Profile – Boeing 727

During 1956 there was steadily mounting competition from other manufacturers for a market for which Boeing knew existed, but had yet to formulate a firm proposal of their own. Chief contenders were the jet Trident, DC-9 and Caravelle and turboprops Electra, Vanguard and Viscount. The decision to proceed with the studying of the 727’s feasibility was taken by Boeing on 6 May, 1958. A team headed by Jack E. Steiner was set up to investigate which course Boeing should take. Many vexing questions were to be solved before the 727, as we know it, was to emerge. A total of 150 different airliner designs over four and a half years were analysed in detail and of these 68 designs were subjected to more than 1,500 hours of wind tunnel testing. Design objectives included the use wherever possible of the tooling used in the construction of the 707/720 series, in order to keep costs down.

An early design was a twin-engined airliner, the Model 727- 257 which featured two pods mounted on struts above and behind the wing. This was abandoned in favour of the Model 727- 625, in which two engines are mounted conventionally in pods below and forward of the wing. Analysis of this model and of another twin-engined airliner the Model 727-264C, with the engines in pods on either side of the aft fuselage, was followed by studies of all major U. S. domestic airlines’ routes. In these route studies, the operational limitations of twin-engined airliners were explored in great detail. The economics of a four-engined airliner, the Model 727-475 (called the Model 720 Jr in Boeing engineering offices because of its similarity to that aircraft) were also taken into consideration. The use of three engines resulted in operational flexibility compared to that of four-engine designs while maintaining operating costs close to that of a two-engine aeroplane.

A guiding influence in these various deliberations were the views of the leading U. S. airlines. Eastern Airlines needed an airliner that could operate from New York’s La Guardia Airport which had a then 4,980 ft. runway. Eastern felt that a four-engine airliner was too expensive to operate and that a twin did not offer an adequate safety margin. United Airlines on the other hand needed an airliner that could effectively cope with hot conditions from Denver’s high altitude airport. United’s bias was towards a four-engine 727. Trans-World Airlines expressed interest in a three-engine 727 to add to the variety of views.

On 1 June, 1959 Boeing initiated the full-scale 727 project. Designers, engineers, production men, financial experts and operations analysts were formed into a team under Steiner’s leadership. Following the survey of possible customers and investigating the powerplants of the size and efficiency required for an airliner of the 727 type, it was decided that the design effort should be towards a three-engine airliner. Actually the team’s earlier preference was for a twin-engine underwing layout but the surveys disproved that course as being the best option. Having elected to use three engines, studies undertaken at that time included designs with three engines grouped around a ‘butterfly’ tail, engines grouped around a twin tail, two wing pods and the third engine in the tail and finally the arrangement found in the Boeing 727.

Analyses of three-engine airliner advantages continued and showed that, compared with a twin-engine airliner, the 727’s range is better, direct operating cost is comparable and operational flexibility and reliability are superior. The three-engine airliner could operate under lower visibility and ceiling limitations which results in better schedule reliability than possible under limitations for operation of a twin-engine aircraft. Statistical analysis showed that operating from New York, a twin-engine airliner can be expected to be delayed by weather more than three times as often as one powered by three or four engines. Jack Steiner noted that the 727 was the first tri-motor airliner built by Boeing since the Model BOA of three decades earlier.

To keep costs down, the design objectives included the use wherever possible of tooling employed in the 707-720 series. Aircraft systems already proven on the 707 were retained in the 727 except for alterations which would result in improvements. A good example of this was that the basic 707 tooling was used in the construction of the upper lobe of the 727 fuselage which was the same width and cross-section as the 707. Besides using $3 million worth of 707 tooling in the construction of the upper lobe, the retention of the 148-inch wide fuselage conferred the same fuselage width benefits familiar to passengers already used to the big jets. Although the upper lobe of the 727 is identical to that of the 707, the fuselage has a circular cross section which differs from the ‘double bubble’ used on the 707. When one considers that the 707 fuselage cross section was itself based on the earlier military C-97 (minus the external crease) the family resemblance becomes even more apparent.

The highly sophisticated wing is an outstanding feature of the 727 design. As the 727 was planned for operation from smaller airfields, a low approach speed and a short ground run were of the utmost importance. Chiefly responsible for these characteristics are the high-lift devices incorporated in the 727 wing. The unique trailing-edge flap is triple-slotted and extends aft down to a 40-degree angle, increasing the wing area by 100 square feet. As the trailing-edge flaps are being extended, the wing leading edge flaps and Kreuger flaps are actuated automatically. The four-segment outboard wing slats and the three-segment Kreuger flaps on the inboard wing extend over virtually the entire span of the wing. This combination of leading-edge and trailing-edge flaps gives the 727 unusually high lift at low speed during the landing approach and during take-off and a fully loaded 727 is thus capable of operating from a 5,000 ft. runway. The approach speed is 20 knots lower than that of an early 707 and below that of an Electra.

Various other improvements were incorporated into the 727 design. To facilitate passenger loading and unloading at smaller airports without ground equipment, the 727 is equipped with self-contained ‘airstairs’. All 727s had stairs located under the aft fuselage which retract flush with the body. The forward entrance stair, an optional feature, telescopes under the door, into the fuselage. Although the 727 retained the same spacious cabin width of the 707 and 720 aircraft, the air conditioning system has been further refined for greater passenger comfort. The new system discharges fresh air into the cabin through two slots in the ceiling above the aisle. This arrangement provides improved air circulation throughout the passenger cabin. Two independently operated, parallel hydraulic systems provide increased reliability of operation. The main components of the hydraulic system are easily accessible for more efficient maintenance. As a reliability measure, dual hydraulic packages power the elevator, ailerons and the rudder simultaneously but independently. For additional safety in the unlikely possibility of a total hydraulic failure, the aircraft can be controlled manually.

During 1960 the time for hard decision making had come for the Boeing management. The existing economic climate could hardly have been worse. They were already experiencing huge costs in the 707 programme and as at the end of 1959 losses had amounted to $200 million which was equivalent to Boeing’s working capital. The designs and data were put before the Board of Directors in February 1960. When one considers the 707 problems, the $100 million tooling costs for the 727 was a daunting prospect. It was decided that the 727 seemed to offer what the airlines required, but it was resolved that 100 orders were wanted to launch production and 1 December 1960 was set as the deadline. During this period a valuable potential order was lost when American Airlines ordered the Lockheed Electra.

One of the final stumbling blocks was the engine selection. The Steiner team favoured the Allison-built Rolls Royce Spey but Eastern Airlines refused to accept a 727 with a non U. S. sourced engine. Boeing finally turned to Pratt and Whitney for the JT8D which was a fan conversion of the well-proven military J52 core. On 30 November just one day before the appointed deadline, Eastern and United both ordered 40 three-engined 727s. Although both of these airlines had earlier expressed reservation with a three-engine version, thy were now convinced of the viability of the Boeing design. On 5 December, 1960, the Boeing president ordered the go-ahead and the construction of a legend was about to begin.

The first 727-100, N7001U was rolled out at Renton on 20 November, 1962 and the first flight took place on the morning of 9 February, 1963 with a crew comprising Lew Wallick (who is now Boeing’s Chief Test Pilot and the Director of Flight Test), Dix Loesch co-pilot and Marvin Schulenberger as the flight engineer. One of the objectives Boeing set out to achieve with the 727 was to make it a pilot’s aeroplane and that meant better flight characteristics than the 707. Basically, the change was made from manual to power controls and the 727 became the first aircraft to have a power control system. That this had been achieved was voiced by Lew Wallick after the maiden flight and he summed it up thus.

“At that time we were comparing the new 727 to the standard of the industry which was the 707. The 727 was a much more responsive, lighter to-control airplane. And, it was a very high-performance airplane. It was a thrill to fly for the first time, especially since I had been so heavily involved in working with Jack Steiner, Joe Sutter (Chief Aerodynamicist) and others. The aeroplane flight controls. . the response. . everything was very close to what I expected it to be. . and by the time we finished the first flight I knew we had a winner. Even though we had looked at just a small portion of the flight envelope, it was obvious we had accomplished what we set out to do and that was to design a pilot’s aeroplane. ”

“When we landed for the first time at Paine Field in about 3,000 ft. “, continued Wallick, “everybody was quite impressed! This was pretty astounding compared to the other jet transports flying at that time that needed 7-8,000 ft. The 727 offered jet service to many airports that were being serviced by propellor aeroplanes. ”

During the 10-month flight test programme, the 727 proved to be much better than the performance guarantees. Jack Steiner recalls that everyone was amazed when United Airlines took delivery of its first 727 and the company’s President announced in a news conference that the 727 was some 10% better than what they had ordered. Steiner said at that time it was unheard of for a customer to admit something like that.

Just prior to its FM certification, the 727 embarked on a 76,000-mile world tour visiting 26 countries. Steiner recalls a particular incident while flying into Tokyo. We had made contact with the tower and every few minutes the controller kept asking our altitude and we kept telling him. We could tell he couldn’t believe how fast we were coming down. Finally he blurted out over the radio “What kind of airplane are you flying anyway?”

“We had some trying times in those first years,” says Steiner, “but we worked out the bugs. I remember distinctly how one problem was brought to my attention. I arrived in Germany for a visit to Lufthansa and was taken to a reception in my honour. I walked into this beautiful room filled with people and there in the corner was a table piled high with metal. It was Lufthansa’s way of telling me our flaps were wearing out too fast. We fixed the problem right away. ”

An illustration of the constant effort to improve the product can be drawn from this statement from Floyd Nestegard. He was the Superintendent of 727 final assembly in the early days and was later to become the Manager of Manufacturing and product Support. “When I deal with customers on the road, they ask me if we’re still building that old 727. I say no, we are not. If you compare the systems, the structure and the wing of the first 727 to say the 1,800th you’d be surprised. Although the fuselage looks the same the inside is completely different. The 727 has been in a constant state of evolution since we started building it. No two of them are the same. The average person outside Boeing doesn’t realise that. They think we’re still building the same 727 we did 20 years ago.”

Type approval of the 727 was granted on 24 December 1963 with deliveries to the major U. S. airlines commencing soon after. On 1 February 1964 Eastern Airlines had the distinction of operating the first 727 service from Miami to Washington and Philadelphia.

As befits such a distinguished marque there were several basic versions of the 727 developed over the span of production. During August 1964 Boeing announced that the 727C was in production. This cargo convertible version drew heavily on Boeing’s freight expertise gained from the 707 family. A large 91-inch by 134-inch cargo door, which had the same dimensions as that offered on the 707-320C, was fitted to the forward fuselage of the 727C. Additional commonality was offered as both aircraft had similar pallet sizes and handling systems. The 727C had a 36,750 lb cargo capacity accommodated on eight pallets. A further development was the 717QC announced during June, 1965. This expanded the versatility of the 727C by offering a quick change from cargo to passenger use and vice versa. The rapid turnaround in the configuration was made possible by mounting the seats on 72-inch by 125-inch carpeted pallets and to further aid the transformation the galleys and toilets were also mounted on pallets.

The initial version of the 727, later referred to as the 727-100 also was updated during production. Interestingly enough some important changes were instituted as the result of representations from the Australian operators. Apart from the initial orders from Eastern and United the order book for the 727 was slow to fill and by the end of 1962 stood at 127 aircraft. Thirty-seven were ordered in 1961 and only 10 in 1962, hardly an auspicious start. Ansett-ANA and TAA were interested in the 727, but the 2,000-mile range required for transcontinental flights was beyond the reach of the existing design. Boeing responded by increasing gross weight by 8,000 lb to 161,000 lb and the fuel capacity by 506 U. S. gallons to 7,680 gallons. In addition, Ansett and TAA also requested the installation of a Collins Flight Director, two additional escape hatches which would permit an increase in passenger accommodation from 109 to 135 under DCA regulations, and larger mainwheel tyres. All 727s delivered after the first Australian delivery were at the new increased gross weight. The first of many orders for the 727 was placed by the Australian airlines, for two each on 9 February, 1963. Gradually the outlook for the 727 brightened and after a slow patch in 1963 in which 20 were ordered, 83 were ordered during 1964.

A major change in the 727 design was announced by Boeing on 5 August, 1965 with the unveiling of the 727-200 series. An increase in length of 20 feet was accomplished by the insertion of two 1 O foot fuselage sections, fore and aft of the wing. The gross weight of 170,000 lb was identical with the latest 727C and 727QC aircraft but the empty weight of the 727-200 was 8,225 lb heavier. Passenger accommodation was either 170 in a high-density, single-class configuration or 126 in a mixed-class arrangement. Apart from the obvious increase in length other engineering changes were made to the 727-200 series. These included the raising by several inches of the inlet lip surrounding the centre engine and the redesigning of it into a circular shape. Heavier capacity brakes were fitted, the centre engine tailpipe was fitted with a protecting skid to resist minor impact damage caused by runway contact and the existing tail skid was strengthened.

The first flight of the 727-200 was on 27 July, 1967 and the type gained certification on 30 November. Northeast was the first airline to place it into service on 14 December on its route from Montreal to destinations along the U. S. East Coast extending from Boston to Fort Lauderdale. Initial deliveries of the 727- 200 had the existing 14,000 lb thrust JT8D-7 of the earlier -100 series installed. There was some loss of airfield performance because of this, however this was_ partially rectified when the intended JT8D-9 of 14;500 lb thrust eventually became available. The more powerful engine enabled an increase in gross weight to 173,000 lb and permitted some improvement in range which had been lost in the stretch to the 200 series. The increased engine power coupled with later developments in systems had successfully restored and increased the range as well as reducing take-off and landing lengths. With full payload and the less powerful engines fitted, range was just under 1,500 miles.

Boeing realised that in the 727-200 they had increased passenger capacity with a commensurate improvement in economics, but this was achieved with a sacrifice in performance. This did not seem to deter the airlines from ordering large numbers of this version and gradually the demand for the 727-100 and 100C began to lessen with production being terminated in 1971. Production of the 727-100 amounted to 408 aircraft with a further 164 examples of the 727-100C/QC version.

Despite the considerable success of the 727-200, Boeing were keen to further improve the design. In the next and final version, the Advanced 727-200, probably the best narrow-body airliner put into production at that time was to evolve. Faced with competition from the newer generation of more efficient and quieter wide-body airliners, Boeing successfully embodied much new technology into the proven design. Pratt and Whitney’s continued improvement of the JT8D was to provide the necessary increased power to cope with the higher gross weight.

The changes were substantial. Fuel was increased to 8,180 U. S. gallons with a further lift to 9,780 gallons offered as an option. The powerplant was the Pratt and Whitney JT8O-9 rated at 14,500 lb thrust or the JT8D-15 of 15,500 lb thrust, both engines fitted in new quiet nacelles to meet FAR noise limits. Structural changes included thicker wing skins, a tougher main landing gear and a heavier nose wheel well. The undercarriage changes also included larger tyres and brakes. Improved passenger accommodation was provided in a wide body style interior fitted with overhead storage compartments blended into the cabin wall. Near vertical side window panels and increased indirect lighting contributed to the wide-body look which was standard on the Advanced 727 and available in retrofit kit form for previous models. All these improvements in the Advanced 727 resulted in a price increase of 5-6% over the previous model. Unfortunately the type became available during a trough in the economic climate and the market was rather subdued. The Australian airlines Ansett and TAA again featured in the 727 story by lodging early orders for it during December, 1970. They had been looking for a larger capacity aircraft to handle increasing PerthEast Coast traffic and the Advanced 727 was selected in preference to the Douglas DC-10 which had been under consideration. The first Advanced 727-200 entered service during June, 1972.

Additional improvements were progressively incorporated into the Advanced 727-200 during its production life. Some of these were a new autopilot system, the Sperry SP150, improved corrosion-resistant materials, Sundstrand Mark II ground proximity warning system, optional OMEGA long-range navigation system and an optional dual-channel automatic landing system which permits operation in weather minimums of 700 ft. forward visibility and 50 ft. decision height. By the time the type was nearing the end of its production life the gross weight had risen to 210,000 lb.

An additional stretch of the 727 was contemplated by Boeing.

This was the 727-300, studies of which originated in 1969. Although initial discussions considered an aircraft powered by two General Electric CF-6s it was decided to retain the familiar three-engine configuration. A fuselage stretch of approximately 15 feet over the 200 series was envisaged, accomplished by two fuselage plugs, in front and behind the wing. Gross weight would have been 210,000 lb and maximum passenger capacity 219 and modifications would have been required to the undercarriage and wings to cope with the weight increase. By the end of 1974 the amount of the stretch was extended to 220 inches and gross weight to 225,000 lb. United were interested in this version but the uncertain economic outlook caused them to defer a decision for a potential 50 aircraft order. Development of this version was eventually abandoned and Boeing concentrated on the 7X7 studies which later resulted in the 757 and 767 twin jets.

As fine an aircraft as it is, it was of course certain that production of the 727 would eventually have to conclude. The new generation of jet transport aircraft such as the 757, 767, MD-80 and A310 with all their inherent benefits, are indicative of the inevitable march of progress in aviation technology.

An era came to a close on 14th August, 1984 when a 727- 2S2F, registered N217FE, line number 1832 was rolled out. This aircraft was a freighter for Federal Express, the last of an order for 15 such aircraft. The last 727-200 passenger aircraft had been rolled out some months earlier on 3 March at Renton. Fittingly, Lew Wallick who had flown the first 727 some 21 years earlier, was on the flight deck for the final 727 rollout. The contribution of the 200 series to the ultimate production tally was an astounding 1,260 aircraft. The first 727, delivered to United Airlines 19 years ago, is still in service. The second aircraft was kept by Boeing as a test and training aircraft and was scrapped in the mid-1970s.

Apart from the immense contribution of the 727 to world aviation, the significant importance to Boeing’s own fortunes were noteworthy. The value of the 1,831 727s sold amounted to about $24 billion in Australian currency, and it was the strength of the orders for the aircraft that helped Boeing weather the severe economic downturn experienced in the late 1960s and early 1970s. The airlines, caught in the grip of a recession, severely pruned their order books. Despite receiving respectable orders for 63 727s in 1969 and 45 in 1970 Boeing had no alternative but to shed employees. An indication of the severity of the situation can be gauged by the fact that Boeing had to reduce their total workforce by 80,000. The influence of this to the Seattle region must have been devastating as Boeing reduced its payroll, which stood at 101,000 in January 1968 to shrink to 37. 700 by the autumn of 1971. During an eight-month period. Boeing did not get an order from the U. S. airlines, although some were received from overseas.

The effect of all this had a dramatic impact on 727 production. From a high of 14 aircraft per month at the end of 1967, production fell to two a month in 1971. As the climate Improved, this increased to eight aircraft a month by 1973, which was brought about by a lift in 727 sales from a low of 26 orders in 1971 to 119 in 1972. As the airlines recovered from the recession, 727 orders built up strongly, particularly during 1976/78 when 371 aircraft were ordered.

So what of the future? Will another aircraft be able to top the seemingly unconquerable 727 production figure? A likely candidate is the Boeing 737, with total sales well over 1,300 aircraft as at time of writing. Perhaps the 757 and 767 will be able to do so or the McDonnell Douglas DC-9/MD-80 with approximately 1,400 orders. Whichever aircraft finally dislodges the 727’s production record, one thing is certain. And that is the huge 727 fleet in worldwide service will make a vast contribution to aviation in the years ahead. As at the 14 August final roll out, 1,787 of the 1,831 727s delivered were still in use with 113 airlines, 20 governments and 40 private organisations providing comfortable, efficient and reliable air travel. That is an achievement of which Boeing must be very proud indeed.