Electrical isolation of angle of attack vane bearings

The bearings of aircraft angle of attack (AOA) vanes are susceptible to lightning strike damage, which causes fluting on the inner and outer races of the bearings and causes the bearings to generate friction, noise, and vibrations. To prevent the bearings from experiencing damage due to lightning strikes, the bearings, the shaft, and/or the mounting plate are configured to create an electric isolator to prevent the electric current from the lightning strike from passing through the bearings, thereby preventing the bearings from incurring lightning strike damage.

BACKGROUND

The present disclosure relates generally to electrically isolating angle of attack vanes. More particularly, this disclosure relates to electrically isolating the bearings of angle of attack vanes.

Angular measurement devices, such as angle of attack (AOA) and side slip angle (SSA) vanes, project from an aircraft body and are free to rotate and align with the prevailing airflow. The angular measurement vane rotates with the prevailing airflow and provides such rotational information to electronics within the aircraft. The trajectory of the aircraft and the degree of rotation of the angular measurement vane is used to calculate the angle of attack or the side slip angle of the aircraft, and such information is provided to the cockpit and to relevant systems on the aircraft.

Angular measurement vanes project outside of the aircraft and into the prevailing airflow. Typically, a shaft extends into the aircraft body from the angular measurement vane and into an electronics enclosure, where electronics measure the rotational displacement of the shaft. Bearings rotatably support the shaft relative to mounting hardware, which mounting hardware is secured to the body of the aircraft. The shaft is thus free to rotate relative to the mounting hardware such that the angular measurement vane is free to rotate with the prevailing airflow. The angular measurement vane, shaft, bearings, and mounting hardware are typically metallic, and the vane and mounting hardware are exposed to the environment, and as such, are particularly susceptible to lightning strikes. The electrical current from a lightning strike on the vane, mounting hardware, or other locations on the aircraft body can pass through the bearings of the angular measurement vane. The large electrical current generated by a lightning strike, which can exceed 130 kilovolts, arcs through the bearings of the angular measurement vane and can cause fluting damage, which can lead to rough or stiff bearing failures.

SUMMARY

According to an aspect of the present disclosure, an angle of attack vane mounting system includes a mounting flange secured to an aircraft, a shaft extending through the mounting flange, a bearing disposed between the mounting flange and the shaft, and an electric isolator. The bearing includes an inner race attached to the shaft and an outer race attached to the mounting flange. The electric isolator is disposed adjacent one of the inner race and the outer race and electrically isolates the bearing such that an electric current is prevented from passing between the inner race and the outer race.

According to another aspect of the present disclosure, an angle of attack vane for an aircraft includes an outboard mounting flange, an inboard mounting flange disposed adjacent the outboard mounting flange, a shaft extending through the outboard mounting flange and the inboard mounting flange, an inboard bearing rotatably supporting the shaft and disposed between the shaft and the inboard mounting flange, an inboard electric isolator configured to prevent an electric current from traveling through the inboard bearing, an outboard bearing rotatably supporting the shaft and disposed between the outboard mounting flange and the shaft, an outboard electric isolator configured to prevent an electric current from traveling through the outboard bearing, and a vane extending from the shaft outboard of the outboard mounting flange.

According to yet another aspect of the present disclosure, a method of preventing lightning strike damage to a bearing of an angle of attack vane includes mounting an angle of attack vane shaft on a bearing disposed between the angle of attack vane shaft and a mounting flange and electrically isolating the bearing such that an electrical current cannot pass between an inner race of the bearing and an outer race of the bearing.

DETAILED DESCRIPTION

During flight, AOA vane18rotates to align with the prevailing airflow. AOA vane18is preferably located forward of wings14. Locating AOA vane18forward of wings14minimizes the effects on AOA vane18of the airflow affected by fuselage12, wings14, or engines16, thereby ensuring the accuracy of AOA vane18. For example, as aircraft10ascends, AOA vane18aligns with the prevailing airflow and indicates a high angle of attack. As aircraft10approaches a cruise altitude AOA vane18continues to track with the prevailing airflow, and AOA vane18thus indicates a lower angle of attack as aircraft10levels off. Because AOA vane18projects from fuselage12, AOA vane18is exposed to the elements and is particularly susceptible to lighting strikes. When lightning strikes AOA vane18the electrical current generated by the lightning strike travels through AOA vane18and seeks a low-impedance path to fuselage12. While AOA vane18is described as measuring the angle of attack, it is understood that AOA vane18may be any angular sensing instrument, such as an AOA vane or a side slip angle vane.

Mounting system20is attached to fuselage12(shown inFIG. 1) and supports AOA vane18. Outboard mounting flange28is disposed outward of and secured to inboard mounting flange30. Shaft26extends through outboard mounting flange28and inboard mounting flange30and communicates with rotary position sensor36. Rotary position sensor36is inboard of shaft26and is configured to sense a rotational displacement of shaft26. Damper38extends about shaft26and typically includes a viscous fluid, such as oil, that dampens the rotation of shaft26, and thus AOA vane18, to slow the response time of AOA vane18to changes in airflow direction. As such, damper38ensures a smooth rotation of AOA vane18, thus providing a smooth reading of the angle of attack. In addition, the damping fluid in damper38absorbs oscillations experienced by shaft26, such as those vibrations experienced due to turbulence, and prevents variations in the angle of attack readings due to unwanted vibrations in shaft26.

Outboard bearing32is disposed between outboard mounting flange28and shaft26and rotationally supports shaft26relative to outboard mounting flange28. Outer race40ais attached to outboard mounting flange28and inner race42ais attached to shaft26. Ball44ais disposed between outer race40aand inner race42aand supports outer race40aand inner race42such that inner race42arotates relative to outer race40a. Inboard bearing34is disposed between inboard mounting flange30and shaft26and rotationally supports shaft26relative to inboard mounting flange30. Outer race40bis attached to inboard mounting flange30and inner race42bis attached to shaft26. Ball44bis disposed between outer race40band inner race42band supports outer race40band inner race42bsuch that inner race42bis free to rotate relative to outer race40b.

Mounting system20is attached to fuselage12(shown inFIG. 1). AOA vane18is rotatably supported by mounting system20with vane body24disposed outboard of fuselage12and shaft26supported by mounting system20. Outboard mounting flange28is typically mounted on an exterior of fuselage12and inboard mounting flange30is mounted opposite of and attached to outboard mounting flange28. In this way, outboard mounting flange28and inboard mounting flange30are attached to fuselage12to secure mounting system20and AOA vane18to fuselage12.

During flight, the prevailing airflow flows over vane body24and vane body24rotates to align with the prevailing airflow. Vane body24aligning with the prevailing airflow causes shaft26to rotate, and rotary position sensor senses the rotational movement of shaft26. Rotary position sensor36senses the rotational displacement of shaft26and communicates that information to other systems on aircraft10(shown inFIG. 1). The rotational displacement of shaft26and other information regarding the trajectory of aircraft10is used by the other systems onboard aircraft10to calculate the angle of attack, side slip angle, and the true direction of aircraft10travel, among other relevant information.

Vane body24and outboard mounting flange28are disposed outboard of fuselage12, and as such, vane body24and outboard mounting flange28are exposed and can attract lightning strikes. When lightning strikes vane body24or outboard mounting flange28, the electrical current seeks the path of least resistance to the metallic aircraft skin, which path of least resistance is typically through outboard bearing32, inboard bearing34, or both. The voltage generated by the lighting strike builds on inner race42aor outer race40auntil the voltage exceeds an insulation level of an oil film layer within outboard bearing32. When the voltage exceeds the insulation level, the voltage arcs through outboard bearing32and creates electrical discharge machining (EDM) pits on inner race42aand outer race40adue to rapid melting and cooling of the metallic inner race42aand outer race40a. Thousands of EDM pits may be created, and over time ball44arolling over the EDM pits can cause fluting damage to outboard bearing32. In addition, the EDM pits can cause friction within outboard bearing32. While the effects of a lightning strike on outboard bearing32have been described, it is understood that the effects of the lightning strike are equally applicable to inboard bearing34. As such, a single lightning strike can create EDM pits in both outboard bearing32and inboard bearing34.

Electric isolator22prevents the electrical current associated with a lightning strike, which may exceed 130 kilovolts, from arcing across either outboard bearing32; thereby damaging outer race40a, inner race42a, or ball44a; or inboard bearing34; thereby damaging outer race40b, inner race42b, or ball44b.

Dielectric barrier46amay be formed from the components of outboard bearing32or inboard bearing34. As such, dielectric barrier46amay take the form of a hybrid bearing or a fully non-conducting bearing. For example, ball44adisposed between outer race40aand inner race42amay be comprised of a material forming dielectric barrier46a. Where ball44ais formed of the material, preferably a ceramic, forming dielectric barrier46a, ball44aforms a non-conducting barrier preventing electrical current from arcing between outer race40aand inner race42a. Dielectric barrier46amay further include a ceramic outer race40aand a ceramic inner race42a, and in this way, outboard bearing32is a fully non-conducting bearing. By having dielectric barrier46abe a ceramic ball44a, a ceramic outer race40a, a ceramic inner race42a, or a combination thereof, electric currents are not conducted through outboard bearing32, and outboard bearing32is thus protected from the high voltage of a lightning strike. While dielectric barrier46ahas been described in relation to outboard bearing32, it is understood that dielectric barrier46aapplies equally to inboard bearing34such that one or more of ball44b, outer race40b, and inner race42bmay be formed of a non-conducting material, such as ceramic, to form dielectric barrier46a.

Hybrid bearings, where ball44aforms dielectric barrier46awhile outer race40aand inner race42aremain conducting, and all-dielectric bearings, where ball44a, outer race40a, and inner race42aform dielectric barrier46a, provide significant advantages. Hybrid bearings provide a higher load rating than all-metal counterparts, thereby increasing the durability and lifespan of the bearings. In addition, hybrid bearings and all-dielectric bearings prevent all electrical currents from passing through the bearing over the expected range of lightning strike voltage. As such, hybrid and all-dielectric bearings both increase the lifespan and utility of outboard bearing32and inboard bearing34, and consequently of AOA vane18, and prevent outboard bearing32and inboard bearing34from being damaged by any electrical signal, whether from a lightning strike or from induced electrical currents, such as those created by variable frequency generators, for example.

Similar to dielectric barrier46a, dielectric barrier46bprevents the electrical current associated with a lightning strike from arcing across either outboard bearing32or inboard bearing34. Dielectric barrier46bforms a shaft-side non-conducting barrier. To form dielectric barrier46b, shaft26constructed from a monolithic, dielectric material. For example, shaft26may be formed from a ceramic, an engineered plastic, or a non-conductive composite material. Having a monolithic, non-conductive shaft26prevents an electrical path from forming through shaft26and to either outboard bearing32or inboard bearing34. In this way, dielectric barrier46bthereby prevents the electric current from flowing through and damaging outboard bearing32and inboard bearing34.

Dielectric barrier46csimilarly prevents an electrical current associated with a lightning strike from arcing between and damaging inner race42aand outer race40a. Dielectric barrier46cforms an outboard mounting flange-side non-conducting barrier about outer race40a. To form dielectric barrier46c, outboard mounting flange28is formed from a monolithic, dielectric material. As such, outboard mounting flange28is preferably comprised of a ceramic, an engineered plastic, or a non-conductive composite material. Dielectric barrier46celectrically isolates outer race40ato prevent an electric current from flowing through outer race40a. As such, outboard bearing32is electrically isolated such that no electric current can flow through outboard bearing32between inner race42aand outer race40a. As such, dielectric barrier46cprevents outboard bearing32from sustaining EDM damage due to lightning strikes.

Similar to dielectric barrier46c, dielectric barrier46delectrically isolates outer race40band prevents an electrical current associated with a lightning strike from arcing between and damaging inner race42band outer race40b. Dielectric barrier46dforms an inboard mounting flange-side non-conducting barrier about outer race40b. To form dielectric barrier46d, inboard mounting flange30preferably comprises a ceramic, an engineered plastic, or a non-conductive composite material. As such, inboard mounting flange30forms dielectric barrier46d, and inboard mounting flange30electrically isolates outer race40b, thereby preventing an electric current from flowing through outer race40b. Inboard bearing34is thus electrically isolated such that an electric current cannot flow through inboard bearing34between inner race42band outer race40b. As such, dielectric barrier46dprevents inboard bearing34from sustaining EDM damage caused by lightning strikes.

While electric isolator22is described as including dielectric barrier46a, dielectric barrier46b, dielectric barrier46c, and dielectric barrier46d, it is understood that electric isolator22may include as few or as many of dielectric barriers46a-das desired. For example, dielectric barrier46aprevents an electric current from arcing between outer race40aand inner race42aby having one or more of ball44a, outer race40a, and inner race42aconsist of a ceramic material. As such, dielectric barrier46aprovides sufficient electrical protection to outboard bearing32and inboard bearing34to prevent outboard bearing32and inboard bearing34from sustaining lightning strike damage. Dielectric barrier46ais thus sufficiently robust to protect outboard bearing32and inboard bearing34and electric isolator may thus include dielectric barrier46aalone. Similarly, dielectric barrier46b, dielectric barrier46c, and dielectric barrier46dprovide sufficient electrical protection to outboard bearing32and inboard bearing34to prevent outboard bearing32and inboard bearing34from sustaining lightning strike damage. Therefore, electric isolator22may include any one or more of dielectric barrier46a, dielectric barrier46b, dielectric barrier46c, and dielectric barrier46d.

Electric isolator22provides significant advantages. Electric isolator22provides increased strength and durability to mounting system20and AOA vane18by including monolithic, non-conducting dielectric barriers46b,46c, and46d. The monolithic, non-conducting dielectric barriers46b,46c, and46dprovide greater structural integrity than metallic alloys, and the monolithic, non-conducting materials also offer greater thermal protection than metallic alloys, thereby reducing the need to heat various components of mounting system20and AOA vane18, such as rotary position sensor36and other electronic components. In addition, various combinations of dielectric barriers46a,46b,46c, and46dprovide robust electrical protection. For example, a combination of dielectric barrier46aand dielectric barrier46bprotects not only outboard bearing32and inboard bearing34from induced voltages, but also protects rotary position sensor36, as well as other electronics, because induced voltages cannot pass through shaft26due to dielectric barrier46b.

Mounting system20is attached to fuselage12(shown inFIG. 1) and supports AOA vane18. Outboard mounting flange28is disposed on an outward side of fuselage12and inboard mounting flange30is disposed on an inboard side of fuselage12. Outboard mounting flange28is attached to inboard mounting flange30to secure mounting system20to fuselage12. Shaft26′ extends through outboard mounting flange28and inboard mounting flange30. Annular notch48aextends into shaft26′ adjacent outboard bearing32, and annular notch48bextends into shaft26′ adjacent inboard bearing34.

Inboard bearing34is disposed between inboard mounting flange30and shaft26′ and rotatably supports shaft26′ relative to inboard mounting flange30. Outer race40bis disposed on inboard mounting flange30and inner race42bis disposed on shaft26′ about annular notch48b. Inner dielectric sleeve50bis disposed within annular notch48bbetween inner race42band shaft26′ such that inner race42bcontacts inner dielectric sleeve50b, but inner dielectric sleeve50bprevents inner race42bfrom contacting shaft26′. Ball44bis disposed between outer race40band inner race42band rotatably supports outer race40band inner race42bsuch that inner race42bis free to rotate relative to outer race40b. Inner dielectric sleeve50aand inner dielectric sleeve50bare formed from a non-conductive material such that an electric current cannot pass through either inner dielectric sleeve50aor inner dielectric sleeve50b.

Vane body24and outboard mounting flange28are disposed outboard of fuselage12, and as such, vane body24and outboard mounting flange28are exposed and can attract lightning. When lightning strikes vane body24or outboard mounting flange28, the electrical current seeks the path of least resistance to the metallic aircraft skin, which path of least resistance is typically through outboard bearing32, inboard bearing34, or both. When the electrical current travels through outboard bearing32, the electrical current arcs between outer race40aand inner race42aand can create EDM pits in outer race40aand inner race42a. Similarly, the electrical current can arc across inboard bearing34between outer race40band inner race42band create EDM pits in outer race40band inner race42b.

Electric isolator22′ prevents the electrical current associated with a lightning strike, which may exceed 130 kilovolts, from arcing across either outboard bearing32or inboard bearing34. Inner dielectric sleeve50aprovides a first dielectric barrier about shaft26between shaft26′ and inner race42asuch that no electric current can travel between inner race42aand shaft26′. As such, inner dielectric sleeve50aprevents the electric current from passing through outboard bearing32because the electric current cannot pass through inner dielectric sleeve50abetween inner race42aand shaft26′. Inner dielectric sleeve50athus electrically isolates outboard bearing32such that the electric current generated by a lightning strike cannot travel through outboard bearing32, thereby preventing outboard bearing32from being damaged due to a lightning strike.

Similar to inner dielectric sleeve50a, inner dielectric sleeve50bprovides a second dielectric barrier about shaft26, between shaft26′ and inner race42bsuch that no electric current can travel between inner race42band shaft26′. As such, inner dielectric sleeve50bprevents the electric current from passing through outboard bearing32because the electric current cannot pass through inner dielectric sleeve50bbetween inner race42band shaft26′. Inner dielectric sleeve50bthus electrically isolates inboard bearing34such that the electric current generated by a lightning strike cannot travel through inboard bearing34, thereby preventing inboard bearing34from being damaged due to a lightning strike.

Electric isolator22′ provides significant advantages. Inner dielectric sleeve50aand inner dielectric sleeve50bprotect outboard bearing32and inboard bearing34from induced voltages caused by lightning strikes, which can reach upwards of 130 kilovolts. Unlike a ceramic coating on inner race42aor inner race42b, which may protect for voltages up to about 3 kilovolts, inner dielectric sleeve50aand inner dielectric sleeve50bprovide robust electrical protection.

Mounting system20is attached to fuselage12(shown inFIG. 1) and supports AOA vane18. Outboard mounting flange28′ is disposed on an outward side of fuselage12and inboard mounting flange30′ is disposed on an inboard side of fuselage12. Outboard mounting flange28′ is attached to inboard mounting flange30′ to secure mounting system20to fuselage12. Shaft26extends through outboard mounting flange28′ and inboard mounting flange30′. Flange notch52aextends annularly about an inner wall of outboard mounting flange28′, and outer dielectric sleeve54ais disposed within flange notch52a. Flange notch52bextends annularly about an inner wall of inboard mounting flange30′, and outer dielectric sleeve54bis disposed within flange notch52b. Outer dielectric sleeve54ais made from a non-conducting material, such as a ceramic, an engineered plastic, or a composite material. Similarly, outer dielectric sleeve54bis made from a non-conducting material, such as a ceramic, an engineered plastic, or a composite material.

Outboard bearing32is disposed between outboard mounting flange28′ and shaft26and rotationally supports shaft26relative to outboard mounting flange28′. Outer race40ais disposed on outer dielectric sleeve54a, which is connected to outboard mounting flange28′ and disposed within flange notch52a. Inner race42ais attached to shaft26, and ball44ais disposed between outer race40aand inner race42a. Inboard bearing34is disposed between inboard mounting flange30′ and shaft26and rotationally supports shaft26relative to inboard mounting flange30′. Outer race40bis disposed on outer dielectric sleeve54b, which is connected to inboard mounting flange30′ and disposed within flange notch52b. Inner race42bis attached to shaft26, and ball44bis disposed between outer race40band inner race42b.

During flight, air flows over vane body24and vane body24rotates to align with the prevailing airflow. Vane body24projects outboard of fuselage12, and outboard mounting flange28′ similarly exposed to the environment outboard of fuselage12. As such, vane body24and outboard mounting flange28′ are exposed and can attract lightning strikes. When lightning strikes vane body24or outboard mounting flange28′ the electric current attempts to travel to the metallic skin of fuselage12. When lightning strikes vane body24, the electrical current travels down vane body24and along shaft26. From shaft26the electrical current generally travels through outboard bearing32and inboard bearing34because outboard bearing32and inboard bearing34present the path of least resistance to the electrical current. Similarly, when lightning strikes outboard mounting flange28′, the path of least electrical resistance for the electrical current to travel through is through outboard bearing32, inboard bearing34, or both. Whether the lightning strikes vane body24or outboard mounting flange28′ the electrical current can arc across outboard bearing32, between outer race40aand inner race42a, thereby creating EDM pits in outer race40aand inner race42a. The electrical current can also arc across inboard bearing34, between outer race40band inner race42b, and create EDM pits in outer race40band inner race42b. The EDM pits in both outboard bearing32can cause friction and can lead to premature bearing of AOA vane failure.

Electric isolator22″ prevents an electrical current associated with a lightning strike, which may exceed 130 kilovolts, from passing through either outboard bearing32or inboard bearing34. Outer dielectric sleeve54aprovides a dielectric barrier between outer race40aand outboard mounting flange28′. Outer dielectric sleeve54aelectrically isolates outboard bearing32to prevent any voltage, from stray electrical currents to those generated by a lightning strike, from passing through and damaging outboard bearing32between inner race42aand outer race40a. In this way, outer dielectric sleeve54aprevents electrical current from flowing through outboard bearing32, as the electric current cannot pass through outer dielectric sleeve54a. Outer dielectric sleeve54athus breaks any electrical pathway through outboard bearing32, thereby protecting outboard bearing32from electrical currents.

Similar to outer dielectric sleeve54a, outer dielectric sleeve54bprovides a dielectric barrier between outer race40band inboard mounting flange30′. Outer dielectric sleeve54is disposed between outer race40band inboard mounting flange30′ such that outer dielectric sleeve54contacts outer race40while preventing inboard mounting flange30′ and outer race40bfrom coming into contact. Outer dielectric sleeve54belectrically isolates inboard bearing34such that any voltage, from stray electrical currents to those generated by a lightning strike, is prevented from passing through and damaging inboard bearing34. In this way, outer dielectric sleeve54bprevents electrical current from flowing through inboard bearing34as the electrical current cannot pass through outer dielectric sleeve54b. Outer dielectric sleeve54bthus breaks any electrical pathway through inboard bearing34, thereby protecting inboard bearing34from electrical currents.

Electric isolator22″ provides significant advantages. Outer dielectric sleeve54aand outer dielectric sleeve54bprotect outboard bearing32and inboard bearing34from induced voltages caused by lightning strikes, which can reach upwards of 130 kilovolts. Unlike a ceramic coating on outer race40aor outer race40b, which may protect for voltages up to about 3 kilovolts, outer dielectric sleeve54aand outer dielectric sleeve54bprovide robust electrical protection.

Mounting system20is attached to fuselage12(shown inFIG. 1) and supports AOA vane18. Outboard mounting flange28is disposed outward of and secured to inboard mounting flange30. Shaft26extends through outboard mounting flange28and inboard mounting flange30and communicates with rotary position sensor36. Rotary position sensor36is inboard of shaft26and is configured to sense a rotational displacement of shaft26. Damper38extends about shaft26and typically includes a viscous fluid, such as oil, that dampens the rotation of shaft26and any vibrations experienced by shaft26. Outboard bearing32is attached to both outboard mounting flange28and shaft26and rotationally supports shaft26relative to outboard mounting flange28. Outer race40ais attached to outboard mounting flange28and inner race42ais attached to shaft26. Ball44ais disposed between outer race40aand inner race42aand supports outer race40aand inner race42such that inner race42arotates relative to outer race40a. Inboard bearing34is attached to both inboard mounting flange30and shaft26and rotationally supports shaft26relative to inboard mounting flange30. Outer race40bis attached to inboard mounting flange30and inner race42bis attached to shaft26. Ball44bis disposed between outer race40band inner race42band supports outer race40band inner race42bsuch that inner race42bis free to rotate relative to outer race40b. Electric isolator22′″ is connected to shaft26and is electrically connected to outboard mounting flange28.

Electric isolator22′″ is a grounding device, such as a grounding ring22a′″ (FIG. 5) or a grounding brush22b′″ (FIG. 5A), connected to shaft26. Electric isolator22′″ provides an alternate low-impedance path from shaft26to outboard mounting flange28, and thus to the skin of fuselage12(shown inFIG. 1). Electric isolator22′″ thus reduces or eliminates voltage on shaft26, and thus on outboard bearing32and inboard bearing34, by preventing voltage from building on shaft26. As such, the electrical current generated by a lightning strike is routed away from outboard bearing32and inboard bearing34, thereby protecting both outboard bearing32and inboard bearing34.

Discussion of Possible Embodiments

An angle of attack vane mounting system includes a mounting flange secured to an aircraft; a shaft extending through the mounting flange; a bearing disposed between the mounting flange and the shaft, wherein the bearing includes an inner race attached to the shaft and an outer race attached to the mounting flange; and an electric isolator disposed adjacent one of the inner race and the outer race and electrically isolating the bearing such that an electric current is prevented from passing between the inner race and the outer race.

The angle of attack vane mounting system of the preceding paragraph can optionally include, additionally and/or alternatively, any one or more of the following features, configurations and/or additional components:

The electric isolator comprises a sleeve disposed between the shaft and the inner race.

The electric isolator comprises a sleeve disposed between the mounting flange and the outer race.

The electric isolator comprises a ceramic rolling element disposed between the inner race and the outer race.

The shaft comprises a dielectric material.

An angle of attack vane for an aircraft an outboard mounting flange; an inboard mounting flange disposed adjacent the outboard mounting flange; a shaft extending through the outboard mounting flange and the inboard mounting flange; an inboard bearing rotatably supporting the shaft and disposed between the shaft and the inboard mounting flange; an inboard electric isolator configured to prevent an electric current from traveling through the inboard bearing; an outboard bearing rotatably supporting the shaft and disposed between the outboard mounting flange and the shaft; an outboard electric isolator configured to prevent an electric current from traveling through the outboard bearing; and a vane extending from the shaft outboard of the outboard mounting flange.

The angle of attack vane of the preceding paragraph can optionally include, additionally and/or alternatively, any one or more of the following features, configurations and/or additional components:

The inboard electric isolator includes a ceramic inboard rolling ball disposed between an inboard outer race of the inboard bearing and an inboard outer race of the bearing, wherein the ceramic inboard rolling ball is configured to prevent an electric current from passing between the inboard inner race and the inboard outer race.

The inboard inner race is a dielectric material and the inboard outer race is the dielectric material.

The dielectric material comprises one of a ceramic, an engineered plastic, or a composite material.

A grounding brush is disposed about the shaft and configured to ground the shaft to a fuselage of the aircraft.

The inboard electric isolator includes a first sleeve disposed about the shaft and adjacent an inboard inner race of the inboard bearing, and the outboard electric isolator comprises a second sleeve disposed about the shaft and adjacent an outboard inner race of the outboard bearing.

The inboard electric isolator comprises a first sleeve disposed between the inboard mounting flange and an inboard inner race of the inboard bearing, and the outboard electric isolator comprises a second sleeve disposed between the outboard mounting flange and an outboard inner race of the outboard bearing.

The outboard mounting flange comprises a dielectric material.

The shaft comprises a dielectric material.

The inboard mounting flange comprises a dielectric material.

A method of preventing lightning strike damage to a bearing of an angle of attack vane includes mounting an angle of attack vane shaft on a bearing disposed between the angle of attack vane shaft and a mounting flange, and electrically isolating the bearing such that an electrical current cannot pass between an inner race of the bearing and an outer race of the bearing.

Mounting a ceramic rolling element between the inner race and the outer race.

Mounting a grounding element on the shaft adjacent the bearing, such that the shaft is grounded to an aircraft.

Mounting a dielectric sleeve on the shaft between the shaft and the inner race.

Mounting a dielectric sleeve on a mounting flange adjacent the outer race of the bearing.