scholarly journals Crack of a helicopter main rotor actuator attachment: failure analysis and lessons learned

2013 ◽  
Vol 7 (26) ◽  
pp. 104-122
Author(s):  
L. Allegrucci ◽  
F. De Paolis ◽  
A. Coletta ◽  
M. Bernabei
Keyword(s):  
Failure Analysis ◽  
Lessons Learned ◽  
Main Rotor ◽  
Helicopter Main Rotor

scholarly journals MATHEMATICAL MODELS OF THE RADAR SIGNAL REFLECTED FROM A HELICOPTER MAIN ROTOR IN APPLICATION TO INVERSE SYNTHESIS OF ANTENNA APERTURE

2019 ◽  
Vol 22 (3) ◽  
pp. 74-87 ◽  
Author(s):  
Sergey R. Heister ◽  
Thai T. Nguyn
Keyword(s):  
Mathematical Models ◽  
Vertical Plane ◽  
Rotor Blades ◽  
Radar Signal ◽  
Main Rotor ◽  
Antenna Aperture ◽  
Radar Images ◽  
Aerial Vehicles ◽  
Propeller Blades ◽  
Helicopter Main Rotor

Introduction. The basis for solving the problem of aircraft recognition is the formation of radar portraits, reflecting the constructive features of aerial vehicles. Portraits, which are radar images of the propellers of aerial vehicles, have high informativeness. These images allow us to distinguish the number and relative position of the propeller blades, as well as the direction of its rotation. The basis for obtaining such images are mathematical models of reflected signals. Objective. The aim of this paper is to develop mathematical models of the radar signal reflected from the helicopter main rotor applied to inverse synthetic aperture radar (ISAR). Methods and materials. ISAR processing is used to produce a radar image of a propeller in a radar with a monochromatic probing signal. The propeller blades in the models are approximated by different geometric shapes. The models used to describe the reflection from the propellers of helicopters and fixed-wing aircraft have significant differences. In the process of moving each blade of the helicopter main rotor makes characteristic movements (flapping, dragging, feathering), as well as bends in a vertical plane. Such movements and bendings of the blades are influence the phase of the signal reflected from the main rotor. It is necessary to take the phase change of the reflected signal into account as accurately as possible when developing an ISAR algorithm for imaging the main rotor. Results. We found that in the centimeter wavelength range the mathematical model of the signal reflected from the helicopter main rotor as a system of blades is most accurately described by representing each blade with a set of isotropic reflectors located on the main rotor’s blade leading and trailing edges. Taking into account the flapping movements and curved shapes of the blades in the model allows you to get as close as possible to the features of the real signal. Conclusion. The developed model which takes into account the flapping movements and bends of the helicopter main rotor blades can be used to improve the ISAR algorithms providing the radar imaging of aerial vehicles.

Failures of bolts in helicopter main rotor drive plate assembly due to improper application of lubricant

2003 ◽  
Vol 10 (4) ◽  
pp. 443-451 ◽  
Author(s):  
N. Eliaz ◽  
G. Gheorghiu ◽  
H. Sheinkopf ◽  
O. Levi ◽  
G. Shemesh ◽  
...  
Keyword(s):  
Main Rotor ◽  
Rotor Drive ◽  
Helicopter Main Rotor ◽  
Plate Assembly

Updated Analysis of Circuit Reliability Test Results

2012 ◽  
Vol 2012 (HITEC) ◽  
pp. 000253-000259
Author(s):  
Milton Watts
Keyword(s):  
Failure Analysis ◽  
Detailed Analysis ◽  
Continuous Improvement ◽  
Oil And Gas ◽  
Lessons Learned ◽  
Reliability Test ◽  
Circuit Reliability ◽  
Test Results ◽  
Life Testing ◽  
Gas Market

The downhole oil and gas market is continually pushing for higher reliability at higher temperatures. Satisfying this need requires continuous improvement, driven by failure analysis of both internal testing and field returns. This paper discusses recent lessons learned from on-going tests. Results of unpowered circuit assembly tests are reviewed. Also, a detailed analysis of separate powered life testing is presented. The internal testing results are further discussed in the context of field return data.

scholarly journals Failure-Analysis Based Redesign of Furnace Conveyor System Components: A Case Study

Metals ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 816 ◽  
Author(s):  
Beatriz González-Ciordia ◽  
Borja Fernández ◽  
Garikoitz Artola ◽  
Maider Muro ◽  
Ángel Sanz ◽  
...  
Keyword(s):  
Failure Analysis ◽  
Hot Stamping ◽  
Mechanical Damage ◽  
Lessons Learned ◽  
Press Hardening ◽  
Metallurgical Analysis ◽  
Standard Design ◽  
Failure Assessment ◽  
Improved Design

Any manufacturing equipment designed from scratch requires a detailed follow-up of the performance for the first units placed in service during the production ramp-up, so that lessons learned are immediately implemented in next deliveries and running equipment is accordingly updated. Component failure analysis is one of the most valuable sources of improvement among these lessons. In this context, a failure-assessment based design revision of the conveying system of a newly developed press hardening furnace is presented. The proposed method starts with a forensic metallurgical analysis of the failed components, followed by an investigation of the working conditions to ensure they match the forensic observations. The results of this approach evidenced an initially unforeseen thermo-mechanical damage produced by a combination of thermal distortions, material ageing, and mechanical fatigue. Once the cause–effect relationship for the failure is backed up by evidence, an improved design is proposed. As a conclusion, a new standard design for the furnace entrance set of rollers in hot stamping lines was established for roller hearth furnaces. The solution can be extended to similar applications, ensuring the same issues will not arise thanks to the lessons learned.

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