FR3039896A1 - IMPROVING OIL LEAK DETECTION DURING ENGINE ASSEMBLY - Google Patents

Abstract

A method is provided for discriminating between a leakage of an engine lubricating oil and a seepage of a light-colored mounting oil, different from the engine lubricating oil, when assembling an engine into a motor. which engine lubricating oil and mounting oil were previously made. In order to quickly detect a leak: - before adding it to the engine, the weight of the mounting oil is added, in weight percent, between 0.002 and 0.5%, and preferably between 0.005 and 0.2%, of the non-organic dye. ionic 1,4-bis (butylamine) anthraquinone (blue 35) of formula C22H26N202, - then, during a seepage or limited leakage of mounting oil, from the engine, the color of the ooze or the leak, and, depending on this color, it is deduced whether or not there is presence of engine lubricating oil in the oozing or leakage.

Description

The invention relates to the detection of oil leaks during the assembly of engines, specifically aviation turbomachines, to meet the performance requirements of turbine engines. gas appliances, whether commercial or military.

Thus, there is provided a method for discriminating between a leakage of an engine lubricating oil and a seepage of a light-colored mounting oil, different from the engine lubricating oil, when assembling a engine in which engine lubricating oil and mounting oil have been previously made.

There are preferred ways to roam a new or remanufactured (or reconditioned) engine.

In addition, the oil currently used in mounting on the above engines does not allow sufficient discrimination between engine lubricating oil leaks and mounting oil seeps. This creates a risk of receiving questions or comments from customers in the event of deliveries of engines where there are oil leaks that are difficult to detect with the current solution (s).

Indeed, in the event of leakage of engine lubricating oil, the mounting oil is mixed with the engine oil. The range of colors of the oils (from yellow to black through orange) does not make it possible to highlight the color of the mixture of the two oils and thus to identify if the drops of oil (s) observed actually come. the engine (leakage) or if it is only a drift of the mounting oil.

In this context, it is important to find a solution to distinguish the mounting oil and lubricating oil from the engine, especially as each new or remanufactured engine undergoes a bench run before being delivered to the customer. Then, after installation on the aircraft, the engine is still running during flight tests. These test hours make it possible to check that the engine is operating normally. They also detect small oil leaks or other minor defects.

In the past, solutions have already been proposed where an oil mixture is used with fluorescein. The relevant areas of the engines are then analyzed with equipment operating under black light which highlights oil leaks.

A problem of this solution is the use of a specific lamp and the quality of the detection which is very low compared to that desired, especially in the case of mixing oils.

Indeed, applied to the automobile, this solution is not effective on the oils used in an aircraft engine because they become fluorescent in the ultraviolet (UV).

These old proposals are therefore relatively difficult to implement. The invention aims on the contrary a solution that allows to reliably ensure a visual detection of leaks of a particular engine lubricating oil, without the aid of apparatus.

It is therefore proposed, in order to rapidly detect a mixture of oils and to prevent the leakage from increasing: - before adding it to the engine, add to the mounting oil and in weight percentage, between 0.002 and 0.5%, and preferably between 0.005 and 0.2% of the nonionic organic dye 1,4-bis (butylamine) anthraquinone (called Sudan Blue or "sudan blue 35", TM) of formula C22H26N2O2, this to increase discrimination by the coloring of the mounting oil, - then, during a seepage (or a still limited leakage) of mounting oil, from the engine, that the color of the ooze (or leakage), and, depending on the color, whether it is determined whether or not there is engine lubricating oil in the ooze (or leak).

As advantages of this particular dye (apart from the choice of color) it may be noted that it is chemically compatible with the mounting oil, soluble in the proportions indicated above and that it does not modify the properties of the oil .

SAE AS5780A defines the basic physical, chemical and performance limits for five viscosity grades (cSt) of gas turbine lubricating oils used in aviation and industrial and marine aviation applications. The standard also describes the standard methods and requirements for laboratories conducting the certification of oils.

The engine concerned may therefore be in particular a turbojet or a turboprop aircraft.

Advantageously, the selected motor and mounting oils will be based on synthetic polyol, such as erythritol derivatives, and will contain various additives including antioxidant additives based on amine and anti-wear additives based on organophosphate ( s).

So that the expected visual identification of the engine and mounting oils and their compatibility both with each other and with respect to the functions that they must fulfill respectively for the lubrication in operational operation and the assembly, are optimal, it is advisable the lubricating oil and mounting oil meet the SAE AS5780 standard, each with a color ranging from colorless to orange.

With reference to this color range, the darkest oil eligible on the day of filing of this French patent application according to SAE AS5780 is the one called: "Exxon Mobil jet 2 / MJOII". Lighter oils are suitable.

In practice, the oils conforming to the SAE AS5780 standard contained in the color range which is suitable in the context of the present application and adapted to constitute an engine lubricating oil and / or mounting, on an aircraft engine, can in particular be one of the following oils, the values being in percentage by weight: a synthetic turbine oil comprising at least one polyol ester containing 1-5% of n-phenyl-1-naphthylamine and 1-5% of tricresyl phosphate (specifically, oil known under the name "BP turbo 2380 or Eastman 2380 Exxon"), - a mixture of synthetic lubricating esters and additives containing n-phenyl-1-naphthylamine, 1-3% of tricresyl phosphate, or diphenylamine derivatives of alkyl (diphenyl amines alkyl), (specifically, oil known under the name "Exxon Mobil jet 2 / MJOII"), - a carboxylic ester with additives containing at least one triaryl phosphate ( such 68937-41-7) <3%, and aromatic amines (such as 90-30-2 and 15721-78-5) <2.5% (specifically, oil known under the name "Turbonycoil 600 / TN600"), - a mixture of synthetic lubricating esters and additives containing 1-3% of alkaryl amine and 1-2% of tricresyl phosphate, (specifically, oil known under the name "Aeroshell turbine oil 560 / ASTO 560"), - a mixture of synthetic lubricating esters and additives containing 96.5% synthetic esters, about 2% aromatic amines, about 1% organic phosphates (tricresyl phosphate), about 0.5% polymethacrylate and less than 0.5% sodium salts. carboxylic acid, (specifically, oil known under the name "Aeroshell turbine oil 500 / ASTO 500"), and / or that the mounting oil is one of the aforementioned.

Thus, for example the oil "Exxon Mobil jet 254" (oil based on a mixture of synthetic lubricating esters and additives containing n-phenyl-1-naphthylamine and 1-3% of tricresyl phosphate precisely ), or the oil "Eastman 2197" or "Exxon Mobil jet 387" will not be usable; too dark, especially, including the clearest of the lot: oil "Eastman 2197".

Among the usable oils, note the following:

The typical characteristics of "Turbonycoil 600 / TN600" oil are as follows:

The typical characteristics of oil "Exxon Mobil jet 2 / MJOII" are as follows:

Viscosity cSt at 40 ° C (102 ° F) 27.6 cSt at 100 ° C (212 ° F) 5.1 cSt at -40 ° C (40 ° F)% change at -40 ° after 72 h 11,000 - 0.15

Pour point, ° C (° F), ASTM D 97 -59 (-74)

Flash point, ° C (° F), ASTM D 92 270 (518)

Fire Point, ° C (° F) 285 (545)

Autoignition Point, ° C (° F) 404 (760) TAN (mg KOH / g) 0.03

Density at 15 ° C kg / L, ASTM D 4052 I, 0035

Evaporative loss,% 6.5 h at 204 ° C, 29.5 in Hg 3.0 10.9 33.7 6.5 h at 232 ° C, 29.5 in Hg 6.5 h at 232 ° C , 5.5 in. Hg (Pressure equivalent to an altitude of 40,000 feet)

Foaming Test, ml Sequence I, 24 ° C Sequence 8 10 8 II, 93.5 ° C Sequence III, 75 ° C (after a 200 ° F test)

Stability test of the foam, after 1 min of rest, 0 ml

Ultrasonic shear stability test, 0.9 variation in kinematic viscosity at 40 ° C,

Ryder Gear Test, Average Ib / In% Hercolube A 2750 115

The typical characteristics of "BP turbo 2380" oil are as follows:

Pour point -57 ° C

Amber color.

Density 980 kg / m3 (0.98 g / cm3) at 15.6 ° C Specific gravity 0.98

Kinematic viscosity: 24.2 mm2 / s (24.2 cSt) at 40 ° C

4.97 mm2 / s (4.97 cSt) at 100 ° C

The typical characteristics of "Aeroshell turbine oil 560 / ASTO 560 and 500" oils, in particular, are as follows (see first and third columns of the table below):

Concerning the "SUDAN BLUE 35" (Sudanese Blue 35), its typical characteristics are as follows:

Molecular formula: C22H26N202

Synonym: Anthraquinone, 1,4-bis (butylamino) - (7Cl, 8Cl); 1,4

Bis (butylamino) anthraquinone; Aizen SOT Blue 2; C Ext. Blue 12; C. L. Solvent Blue 35; Fat Blue B 01; Oil Blue 2N; Oil Soluble Blue 11; Sudan Blue II, blue solvent 35, sudan blue 35;

Appearance: dark blue powder,

Molecular Weight: 350.45404 Density: 1.179 g / cm3 Boiling Point: 568.7 ° C at 760 mmFIg Melting Point: 120-122 ° C (lit.)

Flash point: 187.2 ° C Refractive index: 1.63. The use of a naturally clear and colored blue oil for the assembly operations of engines or engine parts, that is to say the assembly of many of its constituents (assembly oil retained + 0.1% for example) mass of the Blue Sudan dye), and therefore of a color noticeably different from that of the lubricating oils allows the discrimination of engine lubricating oil leaks and mounting oil seeps.

This discrimination is possible by a color change of the oil leakage: - if there is only a mounting oil oozing, the original blue color will remain stable, - if on the other hand there is If there is a leakage of engine lubricating oil due to the mixing of the two oils, a change in color will confirm the leakage of the lubricating oil (variation of the blue to the engine oil passing through the green if the oil engine is light in color). The oil chosen for mounting will preferably be very clear so that the blue color is easily recognizable.

The dark or light character of a color is related to its degree of brightness. The standard AFNOR X 08-010 (Classification of colors) defines orange as a color with a dominant wavelength between 584 nm and 605 nm, saturation and brightness medium to high. The aforementioned pale or light color ranging from colorless to orange can thus favorably have a dominant wavelength of between 525 nm and 605 nm, according to the standard. In practice, the following is recommended in order to make the operations involving the oils in question more reliable: - the mounting oil with the added dye will be used for the assembly of oil pipes of the engine concerned, such as a turbojet or turboprop engine, - during the acceptance test of the end of assembly line engine, the possible seepage will be visualized. - and then examine the color of the oozing (or limited leakage) by its visual control, on a neutral absorbent support.

Thus, in a predefined, identified and systematic manner, a criterion for inspection of the color of the oil present in the vicinity of the oil pipes (the place most likely to leak oil) will be provided after the test. end-of-line reception. The detected leaks can be immediately corrected by tightening the connections and / or the screws at the origin of the leak.

It is stated here that many laboratory tests have been conducted in order to determine this inspection criterion. These tests led to the simulation of engine oil leaks by mixing blue mounting oil with different proportions of the engine lubricating oil and then visually inspecting and then on a cloth support (neutral absorbent support) the variation in the color of the engine oil. mixed.

It was also found that, on oil pipes used in a test bench engine, the color of the oil observed around the pipe was, with the proposed solution, green in case of oil leakage. engine, contrary to the case of the use of oil "Exxon Mobil Jet 254" in mounting (known solution) where the color of the oil observed around the pipe does not make it possible formally to rule on the existence of a engine leak.

Claims (4)

A method of discriminating between a leakage of an engine lubricating oil on an aircraft engine, and a seepage of a light-colored mounting oil, different from the engine lubricating oil, during the period of time. assembling an engine in which engine lubricating oil and mounting oil have been previously provided, characterized in that, in order to rapidly detect a mixture of the oils: - before bringing it into the engine as a percentage by weight, the mounting oil is added between 0.002 and 0.5%, and preferably between 0.005 and 0.2%, of the nonionic organic dye 1,4-bis (butylamine) anthraquinone, of formula C22H26N2O2, - then, during a seepage or a limited leakage of mounting oil, from the engine, the color of the seepage or leak is examined, and, depending on this color, it is deduced whether there is or no presence of engine lubricating oil in the oozing or flight. The method according to claim 1, wherein the engine lubricating oil and the mounting oil are SAE AS5780 compliant oils and vary in color from colorless to orange. The process according to claim 1 or 2, wherein the engine lubricating oil and the mounting oil are each one of the following oils: - a synthetic turbine oil comprising at least one polyol ester containing 1 5% of n-phenyl-1-naphthylamine and 1-5% of tricresyl phosphate (specifically, oil known under the name "BP turbo 2380"), a mixture of synthetic lubricating esters and additives containing n-phenyl-1-naphthylamine, 1-3% tricresyl phosphate, or diphenylamine alkyl derivatives (diphenyl amines alkyl), (specifically, oil known under the name "Exxon Mobil jet 2 / MJOII"), - an ester carboxylic acid with additives containing at least one triaryl phosphate (such as 68937-41-7) <3%, and aromatic amines (such as 90-30-2 and 15721-78-5) <2.5% (specifically, oil known as "Turbonycoil 600 / TN600"), - a mixture of synthetic lubricating esters and additives containing 1-3% alkaryl amine and 1-2% tricresyl phosphate, (specifically, oil known under the name "Aeroshell turbine oil 560 / ASTO 560"), - a mixture of synthetic lubricating esters and additives containing 96.5% synthetic esters, about 2% aromatic amines, about 1% organic phosphates (tricresyl phosphate), about 0.5% polymethacrylate and less than 0.5% carboxylic acid salts (specifically oil known under the name "Aeroshell turbine oil 500 / ASTO 500"). 4. Method according to one of claims 1 to 3, wherein: - the mounting oil with the added dye is used for mounting the engine oil lines, - during the engine end acceptance test line, one visualizes a possible oozing or leakage, - and one examines the color of the oozing or the leakage by its visual control, on a neutral absorbent support.