operation of the truck, nor with normal movements of the operator, when
wearing an appropriate helmet, when entering, leaving or operating the truck.
The overhead guard shall remain firmly secured to its support brackets under
all operating conditions specified herein.
3.21 seat. The seat shall conform to the requirements of SAE J899 except
armrests are not required.
3.22 Rearview mirror. When specified (see 6.2), the truck shall be
equipped with the rearview mirror mounted on the left hand side within the
operator's field of view.
3.23 Exhaust emission requirements for clean bum diesel engine. When
clean burn diesel engine is specified (see 6.2), exhaust emission constituents
shall not exceed the limits set forth below when tested in accordance with
applicable exhaust emission test paragraph of section 4. These emission tests
shall be conducted with a fuel delivery system identical to and calibrated to
give the same fuel delivery rate as the production engine used to demonstrate
conformance to the endurance requirement (see 3.6.16) and to the cold start
requirement (see 3.5). The diesel engine as provided by the manufacturer
shall be capable of satisfying the exhaust emission requirements without the
use of a catalytic convertor, trap oxidizer, water scrubber or other type of
exhaust gas processor with the exception that a mechanical spark arrestor
which meets requirements of Forest Service Standard 5100-la shall be provided.
The spark arrestor shall be sized to meet requirements for engine exhaust flow
at rated engine speed in accordance with Forest Service Standard 5100-la.
However, the spark arrestor shall not be installed during emission testing.
3.23.1 Brake specific exhaust emission of hydrocarbons (HC). carbon
monoxide(CO) and nitric oxides (NOx). When tested in accordance with
220.127.116.11.1, the brake specific exhaust emission of HC shall not exceed 0.5
grams/brake horsepower (g/bhp-hr); CO shall not exceed 5.0 g/bhp-hr; and NOx
shall not exceed 6.0 g/bhp-hr.
3.23.2 Total suspended articulate (TSP). When tested in accordance with
18.104.22.168.2, the TSP shall not exceed 15 grams/hour (g/hr) for 3, 4, 10 and 11
modes of the 13 mode Federal Test Procedure.
3.23.3 Steady state smoke opacity (SSSO). When tested in accordance with
22.214.171.124.3, the SSS0 shall not exceed 5 percent for any mode of the 13 mode
Federal Test Procedure excluding the high load modes of 5, 6, 8, and 9.
3.24 Noise limits. Noise levels produced by the truck shall comply with
the requirements of MIL-STD-1474, except as indicated herein.
The noise level at the operator's position and at 3.28 feet (one
meter) from the perimeter of the truck at all other locations shall
not exceed Category D of table I (85 dB(A)). MIL-STD-1474, 126.96.36.199,
5.2, 5.3, and 5.4 shall not apply. Compliance and non-compliance
with the required noise limits shall be documented based upon test