Background: TQS found out that there was a testing void in avionics Line Replaceable Units (LRUs) at the Depot repair facility. The chassis of avionics LRUs were not being tested separate from the SRUs/CCAs, with few exceptions. Conventional test equipment cannot detect and isolate intermittent connectivity problems due to the scanning nature of digital Automated Test Equipment (ATE). Intermittent failures can be very short in duration (i.e., nanoseconds) and almost always require some environmental stimulus (e.g., vibration and temperature changes). Although not significant on analog power circuits (for example), but can be catastrophic when the occur on flight critical circuits operating at 100MHz or more.
Some of the work TQS accomplished follows:
TQS Contract F42620-00-D-0028: F-16 AN/APG-68 Radar System Modular Low Power Radio Frequency (MLPRF) Line Replaceable Unit (LRU) (2005)
Under the Falcon Flex program supporting the F-16 weapons system, TQS accomplished an in-depth, big data analytics study and determined that the MLPRF had a very high (about 78%) CND/ROTK rate at the depot. There were some MLPRFs that were shipped back and forth to the depot over 12 times a year due to this issue. These intermittent connectivity problems were all missed by conventional depot Automated Test Equipment (ATE).
The F-16 AN/APG-68 Radar System Modular Low Power Radio Frequency (MLPRF) was the LRU had the highest CND/RTOK rate of all F-16 avionics systems. The LRU would report an error code in the field, but subsequently be reported as CND or RTOK and returned to service having passed at least one “sell-off” test (i.e., certified for flight)
• The MLPRF was the top “bad actor” F-16 LRU (i.e., top of the MICAP list) for years
• Most pervasive problem was cracked ribbon cable solder joints (34%)
o Other cracked solder joints, broken coax cables, broken wires, loose crimps, and unsoldered joints were also present
• Fielded ATE did not detect or isolate intermittent connectivity failures
o No chassis tester available to the technician (where almost all of the intermittent connectivity problems resided)
o Technician tried to isolate using a DMM, but could not/took too long
• The original design life of these LRUs was for 20 years, and now the F-16 has been flying around for 30+ years without a chassis upgrade
Results from TQS’s Intermittent Fault Detection & Isolation System (IFDIS) as a result of testing by TQS and the USAF:
More than $13M in annual maintenance costs was avoided by the U.S. Air Force for just this single F-16 avioincs LRU type by reducing the MLPRF CND/RTOK rates at the Depot.
• 403 MLPRF LRU chassis IFDIS tested
• 138 were considered "un-repairable" completely out of service
• 34 had been in the repair depot for over one year
• 11 had been in the repair depot for over three years
• 58% had one or more intermittent failure
• Cost of a replacement MLPRF LRU chassis was $307,000 each
• Over $42M worth of flight hardware recovered
• Mean Time Between Failure (MTBF) increased from 289 hours to 926 hours
• Total Government investment $2.2 million – a 22 times ROI (and counting)
• Reduction in Total Ownership Cost (RTOC) of over $50 million achieved for just this one LRU type
As of December 2017, over 500 MLPRF chassis had been tested by the Intermittent Fault Detection and Isolation System (IFDIS).
The USAF technician used IFDIS to diagnose all of the problems in less than half a day (including set-up). In addition to diagnosing existing intermittent connectivity problems, the IFDIS has also been used as a preventative maintenance aide. After testing with TQS’s IFDIS for these hard to find defects, the actual repair and refurbishment of these chassis was as simple as re-soldering or replacing a connector.
TQS Contract F42620-00-D-0028: F-16 AN/APG-68 Radar System Antenna Line Replaceable Unit (LRU)
Under the Falcon Flex program awarded to TQS supporting the F-16 weapons system, TQS accomplished an in-depth, big data analytics study and determined that the Antenna had a very high (about 55%) CND/ROTK rate at the depot. There were some Antennas that were shipped back and forth to the depot over 10 times a year due to this issue.
• High Mission Impaired Capability Awaiting Parts (MICAP) rates
• Conventional ATE unable to diagnose intermittent failures resulting in CND/TROK issues which degrades the operational reliability and raises MICAP rates
• IFDIS testing quickly identified electronic defects and intermittent failures
TQS Contract F42620-00-D-0028: F-16 AN/APG-68 Radar System Antenna Azimuth Elevation (AZ/EL) Shop Replaceable Unit (SRU)
Under the Falcon Flex program awarded to TQS supporting the F-16 weapons system, TQS accomplished an in-depth, big data analytics study and determined that the AZ/EL cable had a very high (about 50%) CND/ROTK rate at the depot. There were some AZ/EL cables that were shipped back and forth to the depot over 8 times a year due to this issue.
• Current testing methods and equipment unable to identify defects
• Non-reparable item
• Purchase price $1,600.00each
• IFDIS testing required for GO/NO GO testing
• Significantly affected the F-16 readiness rate
Results from TQS and USAF IFDIS testing:
• 95 AZ/EL SRU ribbon cables IFDIS tested
• 76% tested bad and given a NO GO for use on F-16 aircraft
• IFDIS testing of AZ/EL ribbon cables saved the U.S. Air Force over $35,000 in just the first six weeks
IFDIS effectively identifies good and bad cables so that good cables are not unnecessarily discarded, and the bad cables are not put into F-16 aircraft.
TQS Contract FA8222-12-C-0009 [SBIR Sole-Source]: F-16 Central Air Data Computer (CADC) Line Replaceable Unit (LRU)
Under the Falcon Flex program awarded to TQS supporting the F-16 weapons system, TQS accomplished an in-depth, big data analytics study and determined that the CADC had a very high (about 60%) CND/ROTK rate at the depot. There were some CADCs that were shipped back and forth to the depot over 10 times a year due to this issue.
TQS Contract FA8222-13-C-0003 [SBIR Sole-Source]: F-16 Programmable Signal Processor (PSP) Line Replaceable Unit (LRU)
Under the Falcon Flex program awarded to TQS supporting the F-16 weapons system, TQS accomplished an in-depth, big data analytics study and determined that the PSP had a very high (about 50%) CND/ROTK rate at the depot. There were some PSPs that were shipped back and forth to the depot over 8 times a year due to this issue.
TQS Contract N68335-15-C-0025 [SBIR Sole-Source]: IFDIS System & F/A-18 Generator Convertor Unit (GCU) Weapon Replaceable Assembly (WRA) TPSs (G1, G2, G3) for FRCSW
GCUs previously considered Ready for Install (RFI) after comprehensive electrical load testing by the repair depots, but CND/RTOK issues remained.
• Second highest degrader in the NAVAIR inventory
• High CND/RTOK rates
• High Mission Impaired Capability Awaiting Parts (MICAP) rate
• No means or equipment to detect intermittence or reduce CND/RTOK rates
The USN contracted with TQS to provide our IFDIS with a GCU TPS for all three versions of the WRA (G1, G2, and G3).
• Delivered a TQS IFIDS to FRC-SW Coronado
• Delivered a TQS IFDIS to NAS Lemoore
• Delivered a TQS IFDIS to NAS Oceana
Results from TQS and USAF IFDIS testing:
• 80% of the GCUs tested had one or more intermittent circuit that went undetected using conventional ATE
• Repeat GCU load testing was almost eliminated, saving the USN time and getting the GCU back into the filed quicker.
• The IFDIS was also used to find manufacturing defects in new cable assemblies in the WRA.
Subsequently, the USN uses TQS’s IFDIS to accomplish engineering studies. One such effort resulted in resolving a connectivity problem in a GCU “bad actor” at FRC-SW in Coronado (IFDIS Used Successfully by U.S. Navy in Engineering Investigation of F/A-18).
TQS Contract N68335-17-C-0571 [SBIR Sole-Source]: IFDIS System & F/A-18 Generator Convertor Unit (GCU) Weapon Replaceable Assembly (WRA) TPSs (G1, G2, G3) for FRCW and FRCMA
GCUs previously considered Ready for Install (RFI) after comprehensive electrical load testing by the repair depots, but CND/RTOK issues remained.
• Was the second highest degrader in the NAVAIR F/A-18 supply inventory
• High CND/RTOK rates
• High Mission Impaired Capability Awaiting Parts (MICAP) rate
• No means or equipment to detect intermittence or reduce CND/RTOK rates
The USN contracted with TQS to provide our IFDIS with a GCU TPS for all three versions of the WRA (G1, G2, and G3).
• Delivered a TQS IFDIS to FRC-SW Coronado
• Delivered a TQS IFDIS to NAS Lemoore
• Delivered a TQS IFDIS to NAS Oceana
Currently the NAS Lemoore IFDIS and GCU TPS is being used to test G3 GCUs to ensure chassis reliability before modifying those G3s into the G4 configuration.
TQS Contract N68335-17-C-0571 [SBIR Sole-Source]: F/A-18 Radar System Weapon Replaceable Assembly (WRA)
As part of this contract, TQS is providing our IFDIS capability to support the F/A-18 weapons system to improve its readiness and availability by detecting and isolating chassis intermittent connectivity problems in WRAs in the radar and other systems. TQS development continues, and is scheduled for delivery in early 2020.
TQS Purchase Order SUB130212: F-16 Avionics Sustainment Support to FMS Customers
Not only has TQS provided the IFDIS capability to the U.S. military, but TQS has teamed with IEI to provide TQS’s Intermittent Detection and Isolation System (IFDIS) capability to Allied Foreign Militaries by providing intermittent fault detection and failure isolation services for their F-16 avionics systems as well, leveraging TQS’s SBIR success and investment.