This SAE Aerospace Recommended Practice (ARP) describes the multi-pass method for evaluating the filtration performance of fine lube filter elements, commonly utilized in aerospace power and propulsion lubrication systems: gas turbine engines, auxiliary power units (APUs), helicopter transmissions, constant speed drives (CSDs), and integrated drive generators (IDGs).
The document is being revised as follows: (1) Notation included that the ISO 4402 reference in 2.3 has been withdrawn. (2) Para. 5.3.3 specifies a new level of cleanliness, more stringent than the original cleanliness level. (3) In Table 1, filter element rating changed from 1000 to 200 for reliable accuracy of filter element rating. (4) Para. 6.3.3 now includes the instruction to clean the fluid as it is more appropriate to have this instruction be a part of this step, as opposed to being a part of 6.3.2. (5) Para. 6.3.5 now includes the instruction to bypass the clean-up filter element. (6) Validation counts in Table 2 updated based upon the results of the ‘ISO Fine Test Dust (ISO FTD) Particle Count Mini-Round Robin’ conducted by ISO, which is more representative of recent lots of ISO FTD. (7) Volume in 220.127.116.11 changed from 500 mL to 100 mL as the larger volume is not necessary given the high gravimetric levels. (8) New 18.104.22.168 inserted which requires a gravimetric analysis be performed on the injection fluid sample collected in 22.214.171.124, prior to performing the multi-pass test, in order to confirm the concentration of the contaminant injection system prior to performing the test. (9) Adjusted the numbering of the paragraphs in 6.4.3 accordingly. (10) Changed the volume in the newly numbered 126.96.36.199 from 500 mL to 100 mL as the larger volume is not necessary given the high gravimetric levels. (11) Included a notation after 188.8.131.52 discussing the necessity of deleting upstream and downstream counts prior to count stabilization. (12) Editorial changes for clarity.