ASM Failure Analysis Case Histories: Air and Spacecraft最新文献

Helicopter Main Rotor Transmission Output Shaft Failure 直升机主旋翼传动输出轴故障

ASM Failure Analysis Case Histories: Air and Spacecraft Pub Date : 2019-06-01 DOI: 10.31399/asm.fach.aero.c9001505

J. Hutchinson

{"title":"Helicopter Main Rotor Transmission Output Shaft Failure","authors":"J. Hutchinson","doi":"10.31399/asm.fach.aero.c9001505","DOIUrl":"https://doi.org/10.31399/asm.fach.aero.c9001505","url":null,"abstract":"\u0000 A helicopter had just taken off when there was a loud bang and the engine started to overspeed. After landing and inspection, the transmission was disassembled. It was discovered that the assembly containing the output shaft to the main rotor had failed. The output shaft assembly was made up of two parts: the output shaft with an integral 10 in. diam upper disc at approximately mid-section; and a 10 in. diam lower disc. During manufacture, the lower disc was attached to the output shaft by an electron beam weld. The fracture had a single fatigue initiation site, coincident with the annular zone of remelted material on the inner surface of the disc. In the lower disc, the fracture was also 80% fatigue, but high stress, low cycle in nature and contained multiple initiation sites coincident with an electron beam weld bead. It was concluded that fatigue in the upper disc resulted from the presence of a metallurgical stress concentration caused by the electron weld beam impingement on the inner surface of the upper disc. An Airworthiness Directive was issued, and the manufacturer issued a mandatory service bulletin outlining a periodic inspection for the output shaft assembly.","PeriodicalId":326464,"journal":{"name":"ASM Failure Analysis Case Histories: Air and Spacecraft","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114653068","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Corrosion-Fatigue Cracking in an AMS 6415 Steel Aircraft Shaft AMS 6415钢飞机轴的腐蚀疲劳裂纹

ASM Failure Analysis Case Histories: Air and Spacecraft Pub Date : 2019-06-01 DOI: 10.31399/asm.fach.aero.c0046870

{"title":"Corrosion-Fatigue Cracking in an AMS 6415 Steel Aircraft Shaft","authors":"","doi":"10.31399/asm.fach.aero.c0046870","DOIUrl":"https://doi.org/10.31399/asm.fach.aero.c0046870","url":null,"abstract":"\u0000 A hollow, splined alloy steel aircraft shaft (machined from an AMS 6415 steel forging – approximately the same composition as 4340 steel – then quenched and tempered to a hardness of 44.5 to 49 HRC) cracked in service after more than 10,000 h of flight time. The inner surface of the hollow shaft was exposed to hydraulic oil at temperatures of 0 to 80 deg C (30 to 180 deg F). Analysis (visual inspection, 15-30x low magnification examination, 4x light fractograph, chemical analysis, hardness testing) supported the conclusions that the shaft cracked in a region subjected to severe static radial, cyclic torsional, and cyclic bending loads. Cracking originated at corrosion pits on the smoothly finished surface and propagated as multiple small corrosion-fatigue cracks from separate nuclei. The originally noncorrosive environment (hydraulic oil) became corrosive in service because of the introduction of water into the oil. Recommendations included taking additional precautions in operation and maintenance to prevent the use of oil containing any water through filling spouts or air vents. Also, polishing to remove pitting corrosion (but staying within specified dimensional tolerances) was recommended as a standard maintenance procedure for shafts with long service lives.","PeriodicalId":326464,"journal":{"name":"ASM Failure Analysis Case Histories: Air and Spacecraft","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125124559","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Failure of a Steel Bomb Suspension Lug 钢炸弹吊耳失效

ASM Failure Analysis Case Histories: Air and Spacecraft Pub Date : 2019-06-01 DOI: 10.31399/asm.fach.aero.c9001906

M. Pepi

引用次数: 0

Corrosion of Aluminum Alloy 7075-T6 Wing Panel 7075-T6铝合金翼板的腐蚀

ASM Failure Analysis Case Histories: Air and Spacecraft Pub Date : 2019-06-01 DOI: 10.31399/asm.fach.aero.c0006402

{"title":"Corrosion of Aluminum Alloy 7075-T6 Wing Panel","authors":"","doi":"10.31399/asm.fach.aero.c0006402","DOIUrl":"https://doi.org/10.31399/asm.fach.aero.c0006402","url":null,"abstract":"\u0000 New aircraft wing panels extruded from 7075-T6 aluminum exhibited an unusual pattern of circular black interrupted lines, which could not be removed by scouring or light sanding. The panels, subsequent to profiling and machining, were required to be penetrated inspected, shot peened, H2SO4 anodized, and coated with MIL-C-27725 integral fuel tank coating on the rib side. Scanning electron microscopy and microprobe analysis (both conventional energy-dispersive and Auger analyzers) showed that the anodic coating was applied over an improperly cleaned and contaminated surface. The expanding corrosion product had cracked and, in some places, had flaked away the anodized coating. The corrodent had penetrated the base aluminum in the form of subsurface intergranular attack to a depth of 0.035 mm (0.0014 in.). It was recommended that a vapor degreaser be used during cleaning prior to anodizing. A hot inhibited alkaline cleaner was also recommended during cleaning prior to anodizing. The panels should be dichromate sealed after anodizing. The use of deionized water was also recommended during the dichromate sealing operation. In addition, the use of an epoxy primer prior to shipment of the panels was endorsed. Most importantly, surveillance of the anodizing process itself was emphasized.","PeriodicalId":326464,"journal":{"name":"ASM Failure Analysis Case Histories: Air and Spacecraft","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125332349","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Failure of a Carburized Steel Generator-Drive Idler Gear by Pitting Due to Decarburization and Subsurface Oxidation 碳化钢发电机驱动惰轮因脱碳和表面氧化引起的点蚀失效

ASM Failure Analysis Case Histories: Air and Spacecraft Pub Date : 2019-06-01 DOI: 10.31399/asm.fach.aero.c0048257

引用次数: 0

Failure by Stress-Corrosion Cracking of an Ejection Seat Swivel 弹射座椅转轴应力腐蚀开裂失效

ASM Failure Analysis Case Histories: Air and Spacecraft Pub Date : 2019-06-01 DOI: 10.31399/asm.fach.aero.c0006387

引用次数: 0

Hydrogen Embrittlement of Cadmium-Plated Alloy Steel Self-Retaining Bolts in a Throttle-Control Linkage 阀控连杆中镀镉合金钢自扣螺栓的氢脆

ASM Failure Analysis Case Histories: Air and Spacecraft Pub Date : 2019-06-01 DOI: 10.31399/asm.fach.aero.c0048630

{"title":"Hydrogen Embrittlement of Cadmium-Plated Alloy Steel Self-Retaining Bolts in a Throttle-Control Linkage","authors":"","doi":"10.31399/asm.fach.aero.c0048630","DOIUrl":"https://doi.org/10.31399/asm.fach.aero.c0048630","url":null,"abstract":"\u0000 Two clevis-head self-retaining bolts used in the throttle-control linkage of a naval aircraft failed on the aircraft assembly line. Specifications required the bolts to be heat treated to a hardness of 39 to 45 HRC, followed by cleaning, cadmium electroplating, and baking to minimize hydrogen embrittlement. The bolts broke at the junction of the head and shank. The nuts were, theoretically, installed fingertight. The failure was attributed to hydrogen embrittlement that had not been satisfactorily alleviated by subsequent baking. The presence of burrs on the threads prevented assembly to finger-tightness, and the consequent wrench torquing caused the actual fractures. The very small radius of the fillet between the bolt head and the shank undoubtedly accentuated the embrittling effect of the hydrogen. To prevent reoccurrence, the cleaning and cadmium-plating procedures were stipulated to be low-hydrogen in nature, and an adequate post plating baking treatment at 205 deg C (400 deg F), in conformity with ASTM B 242, was specified. A minimum radius for the head-to-shank fillet was specified at 0.25 mm (0.010 in.). All threads were required to be free of burrs. A 10-day sustained-load test was specified for a sample quantity of bolts from each lot.","PeriodicalId":326464,"journal":{"name":"ASM Failure Analysis Case Histories: Air and Spacecraft","volume":"72 2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116393462","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Hydrogen Embrittlement of Aircraft Components 飞机部件的氢脆

ASM Failure Analysis Case Histories: Air and Spacecraft Pub Date : 2019-06-01 DOI: 10.31399/asm.fach.aero.c9001746

Jivan B. Shah

引用次数: 0

Failures in Airplane Engine Crankshafts 飞机发动机曲轴故障

ASM Failure Analysis Case Histories: Air and Spacecraft Pub Date : 2019-06-01 DOI: 10.31399/asm.fach.aero.c9001552

Jivan B. Shah

引用次数: 0

Bending of an Aircraft-Wing Slat Track 机翼板条轨道的弯曲

ASM Failure Analysis Case Histories: Air and Spacecraft Pub Date : 2019-06-01 DOI: 10.31399/asm.fach.aero.c0092142

引用次数: 0