Step 1. With the test item in the chamber and stabilized at standard ambient temperature, adjust the air velocity to 8.9 + 1.3 m/s (1750 + 250 ft/min), or as otherwise determined from the test plan. Step 2. Adjust the dust feed control for a dust concentration of 10.6 ± 7 g/m3 (0.3 + 0.2 g/ft3) Step 3. Unless otherwise specified, maintain the conditions of Steps 1 and 2 for at least 6 hours. If required, periodically reorient the test item to expose other vulnerable faces to the dust stream. SEE THE ABOVE WARNING NOTE REGARDING HEALTH HAZARDS. Step 4. Stop the dust feed. (See paragraph 4.1.1.7.) Reduce the test section air velocity to approximately 1.5 +1 m/s (300 + 200 ft/min) and adjust the temperature to the required high operational temperature (see paragraph 4.1.1.1), or as otherwise determined from the test plan. Step 5. Maintain the Step 4 conditions for a minimum of 1 hour following test item temperature stabilization. Step 6. Adjust the air velocity to that used in Step 1, and restart the dust feed to maintain the dust concentration as in Step 2. Step 7. Continue the exposure for at least 6 hours or as otherwise specified. If required, operate the test item in accordance with the test plan. If the test item fails to operate as intended, follow the guidance in paragraph 4.2.3.3.2. Otherwise proceed to Step 8. Step 8. Stop the dust feed and allow the test item to return to standard ambient conditions at a rate not to exceed 3°C/min (5°F/min). Stop any air flow and allow the dust to settle (possibly up to 12 hours). Step 9. Remove accumulated dust from the test item by brushing, wiping, or shaking, taking care to avoid introduction of additional dust or disturbing any that may have already entered the test item. Do NOT remove dust by either air blast or vacuum cleaning unless these methods are likely to be used in service. Step 10. Perform an operational check in accordance with the approved test plan, and document the results for comparison with pretest data. See paragraph 5.1 for analysis of results. Step 11. Inspect the test item for dust penetration, giving special attention to bearings, grease seals, lubricants, filters, ventilation points, etc. Document the results.