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Fuel Level Tank Sensor Unit

Technical Information

Catalogue No: C0432
Category: Fuel Systems
Object Type: Sensor/Transducer
Object Name: Fuel Level Tank Sensor Unit
Part No: 25/099
Serial No: 109/68
Manufacturer: Elliott Bros (London) Ltd
Division: Aircraft Engine Instruments [AEID]
Platform(s): Bristol Britannia
Year of Manufacture: 1968
Dimensions: Width (mm): 75
Height (mm): 497
Depth (mm): 75
Weight (g): 420
Location: Rack RAA02 [Main Store]
Inscription(s):

Elliott
Elliott Bros (London) Ltd
Ser.No. 109/68
GP 354/099
Tank Unit

Notes:

109/68 made by Elliott Bros in 1968. The mounting flange is also stamped with:
"GP 31243/25 Iss 3 & 9" though the ampersand is inverted!
The Elliott O/H Manufacturing number is 28-40-109 and other sources have the Tank Unit for the Britannia as Pt. No. GP313 and GP354.

These Fuel Tank Gauges work on a capacitive system whereby the tank unit is the capacitor and the fuel is a variable dielectric. The electronic circuits are calibrated to transmit this as a tank quantity.

The ‘Pacitor’ system seems to have been made by a number of companies such as Simmonds Aerocessories of London who advertised the product in 1952 and in that year they acquired Firth Cleveland Instruments and as that became the overall company name from 1953 onwards they are found under the  Firth Cleveland Instruments name. Elliott Bros purchased Firth Cleveland Instruments in 1961 and continued the brand from the Treforest works where they also made Flowmeters and Test sets for these. The former were used with the Beverley, Belvedere, Argosy 660 and long-range Britannia, while the latter were for fuel-flow systems in the refuelling portion of the Valiant tanker and in the Javelin, Buccaneer, Scimitar, Sea Vixen and Sea Venom

In addition Elliotts seem to be making Tank Units under a licence from Honeywell which may be because the an improved design was covered by a US Patent.

The Fuel flow business was important to Elliotts and a new fuel-flow test laboratory—the most advanced in Europe, if not in the world—was opened at Elliott-Automation's Rochester factory on November 20 1964 by Mr Neil Marten, Parliamentary Secretary to the MoA.

Enclosed in a blast-absorbing concrete emplacement, it was designed to test fuel flow equipment for the new generation of supersonic aircraft where fuel temperature of 150°C or higher would be encountered, and units would be required to operate at rigid standards of accuracy under extreme conditions of temperature (up to 200°C ambient) and in areas of extreme vibration.All controls and observers are in a separate building and several closed-circuit TV cameras give a view of critical parts of the system. Hot water and freon are used respectively as heating and cooling media. The laboratory is suitable for developing flow-measurement systems for supersonic airliners or VTOL aircraft. 

The Laboratory can achieve gravimetric calibration accuracy within an error band of ±0.1% of flow rate under the following conditions:

1. Flow rates from 50 to 120,000 lb/hr through three different bores of pipe.

2. Fuel temperatures from -55°C to +180°C.

3. Ambient temperatures from -60°C to +200°C.

There is also a Vibrator capable of producing a maximum thrust of 500 pounds with frequencies of up to 3,000 c.p.s. for resonance searches.

Mass-flow test measurement is effected by weighing the fuel as it accumulates in a tank mounted on a weighing balance, the whole unit being housed in a sealed container filled with nitrogen.

Fuel measurement systems such as Tank capacity, Fuel Flow rate, Fuel Remaining, Fuel Consumed were all big business for Elliott Bros (and subsequent names) and a snapshot of the platforms to which these were fitted can be gained from one of the Company databases:

AV8B, Buccaneer, Concorde, Dominie, EFA, Fiat Rig, Hawk, HS125, HS146 (BAe146), Javelin, Sea Venom, Sea Vixen, Valiant, Scimitar, P1127, Phantom, Phoenix, Trident, Transall C160, MRCA (Tornado), Finnish Hawk, G222, VC10, RB211 and RJ500 engines.........

The old Ministry of Aviation Part Numbers may be of the format of two letters followed by numbers e.g. GP380/101. Elliotts seem to also use a Part Numbering code of the form xx-xxx-xx where the first two digits define the family of devices i.e Fuel system, the next two or three digits define the actual item and the last two define the build standard. In more recent times there may also be a software standard identifier with another two digits. This numbering system seems to have been called the O/H Manufacturing Number (O/H being Overhead?) but is also described as a Coded Number.

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