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An automatic engine-out recovery system
Published in Hans M. Soekkha, Aviation Safety, 2020
At a speed of 50 m/s the aircraft has just started to lift-off to begin its initial climb. The response of the automatically controlled aircraft to an engine failure is shown in Fig. 8. Note the initial tendency of the height to go negative. In effect the engine failure causes the recovery system to drop the nose of the aircraft at lift-off, thereby causing the nosewheel oleo to compress but, because the corresponding rate of change is not very great, the compression is within the oleo capacity. In consequence, the lift-off is effectively delayed by 2.2s i.e. the aircraft travels a further 110m along the runway before lifting off into a climb. The final value of flight path angle attained is about 2.6° which corresponds to a climb rate of 470 ft/min (2.25 m/s) which is greater than the aircraft can produce on a single engine. The reason for this discrepancy is that the simulation has taken into account only the loss of thrust caused by the engine failure.
From BOGSAT to TurboTeam: Collaboration for National Security Teams in the Age of Analytics
Published in Natalie M. Scala, James P. Howard, Handbook of Military and Defense Operations Research, 2020
In a fault tree, the undesired outcome is taken as the top event. For example, the undesired outcome of an aircraft operation is an engine failure. Working backward from this top event, the team might determine there are two ways this could happen: a bird strike or a maintenance problem. Here the team would place a gate. The gates in a fault tree work in different ways. In an OR gate, the output event occurs if any of the input events occur. In an AND gate, the output occurs only if all inputs occur (assuming inputs are independent). There are several other types of gates with more specific purposes. The team might identify a design improvement by requiring a backup system in case of bird strikes – this is a safety feature that would change the gate to a logical AND. When fault trees are assigned event probabilities, the SAM can calculate overall failure probabilities. The FAA team also found that some common causes can introduce dependency relationships between events in the ESDs, which would have been difficult to see in a Fishbone SAT.
Applying the LEOMS to Enterprise Supply Chains
Published in Paul C. Husby, Jerome Hamilton, Make Your Business a Lean Business, 2017
Paul C. Husby, Jerome Hamilton
Using SCOR performance attributes as a guide (see Figure 7.16), at least one metric per category is established. An analogy would be an automobile dashboard containing many gages and lights but missing an oil pressure indicator. Everything seems to be running fine until low oil pressure results in engine failure. Likewise, metrics or key performance indicators need balance to ensure that all important areas of performance are in focus. Once sources of customer value are understood, metrics aligned to those sources and their required performance standards can be defined and validated by customers. MMC chose SCOR model metrics as shown in Figure 7.17; however, possible metrics for each category are not limited to this list and may include level 3 metrics. For example, in the category of delivery reliability, typical choices might include:
Significance of fluid flow characteristics in the hydrogen-fuelled scramjet combustor using flame stabilisation analysis
Published in Australian Journal of Mechanical Engineering, 2021
Figure 2 illustrates the static pressure contours analysed under engine ignition condition. The flow domain is considered to be symmetric for all the four cases because of the symmetry in the computational domain. From the contours it is examined that penetration of the oblique shock waves deep into the isolator with an increase in the injection pressure of the working fluid. The adverse pressure difference at the exit of the isolator increases with the injection pressure. Gerlinger et.al (2008) experimentally characterised the airflow over dual-mode scramjet combustor. It was reported that the increased injection pressure chokes the flame and sway the shock -wave train out of the isolator resulting in inlet un-start. These factors impart fluctuating thermal and pressure loads, reduction in air mass capture, and increase in air drag resulting in catastrophic engine failure. The injection temperature doesn’t have substantial significance over the shock wave within the range of 233–1000 K. The scramjet combustor exit exhibited a noticeable variation in the low-pressure magnitude.