1 Title of the Invention

Drill jig for Windscreen Assembly to achieve Interchangeability(ICY) on Aircraft.

2 Field of the Invention

The present development is related with Military Aviation Industry more particular to interchangeability (ICY) of Windscreen Assembly on military Aircraft in general.

3 Background of the Invention

Windscreen Assembly is a single bubble type with metal configuration and assembled oh Aircraft fuselage assembly at Cockpit forward side. The Windscreen Assembly consists of Windscreen Frame Assembly and Bubble, Windscreen Frames are made up Aluminium Alloy Material using 5 Axis machine and Bubble is made up of Acrylic Sheet using special forming process. Windscreen bubble provides the optical requirements of . weapon aiming with minimum deviations and distortion to avoid any distraction to vision. Windscreen Frame assembly consists of Forward Arch, Rear Arch and Side Frame Left Hand (LH) and Side Frame Right Hand (RH) and these parts positioned, drilled and fastened using a separate Assembly Jig. Windscreen Bubble is positioned, drilled and fastened on Windscreen Frame Assembly.

Windscreen Frame Assembly is positioned, drilled and fastened on Canopy Longeron - LH and Canopy Longeron - RH by layout method without any tool. Hence, achieving ICY is not possible for installation of Windscreen Frame Assembly on Fuselage.

Windscreen Bubble is fabricated and assembled on Windscreen Frame assembly which needs co-ordination with respect to Aircraft Fuselage assembly for its installation. Windscreen Assembly is required for completion of Aircraft Fuselage Assembly, since fastening holes are to be drilled on Fuselage Assembly with Windscreen Frame Assembly during its
assembly build stage to meet the assembly requirement to achieve the contour value. In many aircraft industries, achieving ICY of Windscreen Assembly with Aircraft Fuselage Assembly is difficult due to contoured profile and assembly process. It necessitates a special drill jig set up to achieve ICY of Windscreen Assembly and to avoid waiting time for Windscreen Assembly to complete Aircraft Fuselage Assembly.

3.1 Prior Art

Document GB1060031A with title “A Improvements in Mountings for Aircraft Windscreens” provides the details about on installation of the panel of an aircraft windscreen attached to a supporting structure. Present invention explains about the drilling jig for drilling of Windscreen with its mating parts. Document GB465733A with title, “Improvements in Windscreens for Aircraft" explains about the improvements on functioning of combined Windscreen and Cockpit Cover. This invention explains the method of achieving interchangeability of Windscreen assembly of Aircraft.

Document US2008073931A1 title, “Windscreen Frame and Method of Production for a Windscreen Frame” explains about the production method fora Windscreen Frame. This invention explains about the drill jig designed, fabricated to drilling holes on Windscreen Frame assembly with its mating parts individually.

Document GB429282A with title, “Improvements relating to windscreens, particularly for aircraft”, explains about the opening or closing of the panes may be spring-aided and the operating linkage may be housed within the fixed frame of the windscreen. This approach is not provides any novel approach, but the present approach provides the novel approach on Windscreen drilling and achieving interchangeability.

4 Brief Summary of the Invention

In order to overcome the above issue, a dedicated drill jig is designed and fabricated for drilling holes on Windscreen Frame Assembly and Fuselage
assembly individually with removable locators to facilitate proper clamping/holding by arresting the degrees of freedom while drilling of holes on Windscreen frame and Fuselage assembly separately to ensure required positioning and locking of Windscreen Assembly on Canopy Longerons. This novel development provides achieving the ICY of Windscreen Frame Assembly on Aircraft Fuselage assembly and completion of Fuselage Assembly even without Windscreen assembly.

5 Detail Description of the Drawings

Fig. 1 shows Windscreen Frame Assembly. It indicates Side Frame - LH (1), Side Frame-RH (2), Forward Arch (3) and Rear Arch (4).

Fig. 2 shows Windscreen Assembly with bubble. It indicates Windscreen bubble (5).

Fig. 3 shows Windscreen Assembly with canopy longerons. It indicates Canopy Longeron-LH (6) and Canopy Longeron-RH (7) with Windscreen bubble (5).

Fig. 4 shows Schematic Diagram of Drill Jig with Windscreen Frame Assembly. It indicates the Locators (2 Nos) to control X-Axis (8) and Locators (6 Nos) to control Y-Axis (9) movement of Windscreen Frame Assembly (10) on Base Plate (11).

Fig. 5 shows Schematic Diagram of Drill Jig with Canopy Longeron-LH and Canopy Longeron-RH Drill Jig. It indicates Top Frame Bulkhead Sta#4 (12), Canopy Longeron-LH (6), Canopy Longeron-RH (7), Locator to control X-Axis (1 No) (13) and Locator to control Y-Axis (6 Nos) (14) positioned and locked on Drill Jig Base (11).

Fig.6 shows Schematic Diagram of novel Drill Jig to achieve ICY.

6 Detail Description of the Invention

A Drill Jig (15) for drilling Windscreen Frame (1,2,3,4) Assembly and Canopy Longeron-LH (6), Canopy Longeron-RH (7) is designed and
fabricated. This invention overcomes the present issue as per the details below:

(A) Base plate (11) is made up of Aluminium Alloy material for light weight with flatness accuracy 0.05 mm with length of 1715 mm, width of 926 mm and thickness of 20 mm to avoid warpage (Fig. 4 & Fig. 5).

(B) 8 Nos of fixed locators i.e., 2 Nos (8) & 6 Nos (9) are made up of Aluminium Alloy material used to arrest Windscreen Frame Assembly (10) (Fig.4) movement in X and Y direction by using Bolts and Dowel pins made up of Steel material with accuracy of 0.03 mm during drilling of Windscreen Assembly (10).

(C) 7 Nos of fixed locators i.e., 1 No (13) and 6 Nos (14) are made up of Aluminium Alloy material used to arrest Canopy Longeron-LH (6), Canopy Longeron-RH (7) (Fig.5) movement in X and Y direction by using Bolts and Dowel pins made up of Steel material with accuracy of 0.03 mm during drilling of Canopy Longeron-LH (6), Canopy Longeron-RH (7).

(D) By using above jig setup, position of Windscreen Frame Assembly, Canopy Longeron-LH and Canopy Longeron-RH are ensured by arresting movement in X and Y direction before taking up of drilling operation as per the drawing requirements using Bolts and Dowel Pins arrangements.

(E) Drilling of holes of 6 (H7) diameter on Windscreen Frame Assembly is carried out in stages using special drill guns, drill bits, reamers with special guide bushes at 122 places individually.

(F) Drilling of holes of 6 (H7) diameter on Canopy Longeron-LH and Canopy Longeron-RH are carried out in stages using special drill guns; drill bits, reamers with special guide bushes at 122 places individually.
(G) Drilling of 6 (H7) holes on Windscreen Assembly, Canopy Longeron-LH and Canopy Longeron-RH are carried out separately using specially made drill jig.

By using above novel setup interchangeability on Windscreen Assembly is achieved and waiting time of Windscreen assembly is avoided for completion of Aircraft Fuselage Assembly.