also listed by class as defined in Section 2.  The test bus encountered no Class 1 or Class 2 failures. Of the 32 reported failures, 22 were Class 3 and ten were Class 4.

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 29.19 seconds.

The Shakedown Test produced a maximum final loaded deflection of 0.209 inches with a permanent set ranging between -0.003 to 0.004 inches under a distributed static load of 15,000 lbs. The Distortion Test was completed with all subsystems, doors and escape mechanisms operating properly.  Water leakage was observed during the test at the left rear emergency window & 2nd window, right side are leaking at the window frames.  

The bus submitted for testing was not equipped with any type of tow eyes or tow hooks, therefore, the Static Towing Test 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.  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 12.3 inches.

A Fuel Economy Test was run on simulated central business district, arterial, and commuter courses. The results were 0.60 M/lb, 0.71 M/lb, and 1.21 M/lb respectively; with an overall average of 0.74 M/lb.

A series of Interior and Exterior Noise Tests was performed. These data are listed in Section 7.1 and 7.2 respectively.


Number: 0515
Vin Number: 4UZAACB325CV77432