FlightGlobal.com
Home
Premium
Archive
Video
Images
Forum
Atlas
Blogs
Jobs
Shop
RSS
Email Newsletters
You are in:
Home
Aviation History
1963
1963 - 1985.PDF
788 FLIGHT International 14 November 1963 AIR COMMERCE Type certification of the NAMC YS-II is expected early next year, following successful pro gress of the test programme shared by two aircraft. Powered by two Rolls-Royce RDa.lO turboprops the YS-I I has been ordered by All Nippon, 20; JAL, 5; Japan Defence Agency, two; and Japan Civil Aviation Bureau, one. Deliveries are due in mid-1964. The production programme calls for 150 YS-I Is between 1964 and 1970 THE ONE-ELEVEN INVESTIGATION LAST week's issue of Flight International contained a brief review of the main points in the British Aircraft Corpora tion's interim report on the investigation into the One-Eleven crash. For the record, the following is the full text of the statement:— "At the outset of this interim report everyone in British Aircraft Corporation wishes to express grief at the deaths of the seven men in the aircraft, each of whom had made an outstanding contribu tion to aviation development. The accident underlines the price still paid for progress and strengthens the resolve of everyone con nected with the One-Eleven to see that the programme on the air craft will continue with even greater momentum. "The sequence of events which led up to and caused the accident was available for rapid analysis because of the flight recorders, and the data provided by the Midas was particularly valuable. The knowledge so gained will be of lasting benefit to the safety of avia tion, not just for the One-Eleven but for many other aircraft. The results of the investigations have therefore been, and will continue to be, made known to other manufacturers in this country and overseas. "British Aircraft Corporation wishes to thank the members of the Air Accidents Branch of the Ministry of Aviation for all their help and for the work they have done, and are still doing, on the causes of the accident. The following report has been circulated to a number of airlines and to other interested organizations. "The accident occurred on October 22, at Chicklade, Wiltshire. The impact marks of the aircraft and the distribution of the wreckage show that the aircraft struck the ground in an approxi mately horizontal attitude at a high vertical speed and low forward speed. Severe fire after impact destroyed most of the aircraft except the tail assembly, but flight recorders recovered from the wreckage provided valuable evidence on the manoeuvres which preceded the accident. The first phase of the One-Eleven flight test programme up to the time of the accident had totalled 81hr (53 flights) and had been devoted to a preliminary assessment of the systems and general engineering, measurements of performance, together with handling characteristics, within the speed range from V0 to the approach to the stall. "In general the results of this early phase of test flying have been most encouraging. In that part of the programme devoted to the assessment of stability and handling characteristics during the approach to the stall, and also measurements of Ctmai, 42 ap proaches to the stall and recovery had been satisfactorily com pleted covering a range of flap angles from zero to full flap on CGs of 0.16 SMC and 0.30 SMC. On the 53rd flight, four approaches to the stall in the clean configuration had been carried out at a CG of 0.38 SMC. It was on the fifth test on the same CG with flaps out at 8 degrees that the accident occurred. "Information extracted from the two flight recorders recovered after the accident, one Midas CMM24-7S-E and the other a C.I.D. 02E, has now been analysed in detail and shows that during this test the incidence increased substantially above the figure antici pated. The flight recorders show that the "g" break at the stall was large and abrupt, causing downward acceleration and further rapid increase of incidence. A condition rapidly developed in which it would be impossible for a pilot, even of Lithgow's calibre, to appre ciate the situation soon enough and therefore prevent further build up of incidence. As the incidence increased due to downward acceleration, the elevator started to trail up. This trail up was arrested and partial down elevator applied some 3sec after the "g" break but the aircraft response, as would be expected under these conditions of low forward speed and aft CG, was too slow to stop further increase of incidence. "Eventually the incidence increased to a value where the effec tiveness of tailplane and elevator was reduced to a fraction of the normal value. At this incidence the elevator servo tab power was insufficient to stop the elevator from trailing up and it reached the UP stop in spite of a large push force on the control column. The aircraft continued to descend at a high rate of descent, the fuselage attitude being substantially horizontal, and hit the ground flat. The aircraft did not spin and there is no evidence of structural or mechanical failure. "The flight recorder data indicate that the engines were running and were used during the attempt to recover from the stall. The wreckage indicates that the engines were still revolving when the air craft struck the ground and no evidence has been found which would indicate any in-flight malfunction. "The foregoing statement has been prepared in consultation with the Chief Inspector of Accidents, Ministry of Aviation, who is conducting the enquiry into the cause of the accident. The steps which the Corporation is taking to remedy the situation revealed by the accident consist primarily of alterations to the wing leading edge shape to improve the nose down pitching characteristics of the aeroplane and modifications to the elevator linkage to permit a more direct mechanical connection between the pilot's control and the elevator. The original certification programme was based on the use of three fully instrumentated aircraft. It has now bcen decided that the next four aeroplanes will be fully instrumentated. and be engaged in the certification test programme. Their instru mentation is being changed and augmented to make up for the loss of the first prototype and this will delay the first flight of the nexr aeroplane until early December. The remaining three instrumen tated aeroplanes in the certification programme will follow ai approximately monthly intervals. The modifications describee above, and any others which may prove to be necessary, will pro gressively be incorporated in these aeroplanes. Detailed assessment of the effect on the production programme is still being carried out, but it is considered that deliveries to the first two customers, Britisr United Airways and Braniff Airways, will still commence in the last quarter of 1964." Undoubtedly the availability of flight-recorded data was funds-
Sign up to
Flight Digital Magazine
Flight Print Magazine
Airline Business Magazine
E-newsletters
RSS
Events
