In the early years, with no automation, errors were far from unknown: these included starting a movie that had not been rewound, and getting reels confused, so they were projected in the wrong order. Correcting either of these, assuming that someone could tell that the reels were confused, required a complete stop of both projectors, often turning on the house lights, and a delay of a minute or so while the projectionist corrected the error and restarted a projector. These highly visible gaffes, which embarrassed the theater operators, were eliminated with the single-reel and digital systems.
The IMAX flat screen system uses large format film, a wide and deep screen, and close and quite steep \"stadium\" seating. The effect is to fill the visual field to a greater degree than is possible with conventional wide screen systems. Like the IMAX dome, this is found in major urban areas, but unlike the dome system it is practical to reformat existing movie releases to this method. Also, the geometry of the theater and screen are more amenable to inclusion within a newly constructed but otherwise conventional multiple theater complex than is the dome style theater.
The tail section (which includes the tailboom, intermediate gearbox [IGB], the tail rotor gearbox [TGB], and tail rotor assembly) had completely separated from the airframe and was located close to the main wreckage on the ocean floor. The aft baggage door, aft emergency flotation system bag, cylinders, and associated plumbing also separated from the helicopter.
A remotely operated vehicle (ROV) surveyed the extent of the helicopter breakup and reorientation of the major sections, including a main landing gear adjacent to the main rotor hub and blades (see Photo 1).
The PTM powertrain chapter explains that lubrication of the MGB is through a dual lubrication pump system. The PTM includes a lubrication system schematic for the powertrain that depicts the dual lubrication pumps and a picture of the two external oil pumps mounted on the front of the powertrain. It also notes that if one pump should fail, the lubrication system can still supply sufficient lubrication; however, the pressure will drop to the lower green range (i.e., approximately 45 PSI). The PTM states that if both pumps should fail (loss of all lubrication), safe operation is still possible for a short period of time. There is no mention as to how long the gearbox would be able to continue operating, nor is there an identified recommended maximum time of continued safe operation, following a loss of lubricant in either the PTM or RFM.
This section of the RFM also states that multiple symptoms should be considered a very strong indicator of an impending MGB failure. It continues by stating that if an impending MGB failure is suspected, then the primary consideration is to land the helicopter before failure progresses to gearbox seizure or loss of drive to the main or tail rotor. The RFM did not provide pilots with any guidance as to how long the aircraft would be capable of continued safe operation following a loss of MGB lubricant. Although it is common for helicopter manufacturers to market the run dry Footnote 84 time of the helicopters, there is no regulatory requirement to include run dry time in the RFM.
The autorotation procedure in the S-92A RFM, which does not identify any of the steps as memory items, calls for a reduction of collective to maintain 105% Nr and to establish the helicopter between 80 and 100 KIAS. The next steps of the procedure include lowering the gear, shutting off the fuel switches and throttles and then advising the cabin occupants. If time and altitude permit, the RFM procedure suggests attempting to restart one or both of the engines. If a relight proves unsuccessful, the next step in the procedure is to carry out the autorotative landing as per the RFM.
The certification basis for the S-92A was 14 Code of Federal Regulations Part 29. Footnote 129 According to Part 29.917(b), a design assessment and failure analysis, as per Amendment 29-40, of the entire rotor drive system must be conducted with two purposes. First, it must identify all failures that would prevent continued safe flight or a safe landing. Second, it must identify the means to minimize the likelihood of their occurrence, as far as possible, by a means that is both technically feasible and economically justifiable, as defined in FAA Advisory Circular 29-2C: Certification of Transport Category Rotorcraft (AC 29-2C). The design assessment must include any part necessary to transmit power from the engines to the rotor hubs, including components such as gearboxes, rotor brake assemblies, and supporting bearings for shafting. AC 29-2C also requires that multiple failures be considered in cases where a primary failure is likely to result in a secondary failure.
Following the initial failure of the MGB assembly to pass the 30-minute loss of lubricant test, Sikorsky notified the JAA of a design change in the main rotor gearbox oil system.The JAA agreed that the MGB oil cooler bypass system provided a good method of allowing continued operation in the event that a leak occurred in a component of this system. However, it required Sikorsky and the FAA to substantiate that all other possible failures of the MGB that could result in a rapid loss of oil were extremely remote. Sikorsky's subsequent submission of an analysis of possible failure modes and their likelihood of occurrence was eventually accepted by JAA as confirming compliance with the requirements of JAR 29.927(c). Sikorsky re-issued the appropriate reports and after extensive discussions with the FAA and the JAA, the JAA accepted Sikorsky's means of compliance and the FAA's determination of compliance. The JAA's decision was based on relevant Black Hawk airworthiness data, the inclusion of the bearing monitoring system in the S-92A basic design configuration, and the assumption that service experience on the S-92A would prove to be similar to, or better than, that of the Black Hawk.
Since it is not mandatory to include the run dry time in the RFM, some manufacturers do not make that information readily available to pilots, either in the applicable emergency procedure or in RFM aircraft limitation/performance sections. Following this occurrence, the S-92A gearbox malfunctions section was amended to include a statement which advised pilots that a total loss of MGB oil pressure may result in MGB failure in less than 10 minutes. 153554b96e