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Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.aero.c9001144
EISBN: 978-1-62708-217-4
... Abstract A helicopter was hovering approximately 10 ft above a ship when one spar section failed explosively. Visual inspection revealed a crack had progressed through one member of a dual spar plate assembly at a fold pin lug hole. The remaining spar plate carried the blade load until...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.aero.c0006444
EISBN: 978-1-62708-217-4
... Abstract Helicopter rotor blade components that included the horizontal hinge pin, the associated nut, and the locking washer were examined. Visual examination of the submitted parts revealed that the hinge pin, fabricated from 4340 steel, was broken and that the fracture face showed a flat...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.aero.c9001717
EISBN: 978-1-62708-217-4
... Abstract The US Army Research Laboratory performed a failure investigation on a broken main landing gear mount from an AH-64 Apache attack helicopter. A component had failed in flight, and initially prevented the helicopter from safely landing. In order to avoid a catastrophe, the pilot had...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.aero.c9001583
EISBN: 978-1-62708-217-4
...) requested that the U.S. Army Research Laboratory — Weapons and Materials Research Directorate (ARL) perform a metallurgical investigation of numerous fatigue tested main rotor spindle tie rods from an Army utility helicopter. These components are an integral part of the main rotor hub assembly, and all...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.aero.c9001600
EISBN: 978-1-62708-217-4
... Abstract This paper summarizes the results of a failure analysis investigation of a fractured main support bridge made of 7075 aluminum alloy from an army helicopter. The part, manufactured by “Contractor IT,” failed component fatigue testing while those of the original equipment manufacturer...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.aero.c0046222
EISBN: 978-1-62708-217-4
... Abstract The spindle of a helicopter-rotor blade fractured after 7383 h of flight service. At every overhaul (the spindle that failed was overhauled six times and reworked twice), any spindle that showed wear was reworked by grinding the shank to 0.1 mm (0.004 in.) under the finished diam...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.aero.c9001742
EISBN: 978-1-62708-217-4
... Abstract In a helicopter engine connecting rod, high-cycle, low-stress fatigue fractures in bolts and arms progressed about 75% across the section before the final rupture. Factors involved were insufficient specified preload, inadequate tightening during assembly, and engine overspeed...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.aero.c9001636
EISBN: 978-1-62708-217-4
... Abstract A Lynx helicopter from the Royal Netherlands Navy lost a rotor blade during preparation for take-off. The blade loss was due to failure of a rotor hub arm by fatigue. The arm was integral to the titanium alloy rotor hub. An extensive material based failure analysis covered the hub...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.aero.c9001505
EISBN: 978-1-62708-217-4
... Abstract 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...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.aero.c9001510
EISBN: 978-1-62708-217-4
... direction that must be considered of primary importance in material selection for design configuration. A Navy UH-1N helicopter main rotor blade grip manufactured from a 2014-T6 aluminum alloy forging failed because of a design flaw that left a high residual tensile stress along the short transverse plane...
Series: ASM Failure Analysis Case Histories
Volume: 1
Publisher: ASM International
Published: 01 December 1992
DOI: 10.31399/asm.fach.v01.c9001077
EISBN: 978-1-62708-214-3
... Abstract The failure of a spiral bevel gear from the transmission of a helicopter was discovered when the transmission was removed after an in-flight incident. Two adjacent teeth from the carburized AISI 9310 steel gear were found to have undergone fatigue failure. Internal initiation occurred...
Series: ASM Failure Analysis Case Histories
Volume: 1
Publisher: ASM International
Published: 01 December 1992
DOI: 10.31399/asm.fach.v01.c9001024
EISBN: 978-1-62708-214-3
... Abstract A Marine Corps helicopter crash was investigated. Efforts were directed to the failure of one of the main rotor blades that had apparently separated in the air. The apparent failure of a blade integrity monitor (BIM) system was also considered. The rotor blade comprised a long, hollow...
Series: ASM Failure Analysis Case Histories
Volume: 2
Publisher: ASM International
Published: 01 December 1993
DOI: 10.31399/asm.fach.v02.c9001293
EISBN: 978-1-62708-215-0
... Abstract A forged, cadmium-plated electroslag remelt (ESR) 4340 steel mixer pivot support of the rotor support assembly located on an Army attack helicopter was found to be broken in two pieces during an inspection. Visual inspection of the failed part revealed significant wear on surfaces...
Series: ASM Failure Analysis Case Histories
Volume: 2
Publisher: ASM International
Published: 01 December 1993
DOI: 10.31399/asm.fach.v02.c9001297
EISBN: 978-1-62708-215-0
... Abstract A helicopter tail rotor blade spar failed in fatigue, allowing the blade to separate during flight. The 2014-T652 aluminum alloy blade had a hollow spar shank filled with lead wool ballast and a thermoset polymeric seal. A corrosion pit was present at the origin of the fatigue zone...
Series: ASM Failure Analysis Case Histories
Volume: 2
Publisher: ASM International
Published: 01 December 1993
DOI: 10.31399/asm.fach.v02.c9001298
EISBN: 978-1-62708-215-0
... Abstract A helicopter tail rotor blade spar failed in fatigue, allowing the outer section of the blade to separate in flight. The 7075-T7351 aluminum alloy blade had fiberglass pockets. The blade spar was a hollow “D” shape, and corrosion pits were present on the inner surface of the hollow...
Series: ASM Failure Analysis Case Histories
Volume: 2
Publisher: ASM International
Published: 01 December 1993
DOI: 10.31399/asm.fach.v02.c9001380
EISBN: 978-1-62708-215-0
... to be broken during a maintenance procedure on an Army attack helicopter. Applications The bolt is illustrated in Fig. 1 . Two pitch horn bolts are inserted into the pitch horn assembly which controls the pitch of the helicopter blades during flight. If one of these bolts were to fail in service...
Series: ASM Failure Analysis Case Histories
Volume: 2
Publisher: ASM International
Published: 01 December 1993
DOI: 10.31399/asm.fach.v02.c9001381
EISBN: 978-1-62708-215-0
... Abstract A helicopter main rotor bolt failed in the black-coated region between the threads and the taper section of the shank during assembly. The torque applied was approximately 100 N·m (900 in.·lbf) when the bolt sheared. No other bolts were reported to have failed. The failed bolt material...
Image
Published: 01 January 2002
Fig. 6 Fatigue cracking of a helicopter tail rotor blade. (a) Scanning electron micrograph of the blade showing lead wool ballast in contact with the 2014-T652 aluminum spar bore cavity wall at the failure origin ∼13×. (b) Greater magnification (∼63×) in this same area shows the multiple pits More
Image
Published: 01 June 2019
Fig. 2 Helicopter-blade spindle that fractured in fatigue because it was incompletely shot peened before being plated. (a) Spindle showing fracture region (at fillet between shank and fork). Dimensions given in inches. (b) Longitudinal score mark (region A) and circumferential scratches (arrow More
Image
Published: 01 June 2019
Fig. 1 Eyebolt which attaches rear lift strut to right wing of helicopter failed in service. Note severe corrosion at and near fatigue failure origins in the last (run-out) thread root. More