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U.S. Department of Labor

Mine Safety and Health Administration
201 12th Street South, Suite 401
Arlington, VA 22202-5450

EFFECTIVE DATE:   April 1, 2011 EXPIRATION DATE: 3/31/2024         
LAST VALIDATED: 03/31/2021


FROM:             KEVIN G. STRICKLIN  
                       Administrator for
                       Coal Mine Safety and Health

                      LINDA F. ZEILER
                      Acting Director of Technical Support

SUBJECT:     Approval Plate for Caterpillar Model 3306 PCNA Diesel Engine

This Program Policy Letter (PPL) affects underground coal mine operators using diesel-powered equipment, miners and miners' representatives, and Coal Mine Safety and Health (CMS&H) enforcement personnel.

This PPL clarifies that Caterpillar Model 3306 PCNA diesel engines installed in permissible equipment bearing approval plates (7E-B003) are approved for use in permissible equipment even though the approval plates indicate the engines are approved only as Category B (nonpermissible) engines.

Caterpillar Model 3306 PCNA diesel engines are approved by the Mine Safety and Health Administration (MSHA) under Part 7, Subpart E as both a Category A and B approved engine. Mechanically, there is no difference in the construction and performance of the basic engine. MSHA will permit the use of a Model 3306 PCNA engine that has a Category B approval tag affixed to it to be used in a permissible machine. The gaseous ventilation quantity specified for the Category A approval must be used as required under 75.325(f) through (k) and the Category A gaseous ventilation quantity must be stamped on the permissible machine's approval plate. The ventilation quantity for a Category A, Model 3306 PCNA engine is 9,500 cubic feet per minute.

Part 75.1907(b)(5) states that permissible diesel-powered equipment manufactured on or after November 25, 1999, shall incorporate a power package approved in accordance with Part 7, Subpart F. A Part 7, Subpart F power package must incorporate a Part 7, Subpart E, Category A diesel engine and have a Category A engine approval plate affixed to the engine. The Caterpillar Model 3306 PCNA diesel engines are approved under Part 7, Subpart E as both a Category A and B engine. Some Model 3306 PCNA engines have been installed in permissible machines that have a Category B tag affixed to the engine. Except for the gaseous ventilation rate and particulate index assigned to the engine, there is no mechanical difference between the two engines.

Since the Model 3306 PCNA engine is no longer in production, this tagging issue only affects the current engine inventory. In the past, Caterpillar customers ordered an engine based on an "arrangement number." The arrangement number for the Category A engine includes a water-cooled exhaust manifold. However, many power package manufacturers do not use the Caterpillar water-cooled exhaust manifold for their Subpart F approval. Consequently, a Category B approval tag was affixed to the engine by Caterpillar when customers ordered the Model 3306 PCNA without the water-cooled exhaust manifold.

The Federal Mine Safety and Health Act of 1977 and 30 C.F.R. §§7.82, 7.90, 7.98, 75.1907, and 75.325.

Internet Availability
This program policy letter may be viewed on the Internet by accessing MSHA's home page at ( and choosing Compliance Info then "Program Policy Letters."

Issuing Office and Contact Person
Mine Safety and Health Enforcement, Safety Division
Rodney Adamson, (202) 693-9549

Technical Support, Approval and Certification Center
Jeffrey Moninger, (304) 547-2324

MSHA Program Policy Manual Holders
Miners' Representatives
Coal Mine Operators
Manufacturers of Mine Equipment
Special Interest Groups