Flight-Line Armament Tester Keeps Apache Fleet Mission Ready.
When a system fails and you have to call in a manufacturer representative to troubleshoot and fix the product, it's inconvenient, time consuming, and expensive. But when the product is a Hellfire missile system on an Apache helicopter and you're in the sands of Kuwait or the hills of Kosovo, a system failure can be a lot more than a costly inconvenience.
"Five inadvertent launchings of missiles in operation Desert Storm/Desert Shield" prompted the U. S. Army's Air-to-Ground Missile Systems (AGMS) Project Office to assess the readiness of the fielded Hellfire missile systems, says Andy Perez, logistic management specialist, AGMS Project Managers Office, Redstone Arsenal, Ala.
Despite a built-in test in the aircraft indicating that the Hellfire missile system was fully mission capable (able to fire from all four rails on each launcher), extensive contractor testing found that about half the aircraft couldn't launch one or more missiles. An investigation into these failures revealed that the aircraft's built-in test could not accurately detect system failures. They decided that a unit-level test that could be used on the flight line was required.
The Army looked into upgrading the reliability of the on-board built-in test, but improving the accuracy to an acceptable level wasn't economically feasible, says Perez. When something is changed in the aircraft, a variety of tests must be conducted to verify that it doesn't interfere with the aircraft's other systems, he explains. And with 750 fielded helicopters, making onboard modifications would have been very expensive.
The AGMS wanted a diagnostic system that could pinpoint the cause of failure and indicate how the missile system could be fixed, so troops in the field could make quick, essential repairs. An additional objective was a design that allowed for easy field maintenance using off-the-shelf components when possible to keep costs down.
The AGMS evaluated available off-the-shelf test equipment and found that Marvin Engineering Co. Inc., Inglewood, Calif., had developed a user-friendly armament test that could be used by soldiers with little additional technical training on missile systems testing. While the system was modified and tested, contractor field representatives with extensive knowledge of the aircraft and its missile system were brought in to perform the tests, which increased the readiness of the Apache fleet to 92%.
The Army obviously needed a rugged system that could survive the physical punishment it knew it would be subjected to in a tactical environment, so it stipulated that the system work under the same conditions as military equipment, such as aircraft and launchers.
"The Army gave us the environmental specifications of the Hellfire system [less the missile] and said it had to meet these specs," says Loofie Gutterman, COO at Geotest-Marvin Test Systems, a subsidiary of Marvin Engineering. "The Army was adamant about its stringent conditions. We thought the requirements were a bit overboard as other armament test sets aren't required to comply with military specs. But after we saw the abuse the systems took in the field, we realized they were right."
The result was a portable flight-line test set capable of performing full parametric tests of the Hellfire missile system without missiles. "It is not your typical test set designed to give a `go' or `no-go' signal. It has depot-level testing capabilities that can be performed on the flight line," says Gutterman.
The AN/TSM-205 (known by Geotest as the MEC-2000) has the hardware and software capabilities of a depot tester that conducts a thorough analysis of the helicopter system or launcher and comes up with recommendations for repair.
To conduct a typical test, an operator uses a detachable display unit to control the AN/TSM-205 remotely from the Apache cockpit via a 7,5-m cable. Simple menu-driven prompts on the touch-screen instruct the user to make connections, select the test setup, and repair faulty aircraft or launcher parts. The test set monitors the signals from the cockpit switches to the launcher's rails by emulating missile-generated signals. Built-in safeguards prevent the user from making wrong connections or running the test with live missiles installed.
The two-man test set operates in two modes--quick/full system mode, which determines if missiles can be launched and takes less than 30 min, and full system mode, which isolates failures and requires about 45 min. An additional feature is a stand-alone test for the launcher and its electronics assembly. This test takes about 15 min. When the system detects a failure, it instructs the user which circuit card assembly or wire in the aircraft needs to be repaired or replaced. The test set can also store up to 150 complete system tests, which can be displayed on the touch screen or printed out.
After deploying the test set, Perez says the AGMS Project Office was able to maintain the readiness of the Apache fleet's Hellfire missile systems at more than 90% despite the shift from experienced contractor personal to armament skilled soldier.
"We've had some problems with training as there is a learning curve picking up the necessary skills," says Perez. "But the user-friendliness of the software and the hardware reliability continues to be improved."
Just one test set was supplied to each battalion, so reducing downtime was important for the Army user. Each unit was purchased with a complete spare-parts package, which includes 26 parts in two storage cases. The test set also incorporates a self-test, which verifies that the circuit cards and cables are operational.
"The system was definitely designed with maintenance in mind," says Perez. "The soldier in the field has the ability to make most the routine repairs to the test set."
The chassis is hinged to the front panel to ensure easy access to circuitry, and a small access panel provides for quick replacement of high-current relays.
The AN/TSM-205 meets full military specifications for ambient temperature (-40 to 64 [degrees] C), humidity, salt-fog, dust, vibration, shock, and EMI/RFI. The fiberglass chassis has five shock absorbers that provide horizontal, lateral, and vertical protection against shock and vibration.
It was designed as a general-purpose operational-level test set with the potential to support additional aircraft.
Flight-Line Tester Designed for Tactical Use
The MEC-2000 from Geotest-Marvin Test Systems Inc., Santa Ana, Calif. (a subsidiary of Marvin Engineering Co. Inc.) is a portable measurement system developed field applications. With 12 full-size slots on the passive back-plane open for PC-based instrumentation, I/O or other boards, the modular architecture can be configured for test, data logging, data acquisition, and process control applications.
To protect against high humidity, the circuit boards are conformal coated, and all jumpers and switches are secured using RTV. EMI filters as well as conductive gaskets and grounding strips comply with military specifications.
The combined touch-screen and display meets the same environmental requirements as the chassis by using internal heaters that operate when the ambient temperature falls below 5 [degrees] C. Most of the electrical hardware as well as several PC-based instruments were commercial off-the-shelf components, which kept costs down compared to custom-built systems.
The system can be ordered with a complete operating environment for system configuration. The software includes a touch-panel control, built-in test module, on-line help, and a built-in diagnostic database.
* Geotest-Marvin Test Systems Inc. 2851 S. Pullman St. Santa Ana, CA 92705 949-263-2222 Fax: 949-263-1203 e-mail: email@example.com www. geotestinc.com * U.S. Army Aviation and Missile Command www. redstone.army.mil
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|Publication:||R & D|
|Date:||May 1, 1999|
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