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Aviation History
1968
1968 - 2668.PDF
818 AIR TRANSPORT... then proceeds to question the validity of the ICAO- recommended procedure of carrying out approaches on the QNH setting. The report recommends that the QFE setting should be used; for all take-offs and landings except in cases of high-altitude fields where the scale is inadequate. "In this way," the report says, "misinterpretation . . . wouldbe prevented, since at every airport the pilot reads off the relevant height above the airfield without conversion, quite apart fromthe psychological factors produced by the fact that the altimeter always presents the same appearance on take-off and landing. Bythis measure similar accidents could be prevented in future." While one would echo wholeheartedly (writes John Bentley) the recommendations of the German report, as far as they go, it cannot be said that the investigation itself covered the whale of the picture. The circumstances of this accident bear a striking resemblance in some details to those which surrounded the accident at Ljubljana (reported in Flight for September 12, pages 397-398). Both approaches were made at night and in each case the pilots were apparently using the QNH setting in the belief that it was QFE. In both cases there was evidence that the approach lights could be seen at a distance but that they were blocked out by meteorological conditions. In the Ljubljana accident the VASIs were working; at Frankfurt they were not. In both accidents the aircraft ILS receiving equipment was found tuned to the relevant transmission frequency. In both cases the FLIGHT International, 21 November /'. 68 cause of the accident was determined to be pilot error (implied in the Ljubljana report; stated in that on Frankfurt) connected with the setting of the altimeter. This explanation is not completely watertight in either case. The Ljubljana case has already been covered. In the Frankfun accident no reasonable explanation is given as to why the pilots left the ILS glideslope in the first place and the para- graph in the report, dealing with a supposition that a visual approach below cloud was possible, is hardly credible. Hardly credible, that is, until a map of the Frankfurt zone is studied. The map provided at the back of CAP 310 shows that a section of autobahn runs close to the extended centreline of runway 25R—very close to it in the area of the accident. It is thought by some pilots that lights from vehicles on the autobahn were mistaken for the runway lights. This is just possible if the crew of G-ASOG had become disorientated by cloud during what they thought was going to be a fully visual approach. It still does not, however, explain why they both disregarded the ILS glidepath indications. The discrepancies between the operations manuals and check lists of Air Ferry illustrates the ineffectiveness of "paper safety." Such documents should be checked by the Board of Trade before an AOC is issued—indeed the approval of documenta- tion was one of the bastions of AOC procedure at the time of the accident. The Board of Trade has published the German report without comment. It is a pity that more details of crew duty times were not included, and that no recommendation was made about the carriage of flight recorders. Once again investigators have been forced to rely on surmise and specula- tion when, but for a little more resolve on the part of authority, they could be coming to conclusions on the basis of fact. ELECTRONIC FRISKER A DEVICE developed by Lockheed Missiles and Space Co, of Palo Alto, Cal, has been designed to detect weapons concealed on passengers boarding airliners. Lockheed says that it will detect a weapon concealed in clothing or carry-on baggage. Using a thin-film magnetic sensor, the device is designed to detect the movement of magnetic fields associated with ferrous metal objects such as guns. * If the gadget can successfully spot guns carried by boarding passengers, Lockheed is likely to have a big seller. The grow- ing frequency with which aircraft are hijacked is a nightmare for the industry and dangerous for air travellers. So far, the various escapades have ended without tragedy. Sooner or later, however, there will be a disaster. If a gun goes off, tearing a hole in the pressure hull of an aircraft, there could be a fatal decompression. 8-61 CRASH EVIDENCE THE US National Transportation Safety Board recently issued a summary of evidence taken during the earlier public hearing as part of its investigation into the accident involving a Los Angeles Airways Sikorsky S-61L at Paramount, Cali- fornia, on May 22, 1968, killing all the 20 passengers and the three crew members. A report on the probable cause will be issued in a few months. The accident occurred on the return segment of one of about 30 daily round trips flown between Anaheim, Disney- land and Los Angeles Airport. Witnesses heard "breaking sounds" and saw the main rotor blades strike the aft and forward structure of the aircraft. They then saw portions of the main rotor blades, tail boom and fuselage fall from the helicopter. From an altitude estimated by witnesses as con- siderably less than at which it was seen (2,000ft) a minute or so earlier, the aircraft fell nearly vertically. The visibility was clear and no other aircraft was seen close to the helicopter during the sequence of events preceding the accident. Portions of the main rotor blades, and fore and aft structure of the aircraft, were found back along the final flight path as far as 2,000ft and there was clear evidence that the main rotor blades had struck the fore and aft body of the aircraft in flight. Metallurgical examination of critical fractures revealed no evidence of fatigue failures or improper metal compositions, A witness for Sikorsky explained that the five main rotor blades turn counterclockwise when seen from above and are colour coded for identification as the red, black, white, yellow and blue. Examination of the rotor blades and fuselage damage revealed that the red, black, white and blue blades had struck and penetrated the aft and forward fuselage of the aircraft in that order (see also Flight for October 10, page 562). The yellow blade had struck the right side of the fuselage in the area of the cargo door handle and then wrapped itself under the fuselage to the extent that it struck the right bottom side. The absence of any strikes by the yellow blade in the strike sequence on either the aft or forward areas of the aircraft caused the witness to believe that the yellow blade was then out of the rotor disc and that it had gone out of control and struck the fuselage before the sequence of strikes by the other blades. Evidence indicated that the blade strikes on the aft portion of the aircraft preceded those on the forward part. For the yellow blade to have gone through the gyrations indicated by the physical evidence, it would have had to have been detached from its pitch-change control rod. Examination of the main rotor control head revealed that the yellow blade pitch-change control rod was detached at its rotating swashplate attachment point. A bolt and nut, one of two which secure the pitch-change road trunnion bearing cap to the trailing ear of its rotating swashplate, were missing. The hole in the aluminium cap through which the steel bolt normally passes was intact. The trailing ear was found broken from the rotating swashplate with the bearing cap attached to a small portion of the lug by the other bolt and nut. The bearing, normally press-fitted into the cap, was not in the cap. The missing nut and bolt were not found; however, of 46 bolts of the missing type used in the S-61L, 45 were accounted for. Evidence indicated that, under some force, the bearing cap had been pushed outwards, the bearing came out of its cap and the trunnion became free, releasing the yellow blade pitch- change control rod. The force which pushed out the bearing cap had not been isolated, the witness said, and efforts "must be continued to find this undetermined force."
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