Wednesday, December 5, 2007 - 9:00 AM

Effects of Lubrication of LRU Electrical Connectors-Recent Flight Test Results on F16 Aircraft

William H. Abbott, Battelle Columbus

Extensive work has been done in recent years to evaluate the effectiveness of specific Corrosion Prevention Compounds (CPCs) applied to LRU electrical connectors for the purpose of reducing CNDs, RETOKs, and eventual removals of LRUs from aircraft. This practice has long been allowed according to T.O. 1-1-689.  However, it has seldom been adopted due, in part, to the absence of good supporting technical data describing benefits vs. risks.  LRU removals may lead to a considerable expense in the event that the LRUs are returned to depot for repair.  One mechanism by which such faults may occur could be termed a subtle form of corrosion on the connector contact surfaces.  Thin films may form over time which can be at thicknesses below the limits of visible detection.  In theory and in practical experience such films which are inherently insulators may give rise to intermittent contact to produce the classical CNDs and often sudden failure without warning.  The fact that such films can often not be observed often presents a problem to many maintenance personnel and the casual observer.  One consequence from this fact that is often stated is that connector corrosion “does not occur at our base”.  As a result it is seldom, if ever, recorded in military databases such as REMIS (Air Force).

Studies have been conducted to explore the effectiveness of CPCs/lubricants as an inexpensive means of reducing such failures.  Extensive ground and laboratory tests conducted at Battelle and reported elsewhere have been conducted on all of the CPCs on the QPLs for MIL-C-81309E and MIL-L-87177A.  It was concluded that very few of these materials would exhibit performance characteristics judged to be totally free of known risks for use on electronic/electrical connectors.  When this work was started in the late 90’s, the conclusion was that no more than 3 of these CPCs were suitable for these applications.  With this information now available, two CPCs were selected for initial flight tests using the F16 aircraft as the primary test platform.  Those CPCs were 1) Zip Chem D5026-NS (MIL-C-81309E) and 2) Lektro Tech 87177A/Super Corr B (MIL-L-87177A).  Both of these materials were judged to be technically equivalent in performance with no known engineering risk.  Early flight tests proved this to be the case and with very positive results in terms of reduced LRU removals.

Subsequent to this early work one of these materials (Super Corr B) was changed to provide a more environmentally suitable organic carrier/solvent. As a result, a request was made from Hill, AFB for the laboratory evaluations to be repeated using the new version known as Super Corr A.  This was followed by work through Hill and supported by OSD funding, to repeat the flight tests on as large a sample size as possible on LRUs in the F16 fleet.

The results from these latter studies are the subject of this paper.  This work has involved over 150 aircraft and over 3500 LRUs using only the Super Corr A.  All results remained positive for reduced LRU removal rates.  No negative effects were ever reported from any base.  As in earlier work, it was shown that the effectiveness of these treatments varied greatly among LRUs.

Data will be shown for the benefits observed from an analysis of data reported to the Air Force database.   


See more of Corrosion Resistant Materials I
See more of The 2007 Tri-Service Corrosion Conference (December 3-7, 2007)