Remote gearbox lubricant level gauge system for rotorcraft

1 . An aircraft comprising:

a fuselage;

a vertical stabilizer connected to an aft end of the fuselage, the vertical stabilizer supporting a tail rotor proximate an upper end of the vertical stabilizer;

a gearbox housing within the vertical stabilizer proximate the upper end thereof, the gearbox housing comprising a top, a bottom, and at least one side disposed between the top and the bottom, the gearbox housing containing a lubricant; and

a remote gearbox lubricant level gauging system comprising:

a light source within the gearbox housing;

a plurality of ports in the at least one side of the gearbox housing;

a display disposed on the fuselage at a location remote from the gearbox housing, the display comprising a plurality of indicators and having integrated therewith a switch for controlling activation of the light source; and

a plurality of light tubes connected between the plurality of ports and the plurality of indicators;

wherein the indicators indicate a level of the lubricant contained within the gearbox housing based on the light transmitted via the light tubes; and

wherein the display comprises multiple displays disposed at various points on the fuselage, wherein each of the displays is remote from the gearbox housing.

2 . The aircraft of claim 1 , wherein the light source is powered by a power source of the aircraft.

3 . The aircraft of claim 1 , wherein the light source is powered by a power source located in the fuselage proximate the display.

4 . The aircraft of claim 1 , wherein a side of the gearbox housing comprises a glass plate and wherein light from the light source is directed to the glass plate and light reflected from the glass plate is transmitted by the at least one light tube.

5 . The aircraft of claim 4 , wherein a side of the glass plate external to the gearbox housing comprises a planar surface and a side of the glass plate internal to the gearbox housing comprises a plurality of an array of alternating 45 degree faces.

6 . The aircraft of claim 1 , wherein each of the plurality of light tubes is connected to a respective one of the plurality of ports and wherein each of the indicators corresponds to one of the plurality of light tubes.

7 . The aircraft of claim 1 , wherein the light source comprises a light emitting diode.

8 . A remote gearbox lubricant level gauging system for a rotorcraft, the rotorcraft comprising a fuselage and a vertical stabilizer connected to an aft end of the fuselage, the vertical stabilizer supporting a tail rotor assembly proximate an upper end thereof, the remote gearbox lubricant level gauging system comprising:

a light source that when activated illuminates an interior of a gearbox housing for containing a lubricant, the gearbox housing comprising a top, a bottom, and at least one side disposed between the top and the bottom, the gearbox housing disposed within the tail rotor assembly proximate the upper end of the vertical stabilizer;

at least one port provided in the at least one side of the gearbox housing;

at least one light tube connected to the gearbox housing via the at least one port and configured for transporting light from within the gearbox housing to an observer end of the remote gearbox lubricant level gauging system, the observer end comprising a display panel and located on the fuselage in a location remote from the gearbox housing;

at least one indicator on the display panel for indicating a level of the lubricant contained within the gearbox housing based on the light transported by the at least one light tube; and

a switch for activating and deactivating the light source disposed on the fuselage proximate the display panel; and

a plurality of display panels disposed at various locations on the fuselage and remote from the gearbox housing.

9 . The remote gearbox lubricant level gauging system of claim 8 , wherein the light source is located inside the gearbox housing.

10 . The remote gearbox lubricant level gauging system of claim 8 , wherein the at least one indicator comprises a plurality of indicators on the display panel, wherein each of the indicators corresponds to a different level of lubricant contained within the gearbox housing.

11 . The remote gearbox lubricant level gauging system of claim 8 , further comprising a plurality of light tubes extending between the gearbox housing and the observer end, wherein the display panel comprises a plurality of indicators and each of the indicators corresponds to one of the plurality of light tubes.

12 . The remote gearbox lubricant level gauging system of claim 8 , wherein the at least one light tube comprises a portion having a first end and a second end and a second portion having a first end proximate the second end of the first portion and a second end proximate the observer end, the RGLLG system further comprising a prism positioned in an area between the second end of the first portion and the first end of the second portion such that light transmitted by the at least one light tube is reflected by the prism into the second light tube when the lubricant is not present in the area and is not reflected by the prism into the second light tube when the lubricant is present in the area.

13 . The remote gearbox lubricant level gauging system of claim 8 , wherein the at least one light tube comprises a portion having a first end and a second end and a second portion having a first end proximate the second end of the first portion and a second end proximate the observer end, the RGLLG system further comprising a gap between the second end of the first portion and the first end of the second portion arranged such that light transmitted by the at least one light tube is transmitted through the gap more brightly when the lubricant is present within the gap than when the lubricant is not present within the gap.

14 . The remote gearbox lubricant level gauging system of claim 8 , wherein the light source comprises a plurality of light emitting diodes.

15 . A method for gauging a level of lubricant contained within a gearbox housing of an aircraft comprising a fuselage and a vertical stabilizer for supporting a tail rotor assembly including the gearbox housing, the gearbox housing comprising a top, a bottom, and at least one side disposed between the top and the bottom, the method comprising:

activating a light source within the gearbox housing using a switch;

transporting light generated by the light source from an interior of a gearbox housing to a display panel using a plurality of light tubes each connected to one of a plurality of ports disposed in the at least one side of the gearbox housing, wherein the display panel is disposed on the fuselage at a location remote from the gearbox and wherein the switch is incorporated into the display panel; and

illuminating at least one of a plurality of indicators arranged on the display panel in a vertical configuration based on the light transported using the plurality of light tubes, the illuminated indicators corresponding to a level of lubricant contained within the gearbox housing; wherein the switch is disposed on the fuselage proximate the display panel

wherein the display panel comprises multiple display panels disposed at various points on the fuselage, wherein each of the display panels is remote from the gearbox housing.