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Aviation History
1991
1991 - 2438.PDF
HEADLINES LHTEC continues T800forUH-l LHTEC partners Allison and Garrett say they are continu ing their effort to re-engine the Bell UH-1 Iroquois with their T800, despite the launch of a General Electric (GE) T700- powered Iroquois. Southern Aero is the airframe partner for both programmes (Flight International, 11-17 September), and it is clear that LFITEC was unaware of the GE deal until it was announced. The programmes with the 975kW (1300shp)-class T800 and the more powerful T700 are pursuing some separate markets and some that overlap — nota bly the US Army's utility heli copter requirement, at which the T700 is primarily aimed. Southern Aero is actually fit ting a T700 in the same UH-1 airframe it has used to display a T800, and GE's plans would call for a first flight up to six months before LHTEC. LHTEC vice-president, busi ness development, Ron Alto of Garrett, says: "The T800 UH-1 is still alive and well. "The T700 is a viable engine but the [UH-1] transmission can't take it. LHTEC has never been after upgrading the UH-1 — the T800 is a direct replace ment for the [current LycomingJ T53. You don't have to make a rotor change or anything. The T800 gives the same power as the original engine but at half the size, with less weight and better fuel burn. "We would like to find a focal point. We have several investors who might want the supplemen tal type certificate. We need a prime who has access to the world. We have three potential primes bidding for that. By the end of the year we should have a selection for who will want to do it." Alto notes that the T800- powered HH-65 Dolphin has just made its first flight in a US Coast Guard/Army-funded pro gramme. Although the Coast Guard has decided not to complete the trials, having reached agreement with Lycom ing over the troubled LTS-101, the work serves to demonstrate the engine. • FAA orders review of all thrust-reverser designs BY GUY NORRIS IN LOS ANGELES AND KIERAN DALY IN WASHINGTON DC As a result of the discovery that thrust-reverser deploy ment at high speed can be disas trous, the US Federal Aviation Administration (FAA) is order ing inspections of Pratt & Whit ney (P&W)-powered Boeing 757 thrust reversers, and is review ing reverser designs on all airlin ers with high-bypass engines. This action, the most recent stemming from the Lauda Air Boeing 767 crash investigation, is exceptional in its scope and questioning of the generic de sign of a widely-used airliner system. It follows Boeing's discovery that in-flight deployment of a reverser at high speed can cause major airflow disturbances around the wing and pylon, resulting in loss of lift and con trol. Certification trials at lower speeds did not reveal the phe nomenon. In a letter to interested par ties, the FAA says: "It is possible that modern high-bypass en gines, combined with more effi cient thrust-reversers, have resulted in aircraft which require a new thrust-reverser certifica tion philosophy. In-flight rever sal, under certain flight condi tions, may now be an event similar in magnitude to certain primary flight control failures which must be prevented to avoid loss of the aircraft." Boeing Renton's chief techni- Lack of stealth could kill the B-2 politically B-2 does not meet stealth target The US Department of De fense is refusing to explain shortcomings discovered in the stealth performance of the Northrop B-2, saying that any details would compromise clas sified technology. The Pentagon confirms only that a 26 July flight test revealed that the radar cross section "...does not meet the required levels in signature reduction". It says potential fixes are being studied, but notes that it will be "a major problem" if the short comings cannot be cured. Senior congressmen briefed on the' problem agree that security con cerns makes impossible to re lease any details. The revelation comes at about the most embarassing time pos sible for the programme, be cause US House and Senate delegates are just beginning this year's budget summit. • cal and certification engineer, Bob Kelley-Wickemeyer, says: "We are reviewing design criter ia for all our aircraft and will eventually evaluate all designs against the new criteria." He says the study will last for up to a year. The FAA says the 179 US- based and 14 foreign PW2000- powered 757s have the same directional control valve (DCV) as PW4000-powered 767s which, Boeing tests showed, could lead to in-flight reverser deployment if a particular brand of solenoid pilot valve is con taminated with a freed O-ring. About half of those aircraft are believed to have the suspect valve. Others have an earlier DCV design without O-ring seals. The 757 airworthiness direc tive (AD) requires inspection of the DCV and replacement of the affected valves, together with electrical system checks. The work is to be completed on at least one engine per aircraft within 14 days, in which case the uninspected unit must be deactivated; and on all engines within 24 days. The electrical checks must be repeated every 3,000h. Immediate deactivation is not required, unlike in the 767, be cause of "the added safety fea tures in the 757/PW2000 thrust- reverser". Rolls-Royce (R-R) NEWS IN BRIEF BOGGED BOEING Four incoming flights were cancelled and many more de layed or diverted after an Egyptair Boeing 747 left the runway when landing in heavy rain at Manila OH 4 September. The 747 became bogged down in heavy mud at Holding Area No 2 after a flight from Tokyo Narita. There were no injuries among the 347 passengers. 4 FLIGHT INTERNATIONAL 18 - 24 September, 1991
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