Evaluation of Influence Factors on the Visual Inspection Performance of Aircraft Engine Blades

Background—There are various influence factors that affect visual inspection of aircraft engine blades including type of inspection, defect type, severity level, blade perspective and background colour. The effect of those factors on the inspection performance was assessed. Method—The inspection accuracy of fifty industry practitioners was measured for 137 blade images, leading to N = 6850 observations. The data were statistically analysed to identify the significant factors. Subsequent evaluation of the eye tracking data provided additional insights into the inspection process. Results—Inspection accuracies in borescope inspections were significantly lower compared to piece-part inspection at 63.8% and 82.6%, respectively. Airfoil dents (19.0%), cracks (11.0%), and blockage (8.0%) were the most difficult defects to detect, while nicks (100.0%), tears (95.5%), and tip curls (89.0%) had the highest detection rates. The classification accuracy was lowest for airfoil dents (5.3%), burns (38.4%), and tears (44.9%), while coating loss (98.1%), nicks (90.0%), and blockage (87.5%) were most accurately classified. Defects of severity level S1 (72.0%) were more difficult to detect than increased severity levels S2 (92.8%) and S3 (99.0%). Moreover, visual perspectives perpendicular to the airfoil led to better inspection rates (up to 87.5%) than edge perspectives (51.0% to 66.5%). Background colour was not a significant factor. The eye tracking results of novices showed an unstructured search path, characterised by numerous fixations, leading to longer inspection times. Experts in contrast applied a systematic search strategy with focus on the edges, and showed a better defect discrimination ability. This observation was consistent across all stimuli, thus independent of the influence factors. Conclusions—Eye tracking identified the challenges of the inspection process and errors made. A revised inspection framework was proposed based on insights gained, and support the idea of an underlying mental model.

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Assessment of the Effect of Cleanliness on the Visual Inspection of Aircraft Engine Blades: An Eye Tracking Study

Sensors ◽

10.3390/s21186135 ◽

2021 ◽

Vol 21 (18) ◽

pp. 6135

Author(s):

Jonas Aust ◽

Antonija Mitrovic ◽

Dirk Pons

Keyword(s):

Visual Acuity ◽

Statistical Analysis ◽

Eye Tracking ◽

Visual Inspection ◽

Search Strategy ◽

Aircraft Engine ◽

Inspection Time ◽

Defect Type ◽

Inspection Performance ◽

Different Levels

Background—The visual inspection of aircraft parts such as engine blades is crucial to ensure safe aircraft operation. There is a need to understand the reliability of such inspections and the factors that affect the results. In this study, the factor ‘cleanliness’ was analysed among other factors. Method—Fifty industry practitioners of three expertise levels inspected 24 images of parts with a variety of defects in clean and dirty conditions, resulting in a total of N = 1200 observations. The data were analysed statistically to evaluate the relationships between cleanliness and inspection performance. Eye tracking was applied to understand the search strategies of different levels of expertise for various part conditions. Results—The results show an inspection accuracy of 86.8% and 66.8% for clean and dirty blades, respectively. The statistical analysis showed that cleanliness and defect type influenced the inspection accuracy, while expertise was surprisingly not a significant factor. In contrast, inspection time was affected by expertise along with other factors, including cleanliness, defect type and visual acuity. Eye tracking revealed that inspectors (experts) apply a more structured and systematic search with less fixations and revisits compared to other groups. Conclusions—Cleaning prior to inspection leads to better results. Eye tracking revealed that inspectors used an underlying search strategy characterised by edge detection and differentiation between surface deposits and other types of damage, which contributed to better performance.

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Collaborative Virtual Environment to Simulate on-the-Job Aircraft Inspection Training Aided by Hand Pointing

Proceedings of the Human Factors and Ergonomics Society Annual Meeting ◽

10.1177/154193120504902521 ◽

2005 ◽

Vol 49 (25) ◽

pp. 2216-2220

Author(s):

S. Sadasivan ◽

R. Rele ◽

J. S. Greenstein ◽

A. K. Gramopadhye ◽

J. Masters ◽

...

Keyword(s):

Virtual Environment ◽

Visual Inspection ◽

Training Environment ◽

Virtual Training ◽

Collaborative Virtual Environment ◽

Feedback Training ◽

Inspection Process ◽

Safety And Reliability ◽

The One ◽

Inspection Performance

The human inspector performing visual inspection of an aircraft is the backbone of the aircraft inspection process, a vital element in assuring safety and reliability of an air transportation system. Training is an effective strategy for improving their inspection performance. A drawback of present-day on-the-job (OJT) training provided to aircraft inspectors is the limited exposure to different defect types. Previous studies have shown offline feedback training using virtual reality (VR) simulators to be effective in improving visual inspection performance. This research aims at combining the advantages of VR technology that includes exposure to a wide variety of defects and the one-on-one tutoring approach of OJT by implementing a collaborative virtual training environment. In an immersive collaborative virtual environment (CVE), avatars are used to represent the co-participants. In a CVE, information of where the trainer is pointing can be provided to a trainee as visual deictic reference (VDR). This study evaluates the effectiveness of simulating on-the-job training in a CVE for aircraft inspection training, providing VDR slaved to a 3D mouse used by the trainer for pointing. The results of this study show that the training was effective in improving inspection performance.

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Comparison of Visual and Visual–Tactile Inspection of Aircraft Engine Blades

Aerospace ◽

10.3390/aerospace8110313 ◽

2021 ◽

Vol 8 (11) ◽

pp. 313

Author(s):

Jonas Aust ◽

Antonija Mitrovic ◽

Dirk Pons

Keyword(s):

Classification Accuracy ◽

Visual Inspection ◽

False Positive Rate ◽

Aircraft Engine ◽

Tactile Perception ◽

Inspection Time ◽

Positive Rate ◽

Training Programmes ◽

Engine Maintenance ◽

Inspection Performance

Background—In aircraft engine maintenance, the majority of parts, including engine blades, are inspected visually for any damage to ensure a safe operation. While this process is called visual inspection, there are other human senses encompassed in this process such as tactile perception. Thus, there is a need to better understand the effect of the tactile component on visual inspection performance and whether this effect is consistent for different defect types and expertise groups. Method—This study comprised three experiments, each designed to test different levels of visual and tactile abilities. In each experiment, six industry practitioners of three expertise groups inspected the same sample of N = 26 blades. A two-week interval was allowed between the experiments. Inspection performance was measured in terms of inspection accuracy, inspection time, and defect classification accuracy. Results—The results showed that unrestrained vision and the addition of tactile perception led to higher inspection accuracies of 76.9% and 84.0%, respectively, compared to screen-based inspection with 70.5% accuracy. An improvement was also noted in classification accuracy, as 39.1%, 67.5%, and 79.4% of defects were correctly classified in screen-based, full vision and visual–tactile inspection, respectively. The shortest inspection time was measured for screen-based inspection (18.134 s) followed by visual–tactile (22.140 s) and full vision (25.064 s). Dents benefited the most from the tactile sense, while the false positive rate remained unchanged across all experiments. Nicks and dents were the most difficult to detect and classify and were often confused by operators. Conclusions—Visual inspection in combination with tactile perception led to better performance in inspecting engine blades than visual inspection alone. This has implications for industrial training programmes for fault detection.

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Eye-Tracking Experimental Study Investigating the Influence Factors of Construction Safety Hazard Recognition

Journal of Construction Engineering and Management ◽

10.1061/(asce)co.1943-7862.0001884 ◽

2020 ◽

Vol 146 (8) ◽

pp. 04020091 ◽

Cited By ~ 1

Author(s):

Yu Han ◽

Zhenzhen Yin ◽

Jingjie Zhang ◽

Ruoyu Jin ◽

Tong Yang

Keyword(s):

Experimental Study ◽

Eye Tracking ◽

Influence Factors ◽

Construction Safety ◽

Safety Hazard ◽

Hazard Recognition

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Impact of Feedback Training in Cbt in Visual Inspection

Proceedings of the Human Factors and Ergonomics Society Annual Meeting ◽

10.1177/154193120204602518 ◽

2002 ◽

Vol 46 (25) ◽

pp. 2079-2083 ◽

Cited By ~ 1

Author(s):

Jiao Ma ◽

Colin G. Drury ◽

Ann M. Bisantz

Keyword(s):

Performance Measures ◽

Performance Feedback ◽

Visual Inspection ◽

Search Time ◽

Difficulty Level ◽

Process Assessment ◽

Computer Based Training ◽

Feedback Training ◽

On Line ◽

Inspection Performance

Training has been a consistently effective intervention in improving inspection performance. For example, existing inspection training in the aircraft maintenance domain is mainly a combination of classroom and on-the-job training (OJT). Computer-based training (CBT) has been promoted ever since it was introduced to this domain. In this study we investigate how effectively feedback training can be combined with CBT to improve visual inspection performance. Specifically, we examine the potential positive impacts of performance and process feedback in CBT, given in an on-line manner, on a trainee's performance and process assessment in a visual inspection task. The CBT system for inspection we used was adopted from the ASSIST program (Chen, Gramopadhye and Melloy, 2000). In our computer simulation of a familiar situation, participants were asked to search certain areas inside of a car in order to detect certain targets (dropped coins) with the aid of computerized tools (e.g., a magnifying glass, a flashlight), and fill out an inspection report based upon detection. A significant test effect was found across performance measures. Type of feedback training was found to be significant for search time. Performance measures were significantly correlated with target difficulty level; on-line performance feedback was significantly more efficient in improving performance measures than conventional delayed performance feedback; feedback training did affect process assessment measures.

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Visual techniques for cervical cancer screening in Colombia

Biomédica ◽

10.7705/biomedica.v39i1.4007 ◽

2019 ◽

Vol 39 (1) ◽

pp. 65-74

Author(s):

Óscar Gamboa ◽

Mauricio González ◽

Jairo Bonilla ◽

Joaquín Luna ◽

Raul Murillo ◽

...

Keyword(s):

Cervical Cancer ◽

Cancer Screening ◽

Cervical Cancer Screening ◽

False Positive ◽

Gold Standard ◽

Visual Inspection ◽

Low Grade ◽

High Grade ◽

Detection Rates ◽

Lower Detection

Introduction: Direct visual inspection for cervical cancer screening remains controversial, whereas colposcopy-biopsy is considered the gold standard for diagnosis of preneoplastic cervical lesions.Objectives: To determine the rates of cervical intraepithelial neoplasia grade 2 or more and of false positives for colposcopy and direct visual inspection.Materials and methods: Women aged 25-59 underwent direct visual inspection with acetic acid (VIA), Lugol’s iodine (VIA-VILI), and colposcopy. Punch biopsies were obtained for all positive tests. Using histology as the gold standard, detection and false positive rates were compared for VIA, VIA-VILI, and colposcopy (two thresholds). Sensitivity and false positive ratios with the corresponding 95% confidence intervals were estimated.Results: We included 5,011 women in the analysis and we obtained 602 biopsies. Positivity rates for colposcopy high-grade and low-grade diagnosis were 1.6% and 10.8%. Positivity rates for VIA and VIA-VILI were 7.4% and 9.9%. VIA showed a significantly lower detection rate than colposcopy with low-grade diagnosis as the threshold (SR=0.72; 95% CI 0.57-0.91), and significantly lower false positive rate (FPR=0.70; 95% CI 0.65-0.76). No differences between VIA-VILI and colposcopy low-grade threshold were observed. VIA and VIA-VILI showed significantly higher detection and false positive rates than colposcopy high-grade threshold. Sensitivity rates for visual inspection decreased with age and false positive rates increased. For all age groups, false positive rates for VIA and VIA-VILI were significantly higher than colposcopy.Conclusions: Detection rates for VIA-VILI similar to colposcopy low-grade threshold represent a chance to reduce cervical cancer mortality through see-and-treat approaches among women with limited access to health care. Lower detection rates suggest reviewing high-grade colposcopy findings as the threshold for biopsy in certain settings.

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