This section contains a basic outline of the requirements concerning the safety precautions which had to be observed during the ground servicing of Concorde. Most of the servicing connections for Concorde are positioned on the underside of the aircraft as shown in the picture below under the heading of “Servicing Points”
BRITISH AIRWAYS MAINTENANCE MANUAL
GENERAL – SERVICING WARNING:
FOR THE GROUND ENGINEERS CARRYING OUT SERVICING WORK.
BEFORE PROCEEDING WITH ANY MAINTENANCE WORK ON OR NEAR THE MECHANICAL FLIGHT CONTROLS OR PRIMARY FLIGHT CONTROL SURFACES, LANDING GEARS, ASSOCIATED DOORS OR ANY MOVING COMPONENT, MAKE CERTAIN THAT GROUND SAFETIES AND/OR WARNING NOTICES ARE IN THEIR CORRECT POSITIONS TO PREVENT INADVERTENT OPERATION OFCONTROLS.
BEFORE POWER IS SUPPLIED TO THE AIRCRAFT MAKE CERTAIN THAT ELECTRICAL CIRCUITS UPON WHICH WORK IS IN PROGRESS ARE ISOLATED.
WHEN EQUIPMENT IN RACKS AND/OR FLIGHT COMPARTMENT INSTRUMENTS ARE SUPPLIED WITH POWER FROM THE GROUND POWER UNIT, THE AVIONICS COMPARTMENT COOLING SYSTEM AND APPROPRIATE VENTILATION SYSTEMS MUST BE IN OPERATION.
THE GROUND DEPRESSURIZATION VALVE MUST BE OPEN. FURTHER MORE, IF AMBIENT TEMPERATURE IS ABOVE 30°C IN THE FLIGHT COMPARTMENT THE GROUND AIR PRECONDITIONING SYSTEM MUST BE OPERATION.
Routine servicing points are shown in the illustration below. The only alternative servicing routine is oxygen replenishment, where depleted cylinders may be removed from the aircraft and replaced with serviceable ones.
There are 16 fuel tank water drain valves beneath the under-wing fairings, and 13 in the fuselage and wing skin. These valves permit fuel samples to be taken to check water content and microbial contamination of the fuel.
It is necessary to enter the engine air-intake to replenish the ramp actuator oil.
These areas, shown in the illustration below, indicate the parts of the aircraft which are susceptible to damage. Boundaries of no-step areas are not marked on the aircraft.
Airframe Safety Precautions
Landing gear ground locks have to be fitted to the aircraft when it is parked, and always before towing.
Nose & Visor
Both the nose and visor are normally raised and lowered hydraulically. Whenever work is to be carried out on this area of the aircraft, or near to this area, there must be a safety locking devices fitted to the Nose and Visor operating mechanisms.
Flight Control Surfaces
Clearance has to be assured around the elevons and the rudder prior to applying, or cutting-off the hydraulic power of the aircraft.
Tail Wheel Bay
Before any work can be carried out in the wheel bay, a safety lock had to be fitted.
Oxygen equipment had to be kept clean and uncontaminated. The main reason for this is that many materials, particularly oil and grease, which are liable to ignite spontaneously when they are exposed to oxygen.
Flight Compartment Seats
These seats are electrically power operated. Prior to any work being carried out near to these seats, the appropriate circuit breakers had to be tripped, and the ground crew had to ensure that the power cut-off switches were not illuminated (these switches illuminated in green when the power was ON)
Disconnection and connection of any fluid and pneumatic systems, especially the hydraulic self-sealing couplings, could not be attempted while there was any pressure in the systems
Power Plant Safety Precautions
Any electrical discharge from the ignition units was potentially lethal, so the ground engineers were required by the manual to disconnect the Low Energy supply at lease one minute before attempting to disconnect the High Energy (HE) connection.
The intake ramps and the spill door were hydraulically operated, and therefore extra care had to be taken to ensure that there was no equipment or persons inside the intakes prior to the components be activated. There was specified ground equipment that could be used when entering the intakes to prevent damage to the intake diffuser.
The pneumatic circuits of the engine twin secondary nozzle presented risks of severe accidents. Therefore ever precaution had to be taken with the regard to the moving parts of these nozzles.
During all times while the ground engineers had the electrical ground power unit connected to the aircraft, the air extraction system had to be operated. This ensured that there was adequate cooling of the rack-mounted equipment; also it was required to have the passenger/service doors fully open.
Ground Stability of the Aircraft
During servicing and maintenance when Concorde was standing on its nose and main landing gears, there could be an over-concentration of weight in the rear of the aircraft, which was due to the displacement of on-board fuel, personnel and equipment, and this could cause the aircraft to overbalance. It would then pivot on its main landing gear and tip on to the rear fuselage under-surface causing extensive damage to the aircraft.
Therefore it was necessary before and during servicing and maintenance, to check the weight distribution of the aircraft and ensure that the aircraft did not become tail-heavy. The dominant weight factor affecting the aircraft stability was the on-board fuel displacement which had to be regularly monitored during maintenance, particularly during fuel transfer test, to ensure that the stability of the aircraft is maintained.
Any load added forward of the main landing gear would increase the nose tendency, and therefore the safety margin. Removal of the engines or other equipment from the rearward side of the main landing gear would also increase the stability.
The centre of gravity position of a static grounded aircraft could be determined by using a ground stability chart. This chart could be used to enable the C of G to be worked out under varying conditions from aircraft completely fitted out to those with specific major items removed (As for aircraft storage).