The following specification particularly describes the nature of invention and function of the Hawk .filler cap.
BACKGROUND OF INVENTION:
Filler Cap Assembly is a line replaceable unit used in Fuselage Fuel Tank of Hawk aircraft. The OEM filler cap is failing often and considerable number of filler caps become unserviceable.The spares for subject Filler cap assembly and specification were not available to service this item. This item is developed with new design and process to suit the requirement on aircraft. This invention ensures to maintain the serviceability of Hawk fleet and fulfils vMake in India initiative.

OBJECTIVE OF INVENTION:
The main objective of the invention is to develop a more reliable filler cap with least failure rate for Hawk aircraft. This Filler Cap is developed with inherent design to meet the requirement on aircraft. This invention was initiated to achieve considerable foreign exchange savings and broaden the technology base of our country.

DETAIL DESCRIPTION OF INVENTION:

The Fuel Filler cap assy is used on Hawk Fuselage Fuel Tank.The Fuel Filler Cap Assy consists of Filler Cap housing, Cover Plate, Handle, shaft. Plain pin, Nut, Spring, Plain washer, *0' Rings, Wire locking tab and Split pin made Aerospace grade material. The Filler cap housing, cover plate are machined from bar stock and anodized as per MIL-A-8625 Type II Class 1REV F. The *0' rings are manufactured to Nitrile based rubber to specification DTD 560 Gr.B & Gr.C Qly *P' which is fuel resistance rubber. The spring used is manufactured to specification IS 4454 part 4 Gr 1, Load test had been carried out. The indexing indicator and letters, FWD, shall be stamped on the external surface for properly positioning of the filler cap, to prevent inadvertent lifting of the Filler cap handle by aerodynamic forces.

The locking of the Fuel Filler cap shall be accomplished by rotating the handle in a clockwise direction on adaptor and pressing down the handle to flush down the filler cap housing. The fuel filler cap Assy is designed & developed to withstand a Rated fuel pressure of 50 PSI, proof pressure of 75 PSI and burst pressure of 100 PSI.

The specifications were defined in accordance with Hawk military Aircraft build standard. The Filler Cap Assembly was developed by !ft/s Hindustan Aeronautics Ltd, Bangalore and manufactured in coordination with M/s Micron Engineers, Bangalore.

The indigenous Filler Cap Assembly had undergone all the stringent military qualification testing as recommended by the certification /regulatory agencies to meet the airworthiness requirement of Hawk aircraft.

TEST CARRIED OUT:

The Improved Filler Cap Assembly was subjected to the following environmental and functional tests.

1. Leakage test with Rated Pressure, Proof Pressure & Burst Pressure.

2. Vibration Test

3. Scanning

4. Fuel Resistance test

5. Corrosion Salt Mist Test

6. Endurance Test

7. Strength Test for Lanyard

After above qualification testing, the unit was fitted on the aircraft. Performance of the Filler Cap Assembly was found satisfactory.

CLAIMS:
l)The filler is made with improved design
2)Self-reliance and sufficient foreign exchange saving are achieved.
3)Reduced cycle time for servicing and availability of spares is ensured .