S21AZ
June 10, 2021

To:

Affected Blue Bird Dealers

Subject:

S21AZ, Ford 6.8L Air Compressor Belt

Models Affected:

Model Year:
Model:

Bulletin Duration:

One (1) Year from Date of Issue

Certain 2013 through 2022
Vision School Bus and Non-School Bus

Overview:
Certain 2013 through 2022 model year Blue Bird Vision School and Non-School Bus units has
experienced signs of single strand failing, leading to multiple stands, and eventually belt failure. The belt
composition is not ideal for the life cycle of the bus.
This Service Bulletin will provide owners with a one-time new replacement belt with the more durable
material that is currently being used in production and for service. This Service Bulletin is for part cost
coverage only. No labor reimbursement will be provided.
Affected Units:
Blue Bird Body Company is voluntarily issuing a service bulletin for the following:
 Certain model year 2013 through 2022 Blue Bird Vision School Buses
o manufactured from January 10, 2012 through February 26, 2021
 Certain model year 2013 through 2022 Blue Bird Vision Non-School Buses
o manufactured from November 20, 2012 through November 19, 2020
A separate printout will be provided listing all buses in your territory that are affected by this service
bulletin. Be sure to review your list and advise of any incorrect owner names and/or addresses. Parts
should be ordered through Blue Bird Service Parts.
Repair Parts:
The Parts List outlined in the S21AZ Instructions details the part required to perform Service Bulletin
S19AZ and should be ordered through Blue Bird Service Parts. The belt is based on the engine
generation. Parts are currently available.
Time Allowance:
No labor will be provided to replace the belt with a more durable material belt, per the published
Service Bulletin instructions.

BLUE BIRD BODY COMPANY
P.O. Box 937 – 402 Blue Bird Blvd – Fort Valley, Georgia – (478) 825-2021

Blue Bird Body Company
Page 2

Bulletin Duration:
This Service Bulletin ends one (1) year from date of issue.
Questions:
Questions regarding this bulletin should be directed to your Blue Bird Field Service Engineer.
Regards,

Lisa Hancock
Corporate Recall Administrator
Blue Bird Corporation
3920 Arkwright Road, Suite 200, Macon, Georgia 31210
Phone 478.822.2242
[email protected]

S21AZ

Service Bulletin

S21AZ Ford 6.8L Air Compressor Belt

Models Affected: Certain Blue Bird 2013-2022 Model Year 6.8L Ford Powered Vision Buses
Issue: Certain Units Have Experienced Premature Life of the 3rd Sheave Air Compressor Belt
Corrective Action: Replace Belt with Improved Design
Parts Needed: (Based on engine generation)
Part Number

Description

Quantity

10073619

BELT, DRIVE, FORD 6.8L, AIR COMPRESSOR, GEN 3, CV

1

10072825

BELT, DRIVE, FORD 6.8L, AIR COMPRESSOR, GEN 4, CV

1

WARNING: Always follow all Federal, State, Local and Shop safety standards and use proper safety equipment, and thoroughly read and understand all instructions before performing these procedures.
Park bus on level surface, apply parking brake, turn off ignition key, and chock wheels.
NOTE: Photo below is Gen 4, which is identified by the solid compressor pulley. Gen 3 will have a spoked pulley. Failure to install the correct belt will result in pre-mature failure.
Tools Needed:
 Ribbed or serpentine belt tool with 3/8” square drive adapter
 Side cutters
 HD ty-wrap
 12’ crescent wrench

1. Relieve 2nd sheave belt tension by rotating tensioner clockwise by engaging a ribbed belt tool with a 3/8” square drive adapter, then remove 3rd sheave belt.

Service Bulletin

S21AZ Ford 6.8L Air Compressor Belt

2. Rotate the compressor pulley to where one of the two holes arrives at the 11:00 position. Loop compressor belt over the 2nd to 3rd sheave adapter and place compressor belt over the top of the air compressor pulley.
3. Ty-wrap into place.

4. Rotate compressor pulley clockwise to seat belt and cut and remove ty-wrap.
5. Re-install 2nd sheave belt.
6. Start engine and verify proper operation.