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 ofnew features and improvements. The new model featured many aerodynamic, structural,co*ckpit and cabin features developed for the new -generation 757/767.
Commonality
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, co*ckpit arrangements and procedures to minimise training differences and permit a common type rating.
Engines
The sole powerplant was the CFM-56, the core of which is produced by GE andis virtually identical to the F101 as used in the Rockwell B-1. SNECMA producedthe fan, IP compressor, LP turbine, thrust reversers and all externalaccessories. 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 nacellebottom and intake lip to give the "hamster pouch" look. The engines weremoved forward and raised, level with theupper surface of the wing and tilted 5 degrees up which not only helped theground clearance but also directed the exhaust downwards which reduced theeffects of pylon overheating and gave some vectored thrust to assist take-offperformance. The CFM56-3 proved to be almost 20% more efficient than the JT8D.
Airframe
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 airpenetration 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 foruse on their SD-360 as a reward for their good contract work for Boeing. Whetherthis is true or not, the SD-360 fin certainly looks identical, albeit scaleddown.
Flightdeck
Flight Management System with fully integrated Digital Flight Control System, Autothrottle, Flight Management Computer, Dual laser gyro Inertial Reference System. EFIS CRT displays.
- Performance: Higher ceiling 37,000ft; Higher MTOW; 20% lower fuel burn than -200.
- Engines: High bypass (5:1), 18,500-23,500lb, CFM56-3.
- Fuselage: 44in fwd body extension, 60in aft body extension.
- Wings: Span increased by 11in wingtip extensions; Modified slat aerofoil, flipper flaps & flap track farings. Increased fuel capacity to 16,200kg.
- Tail: Dorsal fairing added for stability during asymmetric conditions; Stabiliser extended 30in due to increased fuselage length.
- Flight Controls: New slats to reduce approach speeds to within a few knots of the much lighter -200. Additional ground spoiler. Stab tip extension.
- Nose Gear: Lengthened 6in and repositioned to help provide the same engine inlet ground clearance as the -200.
- Main Gear: Strengthened wheels, 40 or 42 inch tyres & better brakes for the increased MTOW.
- Flightdeck: EFIS CRT displays replacing many conventional instruments.
Changes that were made to the classics over their production run include:
- Taxy light extinguishing automatically with gear retraction.
- Addition of a strobes AUTO position.
- Light test not illuminating engine, APU & wheel-well fire warnings.
- OVHT/FIRE system test will only show a fault, ie no method of determining whether open or closed circuit.
- Cabin pressure control system (CPCS) & indicators replaced by digital system (DCPCS) which has no standby mode but has a second (alternate) automatic mode.
- Option of a Sundstrand APU with no EGT limits and shorter restart intervals.
- Extra automatic DC fuel pump for APU starts.
- Various comms options such as VHF3, HF, SELCAL, ACARS & TCAS.
- Option of VSCF instead of CSD.
- Dripsticks replaced by floatsticks.
- Option of a fourth fuel tank.
- Refuel preset facility on refuelling panel.
- Alternate nose wheel steering (from system B).
- SIDE window heat now also heats window 3.
- Third automatically tuned DME radio for FMC position.
- Round dial engine instruments replaced by EIS panels.
- APU battery.
- Aspirated TAT probe
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.
Future
There are now three separate cargo-conversion programs (Pemco, IAI Bedek& Goodrich) for the -300 / -400, which will give capacity for 8 / 9 palletsand 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 therebygiving up to 1400 additional cycles.
Aviation Partners Boeing APBareofferingretrofitkits toadd wingletsto any737-300.Known as Special Performance(SP), thewingletsgive a 4.5% dragreductionover thestandardmodel. Thefirst737-300SPwasdelivered9 Jul 2003and theretrofit kitsare expected tobe availablefor the -400by theend 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.
Click for technical specifications
737-300
FF 24 Feb 1984
1113 Built, 514 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 deliveredin June 2003 and is known as the737-300SP.
Cargo Versions
In Oct2003 Pemco of Floridacompletedconversionof thefirst 737-300QC.It has amain cargodoor andthe seatscan beremoved in45mins toallow 8standardpalletswithapprox17,000kgspayload.Pemco alsoconvertsto purefreightersas the 737-300F,these havea 9 pallet/ 18,000kgcapacity.
Israel Aircraft Industries (IAI), Bedek Aviation Group have converted several737-300 BDSF's (BDSF = Bedek Special Freighter) including those of Kitty Hawk Aircargo. The Kitty Hawk aircraft are also fitted with the FuelMizer modification kits from AvAero.
737-300SF conversion by IAI
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.
Click for flightdeck photo and description
Military Versions
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.
