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aerospace materials

UH-60M Black Hawk Helicopters: Reducing friction damage with proven anti-chafe tapesSituation

Operators of the UH-60M Black Hawk helicopters at the US Army

needed a durable and conformable material that prevents chafing

damage caused by the abrasion of tail rotor gearbox fairing and access

panels against the tail boom structure during daily operations.

Challenge

The current provision for anti-chafe material applications in this

area was less than fully effective, resulting in frequent damage to

the structure and fairing sub-assemblies. Consequently, US Army

operators noticed that paint was worn away to expose bare metal

and gouges worn into the structure, requiring replacement and/or

panel repair. Figures 1 and 2 show typical helicopter examples.“The results of this trial provide further proof of how our tapes protect coatings and structures from the destructive forces of vibration-induced chafing and fretting. UH-60 operators can keep more aircraft mission ready while cutting sustainment costs.”

Ross Livington, Gore Product Specialist

Case Study

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Figure 1: Typical chafing damage to the helicopter structure.

Figure 2: Typical fretting damage on helicopter structure.

Solution

Gore engineers worked closely with US Army technicians to install

GORE™ SKYFLEX™ Aerospace Tapes, 730 Series on the gearbox

fairing, tail boom and vertical stabilizer structure at panel mating

surfaces of the UH-60M Black Hawk helicopter. First, the structure

was cleaned prior to installation. Given this tape’s superior

resistance to oil and hydraulic fluids, they then applied Gore’s

730 Series on the tail boom, vertical stabilizer and tail rotor

gearbox fairing contact surfaces. Total preparation time and

tape application took approximately 90 minutes (Figures 3 — 7).

Future tape applications should require less time.

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Figure 3: GORE™ SKYFLEX™ Aerospace Tapes, 730 Series installed on tail rotor gearbox fairing areas.

Figure 5: GORE™ SKYFLEX™ Aerospace Tapes, 730 Series installed on tail rotor gearbox fairing mating surface.

Figure 4: GORE™ SKYFLEX™ Aerospace Tapes, 730 Series installed on tail panel contact areas.

Figure 7: GORE™ SKYFLEX™ Aerospace Tapes, 730 Series installed on tail boom panel contact area. Tape is wrapped around edges of structure and fastener holes.

Figure 6: GORE™ SKYFLEX™ Aerospace Tapes, 730 Series installed on upper vertical tail panel contact areas.

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Figure 8: GORE™ SKYFLEX™ Aerospace Tapes, 730 Series installed on tail rotor gearbox fairing areas after testing.

Figure 10: GORE™ SKYFLEX™ Aerospace Tapes, 730 Series installed on base of vertical tail panel mounting surface after testing.

Figure 9: Tail rotor gearbox fairing areas showed no wear and tear after Gore’s tape was removed.

Figure 11: No damage to the base of vertical tail panel mounting surface after Gore’s tape was removed.

Case Study

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Next, they conducted thorough flight testing through normal operational use. Results showed that Gore’s ePTFE (expanded

polytetrafluoroethylene) tape effectively absorbed friction and wear between the panels and structure through 781 flight hours.

Removing the tape from all application areas revealed the underlying aircraft structure in pristine condition. Although testing exceeded

the planned duration by more than 60 hours, the material could have been left in place for significantly longer. In a normal operational

environment, protection could be restored by replacing only the damaged tape, leaving the undamaged portion in place.

Figures 8 and 9 show how Gore’s 730 Series reliably protected the mating surface by absorbing wear and tear. Comparing figures 10

and 11 (after tape removal) show how Gore’s tape installed on the base of a vertical tail panel mounting surface prevented damage to

the application area.

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Figures 12 and 13 show how Gore’s 730 Series durably protected the structure at the faying surface — a common area for chafing

damage. Gore’s tape applied to the tail rotor gearbox fairing contact areas clearly absorbed all of the friction and wear, leaving the

structure untouched. Similarly, the tape successfully protected the upper tail panel mating surfaces (Figures 14 and 15).

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Figure 12: GORE™ SKYFLEX™ Aerospace Tapes, 730 Series installed on tail rotor gearbox fairing mating surface after testing.

Figure 14: GORE™ SKYFLEX™ Aerospace Tapes, 730 Series installed on upper tail panel contact areas after testing.

Figure 13: Mating surface on vertical tail reflected no wear from installed fairing after Gore’s tape was removed.

Figure 15: Upper tail panel contact areas indicated no wear after Gore’s tape was removed.

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Case Study

Figure 16: GORE™ SKYFLEX™ Aerospace Tapes, 730 Series installed on vertical tail panel contact areas after testing.

Figure 18: GORE™ SKYFLEX™ Aerospace Tapes, 730 Series installed on the upper tail.

Figure 17: Underlying structure showed no damage after Gore’s tape was removed.

Figure 19: No wear revealed on upper tail after Gore’s tape was removed.

Figures 16 — 19 further exhibit how Gore’s 730 Series served as a sacrificial protective barrier between the panel and structure after

781 flight hours. Stress factors inherent to the movement of panels secured with quick release fasteners impart friction at the panel

mating surfaces as evidenced by the tape’s condition. The lack of any damage to the paint indicates the extent to which Gore’s tape

absorbed the severe effects of vibration and friction.

Lastly, figures 20 — 22 reflect the condition of Gore’s 730 Series. The tape’s versatility is proven by its ability to conform to a variety of

contours because it can be wrapped around the edges of the structure and fastener holes. Results after 781 flight hours showed how

Gore’s tape effectively absorbed friction and wear between the panels and structure — revealing a clean, unmarked structure after the

tape was removed.

Figure 21: GORE™ SKYFLEX™ Aerospace Tapes, 730 Series wrapped around edges of tail boom panel contact areas.

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Figure 20: GORE™ SKYFLEX™ Aerospace Tapes, 730 Series installed on tail panel contact areas after 781 hours of operational testing.

Figure 22: Gore’s tape removed to reveal clean, unmarked structure.

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Conclusion

Extensive testing proved how effectively GORE™ SKYFLEX™ Aerospace Tapes, 730 Series provided a sacrificial protective

barrier by reducing friction and protecting the underlying aircraft structure from damage. Even after the extended test

period, Gore’s tape absorbed the effects of continuous vibration and completely prevented chafing damage to the coatings

and structure of the UH-60M Black Hawk helicopter.

While vibration has unfavorable effects on helicopters during daily operations, the likely damage over time can be

mitigated or prevented by applying a durable layer of protective tape such as Gore’s 730 Series between the panel and

structure. Any damage absorbed by the tape can be easily repaired by replacing only the damaged tape areas, restoring

protection and preventing costly structural repair or replacement. Likewise, installing Gore’s tape to comparable airframe

structures should deliver similar results.

GORE™ SKYFLEX™ Aerospace Tapes, 730 Series proved resilient and effective in preventing chafing damage between all

panel mating surfaces — enabling the US Army to reduce labor, maintenance downtime, and lifecycle costs.

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Case Study

W. L. Gore & Associates

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GORE, SKYFLEX, and designs are trademarks of W. L. Gore & Associates. © 2018 W. L. Gore & Associates, Inc. SKY-0369-REF-US-MAR18

Case Study

NOTICE — USE RESTRICTIONS APPLY.Not for use in food, drug, cosmetic or medical device manufacturing, processing, or packaging operations.

GORE™ SKYFLEX™

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This document is for informational purposes only and not a substitute for published technical data. For more information regarding GORE™ SKYFLEX™ Aerospace Materials, visit www.gore.com/skyflex.

Proven Performance with Diverse PortfolioProven by more than 20 years of successful applications, GORE™ SKYFLEX™ Aerospace Materials solve many sealing and surface

protection challenges in civil and military aircraft. They are available in a variety of form-in-place (FIP) tapes and die-cut gaskets in

various sizes. Gore’s tapes and gaskets provide design engineers, manufacturers, and operators with many benefits that simplify

aircraft assembly, and increase availability and throughput, including:

GORE™ SKYFLEX™ Aerospace Tapes, 730 Series

• reliable and predictable surface protection, sealing and

gap filling with highly-conformable materials

• durable protection against mechanical forces, extreme

temperatures, aggressive fluids, and other environmental

hazards

• supports design goals for manufacturing with dry materials

• easier and faster installation from single-component,

non-curing materials

• less replacement and re-work of seals by maintaining

performance over multiple open/close cycles for reduced

life-cycle costs

• low environmental impact and improved safety with

non-hazardous materials

• no operator certification or special handling of materials

required