H-60/S-70 Blade Burn Pod Set ULTRAX Aerospace PN

Transcription

1 H-60/S-70 Blade Burn Pod Set ULTRAX Aerospace PN Blade De-Ice Heater Mat Test Set for H-60/S-70 Aircraft ULTRAX Aerospace White Paper Abstract As part of scheduled 360 hour phase inspection or as unscheduled maintenance, testing of de-ice heater mats in the blades of H-60/S-70 aircraft can be time consuming, taking up to an hour per main blade. ULTRAX Aerospace s new H-60/S-70 Blade Burn Pod Set reduces the time to test main rotor blade de-ice mats from approximately one hour to less than five minutes per blade. The Blade Burn Pod Set achieves this by automating a previously manual operation of setting and holding a precise 1.00 Amp output level during the test. It continuously monitors the output current and element voltage during the test. To protect the blade under test, if it detects a low resistance or over-current condition it automatically disables the current being applied. Further if measured resistance is too high, it continues applying the 1.00 Amp stimuli to the applicable heater mat elements until they fall within passing range or the test is canceled by the operator. WARNING Information contained in this paper is proprietary to ULTRAX Aerospace, Inc. and is intended for the sole use of our customers. It contains technical data whose export is restricted by the Arms Export Control Act (Title 22, U.S.C., Sec 2751, et q.) or the Export Administration Act of 1979, as amended, Title 50, U. S. C., App et seq. Violations of these export laws are subject to severe criminal penalties. Do not disclose or share in any way, this technical information with any US foreign national without prior approval from the appropriate U.S. export control authority. Proprietary to ULTRAX Aerospace Do not distribute without prior authorization from ULTRAX

2 H-60 Main Rotor Blade Heater Mats The H-60 main rotor blade is constructed of a one piece titanium alloy spar, nickel abrasive strip, wire mesh for lightning protection, heater mat for blade de-ice, fiberglass skin covering aft of the leading edge, and a Nomex honeycomb core. (UH-60A Powertrain/ Rotor System , 2008). The de-ice heater mat is an electro-thermal blanket that is bonded into the blade leading edge of equipped H-60 (United States military) and S-70 (exported military and commercial variant) aircraft (see Figure 1). The de-ice wire harness connector provides electrical continuity between the de-ice heater mat and the aircraft de-ice system (see Figure 2). Figure 1 - Location of H-60 Rotor Blade De-Ice Components (TM Operator's Manual for UH-60A Helicopter, UH-60L Helicopter, EH-60A Helicopter, 2003) Figure 2 Location of H-60 Main Rotor Blade De-Ice Wire Harness (TM Aviation Unit and Intermediate Maintenance for Army Models UH-60A, UH- 60L, EH-60A, UH-60Q, and HH-60L Helicopters, 2003) Page 2 of Rev 2

3 Testing of Main Rotor Blade Heater Mats Unscheduled Maintenance Unscheduled heater mat testing is required when the Blade De-ice Self Test button in the cockpit is pressed and a failure is indicated. This failure can be an indication of a higher than expected resistance in the Blade De-ice System. The Blade De-ice Self Test cannot differentiate between a De-ice system problem and problems within the main rotor blades (MRB) or tail rotor blades (TRB), so it is incumbent upon the maintainer to determine the problem. One of the high resistance drivers is oxidation of the solder connection between the heater mat elements and the wiring from the blade de-ice connector on the MRB or TRB. Experience has shown that in many cases, applying a 1 amp current through this connection can burn off the oxidation, lowering the resistance level to the point where the self test can then pass. Experience has also shown however that raising the current level too high above 1 amp can cause permanent blade damage. Scheduled 360 hr Phase Inspection Every 360 hours, the MRB and TRB are removed and the airframe inspected. Prior to reinstallation, the blades are inspected for proper heater mat resistance. The resistance of each heater mat element in the blades is measured via the pins in the de-ice connector using an ohmmeter. If out of tolerance, the TM instructions are to connect the locally fabricated heater mat tester (local fab tool found in Appendix H of TM) and apply 1A of current to attempt to burn off the oxidation and bring the resistance within tolerance. This cannot be achieved with an ohmmeter because the resulting current level applied during ohmmeter measurements is much smaller. Each main rotor blade is constructed with four de-ice zones. Each zone is made up of an array of three heater mat elements connected in a delta wiring configuration (see Figure 3). This equates to 12 element measurements per main blade that have to be performed. To test a single main blade with the TM local fab tool typically requires one hour. Figure 3 H-60 Main Rotor Blade De-Ice Heater Mat Element Configuration and Pin Out (TM Aviation Unit Maintenance Utility System Blade De-Icing System) Page 3 of Rev 2

4 H-60 Tail Rotor Blade Heater Mats De-ice heater mat is also embedded into the leading edge of each tail rotor blade. (Rosen & Potash, 1981) The tail rotor assembly is built around two graphite composite spars running from tip-to-tip and crossing each other at the center to form the four blades. The two spars (paddles) are interchangeable and can be replaced individually. One paddle (two blade edges) has separate de-ice heater mat elements and de-ice electrical connector for both ends. The electrical connector shown in Figure 4 provides the electrical continuity between that blade de-ice heater blanket and the de-ice system. (UH-60A STUDENT HANDOUT UH-60A Powertrain/ Rotor System, 2008). The H-60 de-ice system connects three-phase power across the four tail rotor blades as shown in Figure 5. Testing of H-60 Tail Rotor Blade Heater Mats Similar to main rotor blade testing, an ohmmeter is used to determine if the resistance of tail rotor blade heater mat elements is within tolerance per the TM. Figure 4 H-60 Tail Rotor Blade De- Ice Connection Figure 5 H-60 Tail Rotor De-Ice Heater Mat Element Configuration and Pin Out for Entire Rotor (2 Panels, 4 Blades) (TM Aviation Unit Maintenance Utility System Blade De-Icing System) Page 4 of Rev 2

5 New Approach to Testing H-60/S-70 Blade De-Ice Mats ULTRAX Aerospace s new H-60/S-70 Blade Burn Pod Set reduces heater mat resistance test time to less than five minutes compared to the locally fabricated test tool which can take up to 1 hour per main blade. Blade Burn Pod Set continuously monitors the applied power and if it detects a low resistance or over-current condition, automatically removes power. Also if the measured resistance is too high, it continues applying the 1.00 Amp stimuli to the applicable heater mat elements until they fall within passing range or the test is canceled by the operator. The Blade Burn Pod Set replaces local fab tool TGN , tests all equipped H-60/S-70 model main rotor and tail rotor blades and complies with TM and TM The Blade Burn Pod Set, used with Army-approved UxValidator Series I test unit with Pod Adapter or the UxValidator Series II test unit, simplifies and accelerates the heater mat resistance testing, and when testing blades on aircraft can assist in isolating de-ice system problems by quickly identifying or ruling out the heater mat elements as the source. Main blade heater mat testing is performed by sequentially providing a constant current source to the individual blade heater mat elements. A main blade integrity test is first performed by applying a lower value 0.5 Amp current to verify that resistance of each element is above 6 ohms before proceeding. The Blade Burn Pod Set then applies a precise 1.00 Amp current to each main rotor blade heater mat element, one element at a time, for one second while checking to ensure that the resistance of the element is within TM-specified limits of 7 and 10 ohms. The test will halt after successful completion of all elements or continue for up to 5 minutes depending on the selected mode. The Pod Set similarly tests tail rotor blade heater mat elements by applying 0.50 Amp and verifying that resistance is within TM-specified limits of 6 and 8 ohms. H-60 Main Rotor Blade De-Ice Heater Mat Testing The UxValidator user interface displays a bar graph (see below) of the individual blade heater element resistance readings. This allows the maintainer to quickly determine when the heater element resistance levels are within TM-specified limits. Page 5 of Rev 2

6 Measured resistance values can be saved to a report which can then be printed and/or transferred to a PC for archival. The Pod Set automates the previously manual operation of measuring tail rotor blade heater mat resistances with an ohmmeter. The Pod Set communicates with the UxValidator via high-speed data cable. No long bulky cables, external breakout box or other equipment is required. On-Aircraft Operation Although created for bench-testing of rotor blades, the H-60/S-70 Blade Burn Pod Set may also be used while the blades are still mounted to the aircraft. The set includes a 20-foot data cable to facilitate such testing and help prevent costly removal and transportation of blades that are in compliance. Connecting the H-60/S-70 Blade Burn Pod Set to a UH-60 Tail Rotor Blade H-60/S-70 Blade Burn Pod Set Storage The H-60/S-70 Blade Burn Pod Set is self-contained in its own transit case which includes all of the components of the set. Conclusion H-60/S-70 Blade Burn Pod Set Testing of the de-ice heater mats in the blades of H-60/S-70 aircraft can be time-consuming, taking up to an hour per main blade to test. ULTRAX Aerospace s new H-60/S-70 Blade Burn Pod Set solves this problem by automatically measuring the heater mat resistance while safely applying the 1.00 Amp stimuli, reducing test time from approximately one hour to less than five minutes per blade. ULTRAX Aerospace Incorporated 4200 Northeast Sun Court Lee s Summit Missouri Telephone: Fax: Page 6 of Rev 2