Variable vane lever arm

1 . A vane arm comprising:

a first end and a second end;

a shank extending between the first end and the second end and having a first face and a second face;

a first hole in the shank proximate the first end;

a second hole in the shank proximate the second end;

a transverse groove in the first face and having:

a base;

a first open end and a second open end;

a first side face and a second side face,

wherein:

at least one of the transverse groove first side face and second side face has a first facet at a first angle of 0° to 20° over at least 20% of a depth of the groove;

at least one of the transverse groove first side face and second side face has a second facet at a second angle of 20° to 45° over at least 50% of the depth of the groove; and

the side face having the first facet has a third facet, proximal to the first facet and a third angle of 20° to 45° over at least 20% of the depth of the groove.

2 . The vane arm of claim 1 wherein:

the second hole is of circular footprint.

3 . The vane arm of claim 1 wherein:

the second facet is between the first end and an axis of the second hole; and

the second facet is at said second angle over at least 80% of the depth of the groove.

4 . The vane arm of claim 1 wherein:

the first facet is between the second end and an axis of the second hole.

5 . The vane arm of claim 4 wherein:

the third angle is 20° to 45° over at least 40% of the depth of the groove.

6 . The vane arm of claim 5 wherein:

the second facet is at said second angle over at least 80% of the depth of the groove.

7 . The vane arm of claim 1 wherein:

the third angle is 20° to 45° over at least 40% of the depth of the groove.

8 . The vane arm of claim 7 wherein:

an average depth of the groove is at least 2.5 millimeters;

a distance between centers of the first and second holes is 25 millimeters to 51 millimeters; and

an overall length of the vane arm is no more than 70 millimeters.

9 . The vane arm of claim 1 further comprising:

a third hole between the first hole and the second hole and closer to the first hole.

10 . The vane arm of claim 1 being machined from a nickel alloy.

11 . The vane arm of claim 1 wherein:

an average depth of the groove is at least 2.5 millimeters;

a distance between centers of the first and second holes is 25 millimeters to 51 millimeters; and

an overall length of the vane arm is no more than 70 millimeters.

12 . A vane assembly including the vane arm of claim 1 and further comprising a vane having an airfoil and a shaft protruding from an end of the airfoil, wherein:

the vane shaft extends through the second hole;

the vane shaft has first and second faces respectively abutting the transverse groove first side face and second side face; and

a nut holds the vane arm to the shaft.

13 . The vane assembly of claim 12 wherein:

the vane shaft first and second faces and the transverse groove first side face and second side face are configured to prevent assembly with the vane arm in an orientation 180° about an axis of the shaft.

14 . The vane assembly of claim 13 further comprising:

a pin mounted in and protruding from the first hole.

15 . The vane assembly of claim 12 wherein:

a tab washer is between the nut and the vane arm and has a tab received in third hole between the first hole and the second hole.

16 . A vane stage comprising a plurality of vane assemblies of claim 12 , and further comprising:

a synchronizing ring coupled to the vane arms and having an axis; and

for each vane assembly one or more bearings mounting the vane for rotation about an axis of the vane wherein, rotation of the synchronizing ring about its axis rotates the vanes about their respective axes.

17 . A method for using the vane arm of claim 1 , the method comprising:

installing the arm to a vane so that:

a shaft of the vane extending from an end of an airfoil of the vane passes through the second hole; and

the vane shaft abuts the third hole proximal edge and the first tab distal end edge; and

installing a nut to a threaded portion of the shaft to hold the vane arm to the shaft compressed between the nut and a shoulder of the shaft.

18 . The method of claim 17 further comprising:

installing a pin to the first hole.

19 . The method of claim 17 wherein:

the method is performed with a plurality of vane arms and the respective pins are mounted to a shared synchronizing ring.