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Aviation History
1988
1988 - 0213.PDF
GENERAL AVIATION Helicopter FCS reliability probed LONDON Civil aviation authorities in the UK and USA are consid ering requiring increased redundancy in the hydraulic flight control systems of public transport helicopters. A reliability investigation has begun in response to a report, published last week by the UK Department of Trans port Air Accidents Investi gation Branch, which- doubts that the current minimum requirement of two hydraulic systems without manual reversion gives an acceptable level of safety. The report, which is the result of almost four years of work, raised considerable controversy for its protracted preparation. It details the ditching made by a Boeing Vertol BV-234 Chinook in the North Sea in May 1984. The report says that two separate flight control system mal functions gave intermittent loss of collective pitch control and, if the pilot had not ditched, could have resulted in, almost complete loss of control. The crew and 44 passengers escaped unhurt. There were also three other flight control systems defects which, though not related to the accident, could have had serious repercussions on the system's integrity. One malfunction leading to the control difficulties was intermittent deactivation of a collective lower boost actu ator. That was caused by the fatigue failure of two of three cap screws, which had not been tightened sufficiently and had allowed' hydraulic fluid to escape. Another fault was a tem porary jam in a servo valve. That closed a shut-off valve, which itself jammed because of corrosion, caused by con tamination of the hydraulic fluid with cleaning solvent. The CAA says that in addi tion to reviewing hydraulic system reliability it may make mandatory a crew warning system indicating the position of a bypass valve. The report highlights a series of shortcomings in the operation and maintenance of the helicopter. It says that a number of screws on other actuators were grossly under- torqued and that the operator, British Airways Helicopters, had failed effectively to investigate or resolve similar occurrences before the acci dent. A damaged rear cargo ramp seal had allowed water into the ditched helicopter, which capsized about 80min after ditching. Pre-flight flight control system checks were inade quately specified in the flight manual, and were performed in a way which was not best suited to assessing the condi tion of the hydraulic system. One problem may have gone undetected for several flights. The CAA rejected AAIB calls that bolts ensuring hydraulic fluid retention should be locked and that flight crews should have a fluid loss warning in the cock pit. The call for cockpit warn ing is significant in view of the current AAIB investigation of a Chinook crash in the North Sea in November 1986, in which 45 died. A fatal acci dent enquiry said that condi tion monitoring systems could have been developed which would have warned the crew of the impending gearbox problem, and are now a priority. The rotors collided because of corrosion in a gearbox. Gama welcomes "new enthusiasm" WASHINGTON D.C. ~ Twelve months after predict ing changes in the US indus try, the General Aviation Manufacturers' Association (Gama) is welcoming "new perspectives and enthu siasm", which it sees in the marketplace following several changes of ownership among aircraft builders. Welcoming the advent of such types as the Gulfstream IV, Cessna Cita tion V, Lear 31, turboprop Piper Malibu, and Beech Starship, Gama president Edward Stimpson says "these aircraft will have a positive impact on the future of general aviation" in the USA. Stimpson sees further grounds for encouragement: the impact of deregulation and the declining quality of US airline services to many communities continue to stimulate the use of business aircraft; charter operations are "doing well" in many parts of the USA; and the used- aircraft market is drying up. He says that in recent months retail sales of both new and secondhand business jets have been at their highest levels since 1973. Gama detects a change in the nature of companies who are buying business aircraft. Finance, insurance, real estate, and service industries are the most frequent buyers of business jets, purchasing in 1987 five times the number that they bought ten years previously. In second place is the aviation industry itself (including charter and air taxi operators). In 1977, oil and machinery industries—in second and fifth places, respectively— were significant markets, but last year did not figure in the top five sectors. Sales to service industries have more than doubled, according to Gama, following the shift in the US economy from manu facturing and natural- resource sectors into service- based business. But all is not sweetness and light, 1988 being predicted as "another tough year". Stimp son says that the US economy is presenting mixed signals. "There are signs that the stockmarket crash caused deferral of some orders," although a few may have been retrieved. "Recent predictions on capital spending in 1988 are also mixed, but significant declines are not anticipated." Gama reports that corporate profits are expected to in crease in a number of market sectors, "which is good news". But Stimpson concludes: "This sort of uncertainty, in the economy has always deterred aircraft buying". '• Gama is concerned that the general-aviation industry has a credibility problem. "Un fortunately, in spite of the G A community's solid efforts to search for workable solutions to the complex problems facing the entire air-transport system, we are sometimes incorrectly perceived to be part of the problem, rather than part of the solution." Accordingly, one of Gama's objectives this year is to provide more information to media representatives about the industry and the efforts it is making to work with the US Department of Transporta tion, Federal Aviation Admin istration, and both houses of Congress. It has appointed Henry Ogrodzinski, formerly of the Experimental Aircraft Association, director of com munications. United 747SP attempts record SEATTLE A Boeing 747SP is to be used in an attempt to set a round- the-world record this week end. It has been loaned by United Airlines and is to be flown by a volunteer crew from the US carrier. Some 100 passengers, supporters of the Friendship Foundation set up to help children in need, will pay $5,000 each. The plan is for the aircraft to fly around the world in less than 40hr making just two stops— Athens and Taipei. It will operate from Seattle, depar ting from the city's Museum of Flight at Boeing Field. Dubbed Friendship One, the aircraft will be flown by United's Capt Clay Lacy and is expected to take off on January 28. "We want to draw attention to the plight of the world's children, and those of us in the aviation community participating in this project think that we can do so while we make a mark in the history of American aviation and its technology," says Lacy. BRIEFING AirData's automated flight planning system has won a UK industrial design award. The government-funded Design Council has picked out the product for its ability to process in seconds on a micro computer highly detailed meteorological data. Used by British Midland but aimed at general aviation, the unit is ranked alongside an award- winning guitar synthesizer and a hand-tufted rug. FLIGHT INTERNATIONAL, 30 January 1988 13
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