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Aviation History
2000
2000 - 0399.PDF
CARETH BURGESS 00 ingmaintainability. One characteristic...is the large and heavy main landing gear with three axles. Since it was the first time that Boeing has introduced such huge landing gear, they con ducted in-depth studies to develop a special tool for working on it. We have been working close ly with Boeing to improve the maintenance process and minimise the elapsed time for changing the shock strut seal. We think we can manage to do the work within the same elapsed time as for other aircraft." The airline notes that when changing the engine pre-coolers, the powerplant has to be removed unless a special tool is used. This is "unusual" compared with other types, the air line says, and ANA is considering introducing the Boeing tool for the job. Engine replacement was initially "challeng ing" because of the size of the derated P& W PW4090s mat power the airline's aircraft, but ANA says it can do the job "almost in the same timeframe as other types of engine installed on other types of aircraft such as the Boeing 767". JAL describes the aircraft's key strengths as safety, low fuel consumption and easy maintain ability. "Of course, a very big factor is fuel effi ciency - the 777 uses up to one-diird less fuel and it is 40% cheaper to maintain than a 747- 400." ANA adds diat it is pleased with the cock pit design, and the aircraft "gives passengers a very smooth ride thanks to 'g-force control'". JAL believes the type overall has "no particu lar weaknesses", but adds that "the reliability of the electrical system, including the [Hamilton Sundstrand variable-speed constant frequency] back-up generators, is still lower than we expect." The carrier says it has experienced "many back-up generator failures", adding that "the manufacturer's response has been a litde slow" in resolving this issue. A series .of back-up generator failures has caused damage to engine gearboxes on some 777s (Flight International, 18-24 August, 1999), and the problem threatened to impose ETOPS restrictions on the aircraft. Another problem for JAL has been the integrity of flight control wire bundles, the sub ject of an AD. "Boeing issued a service bulletin to replace some of the bundles, which requires 25h of aeroplane down time," says JAL. ANA says its dispatch reliability is compara tively high, but adds that "the pressure relief shut-off valve has caused some challenges, but we expect to resolve this problem in die near future." ANA adds diat the lack of a humidifier can make the cabin environment slightly dry, but says this is a minor quibble because of the short sector lengths the aircraft is used on. JAL says diere is "nothing exceptional" about the day-to-day maintenance of the engines - a ground, except that its 74m overall length intro duces "spot and taxiway limitations". ANA adds that "the steering is slightly different from odier aircraft types" because of the 777-300's length, but this simply requires getting used to. Both Japanese operators are pleased with the cock pit's layout and function and flight control sys tem, noting in particular that the cockpit displays are easy to read, reducing pilot fatigue. ANA adds that the computerised checklists are useful and innovative. According to JAL, the aircraft falls short only in two areas. The engine power is "a little weak" for the weights at which JAL operates - each PW4090 generates up to 91,7001b thrust, while JAL operates at take-off weights up to 237t. ANA operates its 777-300s at weights of up to •^Hirrfr-'M' Operator All Nippon Airways i:*W.I;«WII»:«'fe.!i!T Powerplant P&W In service 5 On order 2 Total 7 First delivery June 1998 Cathay Pacific Emirates Japan Airlines Korean Air Singapore Airlines Thai International Undisclosed Overall R-R R-R P&W P&W R-R R-R P&W Source: Airclaims CASE database 7 2 5 3 5 4 31 2 3 6 2 2 17 7 4 5 6 11 6 2 48 May 1998 Nov 1999 July 1998 Aug 1999 Dec 1998 Dec 1998 task shared with ANA. Each airline focuses on maintaining different engine modules. JAL has experienced problems with the PW4000's tendency to suffer compressor stall, but this has not led to any in-flight shut-downs since the 777 was introduced. The carrier adds that P&W is preparing service bulletins to reduce the frequency of engine stalls. ANA adds that it is also "working with the manufacturer to learn more about the compressor stall phenom enon and to address any potential issues". JAL seems satisfied with die aircraft's flight handling and says that it is easy to handle on the 234t. Second, JAL adds that brake temperature gets "a little high" during summer, "probably because the wheel size on die landing gear is the same as die 777-200". JAL says the -300's operating costs are "lower than we expected, based on our studies of die aircraft's economics before we decided to order it - especially in maintenance costs". ANA says operating costs are about 25% lower than those of / the 747-400 "largely due to the 777's fuel efficiency". Singapore Airlines GARETH BURGESS 00 FLIGHT INTERNATIONAL 15 - 21 February 2000 ©
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