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![Garrett TPE331 turboprop engine (based on [18], p. 15-3). A. main shaft (engine shaft) with the gas turbine. B. propeller shaft with the reduction gear. 1,2. bearings that support the main shaft. 3,4. bearings that support the propeller shaft. 1. compressor bearing. The TPE331 is called a fixed-shaft engine because the propeller is firmly connected to the gas turbine. The constant-speed engine maintains its speed by a governor on the propeller. The propeller shaft rotates at a constant speed of 1591 rpm in cruise flight. The main shaft of the engine rotates at a constant speed of 41,730 rpm. Power changes are made by increasing the fuel flow (which increases the torque) rather than the engine speed. Most of the air (70%) passing through the engine provides internal cooling. Only about 10% of the air that passes through the engine is actually used in the combustion process. Up to approximately 20% of the compressed air may be bled off for the purpose of heating, cooling, cabin pressurization, and pneumatic systems [18], which appears to](publication/356952998/figure/fig1/AS:1099642183913481@1639186535310/Garrett-TPE331-turboprop-engine-based-on-18-p-15-3-A-main-shaft-engine-shaft.png)
Garrett TPE331 turboprop engine (based on [18], p. 15-3). A. main shaft (engine shaft) with the gas turbine. B. propeller shaft with the reduction gear. 1,2. bearings that support the main shaft. 3,4. bearings that support the propeller shaft. 1. compressor bearing. The TPE331 is called a fixed-shaft engine because the propeller is firmly connected to the gas turbine. The constant-speed engine maintains its speed by a governor on the propeller. The propeller shaft rotates at a constant speed of 1591 rpm in cruise flight. The main shaft of the engine rotates at a constant speed of 41,730 rpm. Power changes are made by increasing the fuel flow (which increases the torque) rather than the engine speed. Most of the air (70%) passing through the engine provides internal cooling. Only about 10% of the air that passes through the engine is actually used in the combustion process. Up to approximately 20% of the compressed air may be bled off for the purpose of heating, cooling, cabin pressurization, and pneumatic systems [18], which appears to
Source publication
![Figure 1. Garrett TPE331 turboprop engine (based on [18], p. 15-3). A....](publication/356952998/figure/fig1/AS:1099642183913481@1639186535310/Garrett-TPE331-turboprop-engine-based-on-18-p-15-3-A-main-shaft-engine-shaft_Q320.jpg)
![Figure 2. A typical ball-bearing [19].](publication/356952998/figure/fig2/AS:1099642183909378@1639186535393/A-typical-ball-bearing-19_Q320.jpg)
![Figure 3. Garrett TPE331 turboprop engine cutaway drawing [20].](publication/356952998/figure/fig3/AS:1099642183909379@1639186535421/Garrett-TPE331-turboprop-engine-cutaway-drawing-20_Q320.jpg)
During its investigations into a series of ten aircraft crashes from 1979 to 1981, US National Transportation Safety Board (NTSB) officials were presented with a hypothesis that “several” of the crashes could have been caused by pilot impairment from breathing oil fumes inflight. The NTSB and their industry partners ultimately dismissed the hypothe...
Contexts in source publication
Context 1
... Garrett TPE331 is a fixed-shaft constant-speed turboprop engine (Figure 1). Its gas turbine consists of a compressor, combustion chamber, and turbine. ...
Context 2
... a normal operation the igniter is not in use because the combustion is self-sustained. The hot and high-velocity combustion gases flow through the turbine rotors, where the energy of the gases is converted to torque exerted on the main shaft (A in Figure 1 Most of the air (70%) passing through the engine provides internal cooling. Only about 10% of the air that passes through the engine is actually used in the combustion process. ...
Context 3
... engine shafts are supported by rolling bearings. The compressor bearing (1 in Figure 1) is a ball-bearing (Figure 2). The same is true for bearings 2 and 3 in Figure 1. ...
Context 4
... compressor bearing (1 in Figure 1) is a ball-bearing (Figure 2). The same is true for bearings 2 and 3 in Figure 1. The engine cutaway drawing is given in Figure 3 and a detail of that picture enlarged is given in Figure 4. ...
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... The term Aerotoxic Syndrome has been proposed to describe a constellation of symptoms reported by pilots and cabin crew following exposure to neurotoxic substances in cabin air (Balouet and Winder 1999). All modern commercial aircraft, except for the Boeing 787 Dreamliner, are designed to "bleed" (extract) air compressed within the engine or auxiliary power unit (APU) for aircraft ventilation (Anderson and Scholz 2021;Chen et al. 2021;CEN 2022). The APU is a smaller gas-turbine-powered unit delivering rotating shaft power and compressor air, primarily used during ground operations. ...
Aerotoxic Syndrome may develop as a result of chronic, low-level exposure to organophosphates (OPs) and volatile organic compounds in the airplane cabin air, caused by engine oil leaking past wet seals. Additionally, acute high-level exposures, so-called "fume events," may occur. However, air quality monitoring studies concluded that levels of inhaled chemicals might be too low to cause adverse effects. The presence of aerosols of nanoparticles (NPs) in bleed air has often been described. The specific hypothesis is a relation between NPs acting as a vector for toxic compounds in the etiology of the Aerotoxic Syndrome. These NPs function as carriers for toxic engine oil compounds leaking into the cabin air. Inhaled by aircrew NPs carrying soluble and insoluble components deposit in the alveolar region, where they are absorbed into the bloodstream. Subsequently, they may cross the blood-brain barrier and release their toxic compounds in the central nervous system. Olfactory absorption is another route for NPs with access to the brain. To study the hypothesis, all published in-flight measurement studies (2003–2023) of airborne volatile (and low-volatile) organic pollutants in cabin air were reviewed, including NPs (10–100 nm). Twelve studies providing data for a total of 387 flights in 16 different large-passenger jet aircraft types were selected. Maximum particle number concentrations (PNC) varied from 104 to 2.8x106 #/cm3 and maximum mass concentrations from 9 to 29 lg/m3. NP-peaks occurred after full-power take-off, in tailwind condition, after auxiliary power unit (APU) bleed air introduction, and after air conditioning pack failure. Chemical characterization of the NPs showed aliphatic hydrocarbons, black carbon, and metallic core particles. An aerosol mass-spectrometry pattern was consistent with aircraft engine oil. It is concluded that chronic exposure of aircrew to NP-aerosols, carrying oil derivatives, maybe a significant feature in the etiology of Aerotoxic Syndrome. Mobile NP measuring equipment should be made available in the cockpit for long-term monitoring of bleed air. Consequently, risk assessment of bleed air should include monitoring and analysis of NPs, studied in a prospective cohort design.
... Fuel tank explosions and disintegration remain among the primary causes of aircraft accidents [1,2]. To address this issue, both the Federal Aviation Administration of the USA (FAA) and the Civil Aviation Administration of China (CAAC) have established airworthiness regulations mandating necessary measures to minimize fuel tank flammability [3]. ...
Oxygen-consuming inerting technology is expected to be the primary method for suppressing aircraft fuel tank fires and explosions in the next generation, with the catalytic reactor serving as its core component. However, the catalytic properties of the developed catalyst have yet to be thoroughly studied, and a primary reaction kinetic equation is needed to support further investigation of the reactor. Thus, this study focuses on the performance of the developed catalyst for RP-3 fuel vapor, with a test bench built to analyze its reaction kinetic characteristics. Initially, we tested the steady-state variation in the fuel vapor concentration (FVC) with fuel temperature and fitted an empirical equation, providing fundamental data for subsequent experiments. Subsequently, we studied the impact of critical parameters, such as the FVC, oxygen concentration (OC), CO2 concentration, and reaction temperature, on the reaction performance. The results demonstrate that the reaction rate is positively correlated with the FVC, OC, and reaction temperature, while CO2 has no impact on the catalytic reaction characteristics. Finally, a kinetic equation for the developed catalyst is summarized based on the experimental data, providing a fundamental equation for simulating research on the catalytic reactor and the oxygen-consuming inerting system.
