The present paper contains results of trying the detonation technology of applying a lightning-protective coating and the results of testing the lightning resistance of samples of structurally similar elements of a nacelle made of polymer composite materials and coated using this technology. A lightning-protective coating was sprayed on samples of structurally similar elements of a nacelle made of carbon fiber prepreg VKU-25. The coating was applied using the CCDS2000 detonation computerized complex developed by the Lavrentyev Institute of Hydrodynamics of the Siberian Branch of the Russian Academy of Sciences. Copper, bronze and aluminum were used as materials for the lightning-protective coating. The thickness of the applied metallized layer was varied from 10 to 20 microns, this providing an extremely low specific gravity of lightning protection at the level of 0.087–0.178 kg/m2 for copper and bronze; 0.027–0.054 kg/m2 for aluminum. Samples with and without lightning-protective coating were tested with a simulated lightning discharge according to the requirements of aviation standards AP-25, including components related to lightning-hazardous zones 1A, 2A, 1B. The combi-nations of components complied with the qualification requirements of KT-160G. According to the results of tests on the lightning resistance of samples made of the VKU-25 carbon fiber prepreg, the functional operability of the detonation technology for any lightning-hazardous zone of the nacelle according to AP-25 has been demonstrated. No through destruction of carbon fiber was found in samples with detonation spraying. Samples without lightning-protective coating turned out to be non-resistant to the lightning current exposure. The tried detonation technology has the technical potential to reduce (up to 3 times) the specific gravity of the conduc-tive layer of the lightning-protective coating used in the engine polymer nacelles of commercially operated aircraft engines.

Volcanic ash clouds emitted into the Earth’s atmosphere by more than a thousand active volcanoes pose an immediate se-rious threat to flight safety, since volcanic ash particles in high concentrations can cause significant damage to aircraft. This article presents the consequences of an aircraft getting into a cloud of volcanic ash (damage to the fuselage and aer-odynamic surfaces of the aircraft, turbojet sustainer engines, antennas, air pressure and temperature receivers, other aircraft sys-tems), and also describes in detail the mechanisms and examples of the impact of volcanic ash on various types aircraft gas tur-bine engines. The global statistics of aircraft hitting volcanic ash clouds from 1935 to 2021 is given. The results of engineering tests of PW F100 bypass gas turbine engines under the influence of volcanic ash in the condi-tions of the scientific and CalspanTechnical Corporation, founded in 1943 in the United States of America, are considered. Also presented are the results of work under the VIPR (Vehicle Integrated Propulsion Research) program of the National Aerospace Agency of the United States of America (NASA) for a comprehensive study of the impact of volcanic ash on the F-117 (PW2040) power plant of the Boeing C-17 Globemaster III military transport aircraft. The results of research by the NASA national agency and the Calspan Corporation are compared with the main data of certification tests of the advanced PD-14 aircraft gas turbine engine developed by JSC «UEC-Aviadvigatel» in the conditions of the closed ground test facility Ts-17T of the FAA «CIAM named after P.I. Baranov» in accordance with the requirements of the European Aviation Safety Agency (EASA).

The study of advanced diagnostic methods and tools for aircraft engines shows that spectral elemental analysis of aerosol emission products has recently become quite widespread in the engine maintenance programs of foreign manufacturers for detecting the turbomachinery parts erosive wear. To determine the elemental composition of aerosols at the gas turbine engine (GTE) outlet, opto-emission and mass spectrometric approaches have been used in various implementations. X-ray photoelectron spectroscopy and inductively coupled plasma mass spectrometry (ICP-MS) are recognized as the most informative and accessible laboratory methods. The most common sampling method is filtration with Teflon analytical membranes. Artificial intelligence technologies are used worldwide to identify and localize the source of the elements flow (a potential area of the GTE parts erosive wear). It has been found that the main problems of applying a multi-element analysis are associated with the sampling procedure, with the potential simultaneous element flow from several engine parts having a similar chemical composition; as well as with the variability of the “background” atmospheric aerosol composition, which is an unavoidable component of atmospheric air, especially in ground-level conditions. The article also presents the first results of the elemental analysis of aerosol particle emission samples from a modern Russian aircraft engine using the X-ray fluorescence method.

The overview of the existing and upcoming types of aircraft engines polymeric composite nacelles lightning protection is presented. It is demonstrated that at present the most widely-used technologies of polymer composites lightning protection in the world and domestic aviation industry consist in using metal foils and meshes. However, the relative weight of the lightning protection comprised of metal foils and meshes (including adhesive and erosion layers) may result in a significant weight gain up to 0.7–0.9 kg per each square meter of the polymer composite nacelle surface. Additionally, the principal disadvantage of metal meshes is high percentage of the open area (80–90 %) leading to decreased engine EMI protection in the event of exposure to electromagnetic impulse from the lightning strike or L/HIRF. Currently, intensive scientific studies are performed in the field of aviation equipment lightning protection in different universities, institutes and companies, mainly in the USA, Europe, Russia and Japan. The potential lightning protection problem solution addressed by the large number of scientific papers is use of coatings made of heatproof polymer composites and polymer binders modified by carbon nanoparticles to develop a better material conductivity. However, this technology is characterized by high costs, low repairability, etc. Various spraying methods are studied. It has been found out that for the lightning protection of the advanced types of nacelles the highly competitive engineering solution is the one that ensures a cardinally low relative weight and high reliability, manufacturability, high EMI protection L/HIRF, low engine life cycle costs including easy in-service repair.