The Boeing 727 is a three-engined jet airliner seating 149 to 189 passengers and intended for short and medium range flights. Boeing developed and introduced it in the 1960s and for many years the 727 was the best selling jet airliner ever. The aircraft played a major role in US domestic traffic, but also in other parts of the world.
In 1959, after a long period of design studies, Boeing started the development of the 727 and officially launched the programme in 1960 after collecting orders for 80 aircraft from Eastern Airlines and United Airlines. Boeing chose a trijet concept, because three engines gave the aircraft better climb performance and more redundancy in the case of an engine failure compared with a twin. Furthermore, the economics were better than of a four-engine jet.
The three Pratt & Whitney JT8D turbofan engines are placed at the rear of the fuselage, under the remarkable T-tail. The inlet of the middle engine is placed in the root of the tail and the air flows through a S-duct to the engine. The 727 was the first Boeing airliner with an APU (auxiliary power unit), a small extra engine which delivers electricity for the aircraft systems on the ground, independent from ground support.
The 727 retained the earlier 707's upper fuselage cross section, but the lower fuselage was redesigned to reduce belly space because passengers on short and medium range flights carry less luggage with them than 707-passengers on international and intercontinental flights. The cockpit design is based on that of the 707 as well. The 727 has a very advanced wing design, including Krueger flaps on the leading edge to increase the wing area for more lift at takeoff and approach. Thanks to this feature the 727 could serve airports with rather short runways.
Three main versions of the 727 exist: the 727-100, the stretched 727-200 and the Advanced 727-200. The 727-100 made its maiden flight on 9 February 1963 and exactly a year later Eastern Airlines introduced the aircraft type into service. Boeing developed variants with an higher gross weight, the 727-100C Convertible and the 727-100QC Quick Change. The C and QC have large main deck cargo doors.
During its first years of production, the 727 didn't sell well. At that time nobody would have believed that it would ever become the world's best-selling jet airliner of its age. To boost sales, Boeing offered a stretched version, the 727-200. It first flew on 27 July 1967 and in December of the same year the US carrier Northeast Airlines became the first operator. Apart from the 6.10 m (20 ft) longer fuselage, Boeing kept the changes as minimal as possible. The engines, the fuel capacity and the maximum take-off weight remained the same.
A disadvantage of the 727-200, however, was its limited range. To overcome this restriction, Boeing developed the Advanced 727-200, which first flew in March 1972. It has more range, higher weights, more powerful engines and a strengthened airframe. The Advanced became the standard production model. For Federal Express, Boeing delivered fifteen aircraft of a freighter version, the Advanced 727-200F.
Boeing stopped production of the 727 in 1984 after building 1832 aircraft: 572 727-100s (408 -100s, 53 -100Cs, and 111 -100QCs), 310 727-200s and 950 Advanced 727-200s (including 15 Advanced 727-200Fs). Today the role of the 727 in air transport has become marginal. When passenger airlines retired their 727s, many were converted into freighters. Early in 2015 less than one hundred 727s are still in airline service.
To make the 727-200 compliant with Stage 3 noise requirements several hushkit programmes were developed to silence the engines. One programme, by Valsan, included replacing the two outboard engines with more modern Pratt & Whitney JT8D-217s and acoustic measures to the centre engine. The US Dee Howard Company upgraded a number of 727-100 freighters for express freight operator UPS by retrofitting them with Rolls Royce Tay turbofans, which improved performance, reduced fuel consumption and made the aircraft silent enough to meet Stage 3 noise requirements. Some 727s have been fitted with winglets to improve performance and reduce fuel consumption.
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