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Constraints and Specialty Requirements
Published in Scott Jackson, Systems Engineering for Commercial Aircraft, 2020
Many maintainability requirements are quantitative and are therefore verifiable. Maintainability cost The principal requirements parameter for maintainability is maintenance cost per 1,000 flight hours (MN$/1000FH). This parameter can be converted into maintenance man-hours per 1,000 flight hours (MMH/1000FH). Material cost per 1,000 flight hours (MT$/1000FH) can also be separately specified.Fault isolation Specific and verifiable time limits can be established for both on-aircraft and off-aircraft fault isolation times. On-aircraft repair time is measured by the mean time to repair (MTTR). A basic maintainability requirement for both safety and economic failures is that “all failures shall be evident” or not affect safety, economics, or operations (for any subsystem or for the aircraft as a whole). Evident can either mean that there is an indication to the crew during the course of their normal duties (alert, light, and so on) or that it would be evident to an observer, such as to a person doing an aircraft walk-around during turnover.
Borrowing Safety Strategies
Published in William J. Reynolds, Safety and Health for the Stage, 2020
The mention of inspections may bring to mind hiring a rigging consultant to inspect and assess the condition of your counterweight rigging system, or engaging an engineer to assess the condition of your orchestra pit lift. Mechanical systems and equipment do require regular inspections to ensure they will operate correctly and reliably. Operational inspections, on the other hand, assure that facilities, production equipment, scenery, public spaces, and many other aspects of a venue or production are in place and ready to use. Many industries utilize operational or visual inspections as part of their routine activities. For instance, OSHA requires a visual inspection (examination) of forklifts before each use: Industrial trucks [forklifts] shall be examined before being placed in service, and shall not be placed in service if the examination shows any condition adversely affecting the safety of the vehicle. Such examination shall be made at least daily.8 Agricultural vehicles and farm equipment are given a daily walk-around visual inspection before each use, starting with the work area.9 The United States Federal Aviation Administration requires pilots to perform a walk-around visual inspection of their aircraft before each flight.
Selection of Air Ambulance Pilots Empathic Airmanship and the Safe Pilot
Published in Robert Bor, Carina Eriksen, Todd P. Hubbard, Ray King, Pilot Selection, 2019
Air ambulance pilots typically work a seven-day schedule with 12-hour shifts covering day or night operations. One week on duty is followed by a week during which the crew is stood down. Pilots are required to live on the base during the duty week. Between missions, pilots constantly monitor the weather for the regions they fly in. This ceaseless weather awareness is important. When the alarm sounds and the air ambulance is scrambled, the pilots muster in the briefing room and decide whether to accept the mission. Prior to take-off, the pilots review the task requirements, draw up the flight plan, file it with air traffic control and discuss the flight with the rest of the crew. Once an ambulance aircraft has landed, the captain meets the arriving flight crew to determine any irregularities and check the technical log. The first officer and the captain alternate roles in performing a general inspection of the aircraft, and after this ‘walk around’, the pilots commence their cockpit checks.
The Promise and Pitfalls of Learning in Immersive Virtual Reality
Published in International Journal of Human–Computer Interaction, 2023
Richard E. Mayer, Guido Makransky, Jocelyn Parong
The first four rows of Table 6 examine the modality principle, which states that people learn better from multimedia messages when the words are spoken rather than printed (Castro-Alonso & Sweller, 1922; Mayer, 2021). Although there is evidence that the modality principle applies to online learning involving lessons presented via desktop computers, an important issue concerns whether the modality principle–and other foundational principles of multimedia design–can be extended to IVR venues. In the first row, O’Neil et al. (2000) asked working adults to don a head-mounted display and walk around in a virtual world consisting of the fuel system of an aircraft. As they explored the fuel system of the aircraft in IVR, key information about each component (such as how open or close a valve) was presented through narration or through printed text. Results indicated that adults performed better on posttests when they received information in spoken form rather than printed form in IVR.
Acoustic and mixing characteristic of CD nozzle with inverted triangular tabs
Published in International Journal of Ambient Energy, 2018
Hussain and Husain (1989) and Gutmark et al. (1989) noticed that jet exhibits three distinct regions of potential core, characteristic decay and far field region in axisymmetric decay. At the potential core region, the centreline velocity is constant. In the characteristics region, the decay depends on the nozzle exit and axis symmetric decay in the region where velocity decay is inversely proportional to the axial distance. Krothapalli, Baganoff, and Karamcheti (1981) found that the shear layer is the main feature for generating the axis symmetric jet. They witnessed jet is originated at the point where shear layer is separated. It occurs at the major nozzle dimension location. Sforza observed that the axis symmetric decay takes place at the region where the jet development in the minor axis is higher than that in the major axis. This is called axis switching. It is a basic feature found in asymmetric jets. Krothapalli found that aspect ratio and axis switching depend on each other. They witnessed that as stream-wise distance increases, the axis switching takes place. Arunkumar and Rathakrishnan (Chauhan, Aravindh Kumar, and Rathakrishnan 2016) demonstrated an experiment on controlled jet at Mach number of 2. They found that the tab along the minor axis produces soaring mixing than the tab along the major axis. Bradbury (Bradbury and Khadem 1975) studied the effect of rectangular tabs and the authors witnessed that when the tabs are placed diametrically opposite, it produces a hefty change in the jet development. It was also found that when the two tabs are placed opposite to each other, the yield gross distortion in the jet production takes place on each side of the tabs. The nozzle used for this investigation is elliptical convergent divergent nozzle. The velocity field is measured at isothermal conditions for all different aspect ratios. The velocity field is calibrated up to 3D. The focus of the current study is to walk around and gain sensible knowledge on turbojets, so that this idea can be directly implemented in advanced aircraft. This paper investigates the jet spread, velocity decay and stream-wise vortices at different operating conditions.