Boeing 737-236 series 1, G-BGJL: Main document - Leonardo

The ground crew also raised an ADD entry in the log to performa trim run at the next visit to
Gatwick (where a trim test-setwas held). It would also appear that, had the flight crews
remaineddissatisfied with the performance of the engine, the aircraftwould have been re-rostered
into Gatwick on the 22nd August forthis work to be performed.
1.6.3 Engine fire warning and suppression systems
The aircraft was fitted with separate FIRE and OVERHEAT detectionsystems designed to alert the
crew to excessive temperatures withinthe engine nacelles. Flight deck indications were by means
ofwarning captions and indicators, augmented in the case of a FIREwarning by an audio warning
(bell sound). Built-in test equipmentenabled serviceability checks to be carried out on both fire
andoverheat systems before each flight.
G-BGJL was typical of Boeing 737 (and other current commercial)aircraft in being equipped with a
conventional "two shot"main engine fire suppression system.
1.6.4 Fuel system
Fuel was carried in three fuel tanks, all of which were integrallyformed within the aircraft's wing
structure. The two main tanksof 4,590 Kg capacity each were formed (one in each wing) by
themain torsion box, and extended from the root rib outboard to aposition close to the wing tip. The
wing centre section formedthe centre auxiliary tank, which had a capacity of 7,416 Kg.
Access to the interior of each main wing tank was provided bymeans of a total of 13 elliptically
shaped removable access panelsvarying in size from approximately 18" by 10" inboardto 16" by 6"
outboard, which were secured flush withthe lower skin surface and sealed against fuel seepage by
an '0'ring gasket. The access panels were manufactured from a cast aluminiumalloy material and
had stiffening webs integrally formed on theupper (internal) surface. The panels were nominally
non-stressedcomponents so far as flight-loads on the wing were concerned;impact strength did not
form a part of the design requirementsfor the wing lower skin, nor the access panel. The cast
aluminiummaterial had an impact strength approximately one quarter thatof the lower wing skin,
which formed the tank floor proper.
1.6.5 Air conditioning system
The aircraft had two air conditioning packs, each with a maximumdelivery rate of 78 lb/min, which
were supplied by the main enginesor by the Auxiliary Power Unit (APU). The conditioned air
wasdistributed throughout the cabin via a system of manifolds andducts leading to the overhead
nozzles and zone supply louvres.Exhaust (stale) air left the cabin via floor level louvres locatedin
the cabin side-wall panels, and made its way into the cavitiessurrounding the cargo hold liners, ie
the interspaces betweenthe fuselage outer skin and the cargo hold side-lining, and thecargo hold
roof-lining and the cabin floor (Appendix 6 Fig b).(The fibreglass wool insulation blankets, which
fill the structuralcavities between the cabin liners and the outer skin, were reducedin thickness
around the hold areas to facilitate the passage ofexhaust air). Approximately 56% of the total cabin
exhaust airwas routed via the floor louvres aft of the wing into the aftcargo hold cavity, from where
it was dumped overboard via themain outflow valve situated in the rear fuselage underbelly.
Approximately36% was routed via floor level grills in the forward cabin, intothe forward hold
cavity, and thence into the electronic equipmentbay where it was used to cool the equipment before
being dumpedoverboard via the electronic equipment bay exhaust. The remainderof the exhaust air
left the aircraft via various local vents andas a result of general leakage.
1.6.6 Cabin windows