Preliminary Requirements

Safety Requirements

WARNING

IT IS THE RESPONSIBILITY OF THE OPERATOR TO OBTAIN AND OBSERVE THE MANUFACTURER'S MATERIAL SAFETY DATA SHEETS FOR CONSUMABLE MATERIALS. THESE CONTAIN INFORMATION SUCH AS, HAZARDOUS INGREDIENTS, PHYSICAL/CHEMICAL CHARACTERISTICS, FIRE, EXPLOSION, REACTIVITY, HEALTH HAZARD DATA, PRECAUTIONS FOR SAFE HANDLING, USE AND CONTROL MEASURES, AND ALSO TO TAKE LOCAL REGULATIONS INTO CONSIDERATION.

Procedure

1. SUBTASK 70-12-11-300-001 Dry Abrasive 500 Grit Blast Procedure

   1. 

      CAUTION

      SURFACE TREATMENT (SUCH AS, ABRASIVE BLASTING), IF NOT DONE CORRECTLY, CAN CAUSE A SMEARED SURFACE. THIS MAKES SURFACE DEFECTS NOT EASY TO FIND DURING NON-DESTRUCTIVE INSPECTIONS. DIFFERENT MATERIAL AND PROCESSES WILL SHOW DIFFERENT EFFECTS. THUS IT IS VERY IMPORTANT TO FOLLOW VERY CAREFULLY THE INSTRUCTIONS IN THE STANDARD PRACTICES/PROCESSES MANUAL AND ENGINE MANUAL. IF CAREFULLY DONE, THE APPROVED NON-DESTRUCTIVE INSPECTION (ESPECIALLY FLUORESCENT PENETRANT INSPECTION) WILL CONTINUE TO HAVE RESULTS THAT ARE VERY ACCURATE.

      

      CAUTION

      IT IS NOT PERMITTED TO MIX THE VARIOUS BLASTING MEDIA.

      

      CAUTION

      THE USE OF ALTERNATIVE SIZE MEDIA OR MATERIAL TO THOSE SPECIFIED IN THE PROCEDURE IS NOT PERMITTED.

      

      CAUTION

      THE BLASTING CABINET AND MEDIA USED IN THIS PROCEDURE ON ENGINE PARTS MUST NOT BE USED TO STRIP CADMIUM PLATED PARTS OR CADMIUM PLATED/PAINTED PARTS, SUCH AS LANDING GEAR.

      

      CAUTION

      THIS PROCEDURE IS NOT APPROVED FOR CLEANING OR STRIPPING TITANIUM PARTS.

      

      CAUTION

      THIS PROCEDURE IS NOT APPROVED TO PREPARE SURFACES FOR BRAZING. REFER TO 70-31-20-310-501 TO PREPARE PART FOR BRAZING.

      Aqueous degrease the part, if necessary, (Refer to SPM TASK 70-11-03-300-503).

   2. 
      CAUTION
      ALWAYS APPLY MASKING TAPE OR INSTALL THE SPECIAL GUARDS TO THE COMPONENT SURFACES WHICH ARE NOT TO BE BLASTED. DO THIS BEFORE YOU BLAST THE COMPONENT. MAKE SURE NO BLASTING MEDIA GOES INTO THE COMPONENT AND BECOMES CAUGHT.

      Mask the part.

      1. Apply masking material to the part, as necessary, to make sure abrasive grit does not become caught in the part.

      2. Use CoMat 02-348 AIRSEAL MASK to protect plasma coated knife edges.

         1. If the CoMat 02-348 AIRSEAL MASK is not sufficient to give the knife-edge airseal protection from the abrasive blast, install the CoMat 02-348 AIRSEAL MASK on the knife-edge airseal, and then apply a cover of masking tape from SPM TASK 70-34-18-380-501.

   3. 
      CAUTION
      IF THE BLAST STREAM STAYS (DWELLS) FOR TOO LONG ON AN AREA OF THE PART, THERE WILL BE UNWANTED EROSION (MATERIAL REMOVAL) IN THAT AREA, WHICH CAN CAUSE PART FAILURE OR DAMAGE THAT IS NOT POSSIBLE TO REPAIR.

      Abrasive blast to remove oxides with CoMat 05-156 ALUMINUM OXIDE ABRASIVE. Use the subsequent parameters:

      1. Nozzle to part distance: 3 in. to 4 in (76 mm to 102 mm).

      2. Angle to work surface: 45 deg to 60 deg.

      3. Air pressure:

         1. Pressure-type machine: 25 lbs/sq in to 30 lbs/sq in (170 kPa to 210 KPa).

         2. Suction-type machine: 50 lbs/sq in 60 lbs/sq in (340 kPa to 420 KPa).

      4. Blast time:

         1. NOTE

            Two seconds is the maximum total time that is usually necessary for the abrasive blast to clean the part.

            Do not let the blast stream dwell for more than two seconds (that is, do not point the blast stream at an area for more than two continuous seconds). Use continuous movement of the nozzle to make sure that the blast stream hits equally all areas where it is necessary to blast.

   4. Blow clean with compressed air.

   5. Remove the mask.

   6. Visually inspect the parts to make sure all the blasting residue has been removed. Repeat as necessary to remove any residual residues.

   7. Apply temporary corrosion preventives, as necessary. Refer to SPM TASK 70-38-37-100-501.