Abnormal ingression of contaminant into the lube system or accelerated lube system component wear can lead to premature loading of lubrication filter elements, resulting in filter element bypass in a conventional filtration system. In order to prevent unfiltered lubricant circulating through the system, many engine manufacturers/operators require shutdown of the engine in flight (IFSD) on indication of filter element bypass. False indication of filter element bypass due to a faulty indication system can also result in unnecessary in-flight engine shutdown. An IFSD can lead to interruption or abortion of the flight, jettisoning of fuel, engine maintenance, and in extreme cases, engine replacement. Associated costs could be as high as $500,000.

In order to address the above, Pall has developed a dual-stage lube filtration system, comprised of a secondary back-up filter element in series with the primary filter element. The secondary filter element provides an acceptable level of filtration in the event of primary filter element bypass, and in-flight engine shut down is not required for engines incorporating the dual-stage filtration system. By preventing IFSDs associated with lube filter element bypass, the dual-stage system prevents disruption of flight schedules and unnecessary maintenance, resulting in substantial cost savings to operators.

The high-performance turbine engines in military aircraft experience buildup of carbonaceous fuel breakdown products in the hot sections of the engines. To help reduce this buildup, a new class of jet fuels (JP8 +100) incorporating a detergent/dispersant additive was developed. The JP8 +100 fuel, while reducing aircraft maintenance, tends to disarm conventional coalescers. Thus "free water" contamination cannot be effectively removed from the fuel.

Pall, working with the U.S. Air Force, U.S. Navy, and a leading aircraft engine manufacturer, has developed coalescer technology which removes "free water" from JP8 +100 fuel without becoming disarmed. Pall is also serving on the standards committees responsible for specifying performance of fuel coalescers.

Pall engages in application research with equipment manufacturers, military government agencies, and universities. The goal of these efforts is to improve filtration technology in order to provide improved fluid system performance for the industry. Some of these projects include:

Investigation of Fine Filtration for Turbofan Engine Lube Systems

This study was undertaken, in conjunction with a large aircraft engine manufacturer, to investigate the feasibility of introducing finer filtration (rated in the 3 -12 micron range) in the lube system of a large commercial turbofan engine. The results showed that incorporating finer filtration in the turbofan is feasible and will result in improved fluid cleanliness levels. This, in turn, could provide reduced particle induced wear of bearings and other lube system components, and hence, lube system reliability improved.

Impact of Fine Filtration on Bearing Life

Pall worked with both NASA and the Imperial College of London on two separate studies which focused on the detrimental effects of contamination on bearing life and the optimal filtration level for maximizing bearing life.

Cabin Air Quality

In conjunction with a large aircraft manufacturer, Pall modeled cabin airflow and measured resulting contamination with different levels of filtration. This was then compared to 100% fresh air systems. Results showed that Pall high-efficiency cabin air filters provide the microbial equivalent of fresh air.

Flight Evaluation of Improved Contamination Control in Hydraulic System

In an effort to improve contamination control in hydraulic systems, Pall is currently working with several major airlines to evaluate finer hydraulic system filtration and on-line sampling.

Filtration to Control Contamination in Engine and APU Pneumatic Systems

Particulate contamination in engine and APU bleed air systems is known to cause pneumatic system component malfunction. Pall is currently participating in an investigation to evaluate the nature of contamination in engine and APU pneumatic systems and the optimal filtration for contamination control in these systems.

Establishing Standards with ASHRAE and SAE

Pall is a member of the ASHRAE Committee which is tasked with establishing standards for air quality in aircraft cabins. The committee is also working with Harvard University to find ways passengers can be protected from the spread of viruses while breathing cabin air.

Pall is also a standing member of SAE. The SAE aerospace committees are responsible for establishing performance and materials standards for aircraft and engine systems. Pall is a key participant in the various SAE subcommittees and task forces involved in filtration technology and contamination control. For example, working with the SAE A-6 committee, Pall is writing new standards for improved hydraulic fluid sampling. This is part of a program to improve contamination control in order to increase hydraulic system reliability.