Method to repair a permanently sealed air data tube

[0002] This application is not related to any pending applications.

[0003] This application is not referenced in any microfiche appendix.

[0004] The present invention generally relates to air data sensing tubes such as, but not limited to, pitot tubes. In particular the present invention relates to a system and method to repair a permanently sealed air data sensing tube.

[0005] The instant invention advances the art and teaches a process whereby internally accommodated components of a permanently sealed air data tube can be replaced and thus extend the useful life of the tube.

[0006] As used herein, the terms “pitot tube”, “pitot static tube”, “sealed pitot tube”, “air data sensing probe”, “air data tube”, “air data sensing tube”, “air data probe”, “pitot probe”, “pitot static probe”, “electrically heated pitot tube”, “aerodynamically compensated static pressure tube”, “electrically heated pitot static probe”, “heated pitot tube”, “heated pitot static tube”, “heated probe”, “pressure sensing instrument for aircraft”, “strut mounted oval static tube”, “multi-functional air data sensing probe” and “aerodynamic air data sensing probe” are used synonymously and interchangeably. The term “strut” relates to an air data tube component which distances a probe component of the air data tube several inches away from a fuselage or other aircraft surface to which the air data tube is attached. The term “probe” when used individually relates interchangeably and synonymously to that component of an air data tube which contains a pitot pressure opening. The probe typically, though not necessarily, embodies one or more moisture drain and/or static port holes as well.

[0007] Air data tubes are used on aircraft for measuring certain parameters such as air speed, altitude, static pressure and other air measurement information and are typically mounted to the body or nose portion of an aircraft. Air data tubes usually contain an electrical heating element to melt off and prevent ice accumulations which can plug the air channel openings of air data tubes during flight.

[0008] Generally, air data tubes have a base section from which the tube's strut component extends at an angle and terminates after connecting to the tube's probe component. Many air data tubes are considered sealed single units, whereby the internal components, heating elements and probe are permanently sealed via conventional methods such as, but not limited to, welding, brazing or soldering. Oftentimes, these joints are hidden as the tube in its totality is plated or otherwise smoothed to allow for better aerodynamics. Consequently, the tube appears absent of any discernable means to access its internal components. In the event that a pitot pressure opening located at the end of the probe tip becomes damaged or eroded due to corrosion, pitot static ports along the probe section become damaged or eroded due to corrosion, a tube's heating element(s) malfunctions, its pitot pressure line leaks or another tube connected component becomes damaged, the entire air data tube is discarded and replaced with an entirely new unit. Such lack of repairability results in increased costs as the entire unit is replaced, irrespective of whether the cause was due to a major or minor problem. Specifically, prior to the teaching of the instant invention, the art lacked teaching, disclosure and claim of a method of disassembly, component replacement/repair and reassembly of permanently sealed air data tubes. Most air data tubes currently used on commercial aircraft built by Boeing, McDonald Douglas and Airbus utilize such permanently sealed tube unit types.

[0009] As a large variety of aircraft models exist, and as specific air data tubes are designed for specific placement on specific aircraft models, the sizes, shapes internal components of air data tubes may vary considerably. However, it should be noted that most air data tubes operate in functionally the same manner. Different manufacturers promote different designs, and many known designs exist. There are many prior art patents for the design and manufacture of air data tubes. The present invention relates to the repair and overhaul of air data tubes that have been designed as unitary or sealed units. The teaching of the instant invention is the art of determining a suitable section or sections of the air data tube to allow for exposure and removal of its internal components, removal of the tube's permanently attached heating element, removal of internal pitot and static tube components, and the replacement of unsuitable components with newly manufactured or refurbished parts, thereby restoring the overall unit to an airworthy status.

[0010] The present invention improves upon the art and fills a major void in the marketplace by enabling an aircraft owner to overhaul an air data tube with newly manufactured major components at a substantially reduced amount of cost. Savings to multiple aircraft owners such as a commercial airlines, or air cargo carriers can result in millions of dollars of cost savings each year. Most large aircraft have between 2 and 8 air data tubes mounted on them. The tubes have an average life span of between 3 and 7 years. From an aircraft owners point of view, use of this invention will transform the air data tube from what was once considered an “expendable” item to a “repairable” item.

[0011] While numerous problems can cause a probe to malfunction and be taken out of service, a few common problems represent the majority of the fatal issues. They are:

[0012] 1. The probe section and its various openings become worn from corrosion and wind damage. If the openings are worn beyond specifications allowed for by the OEM, the entire unit must be discarded and replaced with a new unit.

[0013] 2. Malfunction of the heating element(s). Inability of the heating element to properly heat the probe section and strut of the air data tube can cause ice build up, closing the openings to the air data ports. Since the heating element is permanently attached to the inside wall of the probe section and strut, and since heretofore, the art was absent means by which to gain access to the internal portion of the tube without destroying it, the entire air data tube was discarded and replaced with a new unit.

[0014] The present invention provides for a method of elongating the useful life of these type of air data tubes by teaching a method for opening the air data tube body (strut), and removing components requiring repair or replacement. Having followed and completed the teachings of the instant invention, the air data tube may be returned to service, providing a substantial cost savings to an aircraft owner.

[0015] It is an object of the instant invention to provide a process by which permanently sealed air data tubes may be repaired and returned to useful service.

[0016] It is another object of the instant invention to teach a method by which a broachable area of an air data tube may be identified to allow access to its internally accommodated components for purposes of repair.

[0017] It is a further object of the instant invention to teach a singularly applicable process by which any model of a permanently sealed air data tube may be repaired and returned to useful service.

[0018] An additional object of the instant invention is to reduce costs associated with the replacement of non-repairable air data tubes.

[0019] Other objects and further scope of the applicability of the present invention will become apparent from the detailed description to follow, taken in conjunction with the accompanying drawings wherein like parts are designated by like reference numerals.

[0020] FIG. 1A is an illustration of an aircraft with an air data tube affixed.

[0021] FIGS. 1B through 1C illustrate non-limiting permanently sealed air data tubes of varying design used in association with aircraft speed monitoring as practiced in the invention's preferred embodiment.

[0022] FIG. 2 is a process flow diagram illustrating steps necessary to effectuate the repair of a permanently sealed air data tube according to the invention as practiced in its preferred embodiment.

[0023] FIG. 3A, for purposes of enabling disclosure, is an illustration of a generic air data tube indicating the tube's internally accommodated component structures and positioning therein as revealed by a visual perception means which renders transparent the external portions of an air data tube.

[0024] FIG. 3B is a front view illustration of an air data tube.

[0025] FIG. 3C is an exploded illustration of an air data tube further detailing its internal components.

[0026] FIG. 4 is an exploded illustration of the instant invention having once removed the internal components of the air data tube and cleansed its internal surface areas.

[0027] While the making and using of various embodiments of the present invention are discussed in detail below, it should be appreciated that the present invention provides for inventive concepts capable of being embodied in a variety of specific contexts. The specific embodiments discussed herein are merely illustrative of specific manners in which to make and use the invention and are not to be interpreted as limiting the scope of the instant invention.

[0028] The claims and the specification describe the invention presented and the terms that are employed in the claims draw their meaning from the use of such terms in the specification. The same terms employed in the prior art may be broader in meaning than specifically employed herein. Whenever there is a question between the broader definition of such terms used in the prior art and the more specific use of the terms herein, the more specific meaning is meant.

[0029] While the invention has been described with a certain degree of particularity, it is clear that many changes may be made in the details of construction and the arrangement of components without departing from the spirit and scope of this disclosure. It is understood that the invention is not limited to the embodiments set forth herein for purposes of exemplification, but is to be limited only by the scope of the attached claim or claims, including the full range of equivalency to which each element thereof is entitled.

[0030] The methodology of the present invention is best understood having once overviewed air data tube placement in association with large aircraft and various non-limiting types of air data tubes to which the invention addresses itself. As previously discussed, non-repairable, permanently sealed air data tubes are commonly employed on aircraft such as, but not limited to, Boeing, McDonald Douglas and Airbus. FIGS. 1A through 1C address themselves to this explanation. As can be seen in FIG. 1A, an air data tube 1.05 is affixed to the lower part or nose of an aircraft fuselage 1.06. Depending upon aircraft type and model, an air data tube's placement will vary from the afore noted placement to placement along lower wing surfaces 1.03 (not shown) as well as tail 1.04 and nose 1.02 sections of the aircraft. FIG. 1B illustrates an external view of an air data tube typically used in association with MD-80, MD-90 or DC-9 aircraft wherein 1.14 represents the tube's strut component, 1.08 the tube's pitot pressure line component, 1.11 the tube's heating element electrical connector component and 1.17 the tube's probe component. In FIG. 1B a pitot pressure opening 1.07 in the probe component 1.17 allows incoming air to be introduced into the air data tube's pitot pressure line component 1.08 whereupon it is attached to a pitot pressure fitting 1.09. Various means to attach air data tubes 1.05 to aircraft are utilized with said means well known and practiced by those skilled in the art. In FIGS. 1B, a base 1.12 is utilized to facilitate such aircraft connection purposes. Based upon aircraft and air data tube requirements, the base 1.12 may contain a plurality of components to facilitate the various aircraft connection requirements. Such components without limitation would include, but not be limited to, electrical connectors, pressure fittings, static line pressure fittings, bolts and bolt holes. FIG. 1C further illustrates examples of these additional components. Turning now to FIG. 1C.

[0031] FIG. 1C illustrates yet another version of the air data tube typically used in association with Boeing 737 aircraft and further illustrates multiple static port holes 1.39 connecting to static port lines 1.40 and 1.30. Static port pressure fittings 1.31 and 1.41 are used to facilitate connection to an aircraft. Also shown in FIG. 1C is the air data tube's heating element connecting component(s) 1.11, a pitot pressure line 1.08 and a pitot line pressure fitting 1.09.

[0032] FIG. 2 illustrates and details the process steps necessary to effectuate the repair of an air data tube once disengaged from an aircraft. Said steps as provided in FIG. 2 illustrate a preferred though non-limiting process sequence when practicing the invention in its preferred embodiment. Turning now to FIG. 2.

[0033] As can be seen in FIG. 2 it is first necessary to identify a broachable area of an air data tube whereby the air data tube may be opened to provide access to the internal components accommodated generally within the interior portion of the tube 2.05. This identification is facilitated by any means which would visually represent the location and positioning of the tube's internal component structures. In the invention's preferred embodiment, a common X-ray means provides for such visual perception though it can be easily envisioned where alternative means, such as computerized axial tomography, outer surface removal (abrasive) or tube destruction may be utilized to effectuate this purpose. Once determined for a specific air data tube model, the practice of the invention's identification step may be optionally bypassed.

[0034] Having once determined the general positioning and locations of the internal component structures, the air data tube is broached in those areas providing convenient access to the internally accommodated structures 2.08. Said broaching typically, though not limitedly, calls for a broaching of the air data tube strut component and probe component as well as external pressure fittings and electrical connectors. Once these components have been broached and access to internally accommodated components has been facilitated, the next process step in the invention is to remove all the internally accommodated air data tube components 2.11 which typically include, but are not limited to, at least one static tube component(s), at least one hermetic seal(s), a heating element component, probe component and pitot pressure line component 2.11. The heating element of the internally housed portion of the air data tube is typically attached along and throughout the internal surface areas of probe and strut air data tube components via brazing, welding or other similar means commonly known by those skilled in the art. The invention next calls for the refurbishment of the tube's internal surface areas 2.14. The air data tube components removed from the internal portion of the air data tube are next inspected 2.17 to determine those components requiring replacement and/or refurbishment. The tube is then subsequently reassembled utilizing replacement components 2.20. Without limitation, aircraft connection structures typically include pitot pressure fittings, heating element connecting fixtures, static port line(s), and static port line pressure fittings. Broached portions of the air data tube are next reattached and resealed. In certain circumstances it may be determined that the strut portion of the air data tube requires replacement. In most instances the external surface or surfaces of the air data tube must then be restored to an air worthy condition 2.28. Said restoring typically includes but is not limited to a smoothing out of all reconnected surfaces and an application of an external coating to further seal the exterior surface of the air data tube to further reduce its exposure to corrosive elements. Having discussed the methodology steps required to effectuate the restoration of a permanently sealed air data tube, FIG. 3A provides an illustration of an air data tube example subjected to X-ray analysis to determine internal component structures and placement. Turning now to FIG. 3A.

[0035] FIG. 3A illustrates an air data tube 3.05 when subjected to X-ray analysis 3.06 whereupon internal structural components are revealed. As seen in FIG. 3A, pitot pressure line component 3.08 opens to a pitot pressure opening 3.07 located on the leading edge of the probe component 3.17. Element 3.24 in FIG. 3A illustrates the positioning of a hermetic seal 3.24 within the interior portion of said probe component 3.17. Also positioned within the internal portion of the probe component 3.17 is an electrical heating element 3.11 which is generally affixed via brazing, welding, soldering, or other similarly intended attachment means known and practiced by those skilled in the art to the internal surface of said probe component 3.17. The heating element 3.11 also traverses the strut portion of the air data tube 3.14 and is generally affixed in a similar manner to the internal portion of said strut component 3.14 to thwart icing on the leading edge thereof. FIG. 3A further identifies a strut panel 3.26 of the air data tube strut which has been previously brazed, welded or sealed to form a permanently sealed air data tube. Said section represented as element 3.26 with a strut panel joint or demarcation indicated as 3.19. In most instances, a demarcation line similar to that found in 3.19 can be located using the above noted X-ray detection means on the air data tube's strut 3.14 that shows the original joint used in the manufacturing of the air data tube. However, it should be noted that the invention teaches towards accommodation of any alternative broaching determination means whereby manipulative access to the components accommodated within the internal section of the air data tube may be facilitated.

[0036] FIG. 3B illustrates a front view of an air data tube 3.05 providing further clarity with respect to the positioning and shape of the air data tube's pressure opening 3.07 which allows air to enter the air data tube into a pitot tube pressure line 3.08.

[0037] FIG. 3C illustrates an exploded view illustration of an air data tube 3.05 further detailing its internal components having once broached the tube strut 3.14 and probe 3.17 components. A heating element electrical connector 3.25 is illustrated and is removed, with such removal evidenced and illustrated in FIG. 4. As can be seen in FIG. 3C, the probe section 3.17 has been removed or otherwise opened at location 3.18 to provide access to, and removal of, the heater element component 3.11 and pitot pressure line component 3.08 contained therein. FIG. 3C further illustrates the removal of strut panel 3.26 to provide access to the internally accommodated air data tube components and further detail with respect to a base mounting plate 3.12 used to affix said air data tube 3.05 to an aircraft.

[0038] FIG. 4 illustrates the air data tube having had its internal and external components removed and its internal surface area 4.36 refurbished to allow for insertion, positioning and re-attachment of heating element and other required internal components.

[0039] While this invention has been described to illustrative embodiments, this description is not to be construed in a limiting sense. Various modifications and combinations of the illustrative embodiments as well as other embodiments will be apparent to those skilled in the art upon referencing this disclosure. It is therefore intended that this disclosure encompass any such modifications or embodiments.