Page:CAB Accident Report, New York Airways Flight 600.pdf/3

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metal shaVings were identified as AISIZ/ 1,130 Steel. The only parts m the mix box and aft transmiSSion containing this grade of steel are the bearing liners.

Although subsequent examination of the quill shaft disclosed that it met metallurgical deSign specifications, wear steps ranging from .010 inch to .011; inch had formed ontne drive Slde of each of the rear splines. Two fatigue cracks, 180 degrees apart, had started at the wear steps of two splines at paints where the Splines end to accommodate a retainer pinhole. (See Attachment A.) These two cracks progressed about 1.5 inches helically and stopped. Two other cracks, also 180 degrees apart, initiated at the pinhole, and one of them continued into the central unsplined area of the shaft, where ultimate overload failure occurred.

As a result of its initial findings, the Board made a preliminary announce- ment on October 23, 1963, which revealed the discovery of a failed quill shaft. Further, it stated in part: ". . . The (mail Aeronautics Board is conducting a detailed study of the deSign, manufacture, maintenance and overhaul of the heli- copter's transmiSSion system. The Board investigators W111 focus their efforts on the history of this failed peg? (the quill shaft) to ascertain, if possible, the cause of the fatigue . . . .”

The manufacture of aft transmissmn and mix box components, and initial assembly was accomplished by York Gears, Ltd., of Toronto, Canada, and Steel Prod— ucts Engineer g Company of Springfield, Ohio. The processes included drilling 011 passages,_9. bolt holes, etc., in the transmissmn and mix box castings. The cases and covers of both mix boxes and transmissions were then heated, liners of A181 hlBO steel were "frozen," and pressed into the castings. The transmissmn casting, and the cases and covers of the mix box are mounted on Jig mills, and the liners are bored and ground to the correct diameter. Early in the production his— tory of these cases, machine ShaVILngS were found. Consequently Vertol's quality control department established a new procedure for the inapeotion and cleaning of these assemblies. SpeCifically, prior to the installation of any plugs or gets in the lubrication passages, the inspector was to witness flushing of these cases With water and detergent, then a water rinse, and finally with blast air. This was to be followed by the installation of lubricating Jets, a flush With oil, and then all holes were to be plugged and Jet orifices blocked With grease. AIL final assembly of aft transmiSSion and mix box cemponents in use by New York Airways prior to the seeident, including the above flushing, and the final mating of the aft transmiE-Sion with the mix box, occurred at York Gears, Ltd., and Vertol. Prior to the accident

7/ American Iron and Steel Institute.

3/ On November 1, 1963, the FAA issued an emergency Airworthiness Directive much—established a lEO—hour maxuuum service life for the quill shaft, and required mediate removal of all quill shafts, inspection for any wear on the spline faces of the quill shafts or input pinion and collector gears, and the inspection of oil Jets P/N 107132268-1 and P/N 107D22lLL—1. Following complianca with this directive, New York Airways restored passenger operation on November 14, 1963.

2/ Lubrication of the mix box and aft transmission is prouded by a pressure 55’5th “hi-Ch 36135 Oil into hl needed areas. The mix box case and cover form the Sump. The oil flows through a pump, strainer, cooler, and finally enters the lub— rication network at the top of the mix box. From this point the oil flows through Passages and gate of the mix box and aft transmissmn and drains back to the sump.