Porosity Machine (Item 33, WP 0063 00)  92R (10) Parachute Rigger  Layout on packing table or other suitable area.  UNIT MAINTENANCE  MC-4 RAM AIR FREE-FALL PERSONNEL PARACHUTE SYSTEM  POROSITY PROCEDURES  THIS TASK COVERS:  INITIAL SETUP:  Tools Personnel Required  Equipment Condition •  Inspection  1.  The following techniques and standards have been provided to summarize and/or clarify the desired  design characteristics regarding factors deemed important to the inflation reliability of military ram air  canopies. These standards are intended to assist military riggers responsible for the inspection and  maintenance of ram air personnel parachutes in the identification of canopies, which possess  characteristics, which have been associated with non-airworthy canopies.  POROSITY INSPECTION CRITERIA  0048 00  TM 10-1670-287-23&P  2. Where none had previously existed, tolerances are added to standards, which are intended to define  the maximum acceptable limits of deviation from these desired characteristics. A point system was  devised which will be used to determine the degree of compliance of a particular canopy to the  desired design characteristics. This point scoring system appropriately prioritizes and emphasizes  the issues affecting inflation reliability and general canopy airworthiness. Although a canopy may not  exceed any of the established tolerances, the cumulative effect of multiple minor deviations may also  condemn a canopy. 3.  These procedures are intended to assist the inspecting rigger in identifying canopies, which may  exhibit non-airworthy characteristics. The below procedures will be added to the current standard  inspection criteria and be conducted during in-servicing, every year for land rigs, every five (5) jumps  or one year for water rigs (whichever comes first), and when canopies exhibit poor performance  characteristics during deployment, flight, and/or landing. When a canopy exhibits non-airworthy  characteristics and a permeability-testing machine is not available, the canopy will be removed from  service regardless of the remaining service life.  4.  These procedures apply exclusively to the MC-4, however, the MTl-X, and MTl-S model canopies are  also considered within the family of Ram-Air Personnel Parachute Systems (RAPPS). The  procedures, techniques and parameters are as follows:  a.  Procedure number 1. Fabric Permeability Test:  (1) This procedure requires use of a permeability-testing machine. The machine should be  calibrated and operated in accordance with the manufacturer’s specifications. Record  permeability measurements at a 0.5-inch (water) pressure head (vacuum) differential.  NOTE Testing the fabric along the nose of the top surface is intended to  characterize a canopy’s ability to inflate in a reasonable period of  time. Users are encouraged to test other areas of the canopy to  identify sources of other flight performance problems. For example,  high permeability readings in the tail section may be indicative of a  reduction in flair maneuver performance. If certain sections have  unusually high readings, the rigger should use his/her judgment as  to what corrective action needs to be taken. Change 1  0048 00-1 