Propeller with lightening strike protection

Patent metadata

Field	Value
Publication number	US-9702255-B2
Application number	US-201314091288-A
Country	US
Kind code	B2
Filing date	Nov 26, 2013
Priority date	Nov 26, 2013
Publication date	Jul 11, 2017
Grant date	Jul 11, 2017

Abstract

A propeller blade assembly including a propeller blade having a leading edge, and a trailing edge extending between a tip and a hub, and an electrically conductive band extending longitudinally on either or both of the leading edge and trailing edge. The electrically conductive band secured to the leading edge of the propeller serves as an entry point on the aircraft and conductive channel into the airframe thereby avoiding the potentially damaging effect of the lightening on the carbon fiber composite propeller.

First claim

We claim:

1. A propeller blade assembly, comprising:
a propeller blade having a leading edge, and a trailing edge extending between a tip and a shank, wherein the blade is comprised of multiple layers of composite materials and an outermost layer is fabricated from non-conductive glass;
a collar for mechanically coupling the shank of the blade to a metallic hub of an aircraft; and
an electrically conductive band comprised of metal extending longitudinally on either or both of the leading edge and trailing edge and having a flared end adjacent to the collar, such that a gap exists between the flared end of the band and the metallic hub for lightning to arc therebetween.

2. The propeller blade of claim 1 , wherein the conductive band is applied to the leading edge of the propeller blade.

3. The propeller blade of claim 1 , wherein the blade is devoid of conductive lightning strike protective material on an outer surface of the blade.

4. The propeller blade of claim 1 , wherein the conductive band is applied to the trailing edge of the propeller blade.

5. A propeller system for an aircraft capable of conducting the electrical current from a lightning strike from the propeller to an aircraft airframe, the propeller system comprising:
a carbon-fiber composite propeller blade with a non-conductive fiberglass outer layer having a leading edge, and a trailing edge extending between a tip and a shank;
an electrically conductive band extending longitudinally on the leading edge substantially from the tip to the shank; and
a metallic hub for housing the propeller blade, the hub being electrically coupled to the aircraft airframe and configured to form a gap between the shank end of the electrically conductive band and the hub such that lightning may arc across the gap from the band to the hub.

6. The propeller system of claim 5 , wherein the propeller is fabricated from layers of cloth ply.

7. The propeller system of claim 5 , wherein the electrically conductive band is secured in position over the outer layer of non-conductive glass.

8. The propeller system of claim 5 , wherein the electrically conductive band is secured to the outer layer of non-conductive glass with an adhesive.

9. The propeller system of claim 8 , wherein the adhesive is a waterproof, weather resistant and insulating adhesive.

10. The propeller blade of claim 5 , wherein the blade is substantially devoid of conductive lightning strike protective material on an outer surface of the blade.

11. The propeller system of claim 5 , wherein a portion of the electrically conductive band at the shank end is flared away from the leading edge.

12. A method for limiting damage to an aircraft's composite propeller from a lightning strike, the method comprising:
fabricating a composite propeller blade having a leading edge extending between a tip and a shank;
coating the composite propeller with a non-conductive glass;
securing an electrically conductive band extending longitudinally on either or both of the leading edge and trailing edge, wherein the band extends from the tip of the blade into the shank;
leaving a gap between a flared end of the conductive band and the shank; and
allowing the electrical current to arc from the conductive band to a ground path, wherein the ground path includes a path through a propeller hub.

13. The method of claim 12 , wherein the gap between the flared end of the band and a snap ring receiving groove is in the range of from 0.70 to 0.80 inches.

14. A propeller system for an aircraft capable of conducting an electrical current from a lightning strike from the propeller to an aircraft airframe, the propeller system comprising:
a propeller blade having a leading edge extending between a tip and a shank;
an electrically conductive band extending longitudinally on either or both of the leading edge and trailing edge wherein the electrically conductive band:
(a) is comprised of a nickel alloy;
(b) extends in approximately equal proportion on each side of the leading edge of the propeller blade;
(c) is flared in proximity to the propeller shank;
(d) is of a thickness of no greater than 0.033 inches;
(e) at an edge proximate the propeller shank is adjacent to a hub for retaining the propeller blade that is electrically coupled to the aircraft airframe; and
(f) when the propeller is struck by lightning, electricity is conducted to the flared end of the band and is provided a path to ground.

15. The method of claim 14 , wherein the ground path includes a path through the propeller hub.

Assignees

• Textron Innovations Inc

Inventors

• Martin Billy M
• Davis Kevin A

Classifications

• B64D45/02

  Lightning protectors; Static dischargers · CPC title

• B64C11/26 Primary

  Fabricated blades · CPC title

• F01D5/147 Primary

  Construction, i.e. structural features, e.g. of weight-saving hollow blades (F01D5/148, F01D5/16 and F01D5/20 take precedence; blade shape F01D5/141; blades with cooling or heating channels or cavities F01D5/18; heating, heat-insulating or cooling means on blades F01D5/18) · CPC title

• Y10T29/49332

  Propeller making · CPC title