History & Variants
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*** Updated 24 Feb 2013 ***
The 737-200 was succeeded in 1984 by the 737-300. This was a much quieter, larger and more economical aircraft and contained a host of new features and improvements. The new model featured many aerodynamic, structural, cockpit and cabin features developed for the new -generation 757/767.
One of the objectives was to have a high degree of commonality with the 737-200, the achieved figure was 67% by part count. This gives saving for airlines in maintenance, spares, tools for existing 737-200 operators. Also the aircraft was designed to have similar flying qualities, cockpit arrangements and procedures to minimise training differences and permit a common type rating.
The sole powerplant was the CFM-56, the core of which is produced by GE and is virtually identical to the F101 as used in the Rockwell B-1. SNECMA produced the fan, IP compressor, LP turbine, thrust reversers and all external accessories. The main problem was the size of the engine for ground clearance, this was overcome by mounting the accessories on the lower sides to flatten the nacelle bottom and intake lip to give the "hamster pouch" look. The engines were moved forward and raised, level with the upper surface of the wing and tilted 5 degrees up which not only helped the ground clearance but also directed the exhaust downwards which reduced the effects of pylon overheating and gave some vectored thrust to assist take-off performance. The CFM56-3 proved to be almost 20% more efficient than the JT8D.
Two sections were added to the basic -200 fuselage; a 44in section forward of the wing and a 60in section aft of the wing. Composite materials were used on all flight controls to reduce weight and aluminium alloys used in areas such as wing spars, keel beams and main landing gear beams which improved their strength by up to 12 percent thereby increasing service life.
The wings were extensively redesigned to enhance low speed performance and cruise efficiency. The chord of the leading edge outboard of the engines was extended by 4.4%, this reduced the wing upper surface camber forward of the front spar to increase Mcrit thereby giving better transonic airflow characteristics and improved buffet margins. The span was increased by a wingtip extension of 27.9cm (11in). These two changes had the greatest impact on high speed performance and as a result, the turbulent air penetration speed changed to 280KIAS/.73M.
High lift characteristics were also enhanced by re-sequencing the slats and flaps. The leading edge slat radius was also increased which gave a 2.5kt reduction in Vref over a -200 at the same weight. Other changes to the wing structure included strengthened materials and corrosion protection. Rumour has it that the fin was also "given" to Shorts for use on their SD-360 as a reward for their good contract work for Boeing. Whether this is true or not, the SD-360 fin certainly looks identical, albeit scaled down.
Flight Management System with fully integrated Digital Flight Control System, Autothrottle, Flight Management Computer, Dual laser gyro Inertial Reference System. EFIS CRT displays.
Changes that were made to the classics over their production run include:
Test Pilot Jim McRoberts had the honour of making the first flights of all three of the classics series. The flight test program lasted nine months and the three aircraft flew a total of 1,294 hours. The program was largely uneventful, there were some problems with engine/wing flutter but these were overcome with the addition of a 50kg mass balance at each wingtip. The 737-400 flight test program was a further 400 hours and the 737-500 just 375 hours.
There are now three separate cargo-conversion programs (Pemco, IAI Bedek & Goodrich) for the -300 / -400, which will give capacity for 8 / 9 pallets and a 18,800 / 20,900kg payload respectively.
CFMI are now offering a core upgrade kit which they claim will save up 1% specific fuel consumption. The kit also increases EGT margins by 15C thereby giving up to 1400 additional cycles.
Aviation Partners Boeing APB are offering retrofit kits to add winglets to any 737-300. Known as Special Performance (SP), the winglets give a 4.5% drag reduction over the standard model. The first 737-300SP was delivered 9 Jul 2003 and the retrofit kits are expected to be available for the -400 by the end of 2003.
737 Classics Key Dates:
March 1981: 737-300 accounced.
17 Jan 1984: Prototype 737-300 rolled out.
24 Feb 1984: First flight of 737-300.
24 Jul 1986: EADI & EHSI certified by the FAA.
19 Feb 1988: First flight of 737-400.
25 Feb 1991: 2000th 737 delivered.
15 Jun 1997: A CFM56-3 engine powering a Boeing 737-500 with Braathens S.A.F.E. reached 19,855 cycles without a single shop visit, setting a new world's record for time on wing. The previous record of 19,841 cycles was held by a CFM56-3 engine in service with Southwest Airlines. The CFM56-3C1 engine, which entered Braathens' fleet in October 1991, was removed after nearly six years of service due to life-limited parts in the core.
26 Jan 1998: 3000th 737 rolled out.
9 Dec 1999: Final 737 "Classic" - a 737-400 is rolled out.
14 May 2002: Pemco Aviation Group announces that it has inducted its first aircraft for the new 737-300 cargo conversion program at its Dothan, Alabama facility following the recent certification of its 737-300 Supplemental Type Certificate (STC) by the FAA.
4 Apr 2005: Israel Aircraft Industries (IAI), Bedek Aviation Group delivers first 737-300SF conversion to Kitty Hawk, Inc.
24 Mar 2009: Israel Aircraft Industries (IAI), Bedek Aviation Group delivers first 737-400SF (also known as 737-400BDSF) conversion to GECAS.
FF 24 Feb 1984
1113 Built, 759 In service.
Overall length 33.4m (105ft 7in) and a maximum capacity of 149 passengers. MTOW 63,275kg (139,500lbs)
The first winglet equipped classic was delivered in June 2003 and is known as the 737-300SP.
In Oct 2003 Pemco of Florida completed conversion of the first 737-300QC. It has a main cargo door and the seats can be removed in 45mins to allow 8 standard pallets with approx 17,000kgs payload. Pemco also converts to pure freighters as the 737-300F, these have a 9 pallet / 18,000kg capacity.
Israel Aircraft Industries (IAI), Bedek Aviation Group have converted several 737-300SF's including those of Kitty Hawk Aircargo. The Kitty Hawk aircraft are also fitted with the FuelMizer modification kits from AvAero.
Pemco and IAI both hold supplemental type certificates for 737-300/400 cargo conversions, but are not supported by Boeing. Boeing tried to offer their own 737-300/400 SF freighter conversion with InterContinental Aircraft Services of Taiwan, but dropped the service after five years without a launch customer.
AEI of Miami also offers a 9 pallet 737-300 cargo conversion.
737-300SF conversion by IAI
This is the only known Chinese airborne Command & Control 737. It was developed by Xian Aircraft Corporation in 2005, without Boeing or US approval. The aircraft is owned by China United Airlines, who are the VIP transportation division of the Peoples Liberation Army Air Force. They bought the aircraft from Indonesia in 1990. The PLAAF have 9 737s which are based at Xijiao Airfield, Beijing and flown by the 34th Air Division.
It has three large farings; a SATCOM antenna above the fuselage and two for data-link / communication below.
FF 19 Feb 1988
489 Built, 412 In service.
The Boeing 737-400 was given a further stretch of 2.8m (9ft 6in) over the -300. Giving a length of 36.45m (119ft 7in). A ventral tailskid was installed to prevent tailscrape damage on over-rotation, the FCTM shows that the -400 has the greatest risk of tailstrike of all the series of 737. Passenger capacity was now up to 174, this required two extra overwing exits and a boost to the air-conditioning system to give the necessary increase in air flow rate.
Standard MTOW now up to 65,000kg (143,500lbs) with a 68,000kg (150,000lbs) HGW option. The wings of all -400's were strengthened and flap limiting speeds increased over the -300.
The 737-400SF freighter conversion by ICAS has a 9 pallet capacity although other conversions offer 10.
The 737-400SP is a winglet equipped retrofit. This became available in 2005.
The last of what was known as the 737 Classic series was a Boeing 737-400 (OK-FGS, L/N 3132), delivered to CSA Czech Airlines on 25 February 2000.
FF 30 Jun 1989
388 Built, 313 In service.
The 737-500 (originally known as the 737 Lite and the 737-1000) combined the original length fuselage of the -200, with the various improvements of the -300 and -400. Overall length 31.0m (101ft 9in), MTOW up to 60,555kg (133,500lb).
The 737-500SP is a winglet equipped retrofit. This became available in 2007.