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The Fixed Hoist Test Facility (FHTF), designated ZGS-12000-7, operates in conjunction with the ZGS-10000-5 Mobile Rescue Hoist Ground Support Equipment (RHGSE). This integrated system provides a comprehensive capability for operating the electric BL-29900 rescue hoist off an aircraft, enabling intermediate-level maintenance and troubleshooting procedures.
The primary function of the FHTF is to facilitate the performance of system checks, adjustment of hoist limit switches, levelwind adjustments, and the replacement and conditioning of the wire rope before the Unit Under Test (UUT) is mounted onto an aircraft. This pre-installation maintenance significantly reduces aircraft downtime and the flight time that would otherwise be required for these procedures if performed on the aircraft. It is important to note that the FHTF is not designed to perform a complete acceptance test as per OEM requirements but rather to support maintenance personnel in specific tasks.
The FHTF consists of a robust upright structure that includes an upper weldment assembly, a hanging hoist mount, and a chain hoist. The chain hoist is used for raising and lowering the UUT. A key feature of the system is its load weigh system, which incorporates two load cells. These load cells provide signals to a summing box, where they are combined and sent to a digital display. The load readout can be tared (set to zero) when no load is applied to the rescue hoist hook, ensuring accurate measurements.
Interconnecting cables are provided to link the various components of the FHTF and the RHGSE. The system also includes a receptacle for a three-phase 400 Hz power supply and a 28-volt power supply. Control signals for the UUT are provided by a customer-supplied set of controllers and a pendant. The control pendant connects directly to the front of the crew control panel.
In terms of operation, the upright structure is equipped with a chain hoist that raises the UUT to the top of the structure, where it is then attached to the two load cells. The load cells transmit signals to the summing box, which then sends the summed signals to the display. The load readout can be zeroed to tare the system with no load on the rescue hoist hook. The RHGSE is responsible for providing the tensile load on the wire rope, allowing for the extension of the wire rope under approximately 300 lbs. maximum load and retraction under approximately 600 lbs. maximum load. The 28 volts necessary for the UUT control system are supplied by a power supply located within the junction box. A receptacle is available for connecting a 400 Hz power cart, and a circuit breaker manages the three-phase 400 Hz power.
Installation of the FHTF involves several steps. First, all parts are unpacked and verified for good condition. A forklift is used to lift the base weldment from its pallet and position it near its final location. The base attachment angles are then secured to the I-beam, aligning them using provided labels. Next, the upper brace mount is attached to the I-beam with its fasteners, followed by the load cell summing box. The I-beam is then flipped, and the hoist hanging weldment is attached, utilizing beveled washers on the back surface of the beam flange. With the help of two people or a crane, the I-beam is stood upright. Attaching brackets are then placed and secured with screws. The lower brace corner mount is positioned, and its brackets are loosely attached with one bolt in each corner. The left and right diagonal braces are then mounted loosely between the lower and upper braces. Once all holes are aligned and bolts inserted, all bolts are securely tightened.
The chain hoist support is attached to the top of the hoist hanging weldment, and the chain hoist itself is then attached with the chain cover facing outwards. The nuts on the U-bolts are tightened to secure the chain hoist. The S-shaped load cells are installed onto the upper clevis mounts, and hitch pins are used to prevent the clevis pins from escaping. An extension cord is connected to the chain hoist, and the hook is lowered to allow attachment of the hanging hoist mount. Using the chain hoist control, the hanging hoist mount is lifted and attached to the slider assembly with its two pins, and hitch pin retainer pins are inserted. The hanging hoist mount and slider are then raised upwards using the chain hoist. The lower tie rod ends of the load cell assemblies are engaged with the lower clevis mounts of the hanging hoist mount using two clevis pins and hitch pins. Finally, the controls frame and the three-phase input power receptacle are mounted, along with the load cell readout and 28 VDC power supply box. The summing box is opened, and the load cells and summing box output are connected to the load meter readout as per ZGS-12216-2. The FHTF is then moved to its final position, and the base can be bolted to the floor using the provided attachment angles if desired.
Load cell calibration is a critical maintenance feature. After installing a hoist and making all electrical and mechanical attachments, the load cell readout is configured according to the DP25B-S User manual. This involves setting the input type, decimal point, and dip switch settings. If a 600 lbs load is available, the meter is scaled. With the UUT mounted on the hanging hoist mount and no load, the IN 1 value (unscaled display reading) is stored, and the RD 1 value is set to zero. The UUT hook is then lowered, the 600 lbs weight is attached, and the weight is raised off the ground. The IN 2 reading is stored, and the Rd 2 value is input as 600 lbs. This procedure can be performed with different loads, adjusting the Rd 2 value to the exact weight used, though 600 lbs ensures maximum accuracy.
Installing the UUT involves lowering the hanging hoist mount by raising it with the chain hoist hand control, removing the pins from the lower load cell clevis, and then lowering the hanging mount to the lower position. The UUT is installed onto the post mount with two ½ inch pins. The hanging hoist mount is then raised using the hand control to reattach the two clevis pins, and the chain hoist is lowered to transfer the weight to the load cells. The electrical control boxes are mounted in the frame openings.
System startup involves turning on the load indicator switch and allowing it to initialize. Depending on the calibration, the indicated load may be zero or the combined weight of the UUT and hanging hoist mount. Pressing the Tare button on the load indicator panel will zero the reading. The system operates in conjunction with the Mobile RHGSE, with detailed procedures outlined in ZOM-10000-5. A checklist is provided for system operation. Test procedures are to be followed as described in the OEM's operation and maintenance manual, as they are outside the scope of this manual.
For system maintenance, connections to the UUT should be capped and stored to prevent dirt ingress. Attachments to the manual include an electrical schematic (ZGS-12216-2), component manuals, load cell final calibration sheets, and the strain gauge panel meter user's guide.
The Rescue Hoist FHTF Check List outlines the startup and shutdown procedures. Startup includes lowering the hanging hoist mount, installing the hoist (electrical connectors, bolts/pins), raising the hanging hoist mount (load bolts, lowering chain hoist), connecting control boxes and pendant, moving the mobile GSE into position, pushing the circuit breaker switch on, turning the indicator switch on (zeroing load if needed), lowering the wire rope and hook, attaching them to the mobile GSE, and operating the mobile GSE per instructions. Shutdown involves removing the wire rope and hook from the mobile GSE, stowing the hook, turning off the indicator switch and circuit breaker, removing the mobile GSE, detaching connectors from the hoist, control box, and pendant (if desired), lowering the hanging hoist mount (raising chain hoist, removing load cell pins, lowering assembly), removing electrical cable connectors from the hoist, and finally, removing the hoist.
General| Frequency | 50/60Hz |
|---|---|
| Efficiency | >90% |
| Power Output | 12000 W |
| Phase | Single |
| Cooling Method | Forced Air |
| Protection Features | Overload, Short Circuit |
| Operating Temperature | 0°C to 40°C |
| Storage Temperature | -20°C to 60°C |
| Humidity | 5% to 95% non-condensing |
