The Aerospace Maintenance Competition is back, and this time Barfield will be participating with 3 test benches.
Find below information to prepare you for the competition.
Air Data Testing
For Air Data Testing participants will be working with a DPS500NG. The DPS500NG is Barfield’s latest fully automated, intuitive RVSM compliant air data test set. The DPS500NG is a portable, high precision, dual channel air data pressure test system. This tester is designed to calibrate, test and troubleshoot air data instrumentation and aircraft pitot-static systems. The test set has been designed with functional and reliability features highly suited to withstand the harsh environmental and demanding conditions of the flight line environment. The test set is designed for testing a wide range of commercial and military aircraft, both rotary and fixed wing. Designed with both hardware and software safety features, the DPS500NG provides maximum protection for the test set and the Unit Under Test (UUT). These features include over-range, overlimit, and over-pressurization protection, micro-porous filters, pressure relief valves, UUT isolation in the event of a power failure and more
Check the DPS500NG procedure here
Proper electrical bonding and grounding is critical for aviation operations. This year Barfield released its latest product the BT-700 and BT-700i (intrinsically safe). The Barfield Bond Meter Series are designed with the clearest and most informative displays for mistake-free usage. They quickly produce accurate readings to reduce the time spent measuring. The unique low-power techniques avoid the hassle of power cords or battery chargers. The BT-700/BT-700i will run for 100 hours on 3 standard AA batteries and has auto power-off to preserve them. Probes are often more important than the instrument. This year participants will have the opportunity to work with a Kelvin Clip Probe and a Big Kelvin Display Probe.
The blog post How The Next Generation of Bond Meters Are Helping Aviation Technicians? incorporates videos of how to use the bond meter. The Barfield Bond Meter Quick Start Guide is also a very helpful tool to learn how to use it.
Check the BT700 procedure here (revised version)
RF Antenna Testing
Avionics technicians often are faced with the uncertainty when troubleshooting to decide if the problem is the avionics Line Replaceable Unit (LRU) or the coaxial connection from the LRU to the antenna.
The FlightHawk is a tool that helps avionics professionals mitigate the problem by testing the coaxial connection from the LRU to the antenna. It has two main functionalities:
- Distance to Fault
- Measuring the VSWR (Voltage Standing Wave Ratio) to determine the energy reflection form the antenna
- Some kits come with a power sensor and a terminal load, that allow for testing the power coming out of the LRU. Thus, converting the FlightHawk into a Power Meter
These are some articles and training videos that help understand the use of this tool:
Check the RF Antenna Testing Procedure here
No Fault Found (NFF) is a standard term used in aviation, and typically happens when a part removed from an aircraft, due to poor performance, is sent to an MRO repair shop for testing. The repair shop cannot replicate or find the problem. The MRO shop tests the unit and if it passes all tests, the unit is sent back to the operator as NFF.
Now, the same unit could continue having problems that cannot replicate on the bench. Many times, micro-breaks, bad soldering, vibrations, could create intermittences that are undetectable by standard equipment. The unit is removed and sent back to the MRO shop and the cycle continues. Airlines often-times have a policy to retire the unit after three NFF test results. This unit will be considered “rogue” or unserviceable.
Aircraft OEMs, also have processes to deal with rogue units.
At the MRO level, depending on the Component Maintenance Manual (CMM) for the particular part, Original Equipment Manufacturers (OEM) will provide a set of instructions on how to perform a deep test on the unit. This will entail doing a temperature test and a vibration test to capture the anomaly (“bake and shake”).
It is highly probable that after performing the deep test, with environmental stimulus (“baking and shaking”), the unit is returned to service and continues to present problems.
What are the different intermittence stages in No-
One of the possible reasons that vibration and temperature chambers still would not be able to replicate the problem is related to the sensitivity of the equipment. There are three stages in which intermittences occur.
Stage 1 Stage 2 Stage 2 intermittences graph for NFFs
- Stage-3 hard or semi-hard failures can be captured by most test equipment on the bench or the line.
- Stage-2 faults that manifest intermittently in operation, but pass the deep test, and labeled NFF.
- Stage-1 random low-level nanosecond micro-breaks or noise, likely not operationally evident.
Equipment capturing Stage-3 hard or semi-hard fault is not built and not capable of capturing Stage-1 or Stage-2 intermittent faults where these micro-breaks are detected.
Micro-breaks could occur as follows:
• Cracked solder joint.
• Broken wire.
• Loose crimp connection.
• Loose or corroded wire wrap.
• Corroded connector contact.
• Sprung connector receptacle.
• Deteriorated wire insulation.
• Hairline crack in printed circuit trace.
• Unsoldered connection.
Micro-breaks due to corrosion. Source: Universal Synaptics
Micro-break due to bad contact. Source: Universal Synaptics