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The Barfield DFQ40K Fuel Quantity Test Set is designed for – and is compatible with – all aircraft with AC-capacitance-based, fuel quantity-indicating systems, including those equipped with transient suppressors.
The DFQ40K is able to measure the insulation breakdown of tank units, wiring, and connectors associated with the system, the capacitance of the tank units that measure the level of fuel in the tanks, and the simulation of capacitances required to test and calibrate the aircraft indicating system.
In addition to performing the standard capacitance tests of the tank(s) and or compensator, the DFQ40K has an additional troubleshooting mode that provides the user with a relative indication of a problem associated with the phase of the return current like that provided by the Barfield 2548H tester.
The DFQ40K measures low resistances, DC voltage, and indicator drive current. The unit is also equipped to measure the Distance to Fault to localize problems with the HIZ coax, the continuity of the Shield Monitor (if the aircraft is so equipped), and bonding tests to 0.001 ohms resolution.
The Simulator section has been redesigned to permit direct numeric entry of the desired tank and/or compensator capacitance to be simulated using a numeric keypad.
The panel connector labeled Com Link will be used with a new generation of smart cables. This feature may not be present on the initial release and may be configured as an available option on the test set. The concept is that the DFQ40K will read information stored in the cable specific to the aircraft type under test. At the push of a button, the DFQ40K will perform an Automated Test Routine (ATR) on the aircraft wiring and tank units, resulting in a PASS or FAIL message. Should the test result in a FAIL message, the test set will give a clear indication as to the nature of the failure and likely source.
With the incorporation of the BACK, NEXT, MODE, and RANGE pushbuttons to the panel membrane, switching the overall number of different screens – such as sub-menus to be displayed – is greatly reduced. This simplifies the screens and makes them easier for the operator to learn and navigate. This also makes it possible to remove all predefined FUNCTION pushbuttons and embed those functions into the Soft Function key selection scheme.
Features
- Microprocessor-based
- Completely self-contained AC capacitance fuel quantity test system
- Measures capacitance, insulation, DC voltage, resistance, and distance to fault
- Capacitance simulation and indicator testing
- Custom multi-line backlit graphic display
- Direct keypad entry of Tank and Comp simulation values
- Uses all existing fuel quantity cables
- Uses a new generation of smart cables to perform Automated Test Routines
- Calibration date is available from the display with user alerts to the approaching calibration date
- Numerous user prompts
- Powered by standard “C” batteries with an auto-off feature to conserve batteries
Specifications
- Dimensions: 6" D x 12" W x 14" H (15.2 x 30.5 x 35.6 cm)
- Weight: 10 lbs. (4.54 kg)
| Alternate Models | |
|---|---|
| 101-00420 | Previous Model (2548H) to the DFQ40K |
| 101-01501 | Alternative Manufacturer Model Number |
| 101-01502 | Alternative Manufacturer Model Number |
| 2548H | Previous Model Number |
| General Information | |
|---|---|
| Part # | DFQ40K |
| Manufacturer | Barfield |
| Shipping Information | |
|---|---|
| Product Weight | 7 lbs. |
| Product Dimensions | 15 x 14 x 14 in. |
| Schedule B | 9026107000 |
| ECCN | 7B994 |
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AIRCRAFT COMPATIBILITY
| Compatible Aircraft* |
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QUESTIONS & ANSWERS
It depends on whether the aircraft uses an AC or DC fuel quantity system. The Barfield DFQ40K is specifically designed for AC-powered aircraft, while the Barfield DC400A supports DC-powered platforms.
In addition, some aircraft require unique adapter cables or modules for proper connection. Our aviation specialists can help you confirm compatibility and identify any accessories you may need for your specific aircraft model.
The correct adapter cable depends on the aircraft’s serial number. For Gulfstream III aircraft with serial numbers 000 through 453, you will need adapter cable 101-00474. For serial numbers 454 and higher, the required adapter cable is 101-01439. Using the proper adapter cable ensures accurate fuel quantity testing and system integrity.
Yes. The DFQ40K should be calibrated annually to maintain accuracy and compliance with aviation standards. Every unit we provide includes a current calibration certificate for your records. We also offer calibration services to keep your test equipment operating reliably year after year. Contact our team to arrange calibration support tailored to your operational schedule.
Yes. PJi offers rental options for the DFQ40K Fuel Quantity Test Set to support operators who only need the equipment temporarily. Rentals can be paired with the required adapter modules and cables, making it simple to perform testing without the long-term investment of ownership. Reach out to our aviation specialists to learn more about DFQ40K rentals and availability.
The DFQ40K has a rugged yet compact design, allowing technicians to transport it easily between hangar spaces or to different aircraft. Its digital interface and self-contained unit reduce the need for bulky external components. With its portability and durability, the DFQ40K is well-suited for both field service operations and scheduled maintenance in larger facilities.
Earlier Barfield testers, like the 2548 series, relied on analog displays and less precise measurement tools. The DFQ40K is fully digital, offering improved accuracy, user-friendly controls, and advanced self-test capabilities. It also supports more aircraft types with updated adapter compatibility, making it a long-term investment for modern aviation maintenance environments.
Yes. The Barfield DFQ40K is widely accepted by aviation regulatory authorities, including the FAA and EASA, as an appropriate tool for testing AC fuel quantity systems. Its accuracy and compliance with calibration standards help ensure aircraft meet airworthiness requirements during inspections and scheduled maintenance.
The DFQ40K includes a digital display that allows technicians to view precise readings in real time. Unlike analog systems, the digital interface reduces interpretation errors and improves troubleshooting speed. This makes the DFQ40K especially valuable in environments where accuracy and efficiency are critical.
With its digital accuracy and stable readings, the DFQ40K helps technicians quickly identify wiring issues, tank unit faults, or calibration discrepancies in an aircraft’s fuel system. This reduces downtime by shortening the diagnostic process and preventing unnecessary component replacements. By pinpointing issues efficiently, the DFQ40K contributes to more cost-effective maintenance.
Yes. While the DFQ40K itself is a universal platform for AC fuel quantity systems, individual aircraft often require unique adapter cables or modules to connect properly. PJi provides a range of Barfield aircraft-specific accessories, and our aviation specialists can help identify the exact parts needed for your platform. Using the correct adapters ensures accurate and reliable fuel quantity testing.
Absolutely! The DFQ40K is designed to complement standard MRO and FBO maintenance programs as part of recurring inspection intervals. Ensuring accurate fuel quantity readings directly supports compliance with airworthiness requirements and enhances overall operational safety. Its portability and compatibility make it easy to integrate into multi-aircraft maintenance schedules.
Technicians should be trained in standard fuel quantity testing procedures and familiar with the specific requirements of the aircraft being serviced. The DFQ40K’s digital interface makes it more intuitive than earlier testers, reducing the learning curve.
The DFQ40K is engineered with rugged construction to withstand regular use in demanding hangar and ramp environments. Its housing protects sensitive electronics from physical impact and environmental exposure. With proper care and calibration, the DFQ40K delivers long-lasting reliability even in high-volume maintenance facilities.
If the DFQ40K displays an out-of-range reading, technicians should verify proper adapter connections and check for potential wiring or tank unit issues in the aircraft system. Because the DFQ40K is highly accurate, unusual readings often point to real faults rather than tester errors. Systematic troubleshooting with the DFQ40K can help identify the source of the issue quickly.
In most cases, yes. The DFQ40K is designed to serve as a modern replacement for legacy Barfield testers and similar AC fuel quantity units. However, operators should confirm compatibility with their specific aircraft type and ensure the correct adapters are available. This makes the DFQ40K a future-ready investment for long-term maintenance needs.
